Clinical Pharmacology for Reyataz
Mechanism Of Action
Atazanavir is an HIV-1 antiretroviral drug [see Microbiology].
Pharmacodynamics
Cardiac Electrophysiology
Concentration- and dose-dependent prolongation of the PR interval in the electrocardiogram has been observed in healthy participants receiving atazanavir. In placebo-controlled Study AI424-076, the mean (±SD) maximum change in PR interval from the predose value was 24 (±15) msec following oral dosing with 400 mg of atazanavir (n=65) compared to 13 (±11) msec following dosing with placebo (n=67). The PR interval prolongations in this study were asymptomatic. There is limited information on the potential for a pharmacodynamic interaction in humans between atazanavir and other drugs that prolong the PR interval of the electrocardiogram [see WARNINGS AND PRECAUTIONS].
Electrocardiographic effects of atazanavir were determined in a clinical pharmacology study of 72 healthy participants. Oral doses of 400 mg (maximum recommended dosage) and 800 mg (twice the maximum recommended dosage) were compared with placebo; there was no concentration-dependent effect of atazanavir on the QTc interval (using Fridericia’s correction). In 1793 participants with HIV-1, receiving antiretroviral regimens, QTc prolongation was comparable in the atazanavir and comparator regimens. No atazanavir-treated healthy participant or participant with HIV-1 in clinical trials had a QTc interval >500 msec [see WARNINGS AND PRECAUTIONS].
Pharmacokinetics
The pharmacokinetics of atazanavir were evaluated in adult participants who either were healthy, or with HIV-1, after administration of REYATAZ 400 mg once daily and after administration of REYATAZ 300 mg with ritonavir 100 mg once daily (see Table 17).
Table 17: Steady-State Pharmacokinetics of Atazanavir in Healthy Participants or Participants with HIV-1 in the Fed State
| Parameter |
400 mg once daily |
300 mg with ritonavir 100 mg once daily |
Healthy Participants
(n=14) |
Participants with HIV-1
(n=13) |
Healthy Participants
(n=28) |
Participants with HIV-1
(n=10) |
| Cmax (ng/mL) |
| Geometric mean (CV%) |
5199 (26) |
2298 (71) |
6129 (31) |
4422 (58) |
| Mean (SD) |
5358 (1371) |
3152 (2231) |
6450 (2031) |
5233 (3033) |
| Tmax (h) |
| Median |
2.5 |
2.0 |
2.7 |
3.0 |
| AUC (ng•h/mL) |
| Geometric mean (CV%) |
28132 (28) |
14874 (91) |
57039 (37) |
46073 (66) |
| Mean (SD) |
29303 (8263) |
22262 (20159) |
61435 (22911) |
53761 (35294) |
| T-half (h) |
| Mean (SD) |
7.9 (2.9) |
6.5 (2.6) |
18.1 (6.2)a |
8.6 (2.3) |
| Cmin (ng/mL) |
| Geometric mean (CV%) |
159 (88) |
120 (109) |
1227 (53) |
636 (97) |
| Mean (SD) |
218 (191) |
273 (298)b |
1441 (757) |
862 (838) |
a n=26.
b n=12. |
Figure 1 displays the mean plasma concentrations of atazanavir at steady state after REYATAZ 400 mg once daily (as two 200-mg capsules) with a light meal and after REYATAZ 300 mg (as two 150-mg capsules) with ritonavir 100 mg once daily with a light meal in adult participants with HIV-1.
Figure 1: Mean (SD) Steady-State Plasma Concentrations of Atazanavir 400 mg (n=13) and 300 mg with Ritonavir (n=10) for Adult Participants with HIV-1
Absorption
Atazanavir is rapidly absorbed with a Tmax of approximately 2.5 hours. Atazanavir demonstrates nonlinear pharmacokinetics with greater than dose-proportional increases in AUC and Cmax values over the dose range of 200 to 800 mg once daily. Steady state is achieved between Days 4 and 8, with an accumulation of approximately 2.3-fold.
Food Effect
Administration of REYATAZ with food enhances bioavailability and reduces pharmacokinetic variability. Administration of a single 400-mg dose of REYATAZ with a light meal (357 kcal, 8.2 g fat, 10.6 g protein) resulted in a 70% increase in AUC and 57% increase in Cmax relative to the fasting state. Administration of a single 400-mg dose of REYATAZ with a high-fat meal (721 kcal, 37.3 g fat, 29.4 g protein) resulted in a mean increase in AUC of 35% with no change in Cmax relative to the fasting state. Administration of REYATAZ with either a light meal or highfat meal decreased the coefficient of variation of AUC and Cmax by approximately one-half compared to the fasting state.
Coadministration of a single 300-mg dose of REYATAZ and a 100-mg dose of ritonavir with a light meal (336 kcal, 5.1 g fat, 9.3 g protein) resulted in a 33% increase in the AUC and a 40% increase in both the Cmax and the 24-hour concentration of atazanavir relative to the fasting state. Coadministration with a high-fat meal (951 kcal, 54.7 g fat, 35.9 g protein) did not affect the AUC of atazanavir relative to fasting conditions and the Cmax was within 11% of fasting values. The 24-hour concentration following a high-fat meal was increased by approximately 33% due to delayed absorption; the median Tmax increased from 2.0 to 5.0 hours. Coadministration of REYATAZ with ritonavir with either a light or a high-fat meal decreased the coefficient of variation of AUC and Cmax by approximately 25% compared to the fasting state.
Distribution
Atazanavir is 86% bound to human serum proteins and protein binding is independent of concentration. Atazanavir binds to both alpha-1-acid glycoprotein (AAG) and albumin to a similar extent (89% and 86%, respectively). In a multiple-dose study in participants with HIV-1 dosed with REYATAZ 400 mg once daily with a light meal for 12 weeks, atazanavir was detected in the cerebrospinal fluid and semen. The cerebrospinal fluid/plasma ratio for atazanavir (n=4) ranged between 0.0021 and 0.0226 and seminal fluid/plasma ratio (n=5) ranged between 0.11 and 4.42.
Metabolism
Atazanavir is extensively metabolized in humans. The major biotransformation pathways of atazanavir in humans consisted of monooxygenation and dioxygenation. Other minor biotransformation pathways for atazanavir or its metabolites consisted of glucuronidation, N-dealkylation, hydrolysis, and oxygenation with dehydrogenation. Two minor metabolites of atazanavir in plasma have been characterized. Neither metabolite demonstrated in vitro antiviral activity. In vitro studies using human liver microsomes suggested that atazanavir is metabolized by CYP3A.
Elimination
Following a single 400-mg dose of 14C-atazanavir, 79% and 13% of the total radioactivity was recovered in the feces and urine, respectively. Unchanged drug accounted for approximately 20% and 7% of the administered dose in the feces and urine, respectively. The mean elimination halflife of atazanavir in healthy participants (n=214) and adult participants with HIV-1 (n=13) was approximately 7 hours at steady state following a dose of 400 mg daily with a light meal.
Specific Populations
Renal Impairment
In healthy participants, the renal elimination of unchanged atazanavir was approximately 7% of the administered dose. REYATAZ has been studied in adult participants with severe renal impairment (n=20), including those on hemodialysis, at multiple doses of 400 mg once daily. The mean atazanavir Cmax was 9% lower, AUC was 19% higher, and Cmin was 96% higher in participants with severe renal impairment not undergoing hemodialysis (n=10), than in age-, weight-, and gender-matched participants with normal renal function. In a 4-hour dialysis session, 2.1% of the administered dose was removed. When atazanavir was administered either prior to, or following hemodialysis (n=10), the geometric means for Cmax, AUC, and Cmin were approximately 25% to 43% lower compared to participants with normal renal function. The mechanism of this decrease is unknown. REYATAZ is not recommended for use in treatment-experienced patients with HIV-1 who have end-stage renal disease managed with hemodialysis [see DOSAGE AND ADMINISTRATION].
Hepatic Impairment
REYATAZ has been studied in adult participants with moderate-to-severe hepatic impairment (14 with Child-Pugh B and 2 with Child-Pugh C) after a single 400-mg dose. The mean AUC(0-∞) was 42% greater in participants with impaired hepatic function than in healthy participants. The mean half-life of atazanavir in hepatically impaired participants was 12.1 hours compared to 6.4 hours in healthy participants. A dose reduction to 300 mg is recommended for patients with moderate hepatic impairment (Child-Pugh Class B) who have not experienced prior virologic failure as increased concentrations of atazanavir are expected. REYATAZ is not recommended for use in patients with severe hepatic impairment. The pharmacokinetics of REYATAZ in combination with ritonavir has not been studied in participants with hepatic impairment; thus, coadministration of REYATAZ with ritonavir is not recommended for use in patients with any degree of hepatic impairment [see DOSAGE AND ADMINISTRATION].
Pediatrics
The pharmacokinetic parameters for atazanavir at steady state in pediatric participants taking the powder formulation are summarized in Table 18 by weight ranges [see DOSAGE AND ADMINISTRATION].
Table 18: Steady-State Pharmacokinetics of Atazanavir (powder formulation) with Ritonavir in Pediatric Participants with HIV-1
| Body Weight (range in kg) [n] |
atazanavir with ritonavir Dose (mg) |
Cmax ng/mL Geometric Mean (CV%) |
AUC ng•h/mL Geometric Mean (CV%) |
Cmin ng/mL Geometric Mean (CV%) |
| 5 to <10 [20] |
150/80 |
4131 (55%) |
32503 (61%) |
336 (76%) |
| 5 to <10 [10] |
200/80 |
4466 (59%) |
39519 (54%) |
550 (60%) |
| 10 to <15 [18] |
200/80 |
5197 (53%) |
50305 (67%) |
572 (111%) |
| 15 to <25 [32] |
250/80 |
5394 (46%) |
55687 (45%) |
686 (68%) |
| 25 to <35 [8] |
300/100 |
4209 (52%) |
44329 (63%) |
468 (104%) |
The pharmacokinetic parameters for atazanavir at steady state in pediatric participants taking the capsule formulation were predicted by a population pharmacokinetic model and are summarized in Table 19 by weight ranges that correspond to the recommended doses [see DOSAGE AND ADMINISTRATION].
Table 19: Predicted Steady-State Pharmacokinetics of Atazanavir (capsule formulation) with Ritonavir in Pediatric Participants with HIV-1
| atazanavir with Body Weight ritonavir (range in kg) Dose (mg) |
Cmax ng/mL Geometric Mean (CV%) |
AUC ng•h/mL Geometric Mean (CV%) |
Cmin ng/mL Geometric Mean (CV%) |
| 15 to <35 200/100 |
3303 (86%) |
37235 (84%) |
538 (99%) |
| ≥35 300/100 |
2980 (82%) |
37643 (83%) |
653 (89%) |
Pregnancy
The pharmacokinetic data from pregnant women with HIV-1 receiving REYATAZ Capsules with ritonavir are presented in Table 20.
Table 20: Steady-State Pharmacokinetics of Atazanavir with Ritonavir in Pregnant Women with HIV-1 in the Fed State
| Pharmacokinetic Parameter |
Atazanavir 300 mg with ritonavir 100 mg |
2nd Trimester
(n=5a) |
3rd Trimester
(n=20) |
Postpartumb
(n=34) |
| Cmax ng/mL |
3078.85 |
3291.46 |
5721.21 |
| Geometric mean (CV%) |
(50) |
(48) |
(31) |
| AUC ng•h/mL |
27657.1 |
34251.5 |
61990.4 |
| Geometric mean (CV%) |
(43) |
(43) |
(32) |
| Cmin ng/mLc |
538.70 |
668.48 |
1462.59 |
| Geometric mean (CV%) |
(46) |
(50) |
(45) |
a Available data during the 2nd trimester are limited.
b Atazanavir peak concentrations and AUCs were found to be approximately 28% to 43% higher during the postpartum period (4-12 weeks) than those observed historically in, non-pregnant patients with HIV-1. Atazanavir plasma trough concentrations were approximately 2.2-fold higher during the postpartum period when compared to those observed historically in non-pregnant patients with HIV-1.
c Cmin is concentration 24 hours post-dose. |
Drug Interaction Data
Atazanavir is a metabolism-dependent CYP3A inhibitor, with a Kinact value of 0.05 to 0.06 min-1 and Ki value of 0.84 to 1.0 μM. Atazanavir is also a direct inhibitor for UGT1A1 (Ki=1.9 μM) and CYP2C8 (Ki=2.1 μM).
Atazanavir has been shown in vivo not to induce its own metabolism nor to increase the biotransformation of some drugs metabolized by CYP3A. In a multiple-dose study, REYATAZ decreased the urinary ratio of endogenous 6β-OH cortisol to cortisol versus baseline, indicating that CYP3A production was not induced.
Clinically significant interactions are not expected between atazanavir and substrates of CYP2C19, CYP2C9, CYP2D6, CYP2B6, CYP2A6, CYP1A2, or CYP2E1. Clinically significant interactions are not expected between atazanavir when administered with ritonavir and substrates of CYP2C8. See the complete prescribing information for ritonavir for information on other potential drug interactions with ritonavir.
Based on known metabolic profiles, clinically significant drug interactions are not expected between REYATAZ and dapsone, trimethoprim/sulfamethoxazole, azithromycin, or erythromycin. REYATAZ does not interact with substrates of CYP2D6 (eg, nortriptyline, desipramine, metoprolol).
Drug interaction studies were performed with REYATAZ and other drugs likely to be coadministered and some drugs commonly used as probes for pharmacokinetic interactions. The effects of coadministration of REYATAZ on the AUC, Cmax, and Cmin are summarized in Tables 21 and 22. Neither didanosine EC nor diltiazem had a significant effect on atazanavir exposures (see Table 22 for effect of atazanavir on didanosine EC or diltiazem exposures). REYATAZ did not have a significant effect on the exposures of didanosine (when administered as the buffered tablet), stavudine, or fluconazole. For information regarding clinical recommendations, see DRUG INTERACTIONS.
Table 21: Drug Interactions: Pharmacokinetic Parameters for Atazanavir in the Presence of Coadministered Drugsa
| Coadministered Drug |
Coadministered Drug Dose/Schedule |
REYATAZ Dose/Schedule |
Ratio (90% Confidence Interval) of Atazanavir Pharmacokinetic Parameters with/without Coadministered Drug; No Effect = 1.00 |
| Cmax |
AUC |
Cmin |
| atenolol |
50 mg QD, d 7-11
(n=19) and d19-23 |
400 mg QD, d 1-11
(n=19) |
1.00
(0.89, 1.12) |
0.93
(0.85, 1.01) |
0.74
(0.65, 0.86) |
| clarithromycin |
500 mg BID, d 7-10
(n=29) and d18-21 |
400 mg QD, d 1-10
(n=29) |
1.06
(0.93, 1.20) |
1.28
(1.16, 1.43) |
1.91
(1.66, 2.21) |
didanosine
(ddI)
(buffered tablets) and stavudine
(d4T)b |
ddI: 200 mg x 1 dose, d4T: 40 mg x 1 dose (n=31) |
400 mg x 1 dose simultaneously with ddI and d4T (n=31) |
0.11
(0.06, 0.18) |
0.13
(0.08, 0.21) |
0.16
(0.10, 0.27) |
| ddI: 200 mg x 1 dose, d4T: 40 mg x 1 dose (n=32) |
400 mg x 1 dose 1 h after ddI + d4T
(n=32) |
1.12
(0.67, 1.18) |
1.03
(0.64, 1.67) |
1.03
(0.61, 1.73) |
| efavirenz |
600 mg QD, d 7-20
(n=27) |
400 mg QD, d 1-20
(n=27) |
0.41
(0.33, 0.51) |
0.26
(0.22, 0.32) |
0.07
(0.05, 0.10) |
600 mg QD, d 7-20
(n=13) |
400 mg QD, d 1-6
(n=23) then 300 mg with ritonavir 100 mg QD, 2 h before efavirenz, d 7-20
(n=13) |
1.14
(0.83, 1.58) |
1.39
(1.02, 1.88) |
1.48
(1.24, 1.76) |
| 600 mg QD, d 11-24 (pm) (n=14) |
300 mg QD with ritonavir 100 mg QD, d 1-10 (pm) (n=22), then 400 mg QD with ritonavir 100 mg QD, d 11-24
(pm),
(simultaneously with efavirenz) (n=14) |
1.17
(1.08, 1.27) |
1.00
(0.91, 1.10) |
0.58
(0.49, 0.69) |
| famotidine |
40 mg BID, d 7-12
(n=15) |
400 mg QD, d 1-6
(n=45), d 7-12
(simultaneous administration) (n=15) |
0.53
(0.34, 0.82) |
0.59
(0.40, 0.87) |
0.58
(0.37, 0.89) |
|
40 mg BID, d 7-12
(n=14) |
400 mg QD
(pm), d 1-6
(n=14), d 7-12
(10 h after, 2 h before famotidine) (n=14) |
1.08
(0.82, 1.41) |
0.95
(0.74, 1.21) |
0.79
(0.60, 1.04) |
|
40 mg BID, d 11-20
(n=14)c |
300 mg QD with ritonavir 100 mg QD, d 1-10 (n=46), d 11-20d (simultaneous administration)
(n=14) |
0.86
(0.79, 0.94) |
0.82
(0.75, 0.89) |
0.72
(0.64, 0.81) |
|
20 mg BID, d 11-17
(n=18) |
300 mg QD with ritonavir 100 mg QD and tenofovir DF 300 mg QD, d 1-10 (am)
(n=39), d 11-17 (am)
(simultaneous administration with am famotidine)
(n=18)d,e |
0.91
(0.84, 0.99) |
0.90
(0.82, 0.98) |
0.81
(0.69, 0.94) |
|
40 mg QD
(pm), d18-24
(n=20) |
300 mg QD with ritonavir 100 mg QD and tenofovir DF 300 mg QD, d 1-10 (am)
(n=39), d 18-24 (am)
(12 h after pm famotidine) (n=20)e |
0.89
(0.81, 0.97) |
0.88
(0.80, 0.96) |
0.77
(0.63, 0.93) |
|
40 mg BID, d 18-24
(n=18) |
300 mg QD with ritonavir 100 mg QD and tenofovir DF 300 mg QD, d 1-10
(am)
(n=39), d 18-24
(am)
(10 h after pm famotidine and 2 h before am famotidine)
(n=18)e |
0.74
(0.66, 0.84) |
0.79
(0.70, 0.88) |
0.72
(0.63, 0.83) |
40 mg BID, d 11-20
(n=15) |
300 mg QD with ritonavir 100 mg QD, d 1-10
(am)
(n=46), then 400 mg QD with ritonavir 100 mg QD, d 11-20
(am)
(n=15) |
1.02
(0.87, 1.18) |
1.03
(0.86, 1.22) |
0.86
(0.68, 1.08) |
| grazoprevir/ elbasvir |
grazoprevir 200 mg QD d 1-35
(n = 11) |
300 mg QD with ritonavir 100 mg QD, d 1-35
(n = 11) |
1.12
(1.01, 1.24) |
1.43
(1.30, 1.57) |
1.23
(1.13, 1.34) |
elbasvir 50 mg QD d 1-35
(n = 8) |
300 mg QD with ritonavir 100 mg QD, d 1-35
(n = 8) |
1.02
(0.96, 1.08) |
1.07
(0.98,1.17) |
1.15
(1.02, 1.29) |
| ketoconazole |
200 mg QD, d 7-13
(n=14) |
400 mg QD, d 1-13
(n=14) |
0.99
(0.77, 1.28) |
1.10
(0.89, 1.37) |
1.03
(0.53, 2.01) |
| nevirapinef,g |
200 mg BID, d 1-23
(n=23) |
300 mg QD with ritonavir 100 mg QD, d 4-13, then 400 mg QD with ritonavir 100 mg QD, d 14-23
(n=23)h |
0.72
(0.60, 0.86) 1.02
(0.85, 1.24) |
0.58
(0.48, 0.71) 0.81
(0.65, 1.02) |
0.28
(0.20, 0.40) 0.41
(0.27, 0.60) |
| omeprazole |
40 mg QD, d 7-12
(n=16)i |
400 mg QD, d 1-6
(n=48), d 7-12
(n=16) |
0.04
(0.04, 0.05) |
0.06
(0.05, 0.07) |
0.05
(0.03, 0.07) |
40 mg QD, d 11-20
(n=15)i |
300 mg QD with ritonavir 100 mg QD, d 1-20
(n=15) |
0.28
(0.24, 0.32) |
0.24
(0.21, 0.27) |
0.22
(0.19, 0.26) |
| 20 mg QD, d 17-23 (am) (n=13) |
300 mg QD with ritonavir 100 mg QD, d 7-16 (pm) (n=27), d 1723 (pm) (n=13)i |
0.61
(0.46, 0.81) |
0.58
(0.44, 0.75) |
0.54
(0.41, 0.71) |
20 mg QD, d 17-23
(am) (n=14) |
300 mg QD with ritonavir 100 mg QD, d 7-16 (am) (n=27), then 400 mg QD with ritonavir 100 mg QD, d 17-23 (am) (n=14)l,m |
0.69
(0.58, 0.83) |
0.70
(0.57, 0.86) |
0.69
(0.54, 0.88) |
| pitavastatin |
4 mg QD for 5 days |
300 mg QD for 5 days |
1.13
(0.96, 1.32) |
1.06
(0.90, 1.26) |
NA |
| rifabutin |
150 mg QD, d 15-28 (n=7) |
400 mg QD, d 1-28
(n=7) |
1.34
(1.14, 1.59) |
1.15
(0.98, 1.34) |
1.13
(0.68, 1.87) |
| rifampin |
600 mg QD, d 17-26 (n=16) |
300 mg QD with ritonavir 100 mg QD, d 7-16 (n=48), d 17-26 (n=16) |
0.47
(0.41, 0.53) |
0.28
(0.25, 0.32) |
0.02
(0.02, 0.03) |
| ritonavirn |
100 mg QD, d 11-20 (n=28) |
300 mg QD, d 1-20
(n=28) |
1.86
(1.69, 2.05) |
3.38
(3.13, 3.63) |
11.89
(10.23, 13.82) |
| tenofovir DFo |
300 mg QD, d 9-16
(n=34) |
400 mg QD, d 2-16
(n=34) |
0.79
(0.73, 0.86) |
0.75
(0.70, 0.81) |
0.60
(0.52, 0.68) |
| 300 mg QD, d 15-42 (n=10) |
300 mg with ritonavir 100 mg QD, d 1-42
(n=10) |
0.72p
(0.50, 1.05) |
0.75p (0.58, 0.97) |
0.77p (0.54, 1.10) |
voriconazole
(Participants with at least one functional CYP2C19 allele) |
200 mg BID, d 2-3, 22-30; 400 mg BID, d 1, 21 (n=20) |
300 mg with ritonavir 100 mg QD, d 11-30
(n=20) |
0.87
(0.80, 0.96) |
0.88
(0.82, 0.95) |
0.80
(0.72, 0.90) |
voriconazole
(Participants without a functional CYP2C19 allele) |
50 mg BID, d 2-3, 22-30; 100 mg BID, d 1, 21 (n=8) |
300 mg with ritonavir 100 mg QD, d 11-30
(n=8) |
0.81
(0.66, 1.00) |
0.80
(0.65, 0.97) |
0.69
(0.54, 0.87) |
a Data provided are under fed conditions unless otherwise noted.
b All drugs were given under fasted conditions.
c REYATAZ 300 mg with ritonavir 100 mg once daily coadministered with famotidine 40 mg twice daily resulted in atazanavir geometric mean Cmax that was similar and AUC and Cmin values that were 1.79- and 4.46-fold higher relative to REYATAZ 400 mg once daily alone.
d Similar results were noted when famotidine 20 mg BID was administered 2 hours after and 10 hours before atazanavir 300 mg with ritonavir 100 mg and tenofovir DF 300 mg.
e Coadministration of atazanavir with ritonavir and tenofovir DF was administered after a light meal.
f Study was conducted in participants with HIV-1.
g Compared with atazanavir 400 mg historical data without nevirapine (n=13), the ratio of geometric means (90% confidence intervals) for Cmax, AUC, and Cmin were 1.42 (0.98, 2.05), 1.64 (1.11, 2.42), and 1.25 (0.66, 2.36), respectively, for atazanavir with ritonavir 300/100 mg; and 2.02 (1.42, 2.87), 2.28 (1.54, 3.38), and 1.80 (0.94, 3.45), respectively, for atazanavir with ritonavir 400/100 mg.
h Parallel group design; n=23 for atazanavir with ritonavir and nevirapine, n=22 for atazanavir 300 mg/ritonavir 100 mg without nevirapine. Participants were treated with nevirapine prior to study entry.
i Omeprazole 40 mg was administered on an empty stomach 2 hours before REYATAZ.
j Omeprazole 20 mg was administered 30 minutes prior to a light meal in the morning and REYATAZ 300 mg with ritonavir 100 mg in the evening after a light meal, separated by 12 hours from omeprazole.
k REYATAZ 300 mg with ritonavir 100 mg once daily separated by 12 hours from omeprazole 20 mg daily resulted in increases in atazanavir geometric mean AUC (10%) and Cmin (2.4-fold), with a decrease in Cmax (29%) relative to REYATAZ 400 mg once daily in the absence of omeprazole (study days 1–6).
l Omeprazole 20 mg was given 30 minutes prior to a light meal in the morning and REYATAZ 400 mg with ritonavir 100 mg once daily after a light meal, 1 hour after omeprazole. Effects on atazanavir concentrations were similar when REYATAZ 400 mg with ritonavir 100 mg was separated from omeprazole 20 mg by 12 hours.
m REYATAZ 400 mg with ritonavir 100 mg once daily administered with omeprazole 20 mg once daily resulted in increases in atazanavir geometric mean AUC (32%) and Cmin (3.3-fold), with a decrease in Cmax (26%) relative to REYATAZ 400 mg once daily in the absence of omeprazole (study days 1–6).
n Compared with atazanavir 400 mg QD historical data, administration of atazanavir with ritonavir 300/100 mg QD increased the atazanavir geometric mean values of Cmax, AUC, and Cmin by 18%, 103%, and 671%, respectively.
o Note that similar results were observed in studies where administration of tenofovir DF and REYATAZ was separated by 12 hours.
p Ratio of atazanavir with ritonavir and tenofovir DF to atazanavir with ritonavir. Atazanavir 300 mg with ritonavir 100 mg results in higher atazanavir exposure than atazanavir 400 mg (see footnote o). The geometric mean values of atazanavir pharmacokinetic parameters when coadministered with ritonavir and tenofovir DF were: Cmax = 3190 ng/mL, AUC = 34459 ng•h/mL, and Cmin = 491 ng/mL. Study was conducted in participants with HIV-1.
NA = not available. |
Table 22: Drug Interactions: Pharmacokinetic Parameters for Coadministered Drugs in the Presence of REYATAZa
| Coadministered Drug |
Coadministered Drug Dose/Schedule |
REYATAZ Dose/Schedule |
Ratio (90% Confidence Interval) of Coadministered Drug Pharmacokinetic Parameters with/without REYATAZ; No Effect = 1.00 |
| Cmax |
AUC |
Cmin |
| acetaminophen |
1 g BID, d 1-20 (n=10) |
300 mg QD with ritonavir 100 mg QD, d 11-20 (n=10) |
0.87 (0.77, 0.99) |
0.97 (0.91, 1.03) |
1.26 (1.08, 1.46) |
| atenolol |
50 mg QD, d 7-11 (n=19)and d19-23 |
400 mg QD, d 1-11 (n=19) |
1.34 (1.26, 1.42) |
1.25 (1.16, 1.34) |
1.02 (0.88, 1.19) |
| clarithromycin |
500 mg BID, d 7-10(n=21) and d18-21 |
400 mg QD, d 1-10 (n=21) |
1.50 (1.32, 1.71) OH-clarithromycin: 0.28 (0.24, 0.33) |
1.94 (1.75, 2.16) OH-clarithromycin: 0.30 (0.26, 0.34) |
2.60 (2.35, 2.88) OH-clarithromycin: 0.38 (0.34, 0.42) |
| ddI (enteric-coated [EC] capsules)b |
400 mg d 1 (fasted), d 8 (fed) (n=34) |
400 mg QD, d 2-8 (n=34) |
0.64 (0.55, 0.74) |
0.66 (0.60, 0.74) |
1.13 (0.91, 1.41) |
| 400 mg d 1 (fasted), d 19 (fed) (n=31) |
300 mg QD with ritonavir 100 mg QD, d 9-19 (n=31) |
0.62 (0.52, 0.74) |
0.66 (0.59, 0.73) |
1.25 (0.92, 1.69) |
| diltiazem |
180 mg QD, d 7-11 (n=28) and d 19-23 |
400 mg QD, d 1-11 (n=28) |
1.98 (1.78, 2.19) desacetyl-diltiazem: 2.72 (2.44, 3.03) |
2.25 (2.09, 2.16) desacetyl-diltiazem: 2.65 (2.45, 2.87) |
2.42 (2.14, 2.73) desacetyl-diltiazem: 2.21 (2.02, 2.42) |
| ethinyl estradiol & norethindronec |
Ortho-Novum® 7/7/7 QD, d 1-29 (n=19) |
400 mg QD, d16-29 (n=19) |
ethinyl estradiol: 1.15 (0.99, 1.32) norethindrone: 1.67 (1.42, 1.96) |
ethinyl estradiol: 1.48 (1.31, 1.68) norethindrone: 2.10 (1.68, 2.62) |
ethinyl estradiol: 1.91 (1.57, 2.33) norethindrone: 3.62 (2.57, 5.09) |
| ethinyl estradiol & norgestimated |
Ortho Tri-Cyclen® QD, d 1-28 (n=18), then Ortho Tri-Cyclen® LO QD, d 29-42e (n=14) |
300 mg QD with ritonavir 100 mg QD, d 29-42 (n=14) |
ethinyl estradiol: 0.84 (0.74, 0.95) 17-deacetyl f norgestimate: 1.68 (1.51, 1.88) |
ethinyl estradiol: 0.81 (0.75, 0.87) 17-deacetyl f norgestimate: 1.85 (1.67, 2.05) |
ethinyl estradiol: 0.63 (0.55, 0.71) 17-deacetyl f norgestimate: 2.02 (1.77, 2.31) |
| glecaprevir/ pibrentasvir |
300 mg glecaprevir (n=12) |
300 mg QD with ritonavir 100 mg QD (n=12) |
≥4.06g (3.15, 5.23) |
≥6.53g (5.24, 8.14) |
≥14.3g (9.85, 20.7) |
|
120 mg pibrentasvir (n=12) |
300 mg QD with ritonavir 100 mg QD (n=12) |
≥1.29g (1.15, 1.45) |
≥1.64g (1.48, 1.82) |
≥2.29g (1.95, 2.68) |
| grazoprevir/ elbasvir |
grazoprevir 200 mg QD d 1- 35 (n=12) |
300 mg QD with ritonavir 100 mg QD d 1-35 (n=12) |
6.24 (4.42, 8.81) |
10.58 (7.78, 14.39) |
11.64 (7.96, 17.02) |
|
elbasvir 50 mg QD d 1-35 (n=10) |
300 mg QD with ritonavir 100 mg QD d 1-35 (n=10) |
4.15 (3.46, 4.97) |
4.76 (4.07, 5.56) |
6.45 (5.51, 7.54) |
| methadone |
Stable maintenance dose, d 1-15 (n=16) |
400 mg QD, d 2-15 (n=16) |
(R)-methadoneh 0.91 (0.84, 1.0) total: 0.85 (0.78, 0.93) |
(R)-methadoneh 1.03 (0.95, 1.10) total: 0.94 (0.87, 1.02) |
(R)-methadoneh 1.11 (1.02, 1.20) total: 1.02 (0.93, 1.12) |
| nevirapinei,j |
200 mg BID, d 1-23 (n=23) |
300 mg QD with ritonavir 100 mg QD, d 4-13, then 400 mg QD with ritonavir 100 mg QD, d 14-23 (n=23) |
1.17 (1.09, 1.25) 1.21 (1.11, 1.32) |
1.25 (1.17, 1.34) 1.26 (1.17, 1.36) |
1.32 (1.22, 1.43) 1.35 (1.25, 1.47) |
| omeprazolek |
40 mg single dose, d 7 and d 20 (n=16) |
400 mg QD, d 1-12 (n=16) |
1.24 (1.04, 1.47) |
1.45 (1.20, 1.76) |
NA |
| rifabutin |
300 mg QD, d 1-10 then 150 mg QD, d11-20 (n=3) |
600 mg QD,l d11-20 (n=3) |
1.18 (0.94, 1.48) 25-O-desacetyl-rifabutin: 8.20 (5.90, 11.40) |
2.10 (1.57, 2.79) 25-O-desacetyl-rifabutin: 22.01 (15.97, 30.34) |
3.43 (1.98, 5.96) 25-O-desacetyl-rifabutin: 75.6 (30.1, 190.0) |
|
150 mg twice weekly, d 1-15 (n=7) |
300 mg QD with ritonavir 100 mg QD, d 1-17 (n=7) |
2.49m (2.03, 3.06) 25-O-desacetyl-rifabutin: 7.77 (6.13, 9.83) |
1.48m (1.19, 1.84) 25-O-desacetyl-rifabutin: 10.90 (8.14, 14.61) |
1.40m (1.05, 1.87) 25-O-desacetyl-rifabutin: 11.45 (8.15, 16.10) |
| pitavastatin |
4 mg QD for 5 days |
300 mg QD for 5 days |
1.60 (1.39, 1.85) |
1.31 (1.23, 1.39) |
NA |
| rosiglitazonen |
4 mg single dose, d 1, 7, 17 (n=14) |
400 mg QD, d 2-7, then 300 mg QD with ritonavir 100 mg QD, d 8-17 (n=14) |
1.08 (1.03, 1.13) 0.97 (0.91, 1.04) |
1.35 (1.26, 1.44) 0.83 (0.77, 0.89) |
NA NA |
| rosuvastatin |
10 mg single dose |
300 mg QD with ritonavir 100 mg QD for 7 days |
t 7-foldo |
t 3-foldo |
NA |
| saquinavirp (soft gelatin capsules) |
1200 mg QD, d 1-13 (n=7) |
400 mg QD, d 7-13 (n=7) |
4.39 (3.24, 5.95) |
5.49 (4.04, 7.47) |
6.86 (5.29, 8.91) |
| sofosbuvir/ velpatasvir/ voxilaprevir |
400 mg sofosbuvir single dose (n=15) |
300 mg with100 mg ritonavir single dose (n=15) |
1.29 (1.09, 1.52) sofosbuvir metabolite GS-331007 1.05 (0.99, 1.12) |
1.40 (1.25, 1.57) sofosbuvir metabolite GS-331007 1.25 (1.16, 1.36) |
NA |
| 100 mg velpatasvir single dose (n=15) |
300 mg with 100 mg ritonavir single dose (n=15) |
1.29 (1.07, 1.56) |
1.93 (1.58, 2.36) |
NA |
| 100 mg voxilaprevir single dose (n=15) |
300 mg with 100 mg ritonavir single dose (n=15) |
4.42 (3.65, 5.35) |
4.31 (3.76, 4.93) |
NA |
| tenofovir DFq |
300 mg QD, d 9-16 (n=33)and d 24-30 (n=33) |
400 mg QD, d 2-16 (n=33) |
1.14 (1.08, 1.20) |
1.24 (1.21, 1.28) |
1.22 (1.15, 1.30) |
| 300 mg QD, d 1-7 (pm) (n=14) d 25-34 (pm) (n=12) |
300 mg QD with ritonavir 100 mg QD, d 25-34 (am) (n=12)r |
1.34 (1.20, 1.51) |
1.37 (1.30, 1.45) |
1.29 (1.21, 1.36) |
| voriconazole (Participants with at least one functional CYP2C19 allele) |
200 mg BID, d 2-3, 22-30; 400 mg BID, d 1, 21 (n=20) |
300 mg with ritonavir 100 mg QD, d 11-30 (n=20) |
0.90 (0.78, 1.04) |
0.67 (0.58, 0.78) |
0.61 (0.51, 0.72) |
| voriconazole (Participants without a functional CYP2C19 allele) |
50 mg BID, d 2-3, 22-30; 100 mg BID, d 1, 21 (n=8) |
300 mg with ritonavir 100 mg QD, d 11-30 (n=8) |
4.38 (3.55, 5.39) |
5.61 (4.51, 6.99) |
7.65 (5.71, 10.2) |
| lamivudine and zidovudine |
150 mg lamivudine and 300 mg zidovudine BID, d 1-12 (n=19) |
400 mg QD, d 7-12 (n=19) |
lamivudine: 1.04 (0.92, 1.16) zidovudine: 1.05 (0.88, 1.24) zidovudine glucuronide: 0.95 (0.88, 1.02) |
lamivudine: 1.03 (0.98, 1.08) zidovudine: 1.05 (0.96, 1.14) zidovudine glucuronide: 1.00 (0.97, 1.03) |
lamivudine: 1.12 (1.04, 1.21) zidovudine: 0.69 (0.57, 0.84) zidovudine glucuronide: 0.82 (0.62, 1.08) |
a Data provided are under fed conditions unless otherwise noted.
b 400 mg ddI EC and REYATAZ were administered together with food on Days 8 and 19.
c Upon further dose normalization of ethinyl estradiol 25 mcg with atazanavir relative to ethinyl estradiol 35 mcg without atazanavir, the ratio of geometric means (90% confidence intervals) for Cmax, AUC, and Cmin were 0.82 (0.73, 0.92), 1.06 (0.95, 1.17), and 1.35 (1.11, 1.63), respectively.
d Upon further dose normalization of ethinyl estradiol 35 mcg with atazanavir with ritonavir relative to ethinyl estradiol 25 mcg without atazanavir with ritonavir, the ratio of geometric means (90% confidence intervals) for Cmax, AUC, and Cmin were 1.17 (1.03, 1.34), 1.13 (1.05, 1.22), and 0.88 (0.77, 1.00), respectively.
e All participants were on a 28-day lead-in period; one full cycle of Ortho Tri-Cyclen®. Ortho Tri-Cyclen® contains 35 mcg of ethinyl estradiol. Ortho Tri-Cyclen® LO contains 25 mcg of ethinyl estradiol. Results were dose normalized to an ethinyl estradiol dose of 35 mcg.
f 17-deacetyl norgestimate is the active component of norgestimate.
g Effect of atazanavir with ritonavir on the first dose of glecaprevir and pibrentasvir is reported.
h (R)-methadone is the active isomer of methadone.
i Study was conducted in participants with HIV-1.
j Participants were treated with nevirapine prior to study entry.
k Omeprazole was used as a metabolic probe for CYP2C19. Omeprazole was given 2 hours after REYATAZ on Day 7; and was given alone 2 hours after a light meal on Day 20.
l Not the recommended therapeutic dose of atazanavir.
m When compared to rifabutin 150 mg QD alone d1–10 (n=14). Total of rifabutin and 25-O-desacetyl-rifabutin: AUC 2.19 (1.78, 2.69).
n Rosiglitazone used as a probe substrate for CYP2C8.
o Mean ratio (with/without coadministered drug). ↑ indicates an increase in rosuvastatin exposure.
p The combination of atazanavir and saquinavir 1200 mg QD produced daily saquinavir exposures similar to the values produced by the standard therapeutic dosing of saquinavir at 1200 mg TID. However, the Cmax is about 79% higher than that for the standard dosing of saquinavir (soft gelatin capsules) alone at 1200 mg TID.
q Note that similar results were observed in a study where administration of tenofovir DF and REYATAZ was separated by 12 hours.
r Administration of tenofovir DF and REYATAZ was temporally separated by 12 hours.
NA = not available. |
Microbiology
Mechanism Of Action
Atazanavir (ATV) is an azapeptide HIV-1 protease inhibitor (PI). The compound selectively inhibits the virus-specific processing of viral Gag and Gag-Pol polyproteins in HIV-1-infected cells, thus preventing formation of mature virions.
Antiviral Activity In Cell Culture
Atazanavir exhibits anti-HIV-1 activity with a mean 50% effective concentration (EC50) in the absence of human serum of 2 to 5 nM against a variety of laboratory and clinical HIV-1 isolates grown in peripheral blood mononuclear cells, macrophages, CEM-SS cells, and MT-2 cells. Atazanavir has activity against HIV-1 Group M subtype viruses A, B, C, D, AE, AG, F, G, and J isolates in cell culture. Atazanavir has variable activity against HIV-2 isolates (1.9-32 nM), with EC50 values above the EC50 values of failure isolates. Two-drug combination antiviral activity studies with atazanavir showed no antagonism in cell culture with PIs (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir), NNRTIs (delavirdine, efavirenz, and nevirapine), NRTIs (abacavir, didanosine, emtricitabine, lamivudine, stavudine, tenofovir DF, and zidovudine), the HIV-1 fusion inhibitor enfuvirtide, and two compounds used in the treatment of viral hepatitis, adefovir and ribavirin, without enhanced cytotoxicity.
Resistance
In Cell Culture
HIV-1 isolates with a decreased susceptibility to atazanavir have been selected in cell culture and obtained from patients treated with atazanavir or atazanavir with ritonavir. HIV-1 isolates with 93- to 183-fold reduced susceptibility to atazanavir from three different viral strains were selected in cell culture by 5 months. The substitutions in these HIV-1 viruses that contributed to atazanavir resistance include I50L, N88S, I84V, A71V, and M46I. Changes were also observed at the protease cleavage sites following drug selection. Recombinant viruses containing the I50L substitution without other major PI substitutions were growth impaired and displayed increased susceptibility in cell culture to other PIs (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir). The I50L and I50V substitutions yielded selective resistance to atazanavir and amprenavir, respectively, and did not appear to be cross-resistant.
Clinical Studies Of Treatment-Naive Participants: Comparison Of Ritonavir-Boosted REYATAZ vs Unboosted REYATAZ
Study AI424-089 compared REYATAZ 300 mg once daily with ritonavir 100 mg vs REYATAZ 400 mg once daily when administered with lamivudine and extendedrelease stavudine in treatment-naive participants with HIV-1. A summary of the number of virologic failures and virologic failure isolates with atazanavir resistance in each arm is shown in Table 23.
Table 23: Summary of Virologic Failuresa at Week 96 in Study AI424-089: Comparison of Ritonavir Boosted REYATAZ vs Unboosted REYATAZ: Randomized Participants
|
REYATAZ 300 mg with ritonavir 100 mg
(n=95) |
REYATAZ 400 mg
(n=105) |
| Virologic Failure (≥50 copies/mL) at Week 96 |
15 (16%) |
34 (32%) |
| Virologic Failure with Genotypes and Phenotypes Data |
5 |
17 |
| Virologic Failure Isolates with atazanavir -resistance at Week 96 |
0/5 (0%)b |
4/17 (24%)b |
| Virologic Failure Isolates with I50L Emergence at Week 96c |
0/5 (0%)b |
2/17 (12%)b |
| Virologic Failure Isolates with Lamivudine Resistance at Week 96 |
2/5 (40%)b |
11/17 (65%)b |
a Virologic failure includes participants who were never suppressed through Week 96 and on study at Week 96, had virologic rebound or discontinued due to insufficient viral load response.
b Percentage of Virologic Failure Isolates with genotypic and phenotypic data.
c Mixture of I50I/L emerged in 2 other atazanavir 400 mg-treated participants. Neither isolate was phenotypically resistant to atazanavir. |
Clinical Studies Of Treatment-Naive Participants Receiving REYATAZ 300 mg With Ritonavir 100 mg
In Phase 3 Study AI424-138, an as-treated genotypic and phenotypic analysis was conducted on samples from participants who experienced virologic failure (HIV-1 RNA ≥400 copies/mL) or discontinued before achieving suppression on atazanavir with ritonavir (n=39; 9%) and lopinavir/ritonavir (n=39; 9%) through 96 weeks of treatment. In the atazanavir with ritonavir arm, one of the virologic failure isolates had a 56-fold decrease in atazanavir susceptibility emerge on therapy with the development of PI resistance-associated substitutions L10F, V32I, K43T, M46I, A71I, G73S, I85I/V, and L90M. The NRTI resistance-associated substitution M184V also emerged on treatment in this isolate conferring emtricitabine resistance. Two atazanavir with ritonavir-virologic failure isolates had baseline phenotypic atazanavir resistance and IAS-defined major PI resistance-associated substitutions at baseline. The I50L substitution emerged on study in one of these failure isolates and was associated with a 17-fold decrease in atazanavir susceptibility from baseline and the other failure isolate with baseline atazanavir resistance and PI substitutions (M46M/I and I84I/V) had additional IAS-defined major PI substitutions (V32I, M46I, and I84V) emerge on atazanavir treatment associated with a 3-fold decrease in atazanavir susceptibility from baseline. Five of the treatment failure isolates in the atazanavir with ritonavir arm developed phenotypic emtricitabine resistance with the emergence of either the M184I (n=1) or the M184V (n=4) substitution on therapy and none developed phenotypic tenofovir disoproxil resistance. In the lopinavir/ritonavir arm, one of the virologic failure participant isolates had a 69-fold decrease in lopinavir susceptibility emerge on therapy with the development of PI substitutions L10V, V11I, I54V, G73S, and V82A in addition to baseline PI substitutions L10L/I, V32I, I54I/V, A71I, G73G/S, V82V/A, L89V, and L90M. Six lopinavir/ritonavir virologic failure isolates developed the M184V substitution and phenotypic emtricitabine resistance and two developed phenotypic tenofovir disoproxil resistance.
Clinical Studies Of Treatment-Naive Participants Receiving REYATAZ 400 mg without Ritonavir: atazanavir-resistant clinical isolates from treatment-naive participants who experienced virologic failure on REYATAZ 400 mg treatment without ritonavir often developed an I50L substitution (after an average of 50 weeks of atazanavir therapy), often in combination with an A71V substitution, but also developed one or more other PI substitutions (eg, V32I, L33F, G73S, V82A, I85V, or N88S) with or without the I50L substitution. In treatment-naive participants, viral isolates that developed the I50L substitution, without other major PI substitutions, showed phenotypic resistance to atazanavir but retained in cell culture susceptibility to other PIs (amprenavir, indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir); however, there are no clinical data available to demonstrate the effect of the I50L substitution on the efficacy of subsequently administered PIs.
Clinical Studies Of Treatment-Experienced Participants: In studies of treatment-experienced participants treated with atazanavir or atazanavir with ritonavir, most atazanavir-resistant isolates from participants who experienced virologic failure developed substitutions that were associated with resistance to multiple PIs and displayed decreased susceptibility to multiple PIs. The most common protease substitutions to develop in the viral isolates of participants who failed treatment with atazanavir 300 mg once daily and ritonavir 100 mg once daily (together with tenofovir DF and an NRTI) included V32I, L33F/V/I, E35D/G, M46I/L, I50L, F53L/V, I54V, A71V/T/I, G73S/T/C, V82A/T/L, I85V, and L89V/Q/M/T. Other substitutions that developed on atazanavir with ritonavir treatment including E34K/A/Q, G48V, I84V, N88S/D/T, and L90M occurred in less than 10% of participant isolates. Generally, if multiple PI resistance substitutions were present in the HIV-1 virus of the participant at baseline, atazanavir resistance developed through substitutions associated with resistance to other PIs and could include the development of the I50L substitution. The I50L substitution has been detected in treatment-experienced participants experiencing virologic failure after long-term treatment. Protease cleavage site changes also emerged on atazanavir treatment, but their presence did not correlate with the level of atazanavir resistance.
Clinical Studies of Pediatric Participants in AI424-397 (PRINCE I) and AI424-451 (PRINCE II): Treatment-emergent atazanavir with ritonavir resistance-associated amino acid substitution M36I in the protease was detected in the virus of one participant among treatment failures in AI424-397. In addition, three known resistance-associated substitutions for other PIs arose in the viruses from one participant each (L19I/R, H69K/R, and I72I/V). Reduced susceptibility to atazanavir, ritonavir, or atazanavir with ritonavir was not seen with these viruses. In AI424-451, atazanavir with ritonavir resistance-associated substitutions G16E, V82A/I/T, I84V, and/or L90M arose in the viruses of two participants. The virus population harboring the M46M/V, V82V/I, I84I/V, and L90L/M substitutions acquired phenotypic resistance to ritonavir (ritonavir phenotypic foldchange of 3.5, with a ritonavir cutoff of 2.5-fold change). However, these substitutions did not result in phenotypic resistance to atazanavir (atazanavir phenotypic fold-change of <1.8, with an atazanavir cutoff of 2.2-fold change). Secondary PI resistance-associated amino acid substitutions also arose in the viruses of one participant each, including V11V/I, D30D/G, E35E/D, K45K/R, L63P/S, and I72I/T. Q61D and Q61E/G emerged in the viruses of two participants who failed treatment with atazanavir with ritonavir. Viruses from nine participants in the two studies developed NRTI resistance-associated substitutions: K65K/R (n=1), M184V (n=7), and T215I (n=1).
Cross-Resistance
Cross-resistance among PIs has been observed. Baseline phenotypic and genotypic analyses of clinical isolates from atazanavir clinical trials of PI-experienced participants showed that isolates cross-resistant to multiple PIs were cross-resistant to atazanavir. Greater than 90% of the isolates with substitutions that included I84V or G48V were resistant to atazanavir. Greater than 60% of isolates containing L90M, G73S/T/C, A71V/T, I54V, M46I/L, or a change at V82 were resistant to atazanavir, and 38% of isolates containing a D30N substitution in addition to other changes were resistant to atazanavir. Isolates resistant to atazanavir were also cross-resistant to other PIs with >90% of the isolates resistant to indinavir, lopinavir, nelfinavir, ritonavir, and saquinavir, and 80% resistant to amprenavir. In treatment-experienced participants, PI-resistant viral isolates that developed the I50L substitution in addition to other PI resistance-associated substitution were also cross-resistant to other PIs.
Baseline Genotype/Phenotype And Virologic Outcome Analyses
Genotypic and/or phenotypic analysis of baseline virus may aid in determining atazanavir susceptibility before initiation of atazanavir with ritonavir therapy. An association between virologic response at 48 weeks and the number and type of primary PI resistance-associated substitutions detected in baseline HIV-1 isolates from antiretroviral-experienced participants receiving atazanavir with ritonavir once daily or lopinavir / ritonavir (fixed-dose product) twice daily in Study AI424-045 is shown in Table 24.
Overall, both the number and type of baseline PI substitutions affected response rates in treatment experienced participants. In the atazanavir with ritonavir group, participants had lower response rates when 3 or more baseline PI substitutions, including a substitution at position 36, 71, 77, 82, or 90, were present compared to participants with 1–2 PI substitutions, including one of these substitutions.
Table 24: HIV-1 RNA Response by Number and Type of Baseline PI Substitution, Antiretroviral-Experienced Participants in Study AI424-045, As-Treated Analysis
| Number and Type of Baseline PI Substitutionsa |
Virologic Response = HIV RNA <400 copies/mLb |
atazanavir with ritonavir
(n=110) |
lopinavir/ritonavirc
(n=113) |
| 3 or more primary PI substitutions includingd: |
| D30N |
75% (6/8) |
50% (3/6) |
| M36I/V |
19% (3/16) |
33% (6/18) |
| M46I/L/T |
24% (4/17) |
23% (5/22) |
| I54V/L/T/M/A |
31% (5/16) |
31% (5/16) |
| A71V/T/I/G |
34% (10/29) |
39% (12/31) |
| G73S/A/C/T |
14% (1/7) |
38% (3/8) |
| V77I |
47% (7/15) |
44% (7/16) |
| V82A/F/T/S/I |
29% (6/21) |
27% (7/26) |
| I84V/A |
11% (1/9) |
33% (2/6) |
| N88D |
63% (5/8) |
67% (4/6) |
| L90M |
10% (2/21) |
44% (11/25) |
| Number of baseline primary PI substitutionsa |
| All patients, as-treated |
58% (64/110) |
59% (67/113) |
| 0-2 PI substitutions |
75% (50/67) |
75% (50/67) |
| 3-4 PI substitutions |
41% (14/34) |
43% (12/28) |
| 5 or more PI substitutions |
0% (0/9) |
28% (5/18) |
a Primary substitutions include any change at D30, V32, M36, M46, I47, G48, I50, I54, A71, G73, V77, V82, I84, N88, and L90.
b Results should be interpreted with caution because the subgroups were small.
c Administered as a fixed-dose product.
d There were insufficient data (n<3) for PI substitutions V32I, I47V, G48V, I50V, and F53L. |
The response rates of antiretroviral-experienced participants in Study AI424-045 were analyzed by baseline phenotype (shift in susceptibility in cell culture relative to reference, Table 25). The analyses are based on a select population with 62% of participants receiving an NNRTI-based regimen before study entry compared to 35% receiving a PI-based regimen. Additional data are needed to determine clinically relevant break points for REYATAZ.
Table 25: Baseline Phenotype by Outcome, Antiretroviral-Experienced Participants in Study AI424-045, As-Treated Analysis
| Baseline Phenotypea |
Virologic Response = HIV-1 RNA <400 copies/mLb |
atazanavir with ritonavir
(n=111) |
lopinavir/ritonavirc
(n=111) |
| 0-2 |
71% (55/78) |
70% (56/80) |
| >2-5 |
53% (8/15) |
44% (4/9) |
| >5-10 |
13% (1/8) |
33% (3/9) |
| >10 |
10% (1/10) |
23% (3/13) |
a Fold change susceptibility in cell culture relative to the wild-type reference.
b Results should be interpreted with caution because the subgroups were small.
c Administered as a fixed-dose product. |
Clinical Studies
Adult Participants Without Prior Antiretroviral Therapy
Study AI424-138: a 96-week study comparing the antiviral efficacy and safety of either REYATAZ or lopinavir/ritonavir, each in combination with fixed-dose tenofovir DF-emtricitabine in treatment-naive participants with HIV-1 infection. Study AI424-138 (NCT00272779) was a 96- week, open-label, randomized, multicenter study, comparing REYATAZ (300 mg once daily) with ritonavir (100 mg once daily) to lopinavir/ritonavir (400/100 mg twice daily as fixed-dose product), each in combination with the fixed-dose product, tenofovir DF/emtricitabine (300/200 mg once daily), in 878 antiretroviral treatment-naive participants. Participants had a mean age of 36 years (range: 19-72), 49% were Caucasian, 18% Black, 9% Asian, 23% Hispanic/Mestizo/mixed race, and 68% were male. The median baseline plasma CD4+ cell count was 204 cells/mm³ (range: 2 to 810 cells/mm³) and the mean baseline plasma HIV-1 RNA level was 4.94 log10 copies/mL (range: 2.60 to 5.88 log10 copies/mL). Treatment response and outcomes through Week 96 are presented in Table 26.
Table 26: Outcomes of Treatment Through Week 96 in Treatment-Naïve Adults (Study AI424-138)
| Outcome |
REYATAZ 300 mg with ritonavir 100 mg (once daily) and tenofovir DF/emtricitabine (once daily)a
(n=441) 96 Weeks |
lopinavir/ritonavirb 400 mg/100 mg (twice daily) with tenofovir DF/emtricitabine (once daily)a
(n=437) 96 Weeks |
| Responderc,d,e |
75% |
68% |
| Virologic failuref |
17% |
19% |
| Rebound |
8% |
10% |
| Never suppressed through Week 96 |
9% |
9% |
| Death |
1% |
1% |
| Discontinued due to adverse event |
3% |
5% |
| Discontinued for other reasonsg |
4% |
7% |
a As a fixed-dose product: 300 mg tenofovir DF/200 mg emtricitabine once daily.
b As a fixed-dose product: 400 mg lopinavir/100 mg ritonavir (twice daily).
c Participants achieved HIV-1 RNA <50 copies/mL at Week 96. Roche Amplicor®, v1.5 ultra-sensitive assay.
d Pre-specified ITT analysis at Week 48 using as-randomized cohort: atazanavir with ritonavir 78% and lopinavir/ritonavir 76% (difference estimate: 1.7% [95% confidence interval: -3.8%, 7.1%]).
e Pre-specified ITT analysis at Week 96 using as-randomized cohort: atazanavir with ritonavir 74% and lopinavir/ritonavir 68% (difference estimate: 6.1% [95% confidence interval: 0.3%, 12.0%]).
f Includes viral rebound and failure to achieve confirmed HIV-1 RNA <50 copies/mL through Week 96.
g Includes lost to follow-up, participant’s withdrawal, noncompliance, protocol violation, and other reasons. |
Through 96 weeks of therapy, the proportion of responders among participants with high viral loads (ie, baseline HIV-1 RNA ≥100,000 copies/mL) was comparable for the REYATAZ with ritonavir (165 of 223 participants, 74%) and lopinavir/ritonavir (148 of 222 participants, 67%) arms. At 96 weeks, the median increase from baseline in CD4+ cell count was 261 cells/mm³ for the REYATAZ with ritonavir arm and 273 cells/mm³ for the lopinavir/ritonavir arm.
Study AI424-034: REYATAZ once daily compared to efavirenz once daily, each in combination with fixed-dose lamivudine/zidovudine twice daily. Study AI424-034 (NCT00013897) was a randomized, double-blind, multicenter trial comparing REYATAZ (400 mg once daily) to efavirenz (600 mg once daily), each in combination with the fixed-dose product of lamivudine /zidovudine (150 mg/300 mg) given twice daily, in 810 antiretroviral treatment-naive participants. Participants had a mean age of 34 years (range: 18 to 73), 36% were Hispanic, 33% were Caucasian, and 65% were male. The mean baseline CD4+ cell count was 321 cells/mm³ (range: 64 to 1424 cells/mm³) and the mean baseline plasma HIV-1 RNA level was 4.8 log10 copies/mL (range: 2.2 to 5.9 log10 copies/mL). Treatment response and outcomes through Week 48 are presented in Table 27.
Table 27: Outcomes of Randomized Treatment Through Week 48 in Treatment-Naive Adults (Study AI424-034)
| Outcome |
REYATAZ 400 mg once daily and lamivudine/ zidovudined
(n=405) |
efavirenz 600 mg once daily and lamivudine/ zidovudined
(n=405) |
| Respondera |
67% (32%) |
62% (37%) |
| Virologic failureb |
20% |
21% |
| Rebound |
17% |
16% |
| Never suppressed through Week 48 |
3% |
5% |
| Death |
- |
<1% |
| Discontinued due to adverse event |
5% |
7% |
| Discontinued for other reasonsc |
8% |
10% |
a Participants achieved and maintained confirmed HIV-1 RNA <400 copies/mL (<50 copies/mL) through Week 48. Roche Amplicor® HIV-1 Monitor™ Assay, test version 1.0 or 1.5 as geographically appropriate.
b Includes viral rebound and failure to achieve confirmed HIV-1 RNA <400 copies/mL through Week 48.
c Includes lost to follow-up, participant’s withdrawal, noncompliance, protocol violation, and other reasons.
d As a fixed-dose product: 150 mg lamivudine/300 mg zidovudine twice daily. |
Through 48 weeks of therapy, the proportion of responders among participants with high viral loads (ie, baseline HIV-1 RNA ≥100,000 copies/mL) was comparable for the REYATAZ and efavirenz arms. The mean increase from baseline in CD4+ cell count was 176 cells/mm³ for the REYATAZ arm and 160 cells/mm³ for the efavirenz arm.
Study AI424-008: REYATAZ 400 mg once daily compared to REYATAZ 600 mg once daily, and compared to nelfinavir 1250 mg twice daily, each in combination with stavudine and lamivudine twice daily. Study AI424-008 (NCT identifier not available) was a 48-week, randomized, multicenter trial, blinded to dose of REYATAZ, comparing REYATAZ at two dose levels (400 mg and 600 mg once daily) to nelfinavir (1250 mg twice daily), each in combination with stavudine (40 mg) and lamivudine (150 mg) given twice daily, in 467 antiretroviral treatment-naïve participants. Participants had a mean age of 35 years (range: 18 to 69), 55% were Caucasian, and 63% were male. The mean baseline CD4+ cell count was 295 cells/mm³ (range: 4 to 1003 cells/mm³) and the mean baseline plasma HIV-1 RNA level was 4.7 log10 copies/mL (range: 1.8 to 5.9 log10 copies/mL). Treatment response and outcomes through Week 48 are presented in Table 28.
Table 28: Outcomes of Randomized Treatment Through Week 48 in Treatment-Naive Adults (Study AI424-008)
| Outcome |
REYATAZ 400 mg once daily with lamivudine and stavudine
(n=181) |
nelfinavir 1250 mg twice daily with lamivudine and stavudine
(n=91) |
| Respondera |
67% (33%) |
59% (38%) |
| Virologic failureb |
24% |
27% |
| Rebound |
14% |
14% |
| Never suppressed through Week 48 |
10% |
13% |
| Death |
<1% |
- |
| Discontinued due to adverse event |
1% |
3% |
| Discontinued for other reasonsc |
7% |
10% |
a Participants achieved and maintained confirmed HIV-1 RNA <400 copies/mL (<50 copies/mL) through Week 48. Roche Amplicor® HIV-1 Monitor™ Assay, test version 1.0 or 1.5 as geographically appropriate.
b Includes viral rebound and failure to achieve confirmed HIV-1 RNA <400 copies/mL through Week 48.
c Includes lost to follow-up, participant’s withdrawal, noncompliance, protocol violation, and other reasons. |
Through 48 weeks of therapy, the mean increase from baseline in CD4+ cell count was 234 cells/mm³ for the REYATAZ 400-mg arm and 211 cells/mm³ for the nelfinavir arm.
Adult Participants With Prior Antiretroviral Therapy
Study AI424-045: REYATAZ once daily with ritonavir once daily compared to REYATAZ once daily and saquinavir (soft gelatin capsules) once daily, and compared to lopinavir/ritonavir twice daily, each in combination with tenofovir DF and one NRTI. Study AI424-045 (NCT00035932): was a randomized, multicenter trial comparing REYATAZ (300 mg once daily) with ritonavir (100 mg once daily) to REYATAZ (400 mg once daily) with saquinavir soft gelatin capsules (1200 mg once daily), and to lopinavir/ritonavir (400/100 mg twice daily as fixed-dose product), each in combination with tenofovir DF and one NRTI, in 347 (of 358 randomized) participants who experienced virologic failure on highly active antiretroviral therapy regimens containing PIs, NNRTIs, and NRTIs. The mean time of prior exposure to antiretrovirals was 139 weeks for PIs, 85 weeks for NNRTIs, and 283 weeks for NRTIs. The mean age was 41 years (range: 24 to 74); 60% were Caucasian, and 78% were male. The mean baseline CD4+ cell count was 338 cells/mm³ (range: 14 to 1543 cells/mm³) and the mean baseline plasma HIV-1 RNA level was 4.4 log10 copies/mL (range: 2.6 to 5.88 log10 copies/mL).
Treatment outcomes through Week 48 for the REYATAZ with ritonavir and lopinavir/ritonavir treatment arms are presented in Table 29. REYATAZ with ritonavir and lopinavir/ritonavir were similar for the primary efficacy outcome measure of time-averaged difference in change from baseline in HIV-1 RNA level. Study AI424-045 was not large enough to reach a definitive conclusion that REYATAZ with ritonavir and lopinavir/ritonavir are equivalent on the secondary efficacy outcome measure of proportions below the HIV-1 RNA lower limit of quantification [see Microbiology, Tables 24 and 25].
Table 29: Outcomes of Treatment Through Week 48 in Study AI424-045 (Participants with Prior Antiretroviral Experience)
| Outcome |
REYATAZ 300 mg with ritonavir 100 mg once daily and tenofovir DF and 1 NRTI
(n=119) |
lopinavir/ritonavir (400/100 mg) twice daily and tenofovir DF and 1 NRTI
(n=118) |
Differencea (REYATAZ- lopinavir/ritonavir)b (CI) |
| HIV-1 RNA Change from Baseline (log10 copies/mL)c |
-1.58 |
-1.70 |
+0.12c
(-0.17, 0.41) |
| CD4+ Change from Baseline (cells/mm³)e |
116 |
123 |
-7 (-67, 52) |
| Percent of Participants Respondinge |
| HIV-1 RNA <400 copies/mLc |
55% |
57% |
-2.2%
(-14.8%, 10.5%) |
| HIV-1 RNA <50 copies/mLc |
38% |
45% |
-7.1%
(-19.6%, 5.4%) |
a Time-averaged difference through Week 48 for HIV-1 RNA; Week 48 difference in HIV-1 RNA percentages and CD4+ mean changes, REYATAZ with ritonavir vs lopinavir/ritonavir; CI = 97.5% confidence interval for change in HIV-1 RNA; 95% confidence interval otherwise.
b Administered as a fixed-dose product.
c Roche Amplicor® HIV-1 Monitor™ Assay, test version 1.5.
d Protocol-defined primary efficacy outcome measure.
e Based on participants with baseline and Week 48 CD4+ cell count measurements (REYATAZ with ritonavir, n=85; lopinavir/ritonavir, n=93).
f Participants achieved and maintained confirmed HIV-1 RNA <400 copies/mL (<50 copies/mL) through Week 48. |
No participants in the REYATAZ with ritonavir treatment arm and three participants in the lopinavir/ritonavir treatment arm experienced a new-onset CDC Category C event during the study.
In Study AI424-045, the mean change from baseline in plasma HIV-1 RNA for REYATAZ 400 mg with saquinavir (n=115) was -1.55 log10 copies/mL, and the time-averaged difference in change in HIV-1 RNA levels versus lopinavir/ritonavir was 0.33. The corresponding mean increase in CD4+ cell count was 72 cells/mm³. Through 48 weeks of treatment, the proportion of participants in this treatment arm with plasma HIV-1 RNA <400 (<50) copies/mL was 38% (26%). In this study, coadministration of REYATAZ and saquinavir did not provide adequate efficacy [see DRUG INTERACTIONS].
Study AI424-045 also compared changes from baseline in lipid values. [See ADVERSE REACTIONS]
Study AI424-043 (NCT00028301): Study AI424-043 was a randomized, open-label, multicenter trial comparing REYATAZ (400 mg once daily) to lopinavir/ritonavir (400/100 mg twice daily as fixed-dose product), each in combination with two NRTIs, in 300 participants who experienced virologic failure to only one prior PI-containing regimen. Through 48 weeks, the proportion of participants with plasma HIV-1 RNA <400 (<50) copies/mL was 49% (35%) for participants randomized to REYATAZ (n=144) and 69% (53%) for participants randomized to lopinavir/ritonavir (n=146). The mean change from baseline was -1.59 log10 copies/mL in the REYATAZ treatment arm and -2.02 log10 copies/mL in the lopinavir/ritonavir arm. Based on the results of this study, REYATAZ without ritonavir was inferior to lopinavir/ritonavir in PIexperienced participants with prior virologic failure and is not recommended for such patients.
Pediatric Participants
Pediatric Trials With REYATAZ Capsules
Study AI424-040; PACTG 1020A (NCT00006604)
Assessment of the pharmacokinetics, safety, tolerability, and virologic response of REYATAZ capsules was based on data from this open-label, multicenter clinical trial which included participants from 6 years to 21 years of age. In this study, 105 participants (43 antiretroviral-naive and 62 antiretroviral-experienced) received once daily REYATAZ capsule formulation, with or without ritonavir, in combination with two NRTIs. One-hundred five (105) participants (6 to less than 18 years of age) treated with the REYATAZ capsule formulation, with or without ritonavir, were evaluated. Using an intent-to-treat (ITT) analysis, the overall proportions of antiretroviral-naive and -experienced participants with HIV-1 RNA <400 copies/mL at Week 96 were 51% (22/43) and 34% (21/62), respectively. The overall proportions of antiretroviral-naive and -experienced participants with HIV-1 RNA <50 copies/mL at Week 96 were 47% (20/43) and 24% (15/62), respectively. The median increase from baseline in absolute CD4 count at 96 weeks of therapy was 335 cells/mm³ in antiretroviral-naïve participants and 220 cells/mm³ in antiretroviral-experienced participants.
Pediatric Trials With REYATAZ Oral Powder
Assessment of the pharmacokinetics, safety, tolerability, and virologic response of REYATAZ oral powder was based on data from two open-label, multicenter clinical trials.
- AI424-397 (PRINCE I; NCT01099579): In pediatric participants from 3 months to less than 6 years of age
- AI424-451 (PRINCE II; NCT01335698): In pediatric participants from 3 months to less than 11 years of age
In these studies, 155 participants (59 antiretroviral-naive and 96 antiretroviral-experienced) received once daily REYATAZ oral powder with ritonavir, in combination with two NRTIs.
For inclusion in both trials, treatment-naive participants had to have genotypic sensitivity to REYATAZ and two NRTIs, and treatment-experienced participants had to have documented genotypic and phenotypic sensitivity at screening to REYATAZ and at least 2 NRTIs. Participants exposed only to antiretrovirals in utero or intrapartum were considered treatment-naive. Participants who received REYATAZ or REYATAZ with ritonavir at any time prior to study enrollment or who had a history of treatment failure on two or more protease inhibitors were excluded from the trials.
One hundred thirty-four (134) participants from both studies weighing 5 kg to less than 35 kg treated with REYATAZ oral powder with ritonavir were evaluated. Participants 5 kg to less than 10 kg received either 150 mg or 200 mg REYATAZ and 80 mg ritonavir oral solution; participants 10 kg to less than 15 kg received 200 mg REYATAZ and 80 mg ritonavir oral solution; participants 15 kg to less than 25 kg received 250 mg REYATAZ and 80 mg ritonavir oral solution; and participants 25 kg to less than 35 kg received 300 mg REYATAZ and 100 mg ritonavir.
Using a modified ITT analysis, the overall proportions of antiretroviral-naive and antiretroviralexperienced participants with HIV-1 RNA <400 copies/mL at Week 48 were 79% (41/52) and 62% (51/82), respectively in participants who received REYATAZ oral powder with ritonavir. The overall proportions of antiretroviral-naive and antiretroviral-experienced participants with HIV-1 RNA <50 copies/mL at Week 48 were 54% (28/52) and 50% (41/82), respectively, in participants who received REYATAZ oral powder with ritonavir. The median increase from baseline in absolute CD4 count (percent) at 48 weeks of therapy (last observation carried forward) was 215 cells/mm³ (6%) in antiretroviral-naive participants and 133 cells/mm³ (4%) in antiretroviral-experienced participants who received REYATAZ oral powder with ritonavir.