Clinical Pharmacology for Journavx
Mechanism Of Action
Suzetrigine is a selective blocker of the NaV1.8 voltage-gated sodium channel, compared to other known voltage-gated sodium channels (NaV1.1 through 1.9). NaV1.8 is expressed in peripheral sensory neurons including dorsal root ganglion neurons, where its role is to transmit pain signals (action potentials). By selectively inhibiting NaV1.8 channels, suzetrigine inhibits transmission of pain signals to the spinal cord and brain. M6-SUZ, a major active metabolite, is a less potent inhibitor of NaV1.8 than suzetrigine by 3.7-fold.
Pharmacodynamics
Cardiac Electrophysiology
At 2 times the exposure of the maximum recommended JOURNAVX dose, clinically significant QTc prolongation was not observed.
Pharmacokinetics
The pharmacokinetic parameters for suzetrigine and its major active metabolite, M6-SUZ, are shown in Table 4.
Table 4: Pharmacokinetic Parameters of Suzetrigine and M6-SUZ
|
Suzetrigine |
M6-SUZ (Active Metabolite)a |
| General Information |
| Steady State AUC0-24h (CV%), μg*h/mL |
11.5 (25.6%) |
34.7 (25.6%) |
| Steady State Cmax (CV%), μg/mL |
0.62 (27.7%) |
1.5 (24.5%) |
| Time to 90% Steady State, days |
3 |
5 |
| Mean (CV%) Accumulation Ratio b |
3.4 (30.2%) |
4.5 (30.6%) |
| Absorption |
| Median Tmax (range), hours |
3.0 hours (1.50, 5.03) |
10.0 hours (4.0, 48.1) |
| Distributionc |
| Mean (CV%) Apparent Volume of Distribution, L |
495 (25.0%) |
NA |
| Protein Binding |
99% |
96% |
| Elimination |
| Mean (CV%) Effective Half-Life, hours b |
23.6 (36.2%) |
33.0 (34.9%) |
| Steady State Mean (CV%) Apparent Oral Clearance, L/hours |
13.9 (37.5%) |
NA |
| Metabolism |
| Primary Pathway |
CYP3A |
CYP3A |
| Excretion |
| Primary Pathway |
- Feces: 49.9% (9.1% SUZ and rest as metabolites)
- Urine: 44.0% (primarily as metabolites)
|
AUC: area under the concentration versus time curve; CV: coefficient of variation; Cmax: maximum observed concentration; Tmax: time of maximum concentration; NA: not applicable
a Based on an in vitro electrophysiology assay in human dorsal root ganglion neurons, M6-SUZ is a less potent inhibitor of NaV1.8 than suzetrigine by 3.7-fold.
b Based on simulations of a dose of 50 mg every 12 hours (q12h).
c Suzetrigine and M6-SUZ do not partition preferentially into human red blood cells. |
Effect Of Food
Administration of 100 mg of JOURNAVX (the first dose) with a high-fat meal (800 to 1000 calories, 50% derived from fat), a moderate-fat meal (600 calories, 30% derived from fat), and a low-fat meal (up to 500 calories with no more than 25% derived from fat) resulted in decreased initial concentrations of suzetrigine and M6-SUZ in comparison to a fasted state. The median Tmax of suzetrigine and M6-SUZ in the fasted state was 3 hours and 8 to 10 hours, respectively. When administered in the fed state (high-fat meal or moderate-fat meal) the median Tmax of suzetrigine was delayed to 5 hours and the median Tmax of M6-SUZ was delayed to 24 hours. The Cmax and AUC of suzetrigine and M6-SUZ were not affected by any of the meal conditions, including a high-fat meal consumed one hour after JOURNAVX administration.
Administration of the second JOURNAVX dose of 50 mg with or without regard to meals is predicted to not affect the systemic exposures of suzetrigine and M6-SUZ.
Specific Populations
No clinically significant differences in pharmacokinetics of suzetrigine and M6-SUZ were observed based on age (18-75 years), sex, body weight (44-126 kg), race, and renal impairment (eGFR ≥ 15 mL/min by CKD-EPI equation with adjustment for the body surface area). The effect of renal impairment with eGFR < 15 mL/min on suzetrigine and M6-SUZ pharmacokinetics is unknown.
Patients With Hepatic Impairment
In patients with mild hepatic impairment (Child-Pugh Class A), no clinically significant differences in pharmacokinetics of suzetrigine and M6-SUZ were observed. In patients with moderate hepatic impairment (Child-Pugh Class B), at steady state, suzetrigine AUC0-12h increased by 1.5-fold (90% CI: 1.1-2.1) and Cmax increased by 1.3-fold (90% CI: 1.0-1.7) and M6-SUZ AUC0-12h and Cmax both increased by 1.2-fold (AUC 90% CI: 0.83-1.6; Cmax 90% CI: 0.84-1.6). The effect of severe hepatic impairment (Child-Pugh Class C) on suzetrigine and M6-SUZ pharmacokinetics is unknown.
Drug Interaction Studies
Clinical Studies And Model-Informed Approaches
Strong CYP3A Inhibitors
Concomitant administration of itraconazole (a strong CYP3A inhibitor) with a single dose of JOURNAVX increased the geometric mean (90% CI) AUC0-inf of suzetrigine and M6-SUZ by 4.8-fold (4.3-5.4) and 4.4-fold (3.6-5.4), respectively, while the geometric mean (90% CI) Cmax of suzetrigine increased by 1.5-fold (1.3-1.6) and Cmax of M6-SUZ decreased by 32% (24-39%) [see DRUG INTERACTIONS].
Moderate CYP3A Inhibitors
Concomitant administration of fluconazole (a moderate CYP3A inhibitor) with JOURNAVX with the recommended dosage modification [see DOSAGE AND ADMINISTRATION] is predicted to increase the geometric mean (90% CI) AUCtau of suzetrigine and M6-SUZ by 1.5-fold (1.4-1.5) and 1.2-fold (1.2-1.3), respectively, while the geometric mean (90% CI) Cmax of suzetrigine and M6-SUZ is predicted to increase by 1.4-fold (1.4-1.5) and 1.1-fold (1.1-1.2), respectively, when compared to the regular recommended dosage in the absence of fluconazole [see DOSAGE AND ADMINISTRATION, DRUG INTERACTIONS].
Strong CYP3A Inducers
Concomitant administration of rifampin (strong CYP3A inducer) at steady state with a single dose of JOURNAVX decreased the geometric mean (90% CI) AUC0-inf of suzetrigine and M6-SUZ by 93% (91-94%) and 85% (83-86%), respectively, while the geometric mean (90% CI) Cmax of suzetrigine decreased by 80% (75-83%) and the Cmax of M6-SUZ increased by 1.3-fold (1.1-1.5) [see DRUG INTERACTIONS].
Moderate CYP3A Inducers
Concomitant administration of efavirenz (moderate CYP3A inducer) with a single dose of JOURNAVX is predicted to decrease the geometric mean (90% CI) AUC0-t of suzetrigine and M6-SUZ by 63% (61-65%) and 60% (58-62%), respectively, while the geometric mean (90% CI) Cmax of suzetrigine is predicted to decrease by 29% (27-32%) and M6-SUZ is predicted to increase by 1.3-fold (1.3-1.4), respectively [see DRUG INTERACTIONS].
Sensitive CYP3A Substrates
JOURNAVX administered 50 mg every 12 hours, at steady state decreased the geometric mean (90% CI) AUC0-inf of midazolam (sensitive CYP3A substrate) by 48% (43-53%) and Cmax by 37% (27-45%) [see DRUG INTERACTIONS].
Proton Pump Inhibitors
No clinically significant differences in suzetrigine and M6-SUZ pharmacokinetics were observed when JOURNAVX was used concomitantly with omeprazole.
Other Drugs
No clinically significant differences in the pharmacokinetics of the following drugs were observed when used concomitantly with JOURNAVX: oral digoxin (P-gp substrate), ethinyl estradiol (hormonal contraceptive), or levonorgestrel (hormonal contraceptive).
In Vitro Studies
Cytochrome P450 (CYP450) Enzymes
Suzetrigine inhibits CYP2C8, CYP2C9, and CYP2C19, but is not expected to result in clinically significant drug interactions. Suzetrigine does not inhibit CYP1A2, CYP2B6, CYP2D6, and CYP3A enzymes, and M6-SUZ does not inhibit CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A enzymes. Suzetrigine induces CYP3A and to a lesser extent CYP2B6, CYP2C8, CYP2C9, and CYP2C19. Suzetrigine does not induce CYP1A2.
UDP-Glucuronosyltransferase (UGT)
Suzetrigine does not inhibit UGT1A1.
Transporter Systems
Suzetrigine and M6-SUZ are not substrates of BCRP, OATP1B1 or OATP1B3. Suzetrigine is not a P-gp substrate, but M6-SUZ is a P-gp substrate. Suzetrigine inhibits OATP1B1, OATP1B3 and OAT3 but is not expected to result in clinically significant drug interactions. Suzetrigine does not inhibit BCRP, OAT1, OCT2, MATE1, and MATE2/K transporters. M6-SUZ inhibits OATP1B1, OATP1B3, OAT1, and OAT3 but is not expected to result in clinically significant drug interactions. M6-SUZ does not inhibit P-gp, BCRP, OCT2, MATE1 and MATE2/K transporters.
Clinical Studies
Overview Of Clinical Studies
The efficacy of JOURNAVX in the treatment of moderate to severe acute pain in adults was established in two randomized, double-blind, placebo and active-controlled trials of acute pain, one following full abdominoplasty (Trial 1) [see Clinical Studies] and the other following bunionectomy (Trial 2) [see Clinical Studies]. In each trial, pain intensity was measured using a patient-reported 11-point numeric pain rating scale (NPRS), ranging from 0 to 10, where zero corresponds to no pain and 10 corresponds to the worst pain imaginable.
Patients were eligible for study participation if they had moderate to severe pain on the verbal categorical rating system (VRS) and a pain score of ≥ 4 on the NPRS, within 4 hours of the abdominoplasty completion (Trial 1) or during the 9-hour period after discontinuation of regional anesthesia following bunionectomy (Trial 2). Once eligible, patients were randomized to receive oral JOURNAVX, placebo, or hydrocodone bitartrate/acetaminophen (HB/APAP) for a duration of 48 hours. For the JOURNAVX treatment regimen, patients received an initial loading dose of 100 mg JOURNAVX, followed by 50 mg every 12 hours. For the HB/APAP-control regimen, patients received 5 mg/325 mg every 6 hours. For both studies, 400 mg of ibuprofen every 6 hours, as needed for pain relief, was permitted as a rescue medication.
Moderate To Severe Acute Pain Following Full Abdominoplasty
Trial 1 [NCT05558410] evaluated the efficacy of JOURNAVX over 48 hours in 1,118 adult patients with moderate to severe acute pain following a full abdominoplasty procedure (JOURNAVX n = 447, placebo n = 223, and hydrocodone bitartrate/acetaminophen (HB/APAP) n = 448). The majority of patients were female (98%), and the mean age was 42 years (range: 18 to 69). The study population consisted of 70% White participants, 27% Black or African American participants, 1% Asian participants, 0.8% Native Hawaiian or other Pacific Islander participants, 0.5% American Indian or Alaska Native participants, and 0.9% Other or Multiracial participants, among which 34% identified as Hispanic or Latino. The mean pain score at baseline was 7.4 (range: 4 to 10). All baseline characteristics, including NPRS, VRS, and BMI were generally balanced across treatment arms.
In Trial 1, 89% of patients in the JOURNAVX group completed the treatment period (compared to 75% of patients in the placebo group and 85% of patients in the HB/APAP group), and 9% of patients in the JOURNAVX group discontinued due to lack of efficacy (compared to 22% of patients in the placebo group and 13% of patients in the HB/APAP group).
Efficacy was evaluated by the time-weighted sum of the pain intensity difference from 0 to 48 hours (SPID48) in the JOURNAVX group compared to the placebo group and then to the HB/APAP group. Treatment with JOURNAVX demonstrated statistically significant superior reduction in pain compared to treatment with placebo (see Table 5).
In an exploratory analysis, the time-weighted sum of the pain intensity difference from 0 to 24 hours (SPID24) reported using the least square mean was 48.0 for the JOURNAVX group and 24.2 for the placebo group. The mean pain intensities over time are depicted for the JOURNAVX, placebo, and HB/APAP groups in Figure 1.
Table 5: SPID48 Results in Adults with Moderate to Severe Acute Pain Following Full Abdominoplasty (Trial 1)
| Efficacy Measure |
JOURNAVX
N = 447 |
Placebo
N = 223 |
HB/APAPb
N = 448 |
| LS mean a |
118.4 |
70.1 |
111.8 |
| LS Mean Difference vs placebo (95% CI) P value |
48.4 (33.6, 63.1) < 0.0001 |
- |
- |
| LS Mean Difference vs HB/APAP (95% CI) |
6.6 (-5.4, 18.7) |
- |
- |
LS: Least Squares; CI: Confidence Interval
a A larger value of LS mean indicates better efficacy measured by SPID48.
b HB/APAP = hydrocodone bitartrate/acetaminophen |
Figure 1: Mean Pain Intensity Over Time in Adults with Moderate to Severe Acute Pain Following Full Abdominoplasty (Trial 1)
Note: Pre-rescue pain scores were carried forward for 6 hours following the use of rescue medication. HB/APAP = hydrocodone bitartrate/acetaminophen
Time To Onset Of Pain Relief
The median time to meaningful pain relief (defined as a ≥ 2-point reduction in NPRS) was 119 minutes for patients in the JOURNAVX group and 480 minutes for patients in the placebo group. The median time to onset of perceptible pain relief (defined as a ≥ 1-point reduction in NPRS) for patients in the JOURNAVX group was 34 minutes.
Moderate To Severe Acute Pain Following Bunionectomy
Trial 2 [NCT05553366] evaluated the efficacy of JOURNAVX over 48 hours in 1,073 adult patients with moderate to severe acute pain following bunionectomy (JOURNAVX n = 426, placebo n = 216, and HB/APAP n = 431). The majority of patients were female (85%), and the mean age was 48 years (range: 18 to 75). The study population consisted of 71% White participants, 24% Black or African American participants, 2% Asian participants, 0.2% Native Hawaiian or other Pacific Islander participants, 1% American Indian or Alaska Native participants, and 1% Other or Multiracial participants, and 0.3% with race missing, among which 34% identified as Hispanic or Latino. The mean pain score at baseline was 6.8 (range: 4 to 10). All baseline characteristics, including NPRS, VRS, and BMI were generally balanced across treatment arms.
In Trial 2, 87% of patients in the JOURNAVX group completed the treatment period (compared to 82% of patients in the placebo group and 90% of patients in the HB/APAP group), and 12% of patients in the JOURNAVX group discontinued due to lack of efficacy (compared to 16% of patients in the placebo group and 8% of patients in the HB/APAP group).
Efficacy was evaluated by the time-weighted sum of the pain intensity difference from 0 to 48 hours (SPID48) in the JOURNAVX group compared to the placebo group and then to the HB/APAP group. Treatment with JOURNAVX demonstrated statistically significant superior reduction in pain compared to treatment with placebo (see Table 6).
In an exploratory analysis, the time-weighted sum of the pain intensity difference from 0 to 24 hours (SPID24) reported using the least square mean was 30.6 in the JOURNAVX group and 19.8 in the placebo group. The mean pain intensities over time are depicted for the JOURNAVX, placebo, and HB/APAP groups in Figure 2.
Table 6: SPID48 Results in Adults with Moderate to Severe Acute Pain Following Bunionectomy (Trial 2)
| Efficacy Measure |
JOURNAVX
N = 426 |
Placebo
N = 216 |
HB/APAPb
N = 431 |
| LS mean a |
99.9 |
70.6 |
120.1 |
LS Mean Difference vs placebo (95% CI)
P value |
29.3
(14.0, 44.6)
0.0002 |
- |
- |
| LS Mean Difference vs HB/APAP (95% CI) |
-20.2
(-32.7, -7.7) |
- |
- |
LS: Least Squares; CI: Confidence Interval
a A larger value of LS mean indicates better efficacy measured by SPID48.
b HB/APAP = hydrocodone bitartrate/acetaminophen |
Figure 2: Mean Pain Intensity Over Time in Adults with Moderate to Severe Acute Pain Following Bunionectomy (Trial 2)
Note: Pre-rescue pain scores were carried forward for 6 hours following the use of rescue medication. HB/APAP = hydrocodone bitartrate/acetaminophen
Time To Onset Of Pain Relief
The median time to meaningful pain relief (defined as ≥ 2-point reduction in NPRS) was 240 minutes for patients in the JOURNAVX group and 480 minutes in the placebo group. The median time to onset of perceptible pain relief (defined as a ≥ 1-point reduction in NPRS) for patients in the JOURNAVX group was 60 minutes.