Clinical Pharmacology for Sivextro
Mechanism Of Action
Tedizolid is an antibacterial drug [see Microbiology].
Pharmacodynamics
The AUC/minimum inhibitory concentration (MIC) was shown to best correlate with tedizolid activity in animal infection models.
In the mouse thigh infection model of S. aureus, antistaphylococcal killing activity was impacted by the presence of granulocytes. In granulocytopenic mice (neutrophil count <100 cells/mL), bacterial stasis was achieved at a humanequivalent dose of approximately 2000 mg/day; whereas, in non-granulocytopenic animals, stasis was achieved at a human-equivalent dose of approximately 100 mg/day. The safety and efficacy of SIVEXTRO for the treatment of neutropenic patients (neutrophil counts <1000 cells/mm³) have not been evaluated.
Cardiac Electrophysiology
In a randomized, positive- and placebo-controlled crossover thorough QTc study, 48 enrolled subjects were administered a single oral dose of SIVEXTRO at a therapeutic dose of 200 mg, SIVEXTRO at a supratherapeutic dose of 1200 mg, placebo, and a positive control; no significant effects of SIVEXTRO on heart rate, electrocardiogram morphology, PR, QRS, or QT interval were detected. Therefore, SIVEXTRO does not affect cardiac repolarization.
Pharmacokinetics
Tedizolid phosphate is a prodrug that is converted by phosphatases to tedizolid, the microbiologically active moiety, following oral and intravenous administration. Only the pharmacokinetic profile of tedizolid is discussed further due to negligible systemic exposure of tedizolid phosphate following oral and intravenous administration. Following multiple once-daily oral or intravenous administration, steady-state concentrations are achieved within approximately three days with tedizolid accumulation of approximately 30% (tedizolid half-life of approximately 12 hours). Pharmacokinetic (PK) parameters of tedizolid following oral and intravenous administration of 200 mg once daily tedizolid phosphate in adults are shown in Table 8.
Table 8: Mean (Standard Deviation) Tedizolid Pharmacokinetic Parameters Following Single and Multiple Oral and Intravenous Administration of 200 mg Once-Daily Tedizolid Phosphate in Adults
| Pharmacokinetic Parameters of Tedizolid* |
Oral |
Intravenous |
| Single Dose |
Steady State |
Single Dose |
Steady State |
| Cmax (mcg/mL) |
2.0 (0.7) |
2.2 (0.6) |
2.3 (0.6) |
3.0 (0.7) |
| Tmax (hr)† |
2.5 (1.0 - 8.0) |
3.5 (1.0 - 6.0) |
1.1 (0.9 - 1.5) |
1.2 (0.9 - 1.5) |
| AUC (mcg-hr/mL)‡ |
23.8 (6.8) |
25.6 (8.5) |
26.6 (5.2) |
29.2 (6.2) |
| CL or CL/F (L/hr) |
7.5 (2.3) |
6.9 (1.7) |
6.4 (1.2) |
5.9 (1.4) |
* Cmax, maximum concentration; Tmax, time to reach Cmax; AUC, area under the concentration-time curve; CL, systemic clearance; CL/F, apparent oral clearance
† Median (range)
‡ AUC is AUC0∞ (AUC from time 0 to infinity) for single-dose administration and AUC0-24 (AUC from time 0 to 24 hours) for multiple-dose administration |
Absorption
Peak plasma tedizolid concentrations are achieved within approximately 3 hours following oral administration of the oral tablet under fasting conditions or at the end of the 1 hour intravenous infusion of tedizolid phosphate. The absolute bioavailability of the oral tablet is approximately 91% and no dosage adjustment is necessary between intravenous and oral administration.
Tedizolid phosphate (oral tablet) may be administered with or without food as total systemic exposure (AUC0-∞) is unchanged between fasted and fed (high-fat, high-calorie) conditions.
Distribution
Protein binding of tedizolid to human plasma proteins is approximately 70 to 90%. The mean steady state volume of distribution of tedizolid in healthy adults following a single intravenous dose of tedizolid phosphate 200 mg ranged from 67 to 80 L (approximately twice total body water). Tedizolid penetrates into the interstitial space fluid of adipose and skeletal muscle tissue with exposure similar to free drug exposure in plasma.
Elimination
Metabolism
Other than tedizolid, which accounts for approximately 95% of the total radiocarbon AUC in plasma, there are no other significant circulating metabolites in humans.
There was no degradation of tedizolid in human liver microsomes indicating tedizolid is unlikely to be a substrate for hepatic CYP450 enzymes.
In vitro studies showed that conjugation of tedizolid is mediated via multiple sulfotransferase (SULT) isoforms (SULT1A1, SULT1A2, and SULT2A1).
Excretion
Following single oral administration of 14C-labeled tedizolid phosphate under fasted conditions in adult healthy volunteers, the majority of elimination occurred via the liver, with 82% of the radioactive dose recovered in feces and 18% in urine, primarily as a non-circulating and microbiologically inactive sulfate conjugate. Most of the elimination of tedizolid (>85%) occurs within 96 hours. Less than 3% of the tedizolid phosphate-administered dose is excreted in feces and urine as unchanged tedizolid.
Specific Populations
Based on the population pharmacokinetic analysis, there are no clinically relevant demographic or clinical patient factors (including age, gender, race, ethnicity, weight, body mass index, and measures of renal or liver function) that impact the pharmacokinetics of tedizolid.
Patients With Hepatic Impairment
Following administration of a single 200 mg oral dose of SIVEXTRO, no clinically meaningful changes in mean tedizolid Cmax and AUC0∞ were observed in adult patients with moderate (n=8) or severe (n=8) hepatic impairment (Child-Pugh Class B and C) compared to 8 matched healthy control subjects. No dose adjustment is necessary for patients with hepatic impairment.
Patients With Renal Impairment
Following administration of a single 200 mg intravenous dose of SIVEXTRO to 8 adult subjects with severe renal impairment defined as eGFR <30 mL/min/1.73 m², the Cmax was essentially unchanged and AUC0-∞ was decreased by less than 10% compared to 8 matched healthy control adult subjects. Hemodialysis does not result in meaningful removal of tedizolid from systemic circulation, as assessed in subjects with end-stage renal disease (eGFR <15 mL/min/1.73 m²). No dosage adjustment is necessary in patients with renal impairment or patients on hemodialysis.
Geriatric Patients
The pharmacokinetics of tedizolid were evaluated in a Phase 1 study conducted in elderly healthy volunteers (age 65 years and older, with at least 5 subjects at least 75 years old; n=14) compared to younger control subjects (25 to 45 years old; n=14) following administration of a single oral dose of SIVEXTRO 200 mg. There were no clinically meaningful differences in tedizolid Cmax and AUC0-∞ between elderly subjects and younger control subjects. No dosage adjustment of SIVEXTRO is necessary in elderly patients.
Male And Female Patients
The impact of gender on the pharmacokinetics of SIVEXTRO was evaluated in clinical trials of adult healthy males and females and in a population pharmacokinetics analysis. The pharmacokinetics of tedizolid were similar in males and females. No dosage adjustment of SIVEXTRO is necessary based on gender.
Pediatric Patients
The pharmacokinetics of tedizolid was evaluated in clinical studies in pediatric patients from birth (includes neonates who are at least 26 weeks gestational age and weighing at least 1 kg) to less than 18 years of age (N=249).
Compared to adult patients, tedizolid exposures are higher in pediatric patients (12 to <18 years of age, mean weight: 59.7 kg, weight range: 28 kg to 126 kg in Pediatric Trial 1) following multiple dose administration of a once daily dose of 200 mg IV or oral SIVEXTRO (geometric mean Cmax 3.1 vs. 2.0 mcg/mL, AUC24h 28.6 vs. 21.0 mcg*h/mL); however, this increase in exposure is not considered clinically significant.
The predicted steady state mean pharmacokinetic parameters of tedizolid by the pediatric weight-based dosage in Table 2 and Table 3 are shown in Table 9.
Table 9: Geometric Mean (% CV) Predicted Steady-State Exposures Following Multiple Dose Administration of IV or Oral Tedizolid Phosphate Based Upon the Weight-Banded Dosage in Pediatric Patients Birth* to Less than 18 Years
| Weight (kg) |
Dosage Regimen |
Total Daily Dose |
Route |
Steady- State AUC24h (mcg•h/mL)† |
Steady-State Cmax (mcg/mL) |
| 1 to less than 2 |
3 mg/kg Twice daily |
6 mg to less than12 mg |
IV |
33.1 (29.8) |
2.3 (17.2) |
| 2 to less than 3 |
6 mg Twice daily |
12 mg |
IV |
20.8 (25.6) |
1.8 (15.9) |
| 3 to less than 6 |
12 mg Twice daily |
24 mg |
IV |
26.4 (34.4) |
2.4 (20.7) |
| 6 to less than 10 |
20 mg Twice daily |
40 mg |
IV |
22.5 (43.9) |
2.2 (20.4) |
| 10 to less than 14 |
30 mg Twice daily |
60 mg |
IV |
27.6 (32.1) |
2.7 (19.6) |
| 14 to less than 20 |
40 mg Twice daily |
80 mg |
IV |
28.4 (22.1) |
2.7 (13.0) |
| 20 to less than 35 |
60 mg Twice daily |
120 mg |
IV |
31.4 (29.9) |
2.6 (21.6) |
| At least 35 |
200 mg Once daily |
200 mg |
IV |
30.6 (29.7) |
3.8 (23.9) |
| Oral (tablet) |
29.3 (29.7) |
2.5 (24.4) |
AUC, area under the concentration-time curve; Cmax, maximum concentration; %CV, coefficient of variation.
* Pediatric patients from birth (includes neonates at least 26 weeks gestational age).
† AUC0-24 = 2 × AUC0-12 for twice daily dosing. |
Drug Interaction Studies
Drug Metabolizing Enzymes
Transformation via Phase 1 hepatic oxidative metabolism is not a significant pathway for elimination of SIVEXTRO.
Neither SIVEXTRO nor tedizolid detectably inhibited or induced the metabolism of selected CYP enzyme substrates, suggesting that drug-drug interactions based on oxidative metabolism are unlikely.
Membrane Transporters
The potential for tedizolid or tedizolid phosphate to inhibit transport of probe substrates of important drug uptake (OAT1, OAT3, OATP1B1, OATP1B3, OCT1, and OCT2) and efflux transporters (P-gp and BCRP) was tested in vitro. No clinically relevant interactions are expected to occur with these transporters except BCRP.
Coadministration of multiple oral doses of SIVEXTRO (200 mg once daily) increased the Cmax and AUC of rosuvastatin (10 mg single oral dose), a known BCRP substrate, by approximately 55% and 70%, respectively, in healthy adult subjects [see DRUG INTERACTIONS].
Monoamine Oxidase Inhibition
Tedizolid is a reversible inhibitor of monoamine oxidase (MAO) in vitro. The interaction with MAO inhibitors could not be evaluated in Phase 2 and 3 trials, as subjects taking such medications were excluded from the trials.
Adrenergic Agents
Two placebo-controlled crossover studies were conducted to assess the potential of 200 mg oral SIVEXTRO at steady state to enhance pressor responses to pseudoephedrine and tyramine in healthy adults. No meaningful changes in blood pressure or heart rate were seen with pseudoephedrine. The median tyramine dose required to cause an increase in systolic blood pressure of ≥30 mmHg from pre-dose baseline was 325 mg with SIVEXTRO compared to 425 mg with placebo. Palpitations were reported in 21/29 (72.4%) adult subjects exposed to SIVEXTRO compared to 13/28 (46.4%) exposed to placebo in the tyramine challenge study.
Serotonergic Agents
Serotonergic effects at doses of tedizolid phosphate up to 30-fold above the human equivalent dose did not differ from vehicle control in a mouse model that predicts serotonergic activity. In Phase 3 trials, subjects taking serotonergic agents including antidepressants such as selective serotonin reuptake inhibitors (SSRIs), tricyclic antidepressants, and serotonin 5-hydroxytryptamine (5-HT1) receptor agonists (triptans), meperidine, or buspirone were excluded.
Microbiology
Mechanism Of Action
The antibacterial activity of tedizolid is mediated by binding to the 50S subunit of the bacterial ribosome resulting in inhibition of protein synthesis. Tedizolid inhibits bacterial protein synthesis through a mechanism of action different from that of other non-oxazolidinone class antibacterial drugs; therefore, cross-resistance between tedizolid and other classes of antibacterial drugs is unlikely. The results of in vitro time-kill studies show that tedizolid is bacteriostatic against enterococci, staphylococci, and streptococci.
Resistance
Organisms resistant to oxazolidinones via mutations in chromosomal genes encoding 23S rRNA or ribosomal proteins (L3 and L4) are generally cross-resistant to tedizolid. In the limited number of Staphylococcus aureus strains tested, the presence of the chloramphenicol-florfenicol resistance (cfr) gene did not result in resistance to tedizolid in the absence of chromosomal mutations. Mutations in 23SrRNA (G2576T mutation) have been associated with tedizolid resistance in S. aureus isolates.
Spontaneous mutations conferring reduced susceptibility to tedizolid occur in vitro at a frequency rate of approximately 10-10.
Interaction With Other Antimicrobial Drugs
In vitro drug combination studies with tedizolid and aztreonam, ceftriaxone, ceftazidime, imipenem, rifampin, trimethoprim/sulfamethoxazole, minocycline, clindamycin, ciprofloxacin, daptomycin, vancomycin, gentamicin, amphotericin B, ketoconazole, and terbinafine demonstrate neither synergy nor antagonism.
Antimicrobial Activity
Tedizolid has been shown to be active against most isolates of the following bacteria, both in vitro and in clinical infections, as described in Indications and Usage (1).
Aerobic bacteria
Gram-positive Bacteria
Staphylococcus aureus (including methicillin-resistant [MRSA] and methicillin-susceptible [MSSA] isolates)
Streptococcus pyogenes
Streptococcus agalactiae
Streptococcus anginosus Group (including S. anginosus, S. intermedius, and S. constellatus)
Enterococcus faecalis
The following in vitro data are available, but their clinical significance is unknown. At least 90% of the following bacteria exhibit an in vitro minimum inhibitory concentration (MIC) less than or equal to the susceptible breakpoint for tedizolid against isolates of similar genus or organism group. However, the efficacy of SIVEXTRO in treating clinical infections caused by these bacteria has not been established in adequate and well-controlled clinical trials.
Aerobic bacteria
Gram-positive Bacteria
Staphylococcus epidermidis (including methicillin-susceptible and methicillin-resistant isolates)
Staphylococcus haemolyticus
Staphylococcus lugdunensis
Enterococcus faecium
Susceptibility Testing
For specific information regarding susceptibility test interpretive criteria and associated test methods and quality control standards recognized by FDA for this drug, please see: https://www.fda.gov/STIC
Animal Toxicology And/Or Pharmacology
Repeated-oral and intravenous dosing of tedizolid phosphate in rats in 1 month and 3 month toxicology studies produced dose- and time-dependent bone marrow hypocellularity (myeloid, erythroid, and megakaryocyte), with associated reduction in circulating RBCs, WBCs, and platelets. These effects showed evidence of reversibility and occurred at plasma tedizolid exposure levels (AUC) ≥6-fold greater than the plasma exposure associated with the human therapeutic dose. In a 1-month immunotoxicology study in rats, repeated oral dosing of tedizolid phosphate was shown to significantly reduce splenic B cells and T cells and reduce plasma IgG titers. These effects occurred at plasma tedizolid exposure levels (AUC) ≥3-fold greater than the expected human plasma exposure associated with the therapeutic dose.
Clinical Studies
Acute Bacterial Skin And Skin Structure Infections
Adults
A total of 1333 adults with acute bacterial skin and skin structure infections (ABSSSI) were randomized in two multicenter, multinational, double-blind, non-inferiority trials. Both trials compared SIVEXTRO 200 mg once daily for 6 days versus linezolid 600 mg every 12 hours for 10 days. In Trial 1, patients were treated with oral therapy, while in Trial 2, patients could receive oral therapy after a minimum of one day of intravenous therapy. Patients with cellulitis/erysipelas, major cutaneous abscess, or wound infection were enrolled in the trials. Patients with wound infections could have received aztreonam and/or metronidazole as adjunctive therapy for gram-negative bacterial coverage, if needed. The intent-to-treat (ITT) patient population included all randomized patients.
In Trial 1, 332 patients with ABSSSI were randomized to SIVEXTRO and 335 patients were randomized to linezolid. The majority (91%) of patients treated with SIVEXTRO in Trial 1 were less than 65 years old with a median age of 43 years (range: 18 to 86 years). Patients treated with SIVEXTRO were predominantly male (61%) and White (84%); 13% had BMI ≥35 kg/m², 8% had diabetes mellitus, 35% were current or recent intravenous drug users, and 2% had moderate to severe renal impairment. The overall median surface area of infection was 188 cm². The types of ABSSSI included were cellulitis/erysipelas (41%), wound infection (29%), and major cutaneous abscess (30%). In addition to local signs and symptoms of infection, patients were also required to have at least one regional or systemic sign of infection at baseline, defined as lymphadenopathy (87% of patients), temperature 38°C or higher (16% of patients), white blood cell count greater than 10,000 cells/mm³ or less than 4000 cells/mm³ (42%), or 10% or more band forms on white blood cell differential (4%).
The primary endpoint in Trial 1 was early clinical response defined as no increase from baseline lesion area at 48- 72 hours after the first dose and oral temperature of ≤37.6°C, confirmed by a second temperature measurement within 24 hours in the ITT population.
In Trial 2, 332 patients with ABSSSI were randomized to SIVEXTRO and 334 patients were randomized to linezolid. The majority (87%) of patients treated with SIVEXTRO in Trial 2 were less than 65 years old with a median age of 46 years (range: 17 to 86 years). Patients treated with SIVEXTRO were predominantly male (68%) and White (86%); 16% had BMI ≥35 kg/m², 10% had diabetes mellitus, 20% were current or recent intravenous drug users, and 4% had moderate to severe renal impairment. The overall median surface area of infection was 231 cm². The types of ABSSSI included were cellulitis/erysipelas (50%), wound infection (30%), and major cutaneous abscess (20%). In addition to local signs and symptoms of infection, patients were also required to have at least one regional or systemic sign of infection at baseline, defined as lymphadenopathy (71% of patients), temperature 38°C or higher (31% of patients), white blood cell count greater than 10,000 cells/mm³ or less than 4000 cells/mm³ (53%), or 10% or more band forms on white blood cell differential (16%).
The primary endpoint in Trial 2 was early clinical response defined as at least a 20% decrease from baseline lesion area at 48-72 hours after the first dose in the ITT population (Table 10).
Table 10: Early Clinical Response in the ITT Adult Patient Population
|
SIVEXTRO (200 mg) |
Linezolid (1200 mg) |
Treatment Difference (2-sided 95% CI) |
| No increase in lesion surface area from baseline and oral temperature of <37.6°C, confirmed by a second temperature measurement within 24 hours at 48-72 hours* |
| Trial 1, N |
332 |
335 |
|
| Responder, n (%) |
264 (79.5) |
266 (79.4) |
0.1 (-6.1, 6.2) |
| Trial 2, N |
332 |
334 |
|
| Responder, n (%) |
286 (86.1) |
281 (84.1) |
2.0 (-3.5, 7.3) |
| At least a 20% decrease from baseline in lesion area at 48-72 hours† |
| Trial 1, N |
332 |
335 |
|
| Responder, n (%) |
259 (78.0) |
255 (76.1) |
1.9 (-4.5, 8.3) |
| Trial 2, N |
332 |
334 |
|
| Responder, n (%) |
283 (85.2) |
276 (82.6) |
2.6 (-3.0, 8.2) |
CI=confidence interval
* Primary endpoint for Trial 1; sensitivity analysis for Trial 2
† Primary endpoint for Trial 2; sensitivity analysis for Trial 1 |
An investigator assessment of clinical response was made at the post-therapy evaluation (PTE) (7 - 14 days after the end of therapy) in the ITT and CE (Clinically Evaluable) populations. Clinical success was defined as resolution or near resolution of most disease-specific signs and symptoms, absence or near resolution of systemic signs of infection if present at baseline (lymphadenopathy, fever, >10% immature neutrophils, abnormal WBC count), and no new signs, symptoms, or complications attributable to the ABSSSI requiring further treatment of the primary lesion (Table 11).
Table 11: Investigator-Assessed Clinical Response at Post-therapy Evaluation in ITT and CE Adult Patient Populations from Two Phase 3 ABSSSI Trials
|
SIVEXTRO (200 mg)
n/N (%) |
Linezolid (1200 mg)
n/N (%) |
Treatment Difference (2-sided 95% CI) |
| Trial 1 |
| ITT |
284/332 (85.5) |
288/335 (86.0) |
-0.5 (-5.8, 4.9) |
| CE |
264/279 (94.6) |
267/280 (95.4) |
-0.8 (-4.6, 3.0) |
| Trial 2 |
| ITT |
292/332 (88.0) |
293/334 (87.7) |
0.3 (-4.8, 5.3) |
| CE |
268/290 (92.4) |
269/280 (96.1) |
-3.7 (-7.7, 0.2) |
| CI=confidence interval; ITT=intent-to-treat; CE=clinically evaluable |
Clinical success by baseline pathogens from the primary infection site or blood cultures for the microbiological intent-totreat (MITT) patient population for two integrated Phase 3 ABSSSI studies are presented in Table 12 and Table 13.
Table 12: Early Clinical Response by Baseline Pathogen from Two Phase 3 ABSSSI Adult Trials (MITT Population)
| Pathogen |
No increase in lesion surface area from baseline and oral temperature of ≤37.6°C* |
At least a 20% decrease from baseline in lesion area† |
SIVEXTRO (200 mg)
n/N (%) |
Linezolid (1200 mg)
n/N (%) |
SIVEXTRO (200 mg)
n/N (%) |
Linezolid (1200 mg)
n/N (%) |
| Staphylococcus aureus |
276/329 (83.9) |
278/342 (81.3) |
280/329 (85.1) |
276/342 (80.7) |
| Methicillin-resistant S. aureus |
112/141 (79.4) |
113/146 (77.4) |
114/141 (80.9) |
111/146 (76.0) |
| Methicillin-susceptible S. aureus |
164/188 (87.2) |
167/198 (84.3) |
166/188 (88.3) |
167/198 (84.3) |
| Streptococcus pyogenes |
27/33 (81.8) |
18/20 (90.0) |
25/33 (75.8) |
16/20 (80.0) |
| Streptococcus anginosus Group |
22/30 (73.3) |
26/28 (92.9) |
22/30 (73.3) |
25/28 (89.3) |
| Streptococcus agalactiae |
6/9 (66.7) |
8/10 (80.0) |
6/9 (66.7) |
7/10 (70.0) |
| Enterococcus faecalis |
7/10 (70.0) |
3/4 (75.0) |
6/10 (60.0) |
1/4 (25.0) |
Pooled analysis; n=number of patients in the specific category; N=Number of patients with the specific pathogen isolated from the ABSSSI
* Primary endpoint of Trial 1
† Primary endpoint of Trial 2
Baseline bacteremia in the tedizolid arm with relevant pathogens included two subjects with MRSA, four subjects with MSSA, two subjects with S. pyogenes, one subject with S. agalactiae, and one subject with S. constellatus. All of these subjects were Responders at the 48-72 hour evaluation. At the Post-therapy Evaluation (PTE), 8 of 10 subjects were considered clinical successes. |
Table 13: Clinical Response at PTE by Baseline Pathogen from Two Phase 3 ABSSSI Adult Trials (MITT Population)
| Pathogen |
Clinical Response at PTE |
SIVEXTRO (200 mg)
n/N (%) |
Linezolid (1200 mg)
n/N (%) |
| Staphylococcus aureus |
291/329 (88.5) |
303/342 (88.6) |
| Methicillin-resistant S. aureus |
118/141 (83.7) |
119/146 (81.5) |
| Methicillin-susceptible S. aureus |
173/188 (92.0) |
186/198 (93.9) |
| Streptococcus pyogenes |
30/33 (90.9) |
19/20 (95.0) |
| Streptococcus anginosus Group |
21/30 (70.0) |
25/28 (89.3) |
| Streptococcus agalactiae |
8/9 (88.9) |
8/10 (80.0) |
| Enterococcus faecalis |
7/10 (70.0) |
4/4 (100.0) |
| Pooled analysis; n=number of patients in the specific category; N=Number of patients with the specific pathogen isolated from the ABSSSI Baseline bacteremia in the tedizolid arm with relevant pathogens included two subjects with MRSA, four subjects with MSSA, two subjects with S. pyogenes, one subject with S. agalactiae, and one subject with S. constellatus. All of these subjects were Responders at the 48-72 hour evaluation. At the Post-therapy Evaluation (PTE) 8 of 10 subjects were considered clinical successes. |
Pediatric Patients
The safety and efficacy of SIVEXTRO were investigated in Pediatric Trials 1 and 2. Pediatric Trial 1 included pediatric patients 12 to < 18 years of age who were investigated in a randomized, single blind, active-controlled trial of 120 patients with clinically documented ABSSSI (91 receiving tedizolid, 29 receiving comparator). Patients were randomized in a 3:1 ratio with stratification by geographic region to receive SIVEXTRO IV and/or oral therapy, dosed 200 mg once daily for 6 days, or comparator IV and/or oral therapy, dosed over 10 days. Comparator therapy was selected by the investigator from a list of 5 IV and 4 oral comparators per local standard of care. The most frequently used comparators were cefazolin (11 patients) and vancomycin (8 patients).
Additionally, Pediatric Trial 2 (NCT03176134) evaluated the safety and efficacy of SIVEXTRO in pediatric patients 4 months to <12 years of age in a randomized, single blind, active-controlled trial of 100 patients with clinically documented ABSSSI (75 receiving tedizolid, 25 receiving comparator). Patients were randomized in a 3:1 ratio to receive SIVEXTRO for 6 to 10 days or comparator for 10 to 14 days. SIVEXTRO (IV and/or oral) was dosed as a weight-based dose of 2 to 2.5 mg/kg every 12 hours or as 200 mg given once daily. Patients who received oral therapy received an oral suspension formulation that is not currently approved for use. Comparator therapy was selected from a pre-specified list by the investigator and dosed per local standard of care.
The primary objective of Pediatric Trials 1 and 2 was to evaluate the safety and tolerability of SIVEXTRO. The trials were not powered for comparative inferential efficacy analysis. Clinical response at the test of cure visit (Day 18-25) was assessed by a blinded investigator in the ITT population (all randomized patients). Clinical successes were required to have resolution or near resolution of all related signs and symptoms such that no further antibacterial therapy was needed. Early clinical response, defined as at least a 20% reduction in lesion size at 48-72 hours after start of treatment, was also assessed in the ITT population.
In Pediatric Trial 1, clinical success at test of cure was 96.7% (88/91) in the tedizolid group and 93.1% (27/29) in the comparator group (difference: 3.6%, 95% CI: -6.3, 13.5). Early clinical response at 48-72 hours was 92.3% (84/91) in the tedizolid group and 96.6% (28/29) in the comparator group (difference: -4.2%, 95% CI: -12.9, 4.4).
In Pediatric Trial 2, clinical success at test of cure was 93.3% (70/75) in the tedizolid group and 92.0% (23/25) in the comparator group (difference: 1.3%, 95% CI: -10.7, 13.4). Early clinical response was not adequately assessed in Pediatric Trial 2 because an in-person outpatient visit at this timepoint was not required during the COVID-19 pandemic.