Clinical Trials in Adult Subjects
More than 2,000 adult subjects with HIV-1 infection have been treated with EMTRIVA alone or in combination with other antiretroviral agents for periods of 10 days to 200 weeks in clinical trials.
Because clinical trials are conducted under widely varying conditions, adverse reaction rates observed in the clinical trials of a drug cannot be directly compared to rates in the clinical trials of another drug and may not reflect the rates observed in practice.
The most common adverse reactions (incidence greater than or equal to 10%, any severity) identified from any of the three large, controlled clinical trials include headache, diarrhea nausea, fatigue, dizziness, depression, insomnia, abnormal dreams, rash, abdominal pain, asthenia, increased cough, and rhinitis.
Studies 301A and 303 – Treatment Emergent Adverse Reactions: The most common adverse reactions that occurred in subjects receiving EMTRIVA with other antiretroviral agents in clinical trials 301A and 303 were headache, diarrhea, nausea, and rash, which were generally of mild to moderate severity. Approximately 1% of subjects discontinued participation in the clinical trials due to these events. All adverse reactions were reported with similar frequency in EMTRIVA and control treatment groups with the exception of skin discoloration, which was reported with higher frequency in the EMTRIVA-treated group.
Skin discoloration, manifested by hyperpigmentation on the palms and/or soles, was generally mild and asymptomatic. The mechanism and clinical significance are unknown.
A summary of EMTRIVA treatment-emergent clinical adverse reactions in Studies 301A and 303 is provided in Table 2.
Table 2 Selected Treatment-Emergent Adverse Reactions (All Grades, Regardless of Causality) Reported in ≥3% of EMTRIVA-Treated Subjects in Either Study 301A or 303 (0–48 Weeks) | 303 | 301A |
|---|
| EMTRIVA + ZDV/d4T + NNRTI/PI (N=294) | Lamivudine + ZDV/d4T + NNRTI/PI (N=146) | EMTRIVA + didanosine + efavirenz (N=286) | Stavudine + didanosine + efavirenz (N=285) |
|---|
| Body as a Whole | | | | |
| Abdominal pain | 8% | 11% | 14% | 17% |
| Asthenia | 16% | 10% | 12% | 17% |
| Headache | 13% | 6% | 22% | 25% |
| Digestive System | | | | |
| Diarrhea | 23% | 18% | 23% | 32% |
| Dyspepsia | 4% | 5% | 8% | 12% |
| Nausea | 18% | 12% | 13% | 23% |
| Vomiting | 9% | 7% | 9% | 12% |
| Musculoskeletal | | | | |
| Arthralgia | 3% | 4% | 5% | 6% |
| Myalgia | 4% | 4% | 6% | 3% |
| Nervous System | | | | |
| Abnormal dreams | 2% | <1% | 11% | 19% |
| Depressive disorders | 6% | 10% | 9% | 13% |
| Dizziness | 4% | 5% | 25% | 26% |
| Insomnia | 7% | 3% | 16% | 21% |
| Neuropathy/peripheral neuritis | 4% | 3% | 4% | 13% |
| Paresthesia | 5% | 7% | 6% | 12% |
| Respiratory | | | | |
| Increased cough | 14% | 11% | 14% | 8% |
| Rhinitis | 18% | 12% | 12% | 10% |
| Skin | | | | |
| Rash event Rash event includes rash, pruritus, maculopapular rash, urticaria, vesiculobullous rash, pustular rash, and allergic reaction. | 17% | 14% | 30% | 33% |
Studies 301A and 303 – Laboratory Abnormalities: Laboratory abnormalities in these trials occurred with similar frequency in the EMTRIVA and comparator groups. A summary of Grades 3–4 laboratory abnormalities is provided in Table 3.
Table 3 Treatment-Emergent Grades 3–4 Laboratory Abnormalities Reported in ≥1% of EMTRIVA-Treated Subjects in Either Study 301A or 303 | 303 | 301A |
|---|
| EMTRIVA + ZDV/d4T + NNRTI/PI (N=294) | Lamivudine + ZDV/d4T + NNRTI/PI (N=146) | EMTRIVA + Didanosine + Efavirenz (N=286) | Stavudine + Didanosine + Efavirenz (N=285) |
|---|
| Percentage with grade 3 or grade 4 laboratory abnormality | 31% | 28% | 34% | 38% |
| ALT (>5.0 × ULN ULN = Upper limit of normal ) | 2% | 1% | 5% | 6% |
| AST (>5.0 × ULN) | 3% | <1% | 6% | 9% |
| Bilirubin (>2.5 × ULN) | 1% | 2% | <1% | <1% |
| Creatine kinase (>4.0 × ULN) | 11% | 14% | 12% | 11% |
| Neutrophils (<750 mm3) | 5% | 3% | 5% | 7% |
| Pancreatic amylase (>2.0 × ULN) | 2% | 2% | <1% | 1% |
| Serum amylase (>2.0 × ULN) | 2% | 2% | 5% | 10% |
| Serum glucose <40 or >250 mg/dL) | 3% | 3% | 2% | 3% |
| Serum lipase (>2.0 × ULN) | <1% | <1% | 1% | 2% |
| Triglycerides (>750 mg/dL) | 10% | 8% | 9% | 6% |
Study 934 – Treatment Emergent Adverse Reactions: In Study 934, 511 antiretroviral-naïve subjects received either VIREAD® + EMTRIVA administered in combination with efavirenz (N=257) or zidovudine/lamivudine administered in combination with efavirenz (N=254). Adverse reactions observed in this trial were generally consistent with those seen in previous trials in treatment-experienced or treatment-naïve subjects (Table 4).
Table 4 Selected Treatment-Emergent Adverse ReactionsFrequencies of adverse reactions are based on all treatment-emergent adverse events, regardless of relationship to study drug.
(Grades 2–4) Reported in ≥5% in Any Treatment Group in Study 934 (0–144 Weeks) | TDF From Weeks 96 to 144 of the trial, subjects received TRUVADA with efavirenz in place of VIREAD + EMTRIVA with efavirenz. + EMTRIVA + EFV | AZT/3TC + EFV |
|---|
| N=257 | N=254 |
|---|
| Gastrointestinal Disorder | | |
| Diarrhea | 9% | 5% |
| Nausea | 9% | 7% |
| Vomiting | 2% | 5% |
| General Disorders and Administration Site Condition | | |
| Fatigue | 9% | 8% |
| Infections and Infestations | | |
| Sinusitis | 8% | 4% |
| Upper respiratory tract infections | 8% | 5% |
| Nasopharyngitis | 5% | 3% |
| Nervous System Disorders | | |
| Headache | 6% | 5% |
| Dizziness | 8% | 7% |
| Psychiatric Disorders | | |
| Depression | 9% | 7% |
| Insomnia | 5% | 7% |
| Skin and Subcutaneous Tissue Disorders | | |
| Rash event Rash event includes rash, exfoliative rash, rash generalized, rash macular, rash maculo-papular, rash pruritic, and rash vesicular. | 7% | 9% |
Study 934 – Laboratory Abnormalities: Significant laboratory abnormalities observed in this trial are shown in Table 5.
Table 5 Significant Laboratory Abnormalities Reported in ≥1% of Subjects in Any Treatment Group in Study 934 (0–144 Weeks) | TDF From Weeks 96 to 144 of the trial, subjects received TRUVADA with efavirenz in place of VIREAD + EMTRIVA with efavirenz. + EMTRIVA + EFV | AZT/3TC + EFV |
|---|
| N=257 | N=254 |
|---|
| Any ≥ Grade 3 Laboratory Abnormality | 30% | 26% |
| Fasting Cholesterol (>240 mg/dL) | 22% | 24% |
| Creatine Kinase | | |
| (M: >990 U/L) | 9% | 7% |
| (F: >845 U/L) | | |
| Serum Amylase (>175 U/L) | 8% | 4% |
| Alkaline Phosphatase (>550 U/L) | 1% | 0% |
| AST | | |
| (M: >180 U/L) | 3% | 3% |
| (F: >170 U/L) | | |
| ALT | | |
| (M: >215 U/L) | 2% | 3% |
| (F: >170 U/L) | | |
| Hemoglobin (<8.0 mg/dL) | 0% | 4% |
| Hyperglycemia (>250 mg/dL) | 2% | 1% |
| Hematuria (>75 RBC/HPF) | 3% | 2% |
| Glycosuria (3+) | <1% | 1% |
| Neutrophils (<750/mm3) | 3% | 5% |
| Fasting Triglycerides (>750 mg/dL) | 4% | 2% |
Clinical Trials in Pediatric Subjects
Assessment of adverse reactions is based on data from Study 203, an open label, uncontrolled trial of 116 HIV-1 infected pediatric subjects who received emtricitabine through 48 weeks. The adverse reaction profile in pediatric subjects was generally comparable to that observed in clinical trials of EMTRIVA in adult subjects [See Adverse Reactions (6.1)]. Hyperpigmentation was more frequent in children. Additional adverse reactions identified from this trial include anemia.
Selected treatment-emergent adverse events, regardless of causality, reported in subjects during 48 weeks of treatment were the following: infection (44%), hyperpigmentation (32%), increased cough (28%), vomiting (23%), otitis media (23%), rash (21%), rhinitis (20%), diarrhea (20%), fever (18%), pneumonia (15%), gastroenteritis (11%), abdominal pain (10%), and anemia (7%). Treatment-emergent grades 3–4 laboratory abnormalities were experienced by 9% of pediatric subjects, including elevated amylase (>2.0 × ULN) (n=4), decreased neutrophils (<750/mm3) (n=3), elevated ALT (>5 × ULN) (n=2), elevated CPK (>4 × ULN) (n=2) and one subject each with elevated bilirubin (>3.0 × ULN), elevated GGT (>10 × ULN), elevated lipase (>2.5 × ULN), decreased hemoglobin (<7 g/dL), and decreased glucose (<40 mg/dL).
Antiretroviral Pregnancy Registry: To monitor fetal outcomes of pregnant women exposed to EMTRIVA, an Antiretroviral Pregnancy Registry has been established. Healthcare providers are encouraged to register patients by calling 1–800–258–4263.
Adults
The pharmacokinetics of emtricitabine were evaluated in healthy subjects and HIV-1-infected subjects. Emtricitabine pharmacokinetics are similar between these populations.
Figure 1 shows the mean steady-state plasma emtricitabine concentration-time profile in 20 HIV-1-infected subjects receiving EMTRIVA capsules.
Figure 1 Mean (± 95% CI) Steady-State Plasma Emtricitabine Concentrations in HIV-1 Infected Adults (N=20)
Absorption
Emtricitabine is rapidly and extensively absorbed following oral administration, with peak plasma concentrations occurring at 1–2 hours postdose. Following multiple dose oral administration of EMTRIVA capsules to 20 HIV-1 infected subjects, the (mean ± SD) steady-state plasma emtricitabine peak concentration (Cmax) was 1.8 ± 0.7 µg/mL and the area-under the plasma concentration-time curve over a 24-hour dosing interval (AUC) was 10.0 ± 3.1 µg∙hr/mL. The mean steady-state plasma trough concentration at 24 hours postdose was 0.09 µg/mL. The mean absolute bioavailability of EMTRIVA capsules was 93%, while the mean absolute bioavailability of EMTRIVA oral solution was 75%. The relative bioavailability of EMTRIVA oral solution was approximately 80% of EMTRIVA capsules.
The multiple dose pharmacokinetics of emtricitabine are dose proportional over a dose range of 25–200 mg.
Distribution
In vitro binding of emtricitabine to human plasma proteins was less than 4% and independent of concentration over the range of 0.02–200 µg/mL. At peak plasma concentration, the mean plasma to blood drug concentration ratio was ~1.0 and the mean semen to plasma drug concentration ratio was ~4.0.
Metabolism
In vitro studies indicate that emtricitabine is not an inhibitor of human CYP450 enzymes. Following administration of 14C-emtricitabine, complete recovery of the dose was achieved in urine (~86%) and feces (~14%). Thirteen percent (13%) of the dose was recovered in urine as three putative metabolites. The biotransformation of emtricitabine includes oxidation of the thiol moiety to form the 3'-sulfoxide diastereomers (~9% of dose) and conjugation with glucuronic acid to form 2'-O-glucuronide (~4% of dose). No other metabolites were identifiable.
Elimination
The plasma emtricitabine half-life is approximately 10 hours. The renal clearance of emtricitabine is greater than the estimated creatinine clearance, suggesting elimination by both glomerular filtration and active tubular secretion. There may be competition for elimination with other compounds that are also renally eliminated.
Effects of Food on Oral Absorption
EMTRIVA capsules and oral solution may be taken with or without food. Emtricitabine systemic exposure (AUC) was unaffected while Cmax decreased by 29% when EMTRIVA capsules were administered with food (an approximately 1000 kcal high-fat meal). Emtricitabine systemic exposure (AUC) and Cmax were unaffected when 200 mg EMTRIVA oral solution was administered with either a high-fat or low-fat meal.
Specific Populations
Race, Gender
The pharmacokinetics of emtricitabine were similar in adult male and female subjects, and no pharmacokinetic differences due to race have been identified.
Pediatric Patients
The pharmacokinetics of emtricitabine at steady state were determined in 77 HIV-1 infected pediatric subjects, and the pharmacokinetic profile was characterized in four age groups (Table 6). The emtricitabine exposure achieved in pediatric subjects receiving a daily dose of 6 mg/kg up to a maximum of 240 mg oral solution or a 200 mg capsule is similar to exposures achieved in adult subjects receiving a once-daily dose of 200 mg.
The pharmacokinetics of emtricitabine were studied in 20 neonates born to HIV-1 positive mothers. Each mother received prenatal and intrapartum combination antiretroviral therapy. Neonates received up to 6 weeks of zidovudine prophylactically after birth. The neonates were administered two short courses of emtricitabine oral solution (each 3 mg/kg once daily × 4 days) during the first 3 months of life. The AUC observed in neonates who received a daily dose of 3 mg/kg of emtricitabine was similar to the AUC observed in pediatric subjects aged 3 months to 17 years who received a daily dose of emtricitabine as a 6 mg/kg oral solution up to 240 mg or as a 200 mg capsule (Table 6).
Table 6 Mean ± SD Pharmacokinetic Parameters by Age Groups for Pediatric Subjects and Neonates Receiving EMTRIVA Capsules or Oral Solution | HIV-1-exposed Neonates | HIV-1 Infected Pediatric Subjects |
|---|
| Age | 0–3 mo (N=20)Two pharmacokinetic evaluations were conducted in 20 neonates over the first 3 months of life. Median (range) age of infant on day of pharmacokinetic evaluation was 26 (5–81) days. | 3–24 mo (N=14) | 25 mo–6 yr (N=19) | 7–12yr (N=17) | 13–17 yr (N=27) |
|---|
| Formulation | | | | | |
| Capsule (n) | 0 | 0 | 0 | 10 | 26 |
| Oral Solution (n) | 20 | 14 | 19 | 7 | 1 |
| Dose (mg/kg) Mean (range). | 3.1 (2.9–3.4) | 6.1 (5.5–6.8) | 6.1 (5.6–6.7) | 5.6 (3.1–6.6) | 4.4 (1.8–7.0) |
| Cmax (µg/mL) | 1.6 ± 0.6 | 1.9 ± 0.6 | 1.9 ± 0.7 | 2.7 ± 0.8 | 2.7 ± 0.9 |
| AUC (µg∙hr/mL) | 11.0 ± 4.2 | 8.7 ± 3.2 | 9.0 ± 3.0 | 12.6 ± 3.5 | 12.6 ± 5.4 |
| T1/2 (hr) | 12.1 ± 3.1 | 8.9 ± 3.2 | 11.3 ± 6.4 | 8.2 ± 3.2 | 8.9 ± 3.3 |
Geriatric Patients
The pharmacokinetics of emtricitabine have not been fully evaluated in the elderly.
Patients with Impaired Renal Function
The pharmacokinetics of emtricitabine are altered in subjects with renal impairment [See Warnings and Precautions (5.3)]. In adult subjects with creatinine clearance less than 50 mL/min or with end-stage renal disease (ESRD) requiring dialysis, Cmax and AUC of emtricitabine were increased due to a reduction in renal clearance (Table 7). It is recommended that the dosing interval for EMTRIVA be modified in adult patients with creatinine clearance less than 50 mL/min or in adult patients with ESRD who require dialysis [See Dosage and Administration (2.5)]. The effects of renal impairment on emtricitabine pharmacokinetics in pediatric patients are not known.
Table 7 Mean ± SD Pharmacokinetic Parameters in Adult Subjects with Varying Degrees of Renal FunctionCreatinine Clearance (mL/min) | >80 (N=6) | 50–80 (N=6) | 30–49 (N=6) | <30 (N=5) | ESRD ESRD subjects requiring dialysis <30 (N=5) |
|---|
| Baseline creatinine clearance (mL/min) | 107 ± 21 | 59.8 ± 6.5 | 40.9 ± 5.1 | 22.9 ± 5.3 | 8.8 ± 1.4 |
| Cmax (µg/mL) | 2.2 ± 0.6 | 3.8 ± 0.9 | 3.2 ± 0.6 | 2.8 ± 0.7 | 2.8 ± 0.5 |
| AUC (µg∙hr/mL) | 11.8 ± 2.9 | 19.9 ± 1.2 | 25.1 ± 5.7 | 33.7± 2.1 | 53.2 ± 9.9 |
| CL/F (mL/min) | 302 ± 94 | 168 ± 10 | 138 ± 28 | 99 ± 6 | 64 ± 12 |
| CLr (mL/min) | 213 ± 89 | 121 ± 39 | 69 ± 32 | 30 ± 11 | NA NA = Not Applicable |
Hemodialysis: Hemodialysis treatment removes approximately 30% of the emtricitabine dose over a 3-hour dialysis period starting within 1.5 hours of emtricitabine dosing (blood flow rate of 400 mL/min and a dialysate flow rate of 600 mL/min). It is not known whether emtricitabine can be removed by peritoneal dialysis.
Patients with Hepatic Impairment
The pharmacokinetics of emtricitabine have not been studied in subjects with hepatic impairment; however, emtricitabine is not metabolized by liver enzymes, so the impact of liver impairment should be limited.
Assessment of Drug Interactions
At concentrations up to 14-fold higher than those observed in vivo, emtricitabine did not inhibit in vitro drug metabolism mediated by any of the following human CYP isoforms: CYP1A2, CYP2A6, CYP2B6, CYP2C9, CYP2C19, CYP2D6, and CYP3A4.
Emtricitabine did not inhibit the enzyme responsible for glucuronidation (uridine-5'-disphosphoglucuronyl transferase). Based on the results of these in vitro experiments and the known elimination pathways of emtricitabine, the potential for CYP-mediated interactions involving emtricitabine with other medicinal products is low.
EMTRIVA has been evaluated in healthy volunteers in combination with tenofovir DF, zidovudine, indinavir, famciclovir, and stavudine. Tables 8 and 9 summarize the pharmacokinetic effects of coadministered drug on emtricitabine pharmacokinetics and effects of emtricitabine on the pharmacokinetics of coadministered drug.
Table 8 Drug Interactions: Change in Pharmacokinetic Parameters for Emtricitabine in the Presence of the Coadministered DrugAll interaction trials conducted in healthy volunteers.
| Coadministered Drug | Dose of Coadministered Drug (mg) | Emtricitabine Dose (mg) | N | % Change of Emtricitabine Pharmacokinetic Parameters ↑ = Increase; ⇔ = No Effect; NA = Not Applicable (90% CI) |
|---|
| Cmax | AUC | Cmin |
|---|
| Tenofovir DF | 300 once daily × 7 days | 200 once daily × 7 days | 17 | ⇔ | ⇔ | ↑ 20 (↑ 12 to ↑ 29) |
| Zidovudine | 300 twice daily × 7 days | 200 once daily × 7 days | 27 | ⇔ | ⇔ | ⇔ |
| Indinavir | 800 × 1 | 200 × 1 | 12 | ⇔ | ⇔ | NA |
| Famciclovir | 500 × 1 | 200 × 1 | 12 | ⇔ | ⇔ | NA |
| Stavudine | 40 × 1 | 200 × 1 | 6 | ⇔ | ⇔ | NA |
Table 9 Drug Interactions: Change in Pharmacokinetic Parameters for Coadministered Drug in the Presence of EmtricitabineAll interaction trials conducted in healthy volunteers.
| Coadministered Drug | Dose of Coadministered Drug (mg) | Emtricitabine Dose (mg) | N | % Change of Coadministered Drug Pharmacokinetic Parameters ↑ = Increase; ⇔ = No Effect; NA = Not Applicable (90% CI) |
|---|
| Cmax | AUC | Cmin |
|---|
| Tenofovir DF | 300 once daily × 7 days | 200 once daily × 7 days | 17 | ⇔ | ⇔ | ⇔ |
| Zidovudine | 300 twice daily × 7 days | 200 once daily × 7 days | 27 | ↑ 17 (↑ 0 to ↑ 38) | ↑ 13 (↑ 5 to↑ 20) | ⇔ |
| Indinavir | 800 × 1 | 200 × 1 | 12 | ⇔ | ⇔ | NA |
| Famciclovir | 500 × 1 | 200 × 1 | 12 | ⇔ | ⇔ | NA |
| Stavudine | 40 × 1 | 200 × 1 | 6 | ⇔ | ⇔ | NA |
Mechanism of Action
Emtricitabine, a synthetic nucleoside analog of cytidine, is phosphorylated by cellular enzymes to form emtricitabine 5'-triphosphate. Emtricitabine 5'-triphosphate inhibits the activity of the HIV-1 reverse transcriptase by competing with the natural substrate deoxycytidine 5'-triphosphate and by being incorporated into nascent viral DNA which results in chain termination. Emtricitabine 5'-triphosphate is a weak inhibitor of mammalian DNA polymerase α, β, ε, and mitochondrial DNA polymerase γ.
Antiviral Activity
The antiviral activity in cell culture of emtricitabine against laboratory and clinical isolates of HIV-1 was assessed in lymphoblastoid cell lines, the MAGI-CCR5 cell line, and peripheral blood mononuclear cells. The 50% effective concentration (EC50) value for emtricitabine was in the range of 0.0013–0.64 µM (0.0003–0.158 µg/mL). In drug combination trials of emtricitabine with nucleoside reverse transcriptase inhibitors (NRTIs) (abacavir, lamivudine, stavudine, tenofovir, zalcitabine, zidovudine), non-nucleoside reverse transcriptase inhibitors (NNRTIs) (delavirdine, efavirenz, nevirapine), and protease inhibitors (amprenavir, nelfinavir, ritonavir, saquinavir), additive to synergistic effects were observed. Emtricitabine displayed antiviral activity in cell culture against HIV-1 clades A, B, C, D, E, F, and G (EC50 values ranged from 0.007–0.075 µM) and showed strain-specific activity against HIV-2 (EC50 values ranged from 0.007–1.5 µM).
The in vivo activity of emtricitabine was evaluated in two clinical trials in which 101 subjects were administered 25–400 mg a day of EMTRIVA as monotherapy for 10–14 days. A dose-related antiviral effect was observed, with a median decrease from baseline in plasma HIV-1 RNA of 1.3 log10 at a dose of 25 mg once daily and 1.7 log10 to 1.9 log10 at a dose of 200 mg once daily or twice daily.
Resistance
Emtricitabine-resistant isolates of HIV-1 have been selected in cell culture and in vivo. Genotypic analysis of these isolates showed that the reduced susceptibility to emtricitabine was associated with a substitution in the HIV-1 reverse transcriptase gene at codon 184 which resulted in an amino acid substitution of methionine by valine or isoleucine (M184V/I).
Emtricitabine-resistant isolates of HIV-1 have been recovered from some subjects treated with emtricitabine alone or in combination with other antiretroviral agents. In a clinical trial of treatment-naïve subjects treated with EMTRIVA, didanosine, and efavirenz [See Clinical Studies (14.1)], viral isolates from 37.5% of subjects with virologic failure showed reduced susceptibility to emtricitabine. Genotypic analysis of these isolates showed that the resistance was due to M184V/I substitutions in the HIV-1 reverse transcriptase gene.
In a clinical trial of treatment-naïve subjects treated with either EMTRIVA, VIREAD, and efavirenz or zidovudine/lamivudine and efavirenz [See Clinical Studies (14.1)], resistance analysis was performed on HIV-1 isolates from all confirmed virologic failure subjects with greater than 400 copies/mL of HIV-1 RNA at Week 144 or early discontinuation. Development of efavirenz resistance-associated substitutions occurred most frequently and was similar between the treatment arms. The M184V amino acid substitution, associated with resistance to EMTRIVA and lamivudine, was observed in 2/19 analyzed subject isolates in the EMTRIVA + VIREAD group and in 10/29 analyzed subject isolates in the lamivudine/zidovudine group. Through 144 weeks of Study 934, no subjects have developed a detectable K65R substitution in their HIV-1 as analyzed through standard genotypic analysis.
Cross Resistance
Cross-resistance among certain nucleoside analog reverse transcriptase inhibitors has been recognized. Emtricitabine-resistant isolates (M184V/I) were cross-resistant to lamivudine and zalcitabine but retained sensitivity in cell culture to didanosine, stavudine, tenofovir, zidovudine, and NNRTIs (delavirdine, efavirenz, and nevirapine). HIV-1 isolates containing the K65R substitution, selected in vivo by abacavir, didanosine, tenofovir, and zalcitabine, demonstrated reduced susceptibility to inhibition by emtricitabine. Viruses harboring substitutions conferring reduced susceptibility to stavudine and zidovudine (M41L, D67N, K70R, L210W, T215Y/F, K219Q/E) or didanosine (L74V) remained sensitive to emtricitabine. HIV-1 containing the K103N substitution associated with resistance to NNRTIs was susceptible to emtricitabine.
Study 934
Data through 144 weeks are reported for Study 934, a randomized, open-label, active-controlled multicenter clinical trial comparing EMTRIVA + tenofovir DF administered in combination with efavirenz versus zidovudine/lamivudine fixed-dose combination administered in combination with efavirenz in 511 antiretroviral- naïve subjects. From Weeks 96 to 144 of the trial, subjects received EMTRIVA/tenofovir DF fixed-dose combination with efavirenz in place of EMTRIVA + tenofovir DF with efavirenz. Subjects had a mean age of 38 years (range 18–80); 86% were male, 59% were Caucasian, and 23% were Black. The mean baseline CD4+ cell count was 245 cells/mm3 (range 2–1191) and median baseline plasma HIV-1 RNA was 5.01 log10 copies/mL (range 3.56–6.54). Subjects were stratified by baseline CD4+ cell count (< or ≥200 cells/mm3); 41% had CD4+ cell counts <200 cells/mm3 and 51% of subjects had baseline viral loads >100,000 copies/mL. Treatment outcomes through 48 and 144 weeks for those subjects who did not have efavirenz resistance at baseline are presented in Table 10.
Table 10 Outcomes of Randomized Treatment at Week 48 and 144 (Study 934)| Outcomes | Week 48 | Week 144 |
|---|
EMTRIVA +TDF +EFV (N=244) | AZT/3TC +EFV (N=243) | EMTRIVA +TDF +EFV (N=227) | AZT/3TC +EFV (N=229) |
|---|
| Responder | 84% | 73% | 71% | 58% |
| Virologic failure Includes confirmed viral rebound and failure to achieve confirmed <400 copies/mL through Weeks 48 and 144. | 2% | 4% | 3% | 6% |
| Rebound | 1% | 3% | 2% | 5% |
| Never suppressed | 0% | 0% | 0% | 0% |
| Change in antiretroviral regimen | 1% | 1% | 1% | 1% |
| Death | <1% | 1% | 1% | 1% |
| Discontinued due to adverse event | 4% | 9% | 5% | 12% |
| Discontinued for other reasons Includes lost to follow-up, subject withdrawal, noncompliance, protocol violation and other reasons. | 10% | 14% | 20% | 22% |
Through Week 48, 84%, and 73% of subjects in the EMTRIVA + tenofovir DF group and the zidovudine/lamivudine group, respectively, achieved and maintained HIV-1 RNA <400 copies/mL (71% and 58% through Week 144). The difference in the proportion of subjects who achieved and maintained HIV-1 RNA <400 copies/mL through 48 weeks largely results from the higher number of discontinuations due to adverse events and other reasons in the zidovudine/lamivudine group in this open-label trial. In addition, 80% and 70% of subjects in the EMTRIVA + tenofovir DF group and the zidovudine/lamivudine group, respectively, achieved and maintained HIV-1 RNA <50 copies/mL through Week 48 (64% and 56% through Week 144). The mean increase from baseline in CD4+ cell count was 190 cells/mm3 in the EMTRIVA + tenofovir DF group and 158 cells/mm3 in the zidovudine/lamivudine group at Week 48 (312 and 271 cells/mm3 at Week 144).
Through 48 weeks, 7 subjects in the EMTRIVA + tenofovir DF group and 5 subjects in the zidovudine/lamivudine group experienced a new CDC Class C event (10 and 6 subjects through 144 weeks).
Study 301A
Study 301A was a 48-week double-blind, active-controlled, multicenter clinical trial comparing EMTRIVA (200 mg once daily) administered in combination with didanosine and efavirenz versus stavudine, didanosine, and efavirenz in 571 antiretroviral naïve adult subjects. Subjects had a mean age of 36 years (range 18–69); 85% were male, 52% Caucasian, 16% African-American, and 26% Hispanic. Subjects had a mean baseline CD4+ cell count of 318 cells/mm3 (range 5–1317) and a median baseline plasma HIV-1 RNA of 4.9 log10 copies/mL (range 2.6–7.0). Thirty-eight percent of subjects had baseline viral loads >100,000 copies/mL and 31% had CD4+ cell counts <200 cells/mL. Treatment outcomes are presented in Table 11.
Table 11 Outcomes of Randomized Treatment at Week 48 (Study 301A)| Outcomes | EMTRIVA + Didanosine + Efavirenz (N=286) | Stavudine + Didanosine + Efavirenz (N=285) |
|---|
| Responder Subjects achieved and maintained confirmed HIV RNA <400 copies/mL (<50 copies/mL) through Week 48. | 81% (78%) | 68% (59%) |
| Virologic Failure Includes subjects who failed to achieve virologic suppression or rebounded after achieving virologic suppression. | 3% | 11% |
| Death | 0% | <1% |
| Discontinuation Due to Adverse Event | 7% | 13% |
| Discontinuation for Other Reasons Includes lost to follow-up, subject withdrawal, non-compliance, protocol violation, and other reasons. | 9% | 8% |
The mean increase from baseline in CD4+ cell count was 168 cells/mm3 for the EMTRIVA arm and 134 cells/mm3 for the stavudine arm.
Through 48 weeks, in the EMTRIVA group, 5 subjects (1.7%) experienced a new CDC Class C event compared to 7 subjects (2.5%) in the stavudine group.
Study 303
Study 303 was a 48 week, open-label, active-controlled, multicenter clinical trial comparing EMTRIVA (200 mg once daily) to lamivudine, in combination with stavudine or zidovudine and a protease inhibitor or NNRTI in 440 adult subjects who were on a lamivudine-containing triple-antiretroviral drug regimen for at least 12 weeks prior to trial entry and had HIV-1 RNA ≤400 copies/mL.
Subjects were randomized 1:2 to continue therapy with lamivudine (150 mg twice daily) or to switch to EMTRIVA (200 mg once daily). All subjects were maintained on their stable background regimen. Subjects had a mean age of 42 years (range 22–80); 86% were male, 64% Caucasian, 21% African-American, and 13% Hispanic. Subjects had a mean baseline CD4+ cell count of 527 cells/mm3 (range 37–1909), and a median baseline plasma HIV-1 RNA of 1.7 log10 copies/mL (range 1.7–4.0).
The median duration of prior antiretroviral therapy was 27.6 months. Treatment outcomes are presented in Table 12.
Table 12 Outcomes of Randomized Treatment at Week 48 (Study 303)| Outcomes | EMTRIVA + ZDV/d4T + NNRTI/PI (N=294) | Lamivudine + ZDV/d4T + NNRTI/PI (N=146) |
|---|
| Responder Subjects achieved and maintained confirmed HIV RNA <400 copies/mL (<50 copies/mL) through Week 48. | 77% (67%) | 82% (72%) |
| Virologic Failure Includes subjects who failed to achieve virologic suppression or rebounded after achieving virologic suppression. | 7% | 8% |
| Death | 0% | <1% |
| Discontinuation Due to Adverse Event | 4% | 0% |
| Discontinuation for Other Reasons Includes lost to follow-up, subject withdrawal, non-compliance, protocol violation, and other reasons. | 12% | 10% |
The mean increase from baseline in CD4+ cell count was 29 cells/mm3 for the EMTRIVA arm and 61 cells/mm3 for the lamivudine arm.
Through 48 weeks, in the EMTRIVA group 2 subjects (0.7%) experienced a new CDC Class C event compared to 2 subjects (1.4%) in the lamivudine group.
Capsules
The size 1 hard gelatin capsules with a blue cap and white body contain 200 mg of emtricitabine, are printed with "200 mg" in black on the cap and "GILEAD" and the corporate logo in black on the body, and are available in unit of use bottles (closed with induction sealed child-resistant closures) of:
- 30 capsules (NDC 61958–0601–1).
Oral Solution
The oral solution is a clear, orange to dark orange liquid, contains 10 mg/mL of emtricitabine, and is available in unit of use plastic, amber bottles (closed with child resistant closures and packaged with a marked dosing cup) of:
- 170 mL (NDC 61958–0602–1).
© 2017 Gilead Sciences, Inc. All rights reserved.
Manufactured for and distributed by:
Gilead Sciences, Inc.
Foster City, CA 94404
COMPLERA, DESCOVY, EMTRIVA, GENVOYA, ODEFSEY, STRIBILD, TRUVADA, and VIREAD are trademarks of Gilead Sciences, Inc., or its related companies. ATRIPLA is a trademark of Bristol-Myers Squibb & Gilead Sciences, LLC. All other trademarks referenced herein are the property of their respective owners.
21-500-896-GS-018