Mechanism of Action
Emtricitabine is an antiviral drug. [See CLINICAL PHARMACOLOGY]
Pharmacokinetics
Adult Subjects
The pharmacokinetics of emtricitabine were evaluated in healthy volunteers
and HIV-1-infected individuals. 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 post-dose. 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 post-dose 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 < 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.
Special Populations
Race, Gender
The pharmacokinetics of emtricitabine were similar in adult male and female
patients 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 children, and the pharmacokinetic profile was characterized in
four age groups (Table 6). The emtricitabine exposure achieved in children 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 adults 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 x 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 patients 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 Patients and Neonates Receiving EMTRIVA Capsules or Oral Solution
| |
HIV-1-exposed Neonates |
HIV-1-infectedPediatric Patients |
| 3-24 mo |
25 mo-6 yr |
7-12yr |
13-17 yr |
| Age |
0-3 mo
(N=20)a |
(N=14) |
(N=19) |
(N=17) |
(N=27) |
| Formulation |
|
| Capsule (n) |
0 |
0 |
0 |
10 |
26 |
| Oral Solution (n) |
20 |
14 |
19 |
7 |
1 |
| Dose (mg/kg)b |
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 |
a.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.
b.Mean (range) |
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 patients with renal impairment
[See WARNINGS and PRECAUTIONS]. In adult
patients with creatinine clearance < 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
< 50 mL/min or in adult patients with ESRD who require dialysis [See DOSAGE
AND ADMINISTRATION]. The effects of renal impairment on emtricitabine
pharmacokinetics in pediatric patients are not known.
Table 7: Mean ± SD Pharmacokinetic Parameters in Adult Patients
with Varying Degrees of Renal Function
| Creatinine Clearance (mL/min) |
>80
(N=6) |
50-80
(N=6) |
30-49
(N=6) |
<30
(N=5) |
ESRDa <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 |
NAb |
a. ESRD patients requiringdialysis
b. 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 patients 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
disoproxil fumarate (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 Druga
| Coadministered Drug |
Dose of Coadministered Drug (mg) |
Emtricitabine Dose (mg) |
N |
% Change of Emtricitabine Pharmacokinetic Parametersb
(90% CI) |
| Cmax |
AUC |
Cmin |
| Tenofovir DF |
300 once daily x 7 days |
200 once daily x 7 days |
17 |
⇔ |
⇔ |
↑20
(↑12 to ↑29) |
| Zidovudine |
300 twice daily x 7 days |
200 once daily x 7 days |
27 |
⇔ |
⇔ |
⇔ |
| Indinavir |
800 x 1 |
200 x 1 |
12 |
⇔ |
⇔ |
NA |
| Famciclovir |
500 x 1 |
200 x 1 |
12 |
⇔ |
⇔ |
NA |
| Stavudine |
40 x 1 |
200 x 1 |
6 |
⇔ |
⇔ |
NA |
a.All interaction studies conducted in healthy
volunteers.
b↑= Increase; ↓= Decrease; ⇔= No Effect; NA =
Not Applicable |
Table 9: Drug Interactions: Change in Pharmacokinetic Parameters
for Coadministered Drug in the Presence of Emtricitabinea
| Coadministered Drug |
Dose of Coadministered Drug (mg) |
Emtricitabine Dose (mg) |
N |
% Change of Coadministered Drug Pharmacokinetic Parametersb
(90% CI) |
| Cmax |
AUC |
Cmin |
| Tenofovir DF |
300 once daily x 7 days |
200 once daily x 7 days |
17 |
⇔ |
⇔ |
⇔ |
| Zidovudine |
300 twice daily x 7 days |
200 once daily x 7 days |
27 |
↑17
(↑0 to ↑38) |
↑13
(↑5 to ↑20) |
⇔ |
| Indinavir |
800 x 1 |
200 x 1 |
12 |
⇔ |
⇔ |
NA |
| Famciclovir |
500 x 1 |
200 x 1 |
12 |
⇔ |
⇔ |
NA |
| Stavudine |
40 x 1 |
200 x 1 |
6 |
⇔ |
⇔ |
NA |
a. All interaction studies conducted inhealthy
volunteers.
b↑= Increase; ↓= Decrease; ⇔= No Effect; NA = Not Applicable
|
Microbiology
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 studies
of emtricitabine with nucleoside reverse transcriptase inhibitors (abacavir,
lamivudine, stavudine, tenofovir, zalcitabine, zidovudine), non-nucleoside reverse
transcriptase inhibitors (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 patients 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 patients treated with emtricitabine alone
or in combination with other antiretroviral agents. In a clinical study of treatment-naive
patients treated with EMTRIVA, didanosine, and efavirenz [See Clinical Studies],
viral isolates from 37.5% of patients 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 study of treatment-naive patients treated with either EMTRIVA,
VIREAD, and efavirenz or zidovudine/lamivudine and efavirenz [See Clinical
Studies], resistance analysis was performed on HIV-1 isolates from all confirmed
virologic failure patients with > 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 patient isolates in the EMTRIVA + VIREAD group
and in 10/29 analyzed patient isolates in the lamivudine/zidovudine group. Through
144 weeks of Study 934, no patients 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.
Clinical Studies
Treatment-Naive Adult Patients
Study 934
Data through 144 weeks are reported for Study 934, a randomized, open-label,
active-controlled multicenter study comparing EMTRIVA + VIREAD administered
in combination with efavirenz versus zidovudine/lamivudine fixed-dose combination
administered in combination with efavirenz in 511 antiretroviral-naive patients.
From Weeks 96 to 144 of the study, patients received emtricitabine + tenofovir
disoproxil fumarate (tenofovir DF) with efavirenz in place of EMTRIVA + tenofovir
DF with efavirenz. Patients 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). Patients were
stratified by baseline CD4+ cell count ( < or ≥ 200 cells/mm3);
41% had CD4+ cell counts < 200 cells/mm3 and 51% of
patients had baseline viral loads > 100,000 copies/mL. Treatment outcomes
through 48 and 144 weeks for those patients 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 + TD F+ EFV
(N=244) |
AZT/3TC + EFV
(N=243) |
EMTRIVA + TDF + EFV
(N=227)a |
AZT/3TC + EFV
(N=229)a |
| Responderb |
84% |
73% |
71% |
58% |
| Virologic failurec |
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 reasons4d |
10% |
14% |
20% |
22% |
a. Patients who were responders at Week 48 or Week
96 (HIV-1 RNA < 400 copies/mL) but did not consent to continue study after
Week 48 or Week 96 were excluded from analysis.
b. Patients achieved and maintained confirmed HIV-1 RNA < 400
copies/mL through Weeks 48 and 144.
c. Includes confirmed viral rebound and failure to achieve confirmed
< 400 copies/mL through Weeks 48 and 144.
d. Includes lost to follow-up, patient withdrawal, noncompliance,
protocol violation and other reasons. |
Through Week 48, 84% and 73% of patients 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 patients 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 study. In addition, 80% and 70% of patients 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 patients in the EMTRIVA + tenofovir DF group and 5 patients
in the zidovudine/lamivudine group experienced a new CDC Class C event (10 and
6 patients through 144 weeks).
Study 301A
Study 301A was a 48 week double-blind, active-controlled multicenter study
comparing EMTRIVA (200 mg once daily) administered in combination with didanosine
and efavirenz versus stavudine, didanosine and efavirenz in 571 antiretroviral
naive adult patients. Patients had a mean age of 36 years (range 18-69), 85%
were male, 52% Caucasian, 16% African-American and 26% Hispanic. Patients 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 patients had baseline viral loads > 100,000
copies/mL and 31% had CD4+ cell counts < 200 cells/mL. Treatment
outcomes are presented in Table 11 below.
Table 11: Outcomes of Randomized Treatment at Week 48 (Study
301A)
| Outcomes |
EMTRIVA + Didanosine + Efavirenz
(N=286) |
Stavudine + Didanosine + Efavirenz
(N=285) |
| Respondera |
81% (78%) |
68% (59%) |
| Virologic Failureb |
3% |
11% |
| Death |
0% |
<1% |
| Study Discontinuation Due to Adverse Event |
7% |
13% |
| Study Discontinuation for Other Reasonsc |
9% |
8% |
a.Patients achieved and maintained confirmed HIV
RNA<400 copies/mL (<50 copies/mL) through Week 48.
b.Includes patients who failed to achieve virologic suppressionor
rebounded after achieving virologic suppression.
c.Includes lost to follow-up, patient withdrawal,non-compliance,
protocol violation and other reasons. |
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 patients (1.7%) experienced a new
CDC Class C event, compared to 7 patients (2.5%) in the stavudine group.
Treatment-Experienced Adult Patients
Study 303
Study 303 was a 48 week, open-label, active-controlled multicenter study comparing
EMTRIVA (200 mg once daily) to lamivudine, in combination with stavudine or
zidovudine and a protease inhibitor or NNRTI in 440 adult patients who were
on a lamivudine-containing triple-antiretroviral drug regimen for at least 12
weeks prior to study entry and had HIV-1 RNA 400 copies/mL.
Patients were randomized 1:2 to continue therapy with lamivudine (150 mg twice
daily) or to switch to EMTRIVA (200 mg once daily). All patients were maintained
on their stable background regimen. Patients had a mean age of 42 years (range
22-80), 86% were male, 64% Caucasian, 21% African-American and 13% Hispanic.
Patients 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 below.
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) |
| Respondera |
77% (67%) |
82% (72%) |
| Virologic Failureb |
7% |
8% |
| Death |
0% |
<1% |
| Study Discontinuation Due to Adverse Event |
4% |
0% |
| Study Discontinuation for Other Reasons3c |
12% |
10% |
a.Patients achieved and maintained confirmed HIV
RNA<400 copies/mL (<50 copies/mL) through Week 48.
b.Includes patients who failed to achieve virologic suppressionor
rebounded after achieving virologic suppression.
c.Includes lost to follow-up, patient withdrawal, non-compliance,
protocol violation and other reasons. |
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 patients (0.7%) experienced a new CDC Class C event, compared to 2 patients (1.4%) in the lamivudine group.
Pediatric Patients
In three open-label, non-randomized clinical studies, emtricitabine was administered
to 169 HIV-1 infected treatment-naive and experienced (defined as virologically
suppressed on a lamivudine containing regimen for which emtricitabine was substituted
for lamivudine) patients between 3 months and 21 years of age. Patients received
once-daily EMTRIVA oral solution (6 mg/kg to a maximum of 240 mg/day) or EMTRIVA
capsules (a single 200 mg capsule once daily) in combination with at least two
other antiretroviral agents. Patients had a mean age of 7.9 years (range 0.3-21),
49% were male, 15% Caucasian, 61% Black and 24% Hispanic.
Patients had a median baseline HIV-1 RNA of 4.6 log10 copies/mL
(range 1.7-6.4) and a mean baseline CD4+ cell count of 745 cells/mm3
(range 2-2650). Through 48 weeks of therapy, the overall proportion of patients
who achieved and sustained an HIV-1 RNA < 400 copies/mL was 86%, and < 50
copies/mL was 73%. The mean increase from baseline in CD4+ cell count
was 232 cells/mm3 (-945, +1512). The adverse reaction profile observed
during these clinical trials was similar to that of adult patients, with the
exception of the occurrence of anemia and higher frequency of hyperpigmentation
in children [See ADVERSE REACTIONS].
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 x 4 days) during the first 3 months of life.
Emtricitabine exposures in neonates were similar to the exposures achieved in
patients > 3 months to 17 years [See CLINICAL PHARMACOLOGY]. During
the two short dosing periods on emtricitabine there were no safety issues identified
in the treated neonates.
All neonates were HIV-1 negative at the end of the study; the efficacy of emtricitabine in preventing or treating HIV-1 could not be determined.
Last updated on RxList: 7/7/2008