Microbiology
Mechanism of Action
Nelfinavir is an inhibitor of the HIV-1 protease. Inhibition of the viral protease
prevents cleavage of the gag and gag-pol polyprotein resulting
in the production of immature, non-infectious virus.
Antiviral Activity In Vitro
The antiviral activity of nelfinavir in vitro has been demonstrated
in both acute and/or chronic HIV infections in lymphoblastoid cell lines, peripheral
blood lymphocytes and monocytes/macrophages. Nelfinavir was found to be active
against several laboratory strains and clinical isolates of HIV-1 and the HIV-2
strain ROD. The EC95 (95% effective concentration) of nelfinavir ranged from
7 to 196 nM. Drug combination studies with protease inhibitors showed nelfinavir
had antagonistic interactions with indinavir, additive interactions with ritonavir
or saquinavir and synergistic interactions with amprenavir and lopinavir. Minimal
to no cellular cytotoxicity was observed with any of these protease ihibitors
alone or in combination with nelfinavir. In combination with reverse transcriptase
inhibitors, nelfinavir demonstrated additive (didanosine or stavudine) to synergistic
(abacavir, delavirdine, efavirenz, emtricitabine, lamivudine, nevirapine, tenofovir,
zalcitabine or zidovudine) antiviral activity in vitro without enhanced
cytotoxicity. Nelfinavir's anti-HIV activity was not antagonized by the anti-HCV
drug ribavirin.
Drug Resistance
HIV-1 isolates with reduced susceptibility to nelfinavir have been selected
in vitro. HIV isolates from selected patients treated with nelfinavir
alone or in combination with reverse transcriptase inhibitors were monitored
for phenotypic (n=19) and genotypic (n=195, 157 of which were evaluable) changes
in clinical trials over a period of 2 to 82 weeks. One or more viral protease
mutations at amino acid positions 30, 35, 36, 46, 71, 77 and 88 were detected
in the HIV-1 of > 10% of patients with evaluable isolates. The overall incidence
of the D30N mutation in the viral protease of evaluable isolates (n=157) from
patients receiving nelfinavir monotherapy or nelfinavir in combination with
zidovudine and lamivudine or stavudine was 54.8%. The overall incidence of other
mutations associated with primary protease inhibitor resistance was 9.6% for
the L90M substitution whereas substitutions at 48, 82, or 84 were not observed.
Of the 19 clinical isolates for which both phenotypic and genotypic analyses
were performed, 9 showed reduced susceptibility (5- to 93-fold) to nelfinavir
in vitro. All 9 patient isolates possessed one or more mutations in the
viral protease gene. Amino acid position 30 appeared to be the most frequent
mutation site.
Cross-resistance
Non-clinical Studies- Patient-derived recombinant HIV isolates
containing the D30N mutation (n=4) and demonstrating high-level ( > 10-fold)
NFVresistance remained susceptible ( < 2.5-fold resistance) to amprenavir,
indinavir, lopinavir, and saquinavir, in vitro. Patient-derived recombinant
HIV isolates containing the L90M mutation (n=8) demonstrated moderate to high-level
resistance to NFV and had varying levels of susceptibility to amprenavir, indinavir,
lopinavir, and saquinavir, in vitro. Most patient-derived recombinant
isolates with phenotypic and genotypic evidence of reduced susceptibility ( > 2.5-fold)
to amprenavir, indinavir, lopinavir, and/or saquinavir demonstrated high-level
cross-resistance to nelfinavir, in vitro. Mutations associated with resistance
to other PIs (e.g. G48V, V82A/F/T, I84V, L90M) appeared to confer high-level
cross-resistance to NFV. Following ritonavir therapy 6 of 7 clinical isolates
with decreased ritonavir susceptibility (8- to 113-fold) in vitro compared
to baseline also exhibited decreased susceptibility to nelfinavir in vitro
(5- to 40-fold). Cross-resistance between nelfinavir and reverse transcriptase
inhibitors is unlikely because different enzyme targets are involved. Clinical
isolates (n=5) with decreased susceptibility to lamivudine, nevirapine or zidovudine
remain fully susceptible to nelfinavir in vitro.
Clinical Studies
There have been no controlled or comparative studies evaluating the virologic
response to subsequent protease inhibitor-containing regimens in patients who
have demonstrated loss of virologic response to a nelfinavir-containing regimen.
However, virologic response was evaluated in a single-arm prospective study
of 26 patients with extensive prior antiretroviral experience with reverse transcriptase
inhibitors (mean 2.9) who had received VIRACEPT for a mean duration of 59.7
weeks and were switched to a ritonavir (400 mg BID)/saquinavir hard-gel (400
mg BID) containing regimen after a prolonged period of VIRACEPT failure (median
48 weeks). Sequence analysis of HIV-1 isolates prior to switch demonstrated
a D30N or an L90M substitution in 18 and 6 patients, respectively. Subjects
remained on therapy for a mean of 48 weeks (range 40 to 56 weeks) where 17 of
26 (65%) subjects and 13 of 26 (50%) subjects were treatment responders with
HIV RNA below the assay limit of detection ( < 500 HIV RNA copies/mL, Chiron
bDNA) at 24 and 48 weeks, respectively.
Pharmacokinetics
The pharmacokinetic properties of nelfinavir were evaluated in healthy volunteers
and HIV-infected patients; no substantial differences were observed between
the two groups.
Absorption
Pharmacokinetic parameters of nelfinavir (area under the plasma concentration-time
curve during a 24-hour period at steady-state [AUC24], peak plasma concentrations
[Cmax], morning and evening trough concentrations [Ctrough]) from a pharmacokinetic
study in HIV-positive patients after multiple dosing with 1250 mg (five 250
mg tablets) twice daily (BID) for 28 days (10 patients) and 750 mg (three 250
mg tablets) three times daily (TID) for 28 days (11 patients) are summarized
in Table 1.
Table 1 : Summary of a Pharmacokinetic Study in HIV-positive
Patients with Multiple Dosing of 1250 mg (five 250 mg tablets) BID for 28 days
and 750 mg (three 250 mg tablets) TID for 28 days
| Regimen |
AUC24
mg•h/L |
Cmax
mg/L |
Ctrough
Morning
mg/L |
Ctrough
Afternoon or
Evening mg/L |
| 1250 mg Bid |
52.8 ±15.7 |
4.0 ± 0.8 |
2.2 ± 1.3 |
0.7 ± 0.4 |
| 750 mg Tid |
43.6 ±17.8 |
3.0 ± 1.6 |
1.4 ± 0.6 |
1.0 ± 0.5 |
| data are mean ± SD |
The difference between morning and afternoon or evening trough concentrations
for the TID and BID regimens was also observed in healthy volunteers who were
dosed at precisely 8- or 12-hour intervals.
In healthy volunteers receiving a single 1250 mg dose, the 625 mg tablet was
not bioequivalent to the 250 mg tablet formulation. Under fasted conditions
(n=27), the AUC and Cmax were 34% and 24% higher, respectively, for the 625
mg tablets. In a relative bioavailability assessment under fed conditions (n=28),
the AUC was 24% higher for the 625 mg tablet; the Cmax was comparable for both
formulations. In HIV-1 infected subjects (N = 21) receiving multiple doses of
1250 mg BID under fed conditions, the 625 mg formulation was bioequivalent to
the 250 mg formulation based on similarity in steady state exposure (Cmax and
AUC).
Table 2 shows the summary of the steady state pharmacokinetic parameters (mean
± s.d.) of nelfinavir after multiple dose administration of 1250 mg BID
(2 x 625 tablets) to HIV-infected patients (N = 21) for 14 days.
Table 2 : Summary of the steady state pharmacokinetic parameters
(mean ± s.d.) of nelfinavir after multiple dose administration of 1250
mg BID (2 x 625 tablets) to HIV-infected patients (N = 21) for 14 days.
| Regimen |
AUC 12
mg•h/L |
Cmax
mg/L |
Cmin
mg/L |
| 1250 mg BID |
35.3 (16.4) |
4.7 (1.9) |
1.5 (1.0) |
AUC12: Steady state AUC
Cmax: Maximum plasma concentration at steady state
Cmin: Minimum plasma concentration at steady state |
In healthy volunteers receiving a single 750 mg dose under fed conditions,
nelfinavir concentrations were similar following administration of the 250 mg
tablet and oral powder.
Effect of Food on Oral Absorption
Food increases nelfinavir exposure and decreases nelfinavir pharmacokinetic
variability relative to the fasted state. In one study, healthy volunteers received
a single dose of 1250 mg of VIRACEPT 250 mg tablets (5 tablets) under fasted
or fed conditions (three different meals). In a second study, healthy volunteers
received single doses of 1250 mg VIRACEPT (5 x 250 mg tablets) under fasted
or fed conditions (two different fat content meals). The results from the two
studies are summarized in Table 3 and Table 4, respectively.
Table 3 : Increase in AUC, Cmax and Tmax for Nelfinavir in
Fed State Relative to Fasted State Following 1250 mg VIRACEPT (5 x 250 mg tablets)
| Number of Kcal |
% Fat |
Number of subjects |
AUC fold increase |
Cmax fold increase |
Increase in Tmax (hr) |
| 125 |
20 |
n=21 |
2.2 |
2.0 |
1.00 |
| 500 |
20 |
n=22 |
3.1 |
2.3 |
2.00 |
| 1000 |
50 |
n=23 |
5.2 |
3.3 |
2.00 |
Table 4 : Increase in Nelfinavir AUC, C max and T max in
Fed Low Fat (20%) versus High fat (50%) State Relative to Fasted State Following
1250 mg VIRACEPT (5 x 250 mg tablets)
| Number of Kcal |
% Fat |
Number of subjects |
AUC fold increase |
Cmax fold increase |
Increase in Tmax (hr) |
| 500 |
20 |
n=22 |
3.1 |
2.5 |
1.8 |
| 500 |
50 |
n=22 |
5.1 |
3.8 |
2.1 |
Nelfinavir exposure can be increased by increasing the calorie or fat content
in meals taken with VIRACEPT.
A food effect study has not been conducted with the 625 mg tablet. However,
based on a cross-study comparison (n=26 fed vs. n=26 fasted) following single
dose administration of nelfinavir 1250 mg, the magnitude of the food effect
for the 625 mg nelfinavir tablet appears comparable to that of the 250 mg tablets.
VIRACEPT should be taken with a meal.
Distribution
The apparent volume of distribution following oral administration of nelfinavir
was 2-7 L/kg. Nelfinavir in serum is extensively protein-bound ( > 98%).
Metabolism
Unchanged nelfinavir comprised 82-86% of the total plasma radioactivity after
a single oral 750 mg dose of 14C-nelfinavir. In vitro, multiple cytochrome
P-450 enzymes including CYP3A and CYP2C19 are responsible for metabolism of
nelfinavir. One major and several minor oxidative metabolites were found in
plasma. The major oxidative metabolite has in vitro antiviral activity
comparable to the parent drug.
Elimination
The terminal half-life in plasma was typically 3.5 to 5 hours. The majority
(87%) of an oral 750 mg dose containing 14C-nelfinavir was recovered in the
feces; fecal radioactivity consisted of numerous oxidative metabolites (78%)
and unchanged nelfinavir (22%). Only 1-2% of the dose was recovered in urine,
of which unchanged nelfinavir was the major component.
Special Populations
Hepatic Insufficiency
The steady-state pharmacokinetics of nelfinavir (1250 mg BID for 2 weeks) was
studied in HIV-seronegative subjects with mild (Child-Pugh Class A; n=6) or
moderate (Child-Pugh Class B; n=6) hepatic impairment. When compared with subjects
with normal hepatic function, the Cmax and AUC of nelfinavir were not significantly
different in subjects with mild hepatic impairment but were increased by 22%
and 62% respectively in subjects with moderate hepatic impairment. The steadystate
pharmacokinetics of nelfinavir has not been studied in HIV-seronegative subjects
with severe hepatic impairment.
The steady-state pharmacokinetics of nelfinavir has not been studied in HIV-positive
patients with any degree of hepatic impairment.
Renal Insufficiency
The pharmacokinetics of nelfinavir have not been studied in patients with renal
insufficiency; however, less than 2% of nelfinavir is excreted in the urine,
so the impact of renal impairment on nelfinavir elimination should be minimal.
Gender and Race
No significant pharmacokinetic differences have been detected between males
and females. Pharmacokinetic differences due to race have not been evaluated.
Pediatrics
The pharmacokinetics of nelfinavir have been investigated in 5 studies in pediatric
patients from birth to 13 years of age either receiving VIRACEPT three times
or twice daily. The dosing regimens and associated AUC24 values are summarized
in Table 5.
Table 5 :Summary of Steady-state AUC24 of Nelfinavir in
Pediatric Studies
| Protocol no. |
Dosing regimen1 |
N2 |
Age |
AUC24(mg•hr/L)
arithmetic mean± SD |
| AG1343-524 |
20 (19-28) mg/k g TID |
14 |
2-13years |
56.1± 29.8 |
| PACTG-725 |
55 (48-60) mg/kg BID |
6 |
3-11years |
101.8±56.1 |
| PENTA 7 |
40 (34-43) mg/kg TID |
4 |
2-9months |
33.8± 8.9 |
| PENTA 7 |
75 (55-83) mg/kg BID |
12 |
2-9months |
37.2± 19.2 |
| PACTG-353 |
40 (14-56) mg/kg BID |
10 |
6 weeks
1 week |
44.1± 27.4
45.8± 32.1 |
1 Protocol specified dose (actual dose range)
2 N: number of subjects with evaluable pharmacokinetic results
Ctrough values are not presented in the table because they
are not available for all studies |
Pharmacokinetic data are also available for 86 patients (age 2 to 12 years)
who received VIRACEPT 25-35 mg/kg TID in Study AG1343-556. The pharmacokinetic
data from Study AG1343-556 were more variable than data from other studies conducted
in the pediatric population; the 95% confidence interval for AUC24 was 9 to
121 mg.hr/L.
Overall, use of VIRACEPT in the pediatric population is associated with highly
variable drug exposure. The high variability may be due to inconsistent food
intake in pediatric patients. (See PRECAUTIONS:
Pediatric Use, DOSAGE AND ADMINISTRATION.)
Geriatric Patients
The pharmacokinetics of nelfinavir have not been studied in patients over 65
years of age.
Drug Interactions
(also see CONTRAINDICATIONS, WARNINGS,
PRECAUTIONS: DRUG INTERACTIONS)
CYP3A and CYP2C19 appear to be the predominant enzymes that metabolize nelfinavir
in humans. The potential ability of nelfinavir to inhibit the major human cytochrome
P450 enzymes (CYP3A, CYP2C19, CYP2D6, CYP2C9, CYP1A2 and CYP2E1) has been investigated
in vitro. Only CYP3A was inhibited at concentrations in the therapeutic
range. Specific drug interaction studies were performed with nelfinavir and
a number of drugs. Table 6 summarizes the effects of nelfinavir on the geometric
mean AUC, Cmax and Cmin of coadministered drugs. Table 7 shows the effects of
coadministered drugs on the geometric mean AUC, Cmax and Cmin of nelfinavir.
Table 6: Drug Interactions: Changes in Pharmacokinetic Parameters
for Coadministered Drug in the Presence of VIRACEPT
| Coadministered Drug |
Nelfinavir Dose |
N |
% Change of Coadministered Drug Pharmacokinetic
Parameters1 (90% CI) |
| AUC |
Cmax |
Cmin |
| HIV -Protease Inhibitors |
| Indinavir 800 mg Single Dose |
750 mg q8h x 7days |
6 |
↑51%
(↑29 -↑77%) |
↓10%
(↓28 -↑13%) |
NA |
| Ritonavir 500 mg Single Dose |
750 mg q8h x 5doses |
10 |
↔ |
↔ |
NA |
| Saquinavir 1200 mg Single Dose2 |
750 mg tid x 4days |
14 |
↑392%
(↑291 -↑521%) |
↑179%
(↑117 -↑259%) |
NA |
| Amprenavir 800 mg tid x 14 days |
750 mg tid x 14days |
6 |
↔ |
↓14%
(↓38 -↑20%) |
↑189%
(↑52 -↑448%) |
| Nucleoside Reverse Transcriptase Inhibitors |
| Lamivudine 150 mg Single Dose |
750 mg q8h x 7-10 days |
11 |
↑10%
(↑2-↑18%) |
↑31%
(↑9-↑56%) |
NA |
| Stavudine 30 -40 mg bid x 56 days |
750 mg tid x 56days |
8 |
See footnote 3 |
| Zidovudine 200 mg Single Dose |
750 mg q8h x 7-10 days |
11 |
↓35%
(↓29 -↓40%) |
↓31%
(↓13 -↓46%) |
NA |
| Non -Nucleoside Reverse Transcriptase Inhibitors |
| Efavirenz 600 mg qd x 7 days |
750 mg q8h x 7days |
10 |
↓12%
(↓31 -↑12%) |
↓12%
(↓29 -↑8%) |
↓22%
(↓54 -↑32%) |
| Nevirapine 200 mg qd x 14 days3 Follow ed by 200 mg bid x
14 days |
750 mg tid x 36days |
23 |
|
See footnote 3 |
|
| Delavirdine 400 mg q8h x 14 days |
750 mg q8h x 7days |
7 |
↓31%
(↓57 -↑10%) |
↓27%
(↓49 -↑4%) |
↓33%
(↓70 -↑49%) |
| Anti-infective Agents |
| Rifabutin 150 mg qdx 8 days 4 |
750 mg q8h x 7-8 days 5 |
12 |
↑83%
(↑72 -↑96%) |
↑19%
(↑11 -↑28%) |
↑177%
(↑144 -↑215%) |
| Rifabutin 300 mg qd x 8 days |
750 mg q8h x 7-8 days |
10 |
↑207%
(↑161 -↑263%) |
↑146%
(↑118 -↑178%) |
↑305%
(↑245 -↑375%) |
| Azithromycin 1200 mg Single Dose |
750 mg tid x 11days |
12 |
↑112%
(↑80 -↑150%) |
↑136%
(↑77 -↑215%) |
NA |
| HMG -CoA Reductase Inhibitors |
| Atorvastatin 10 mg qd x 28 days |
1250 m g bid x 14 days |
15 |
↑74%
(↑41 -↑116%) |
↑122%
(↑68 -↑193%) |
↑39%
(↓21 -↑145%) |
| Simvastatin 20 mg qd x 28 days |
1250 m g bid x 14 days |
16 |
↑505%
(↑393 -↑643%) |
↑517%
(↑367 -↑715%) |
ND |
| Other Agents |
| Ethinyl estradiol 35mg qd x 15 days |
750 mg q8h x 7days |
12 |
↓47%
(↓42 -↓52%) |
↓28%
(↓16 -↓37%) |
↓62%
(↓57 -↓67%) |
| Norethindrone 0.4 mg qd x 15 days |
750 mg q8h x 7days |
12 |
↓18%
(↓13 -↓23%) |
↔ |
↓46%
(↓38 -↓53%) |
| Methadone 80 mg + /- 21 mg qd 6 > 1 month |
1250 m g bid x 8 days |
13 |
↓47%
(↓42 -↓51%) |
↓46%
(↓42 -↓49%) |
↓53%
(↓49 -↓57%) |
| Phenytoin 300 mg qd x 14 days7 |
1250 m g bid x 7 days |
12 |
↓29%
(↓17 -↓39%) |
↓21%
(↓12 -↓29%) |
↓39%
(↓27 -↓49%) |
NA: Not relevant for single-dose treatment;
ND: Cannot be determined
1 ↑ Indicates increase ↓ Indicates decrease ↔
Indicates no change (geometric mean exposure increased or decreased <
10%)
2 Using the soft-gelatin capsule formulation of saquinavir
1200 mg
3 Based on non-definitive cross-study comparison, drug plasma
concentrations appeared to be unaffected by coadministration
4 Rifabutin 150 mg qd changes are relative to Rifabutin 300
mg qd x 8 days without coadministration with nelfinavir
5 Comparable changes in rifabutin concentrations were observed
with VIRACEPT 1250 mg q12h x 7 days
6 Changes are reported for total plasma methadone; changes
for the individual R-enantiomer and Senantiomer were similar
7 Phenytoin exposure measures are reported for total phenytoin
exposure. The effect of nelfinavir on unbound phenytoin was similar |
Table 7: Drug Interactions: Changes in Pharmacokinetic Parameters
for Nelfinavir in the Presence of the Coadministered Drug
| Coadministered Drug |
Nelfinavir Dose |
N |
% Change of Nelfinavir Pharmacokinetic
Parameters1 (90% CI) |
| AUC |
Cmax |
Cmin |
| HIV -Protease Inhibitors |
| Indinavir 800 mg q8h x7 days |
750 mg Single Dose |
6 |
↑83%
(↑42 -↑137%) |
↑31%
(↑16 -↑48%) |
NA |
| Ritonavir 500 mg q12h x 3 doses |
750 mg Single Dose |
10 |
↑152%
(↑96 -↑224%) |
↑44%
(↑28 -↑63%) |
NA |
| Saquinavir 1200 mg tid x 4 days 2 |
750 mg Single Dose |
14 |
↑18%
(↑7-↑30%) |
↔ |
NA |
| Amprenavir 800 mg tid x 14 days |
750 mg tid x 14days |
6 |
See footnote 3 |
| Nucleoside Reverse Transcriptase Inhibitors |
| Didanosine 200 mg Single Dose |
750 mg Single Dose |
9 |
↔ |
↔ |
NA |
| Zidovudine 200 mg + Lamivudine 150 mg Single Dose |
750 mg q8h x 7-10 days |
11 |
↔ |
↔ |
↔ |
| Non -Nucleoside Reverse Transcriptase Inhibitors |
| Efavirenz 600 mg qd x 7 days |
750 mg q 8h x 7days |
7 |
↑20%
(↑8-↑34%) |
↑21%
(↑10 -↑33%) |
↔ |
| Nevirapine 200 mg qd x 14 days Follow ed by 200 mg bid x 14 days |
750 mg tid x 36days |
23 |
↔ |
↔ |
↓32%
(↓50 -↑5%) |
| Delavirdine 400 mg q8h x 7 days |
750 mg q8h x 14days |
12 |
↑107%
(↑83 -↑135%) |
↑88%
(↑66 -↑113%) |
↑136%
(↑103 -↑175%) |
| Anti-infective Agents |
| Ketoconazole 400 mg qd x 7 days |
500 mg q 8h x 5-6 days |
12 |
↑35%
(↑24 -↑46%) |
↑25%
(↑11 -↑40%) |
↑14%
(↓23 -↑69%) |
| Rifabutin 150 mg qd x 8 days |
750 mg q8h x 7-8 days |
11 |
↓23%
(↓14 - ↓31%) |
↓18%
(↓8 - ↓27%) |
↓25%
(↓8 - ↓39%) |
| 1250 m g q12h x 7-8 days |
11 |
↔ |
↔ |
↓15%
(↓43 -↑27%) |
| Rifabutin 300 mg qd x 8 days |
750 mg q8h x 7-8 days |
10 |
↓32%
(↓15 - ↓46%) |
↓24%
(↓10 - ↓36%) |
↓53%
(↓15 - ↓73 %) |
| Rifampin 600 mg qd x 7 days |
750 mg q8h x 5-6 days |
12 |
↓83%
(↓79 - ↓86%) |
↓76%
(↓69 - ↓82%) |
↓92%
(↓86 - ↓95%) |
| Azithromycin 1200 mg Single Dose |
750 mg tid x 9days |
12 |
↓15%
(↓7 - ↓22%) |
↓10%
(↓19 -↑1%) |
↓29%
(↓19 - ↓38%) |
| HMG -CoA Reductase Inhibitors |
| Atorvastatin 10 mg qd x 28 days |
1250 m g bid x 14 days |
15 |
See footnote3 |
| Simvastatin 20 mg qd x 28 days |
1250 m g bid x 14 days |
16 |
See footnote3 |
| Other Agents |
| Methadone 80 mg + / -21 mg qd > 1 month |
1250 m g bid x 8 days |
13 |
See footnote3 |
| Phenytoin 300 mg qd x 7 days |
125 0 mg bid x 14 days |
15 |
↔ |
↔ |
↓18%
(↓45 -↑23%) |
| Omeprazole 40 mg qd x 4 days administered 30 minutes before nelfinavir |
1250 m g bid x 4 days |
19 |
↓36%
(↓20 -↓49%) |
↓37%
(↓23 -↓49%) |
↓39%
(↓15 -↓57%) |
NA: Not relevant for single-dose treatment
1 ↑ Indicates increase ↓ Indicates decrease ↔
Indicates no change (geometric mean exposure increased or decreased <
10%)
2 Using the soft-gelatin capsule formulation of saquinavir
1200 mg
3 Based on non-definitive cross-study comparison, nelfinavir
plasma concentrations appeared to be unaffected by coadministration |
For information regarding clinical recommendations see CONTRAINDICATIONS,
WARNINGS, PRECAUTIONS: DRUG
INTERACTIONS.
Description of Studies
In the clinical studies described below, efficacy was evaluated by the percent
of patients with plasma HIV RNA < 400 copies/mL (Studies 511 and 542) or
< 500 copies/Ml (Study ACTG 364), using the Roche RT-PCR (Amplicor) HIV-1
Monitor or < 50 copies/mL, using the Roche HIV-1 Ultrasensitive assay (Study
Avanti 3). In the analysis presented in each figure, patients who terminated
the study early for any reason, switched therapy due to inadequate efficacy
or who had a missing HIV-RNA measurement that was either preceded or followed
by a measurement above the limit of assay quantification were considered to
have HIV-RNA above 400 copies/mL, above 500 copies/mL, or above 50 copies/mL
at subsequent time points, depending on the assay that was used.
Studies in Antiretroviral Treatment Naïve Patients
Study 511: VIRACEPT + zidovudine + lamivudine versus zidovudine + lamivudine
Study 511 was a double-blind, randomized, placebo controlled trial comparing
treatment with zidovudine (ZDV; 200 mg TID) and lamivudine (3TC; 150 mg BID)
plus 2 doses of VIRACEPT (750 mg and 500 mg TID) to zidovudine (200 mg TID)
and lamivudine (150 mg BID) alone in 297 antiretroviral naive HIV-1 infected
patients (median age 35 years [range 21 to 63], 89% male and 78% Caucasian).
Mean baseline CD4 cell count was 288 cells/mm³ and mean baseline plasma
HIV RNA was 5.21 log10 copies/mL (160,394 copies/mL). The percent of patients
with plasma HIV RNA < 400 copies/mL and mean changes in CD4 cell count are
summarized in Figures 1 and 2, respectively.
Figure 1 : Study 511: Percentage of Patients With HIV RNA
Below 400 Copies/mL
Figure 2 : Study 511: Mean Change From Baseline in CD4 Cell
Counts
Study 542: VIRACEPT BID + stavudine + lamivudine compared to VIRACEPT TID
+ stavudine + lamivudine
Study 542 is an ongoing, randomized, open-label trial comparing the HIV RNA
suppression achieved by VIRACEPT 1250 mg BID versus VIRACEPT 750 mg TID in patients
also receiving stavudine (d4T; 30-40 mg BID) and lamivudine (3TC; 150 mg BID).
Patients had a median age of 36 years (range 18 to 83), were 84% male, and were
91% Caucasian. Patients had received less than 6 months of therapy with nucleoside
transcriptase inhibitors and were naïve to protease inhibitors. Mean baseline
CD4 cell count was 296 cells/mm³ and mean baseline plasma HIV RNA was 5.0
log10 copies/mL (100,706 copies/mL).
Results showed that there was no significant difference in mean CD4 cell count
among treatment groups; the mean increases from baseline for the BID and TID
arms were 150 cells/mm³ at 24 weeks and approximately 200 cells/mm³
at 48 weeks.
The percent of patients with HIV RNA < 400 copies/mL is summarized in Figure
3. The outcomes of patients through 48 weeks of treatment are summarized in
Table 8.
Figure 3 : Study 542: Percentage of Patients With HIV RNA
Below 400 Copies/mL
Table 8 : Outcomes of Randomized Treatment Through 48 Weeks
| Outcome |
VI RACEPT 1250 mg BID Regimen |
VI RACEPT 750 mg TID Regimen |
| Number of patients evaluable* |
323 |
192 |
| HI V RNA < 400 copies/mL |
198 (61%) |
111 (58%) |
| HI V RNA ≥ 400 copies/mL |
46 (14%) |
22 (11%) |
| Discontinued due to VIRACEPT toxicity** |
9 (3%) |
2 (1%) |
| Discontinued due to other antiretroviral agents' toxicity** |
3 (1%) |
3 (2%) |
| Others*** |
67 (21%) |
54 (28%) |
*Twelve patients in the BID arm and fourteen
patients in the TID arm had not yet reached 48 weeks of therapy.
**These rates only reflect dose-limiting toxicities that were counted
as the initial reason for treatment failure in the analysis (see ADVERSE
REACTIONS for a description of the safety profile of these regimens).
***Consent withdrawn, lost to follow-up, inter current illness, noncompliance
or missing data; all assumed as failures. |
Study Avanti 3: VIRACEPT TID + zidovudine + lamivudine compared to zidovudine
+ lamivudine
Study Avanti 3 was a placebo-controlled, randomized, double-blind study designed
to evaluate the safety and efficacy of VIRACEPT (750 mg TID) in combination
with zidovudine (ZDV; 300 mg BID) and lamivudine (3TC; 150 mg BID) (n=53) versus
placebo in combination with ZDV and 3TC (n=52) administered to antiretroviral-naïve
patients with HIV infection and a CD4 cell count between 150 and 500 cells/ìL.
Patients had a mean age of 35 (range 22-59), were 89% male, and 88% Caucasian.
Mean baseline CD4 cell count was 304 cells/mm³ and mean baseline plasma
HIV RNA was 4.8 log10 copies/mL (57,887 copies/mL). The percent of
patients with plasma HIV RNA < 50 copies/mL at 52 weeks was 54% for the VIRACEPT
+ ZDV + 3TC treatment group and 13% for the ZDV + 3TC treatment group.
Studies in Antiretroviral Treatment Experienced Patients
Study ACTG 364: VIRACEPT TID + 2NRTIs compared to efavirenz + 2NRTIs compared
to VIRACEPT + efavirenz + 2NRTIs
Study ACTG 364 was a randomized, double-blind study that evaluated the combination
of VIRACEPT 750 mg TID and/or efavirenz 600 mg QD with 2 NRTIs (either didanosine
[ddI] + d4T, ddI + 3TC, or d4T + 3TC) in patients with prolonged prior nucleoside
exposure who had completed 2 previous ACTG studies. Patients had a mean age
of 41 years (range 18 to 75), were 88% male, and were 74% Caucasian. Mean baseline
CD4 cell count was 389 cells/mm³ and mean baseline plasma HIV RNA was 3.9
log10 copies/mL (7,954 copies/mL).
The percent of patients with plasma HIV RNA < 500 copies/mL at 48 weeks
was 42%, 62%, and 72% for the VIRACEPT (n=66), EFV (n=65), and VIRACEPT + EFV
(n=64) treatment groups, respectively. The 4-drug combination of VIRACEPT +
EFV + 2 NRTIs was more effective in suppressing plasma HIV RNA in these patients
than either 3-drug regimen.
Last updated on RxList: 2/10/2009