Microbiology
Mechanism of Action: HIV-1 protease is an enzyme required for
the proteolytic cleavage of the viral polyprotein precursors into the individual
functional proteins found in infectious HIV-1. Indinavir binds to the protease
active site and inhibits the activity of the enzyme. This inhibition prevents
cleavage of the viral polyproteins resulting in the formation of immature non-infectious
viral particles.
Antiretroviral Activity In Vitro: The in vitro activity
of indinavir was assessed in cell lines of lymphoblastic and monocytic origin
and in peripheral blood lymphocytes. HIV-1 variants used to infect the different
cell types include laboratory-adapted variants, primary clinical isolates and
clinical isolates resistant to nucleoside analogue and nonnucleoside inhibitors
of the HIV-1 reverse transcriptase. The IC95 (95% inhibitory concentration)
of indinavir in these test systems was in the range of 25 to 100 nM. In drug
combination studies with the nucleoside analogues zidovudine and didanosine,
indinavir showed synergistic activity in cell culture. The relationship between
in vitro susceptibility of HIV-1 to indinavir and inhibition of HIV-1
replication in humans has not been established.
Drug Resistance: Isolates of HIV-1 with reduced susceptibility
to the drug have been recovered from some patients treated with indinavir. Viral
resistance was correlated with the accumulation of mutations that resulted in
the expression of amino acid substitutions in the viral protease. Eleven amino
acid residue positions, (L10l/V/R, K20l/M/R, L24l, M46l/L, l54A/V, L63P, l64V,
A71T/V, V82A/F/T, l84V, and L90M), at which substitutions are associated with
resistance, have been identified. Resistance was mediated by the co-expression
of multiple and variable substitutions at these positions. No single substitution
was either necessary or sufficient for measurable resistance ( ≥ 4-fold increase
in IC95). In general, higher levels of resistance were associated
with the co-expression of greater numbers of substitutions, although their individual
effects varied and were not additive. At least 3 amino acid substitutions must
be present for phenotypic resistance to indinavir to reach measurable levels.
In addition, mutations in the p7/ p1 and p1/ p6 gag cleavage sites were observed
in some indinavir resistant HIV-1 isolates.
In vitro phenotypic susceptibilities to indinavir were determined for
38 viral isolates from 13 patients who experienced virologic rebounds during
indinavir monotherapy. Pre-treatment isolates from five patients exhibited indinavir
IC95 values of 50-100 nM. At or following viral RNA rebound (after 12-76 weeks
of therapy), IC95 values ranged from 25 to > 3000 nM, and the viruses
carried 2 to 10 mutations in the protease gene relative to baseline.
Cross-Resistance to Other Antiviral Agents: Varying degrees of
HIV-1 cross-resistance have been observed between indinavir and other HIV-1
protease inhibitors. In studies with ritonavir, saquinavir, and amprenavir,
the extent and spectrum of cross-resistance varied with the specific mutational
patterns observed. In general, the degree of cross-resistance increased with
the accumulation of resistance-associated amino acid substitutions. Within a
panel of 29 viral isolates from indinavir-treated patients that exhibited measurable
( ≥ 4-fold) phenotypic resistance to indinavir, all were resistant to ritonavir.
Of the indinavir resistant HIV-1 isolates, 63% showed resistance to saquinavir
and 81% to amprenavir.
Pharmacokinetics
Absorption: Indinavir was rapidly absorbed in the fasted state
with a time to peak plasma concentration (Tmax) of 0.8 ± 0.3 hours (mean
± S.D.) (n=11). A greater than dose-proportional increase in indinavir
plasma concentrations was observed over the 200-1000 mg dose range. At a dosing regimen of 800 mg every 8 hours, steady-state area under the plasma concentration
time curve (AUC) was 30,691 ± 11,407 nM•hour (n=16), peak plasma
concentration (Cmax) was 12,617 ± 4037 nM (n=16), and plasma concentration
eight hours post dose (trough) was 251 ± 178 nM (n=16).
Effect of Food on Oral Absorption: Administration of indinavir
with a meal high in calories, fat, and protein (784 kcal, 48.6 g fat, 31.3 g
protein) resulted in a 77% ± 8% reduction in AUC and an 84% ±
7% reduction in Cmax (n=10). Administration with lighter meals (e.g., a meal
of dry toast with jelly, apple juice, and coffee with skim milk and sugar or
a meal of corn flakes, skim milk and sugar) resulted in little or no change
in AUC, Cmax or trough concentration.
Distribution: Indinavir was approximately 60% bound to human
plasma proteins over a concentration range of 81 nM to 16,300 nM.
Metabolism: Following a 400-mg dose of 14C-indinavir,
83 ± 1% (n=4) and 19 ± 3% (n=6) of the total radioactivity was
recovered in feces and urine, respectively; radioactivity due to parent drug
in feces and urine was 19.1% and 9.4%, respectively. Seven metabolites have
been identified, one glucuronide conjugate and six oxidative metabolites. In
vitro studies indicate that cytochrome P-450 3A4 (CYP3A4) is the major enzyme
responsible for formation of the oxidative metabolites.
Elimination: Less than 20% of indinavir is excreted unchanged
in the urine. Mean urinary excretion of unchanged drug was 10.4 ± 4.9%
(n=10) and 12.0 ± 4.9% (n=10) following a single 700-mg and 1000-mg dose,
respectively. Indinavir was rapidly eliminated with a half-life of 1.8 ±
0.4 hours (n=10). Significant accumulation was not observed after multiple dosing
at 800 mg every 8 hours.
Special Populations
Hepatic Insufficiency: Patients with mild to moderate hepatic
insufficiency and clinical evidence of cirrhosis had evidence of decreased metabolism
of indinavir resulting in approximately 60% higher mean AUC following a single
400-mg dose (n=12). The half-life of indinavir increased to 2.8 ± 0.5
hours. Indinavir pharmacokinetics have not been studied in patients with severe
hepatic insufficiency (see DOSAGE AND ADMINISTRATION,
Hepatic Insufficiency).
Renal Insufficiency: The pharmacokinetics of indinavir have not
been studied in patients with renal insufficiency.
Gender: The effect of gender on the pharmacokinetics of indinavir
was evaluated in 10 HIV seropositive women who received CRIXIVAN 800 mg every
8 hours with zidovudine 200 mg every 8 hours and lamivudine 150 mg twice a day
for one week. Indinavir pharmacokinetic parameters in these women were compared
to those in HIV seropositive men (pooled historical control data). Differences
in indinavir exposure, peak concentrations, and trough concentrations between
males and females are shown in Table 1 below:
Table 1
| PK Parameter |
% change in PK parameter for females relative
to males |
90% Confidence Interval |
| AUC0-8h (nM•hr) |
↓13% |
(↓32%,↑12%) |
| Cmax (nM) |
↓13% |
(↓32%,↑10%) |
| C8h (nM) |
↓22% |
(↓47%,↑15%) |
| ↓Indicates a decrease in the PK parameter; ↑indicates
an increase in the PK parameter. |
The clinical significance of these gender differences in the pharmacokinetics of indinavir is not known.
Race: Pharmacokinetics of indinavir appear to be comparable in
Caucasians and Blacks based on pharmacokinetic studies including 42 Caucasians
(26 HIV-positive) and 16 Blacks (4 HIV-positive).
Pediatric: The optimal dosing regimen for use of indinavir in
pediatric patients has not been established. In HIV-infected pediatric patients
(age 4-15 years), a dosage regimen of indinavir capsules, 500 mg/m2
every 8 hours, produced AUC0-8hr of 38,742 ± 24,098 nM•hour
(n=34), Cmax of 17,181 ± 9809 nM (n=34), and trough concentrations of
134 ± 91 nM (n=28). The pharmacokinetic profiles of indinavir in pediatric
patients were not comparable to profiles previously observed in HIV-infected
adults receiving the recommended dose of 800 mg every 8 hours. The AUC and Cmax
values were slightly higher and the trough concentrations were considerably
lower in pediatric patients. Approximately 50% of the pediatric patients had
trough values below 100 nM; whereas, approximately 10% of adult patients had
trough levels below 100 nM. The relationship between specific trough values
and inhibition of HIV replication has not been established.
Pregnant Patients: The optimal dosing regimen for use of indinavir
in pregnant patients has not been established. A CRIXIVAN dose of 800 mg every
8 hours (with zidovudine 200 mg every 8 hours and lamivudine 150 mg twice a
day) has been studied in 16 HIV-infected pregnant patients at 14 to 28 weeks
of gestation at enrollment (study PACTG 358). The mean indinavir plasma AUC0-8hr
at weeks 30-32 of gestation (n=11) was 9231 nM•hr, which is 74% (95% CI:
50%, 86%) lower than that observed 6 weeks postpartum. Six of these 11 (55%)
patients had mean indinavir plasma concentrations 8 hours post-dose (Cmin) below assay threshold of reliable quantification. The pharmacokinetics of indinavir
in these 11 patients at 6 weeks postpartum were generally similar to those observed
in non-pregnant patients in another study (see PRECAUTIONS,
Pregnancy).
Drug Interactions
(also see CONTRAINDICATIONS, WARNINGS,
PRECAUTIONS: DRUG INTERACTIONS)
Indinavir is an inhibitor of the cytochrome P450 isoform CYP3A4. Coadministration
of CRIXIVAN and drugs primarily metabolized by CYP3A4 may result in increased
plasma concentrations of the other drug, which could increase or prolong its therapeutic and adverse effects (see CONTRAINDICATIONS and WARNINGS).
Based on in vitro data in human liver microsomes, indinavir does not
inhibit CYP1A2, CYP2C9, CYP2E1 and CYP2B6. However, indinavir may be a weak
inhibitor of CYP2D6.
Indinavir is metabolized by CYP3A4. Drugs that induce CYP3A4 activity would be expected to increase the clearance of indinavir, resulting in lowered plasma concentrations of indinavir. Coadministration of CRIXIVAN and other drugs that inhibit CYP3A4 may decrease the clearance of indinavir and may result in increased plasma concentrations of indinavir.
Drug interaction studies were performed with CRIXIVAN and other drugs likely
to be coadministered and some drugs commonly used as probes for pharmacokinetic
interactions. The effects of coadministration of CRIXIVAN on the AUC, Cmax and
Cmin are summarized in Table 2 (effect of other drugs on indinavir) and Table
3 (effect of indinavir on other drugs). For information regarding clinical recommendations,
see Table 9 in PRECAUTIONS.
Table 2 - Drug Interactions: Pharmacokinetic Parameters for
Indinavir in the Presence of the Coadministered Drug (See PRECAUTIONS,
Table 9 for Recommended Alterations in Dose or Regimen)
| Coadministered drug |
Dose of Coadministered drug
(mg) |
Dose of CRIXIVAN (mg) |
n |
Ratio (with/without coadministered drug)
of Indinavir Pharmacokinetic Parameters (90% CI); No Effect =1.00 |
| C max |
AUC |
C min |
| Cimetidine |
600 twice daily, 6 days |
400 single dose |
12 |
1.07
(0.77, 1.49) |
0.98
(0.81, 1.19) |
0.82
(0.69, 0.99) |
| Clarithromycin |
500 q12h, 7 days |
800 three times daily, 7 days |
10 |
1.08
(0.85, 1.38) |
1.19
(1.00, 1.42) |
1.57
(1.16, 2.12) |
| Delavirdine |
400 three times daily |
400 three times daily, 7 days |
28 |
0.641
(0.48, 0.86) |
No significant change1 |
2.181
(1.16, 4.12) |
| Delavirdine |
400 three times daily |
600 three times daily, 7 days |
28 |
No significant change |
1.531
(1.07, 2.20) |
3.981
(2.04, 7.78) |
| Efavirenz2 |
600 once daily, 10 days |
1000 three times daily, 10 daysAfter morning dose |
20 |
No significant change1 |
0.671
(0.61, 0.74) |
0.611
(0.49, 0.76) |
| After afternoon dose |
No significant change1 |
0.631
(0.54, 0.74) |
0.481
(0.43, 0.53) |
| After evening dose |
0.711
(0.57, 0.89) |
0.541
(0.46, 0.63) |
0.431
(0.37, 0.50) |
| Fluconazole2 |
400 once daily, 8 days |
1000 three times daily, 7 days |
11 |
0.87
(0.72, 1.05) |
0.76
(0.59, 0.98) |
0.90
(0.72, 1.12) |
| Grapefruit Juice |
8 oz. |
400 single dose |
10 |
0.65
(0.53, 0.79) |
0.73
(0.60, 0.87) |
0.90
(0.71, 1.15) |
| Isoniazid |
300 once daily in the morning, 8 days |
800 three times daily, 7 days |
11 |
0.95
(0.88, 1.03) |
0.99
(0.87, 1.13) |
0.89
(0.75, 1.06) |
| Itraconazole |
200 twice daily, 7 days |
600 three times daily, 7 days |
12 |
0.781
(0.69, 0.88) |
0.991
(0.91, 1.06) |
1.491
(1.28, 1.74) |
| Ketoconazole |
400 once daily, 7 days |
600 three times daily, 7 days |
12 |
0.691
(0.61, 0.78) |
0.801
(0.74, 0.87) |
1.291
(1.11, 1.51) |
| 400 once daily, 7 days |
400 three times daily, 7 days |
12 |
0.421
(0.37, 0.47) |
0.441
(0.41, 0.48) |
0.731
(0.62, 0.85) |
| Methadone |
20-60 once daily in the morning, 8 days |
800 three times daily, 8 days |
10 |
See text below for discussion of interaction. |
| Quinidine |
200 single dose |
400 single dose |
10 |
0.96
(0.79, 1.18) |
1.07
(0.89, 1.28) |
0.93
(0.73, 1.19) |
| Rifabutin |
150 once daily in the morning, 10 days |
800 three times daily, 10 days |
14 |
0.80
(0.72, 0.89) |
0.68
(0.60, 0.76) |
0.60
(0.51, 0.72) |
| Rifabutin |
300 once daily in the morning, 10 days |
800 three times daily, 10 days |
10 |
0.75
(0.61, 0.91) |
0.66
(0.56, 0.77) |
0.61
(0.50, 0.75) |
| Rifampin |
600 once daily in the morning, 8 days |
800 three times daily, 7 days |
12 |
0.13
(0.08, 0.22) |
0.08
(0.06, 0.11) |
Not Done |
| Ritonavir |
100 twice daily, 14 days |
800 twice daily, 14 days |
10, 163 |
See text below for discussion of interaction. |
| Ritonavir |
200 twice daily, 14 days |
800 twice daily, 14 days |
9, 163 |
See text below for discussion of interaction. |
| Sildenafil |
25 single dose |
800 three times daily |
6 |
See text below for discussion of interaction. |
| St. John's wort (Hypericum perforatum, standardized to 0.3 %
hypericin) |
300 three times daily with meals, 14 days |
800 three times daily |
8 |
Not Available |
0.46
(0.34, 0.58)4 |
0.19
(0.06, 0.33)4 |
| Stavudine (d4T)2 |
40 twice daily, 7 days |
800 three times daily, 7 days |
11 |
0.95
(0.80, 1.11) |
0.95
(0.80, 1.12) |
1.13
(0.83, 1.53) |
| Trimethoprim/ Sulfamethoxazole |
800 Trimethoprim/160 Sulfamethoxazoleq12h, 7 days |
400 four times daily, 7 days |
12 |
1.12
(0.87, 1.46) |
0.98
(0.81, 1.18) |
0.83
(0.72, 0.95) |
| Zidovudine2 |
200 three times daily, 7 days |
1000 three times daily, 7 days |
12 |
1.06
(0.91, 1.25) |
1.05
(0.86, 1.28) |
1.02
(0.77, 1.35) |
| Zidovudine/Lamivudine (3TC)2 |
200/150 three times daily, 7 days |
800 three times daily, 7 days |
6, 95 |
1.05
(0.83, 1.33) |
1.04
(0.67, 1.61) |
0.98
(0.56, 1.73) |
All interaction studies conducted in healthy,
HIV-negative adult sub ects, unless otherwise indicated.
1 Relative to indinavir 800 mg three times daily alone.
2 Study conducted in HIV-positive subjects.
3 Comparison to historical data on 16 subjects receiving indinavir
alone.
4 95% CI.
5 Parallel group design; n for indinavir + coadministered drug,
n for indinavir alone. |
Table 3: Drug Interactions: Pharmacokinetic Parameters for
Coadministered Drug in the Presence of Indinavir (See PRECAUTIONS,
Table 9 for Recommended Alterations in Dose or Regimen)
| Coadministered drug |
Dose of Coadministered drug
(mg) |
Dose of CRIXIVAN (mg) |
n |
Ratio (with/without CRIXIVAN) of Coadministered
Drug Pharmacokinetic Parameters (90% CI); No Effect =1.00 |
| C max |
AUC |
C min |
| Clarithromycin |
500 twice daily, 7 days |
800 three times daily, 7 days |
12 |
1.19
(1.02, 1.39) |
1.47
(1.30, 1.65) |
1.97
(1.58, 2.46)
n=11 |
| Efavirenz |
200 once daily, 14 days |
800 three times daily, 14 days |
20 |
No significant change |
No significant change |
-- |
| Ethinyl Estradiol (ORTHO-NOVUM 1/35)1 |
35 mcg, 8 days |
800 three times daily, 8 days |
18 |
1.02
(0.96, 1.09) |
1.22
(1.15, 1.30) |
1.37
(1.24, 1.51) |
| Isoniazid |
300 once daily in the morning, 8 days |
800 three times daily, 8 days |
11 |
1.34
(1.12, 1.60) |
1.12
(1.03, 1.22) |
1.00
(0.92, 1.08) |
| Methadone2 |
20-60 once daily in the morning, 8 days |
800 three times daily, 8 days |
12 |
0.93
(0.84, 1.03) |
0.96
(0.86, 1.06) |
1.06
(0.94, 1.19) |
| Norethindrone (ORTHO-NOVUM 1/35)1 |
1 mcg, 8 days |
800 three times daily, 8 days |
18 |
1.05
(0.95, 1.16) |
1.26
(1.20, 1.31) |
1.44
(1.32, 1.57) |
Rifabutin
*150 mg once daily in the morning, 11 days + indinavir compared to 300
mg once daily in the morning, 11 days alone |
150 once daily in the morning, 10 days |
800 three times daily, 10 days |
14 |
1.29
(1.05, 1.59) |
1.54
(1.33, 1.79) |
1.99
(1.71, 2.31)
n=13 |
| 300 once daily in the morning, 10 days |
800 three times daily, 10 days |
10 |
2.34
(1.64, 3.35) |
2.73
(1.99, 3.77) |
3.44
(2.65, 4.46)
n=9 |
| Ritonavir |
100 twice daily, 14 days |
800 twice daily, 14 days |
10, 43 |
1.61
(1.13, 2.29) |
1.72
(1.20, 2.48) |
1.62
(0.93, 2.85) |
| 200 twice daily, 14 days |
800 twice daily, 14 days |
9, 53 |
1.19
(0.85, 1.66) |
1.96
(1.39, 2.76) |
4.71
(2.66, 8.33)
n=9, 4 |
Saquinavir
Hard gel formulation |
600 single dose |
800 three times daily, 2 days |
6 |
4.7
(2.7, 8.1) |
6.0
(4.0, 9.1) |
2.9
(1.7, 4.7)4 |
| Soft gel formulation |
800 single dose |
800 three times daily, 2 days |
6 |
6.5
(4.7, 9.1) |
7.2
(4.3, 11.9) |
5.5
(2.2, 14.1)4 |
| Soft gel formulation |
1200 single dose |
800 three times daily, 2 days |
6 |
4.0
(2.7, 5.9) |
4.6
(3.2, 6.7) |
5.5
(3.7, 8.3)4 |
| Sildenafil |
25 single dose |
800 three times daily |
6 |
See text below for discussion of interaction. |
| Stavudine5 |
40 twice daily, 7 days |
800 three times daily, 7 days |
13 |
0.86
(0.73, 1.03) |
1.21
(1.09, 1.33) |
Not Done |
| Theophylline |
250 single dose (on Days 1 and 7) |
800 three times daily, 6 days (Days 2 to 7) |
12, 43 |
0.88
(0.76, 1.03) |
1.14
(1.04, 1.24) |
1.13
(0.86, 1.49)
n=7, 3 |
Trimethoprim/ Sulfamethoxazole
Trimethoprim |
800 Trimethoprim/160 Sulfamethoxazoleq12h, 7 days |
400 q6h, 7 days |
12 |
1.18
(1.05, 1.32) |
1.18
(1.05, 1.33) |
1.18
(1.00, 1.39) |
Trimethoprim/ Sulfamethoxazole
Sulfamethoxazole |
800 Trimethoprim/160 Sulfamethoxazoleq12h, 7 days |
400 q6h, 7 days |
12 |
1.01
(0.95, 1.08) |
1.05
(1.01, 1.09) |
1.05
(0.97, 1.14) |
| Vardenafil |
10 single dose |
800 three times daily |
18 |
See text below for discussion of interaction. |
| Zidovudine5 |
200 three times daily, 7 days |
1000 three times daily, 7 days |
12 |
0.89
(0.73, 1.09) |
1.17
(1.07, 1.29) |
1.51
(0.71, 3.20)
n=4 |
| Zidovudine/Lamivudine5 Zidovudine |
200/150 three times daily, 7 days |
800 three times daily, 7 days |
6, 73 |
1.23
(0.74, 2.03) |
1.39
(1.02, 1.89) |
1.08
(0.77, 1.50)
n=5, 5 |
| Zidovudine/Lamivudine5 Lamivudine |
200/150 three times daily, 7 days |
800 three times daily, 7 days |
6, 73 |
0.73
(0.52, 1.02) |
0.91
(0.66, 1.26) |
0.88
(0.59, 1.33) |
All interaction studies conducted in healthy,
HIV-negative adult subjects, unless otherwise indicated. 1
Registered trademark of Ortho Pharmaceutical Corporation
2 Study conducted in subjects on methadone maintenance.
3 Parallel group design; n for coadministered drug + indinavir,
n for coadministered drug alone.
4 C6hr
5 Study conducted in HIV-positive subjects. |
Delavirdine: Delavirdine inhibits the metabolism of indinavir
such that coadministration of 400-mg or 600-mg indinavir three times daily with
400-mg delavirdine three times daily alters indinavir AUC, Cmax and Cmin (see
Table 2). Indinavir had no effect on delavirdine pharmacokinetics (see
DOSAGE AND ADMINISTRATION, Concomitant Therapy,
Delavirdine), based on a comparison to historical delavirdine pharmacokinetic
data.
Methadone: Administration of indinavir (800 mg every 8 hours)
with methadone (20 mg to 60 mg daily) for one week in subjects on methadone
maintenance resulted in no change in methadone AUC. Based on a comparison to
historical data, there was little or no change in indinavir AUC.
Ritonavir: Compared to historical data in patients who received
indinavir 800 mg every 8 hours alone, twice-daily coadministration to volunteers
of indinavir 800 mg and ritonavir with food for two weeks resulted in a 2.7-fold
increase of indinavir AUC24h, a 1.6-fold increase in indinavir Cmax,
and an 11-fold increase in indinavir Cmin for a 100-mg ritonavir dose and a
3.6-fold increase of indinavir AUC24h, a 1.8-fold increase in indinavir
Cmax, and a 24-fold increase in indinavir Cmin for a 200-mg ritonavir dose.
In the same study, twice-daily coadministration of indinavir (800 mg) and ritonavir
(100 or 200 mg) resulted in ritonavir AUC24h increases versus the
same doses of ritonavir alone (see Table 3).
Sildenafil: The results of one published study in HIV-infected
men (n=6) indicated that coadministration of indinavir (800 mg every 8 hours
chronically) with a single 25-mg dose of sildenafil resulted in an 11% increase
in average AUC0-8hr of indinavir and a 48% increase in average indinavir
peak concentration (Cmax) compared to 800 mg every 8 hours alone. Average sildenafil
AUC was increased by 340% following coadministration of sildenafil and indinavir
compared to historical data following administration of sildenafil alone (see
WARNINGS, Drug Interactions and PRECAUTIONS:
DRUG INTERACTIONS).
Vardenafil: Indinavir (800 mg every 8 hours) coadministered with
a single 10-mg dose of vardenafil resulted in a 16-fold increase in vardenafil
AUC, a 7-fold increase in vardenafil Cmax, and a 2-fold increase in vardenafil
half-life (see WARNINGS, Drug Interactions
and PRECAUTIONS: DRUG INTERACTIONS).
Description of Studies
In all clinical studies, with the exception of ACTG 320, the AMPLICOR HIV MONITOR assay was used to determine the level of circulating HIV RNA in serum. This is an experimental use of the assay. HIV RNA results should not be directly compared to results from other trials using different HIV RNA assays or using other sample sources.
Study ACTG 320 was a multicenter, randomized, double-blind clinical endpoint
trial to compare the effect of CRIXIVAN in combination with zidovudine and lamivudine
with that of zidovudine plus lamivudine on the progression to an AIDS-defining
illness (ADI) or death. Patients were protease inhibitor and lamivudine naive
and zidovudine experienced, with CD4 cell counts of ≤ 200 cells/mm3.
The study enrolled 1156 HIV-infected patients (17% female, 28% Black, 18% Hispanic,
mean age 39 years). The mean baseline CD4 cell count was 87 cells/mm3.
The mean baseline HIV RNA was 4.95 log10 copies/mL (89,035 copies/mL).
The study was terminated after a planned interim analysis, resulting in a median
follow-up of 38 weeks and a maximum follow-up of 52 weeks. Results are shown
in Table 4 and Figures 1 & 2.
Table 4: ACTG 320
| |
Number (%) of Patients with AIDS-defining Illness or Death |
| Endpoint |
IDV+ZDV+L
(n=577) |
ZDV+L
(n=579) |
| HIV Progression or Death |
35 (6.1) |
63 (10.9) |
| Death* |
10 (1.7) |
19 (3.3) |
* The number of deaths is inadequate to assess the impact of Indinavir
on survival.
IDV = Indinavir, ZDV = Zidovudine, L = Lamivudine
|
Study ACTG 320: Figure 1: Indinavir Protocol ACTG 320 Zidovudine
Experienced Plasma Viral RNA - Proportions Below 400 copies/mL
Study ACTG 320: Figure 2: ACTG 320 Zidovudine Experienced
CD4 Cell Counts - Mean Change from Baseline
Study 028, a double-blind, multicenter, randomized, clinical endpoint trial
conducted in Brazil, compared the effects of CRIXIVAN plus zidovudine with those
of CRIXIVAN alone or zidovudine alone on the progression to an ADI or death,
and on surrogate marker responses. All patients were antiretroviral naive with
CD4 cell counts of 50 to 250 cells/mm3. The study enrolled 996 HIV-1
seropositive patients [28% female, 11% Black, 1% Asian/Other, median age 33
years, mean baseline CD4 cell count of 152 cells/mm3, mean serum
viral RNA of 4.44 log10 copies/mL (27,824 copies/mL)]. Treatment
regimens containing zidovudine were modified in a blinded manner with the optional
addition of lamivudine (median time: week 40). The median length of follow-up
was 56 weeks with a maximum of 97 weeks. The study was terminated after a planned
interim analysis, resulting in a median follow-up of 56 weeks and a maximum
follow-up of 97 weeks. Results are shown in Table 5 and Figures 3 and 4.
Table 5: Protocol 028
| Endpoint |
Number (%) of Patients with AIDS-defining
Illness or Death |
IDV+ZDV
(n=332) |
IDV
(n=332) |
ZDV
(n=332) |
| HIV Progression or Death |
21 (6.3) |
27 (8.1) |
62 (18.7) |
| Death* |
8 (2.4) |
5 (1.5) |
11 (3.3) |
| * The number of deaths is inadequate to assess
the impact of Indinavir on survival. |
Study 028: Figure 3: Indinavir Protocol 028 Zidovudine Naive
Viral RNA - Proportions Below 500 Copies/mL in Serum
Study 028: Figure 4: Indinavir Protocol 028 Zidovudine Naive
CD4 Cell Counts - Mean Change from Baseline
Study 035 was a multicenter, randomized trial in 97 HIV-1 seropositive patients
who were zidovudine-experienced (median exposure 30 months), protease-inhibitor-
and lamivudine-naive, with mean baseline CD4 count 175 cells/mm3
and mean baseline serum viral RNA 4.62 log10 copies/mL (41,230 copies/mL).
Comparisons included CRIXIVAN plus zidovudine plus lamivudine vs. CRIXIVAN alone
vs. zidovudine plus lamivudine. After at least 24 weeks of randomized, double-blind
therapy, patients were switched to open-label CRIXIVAN plus lamivudine plus
zidovudine. Mean changes in log10 viral RNA in serum, the proportions
of patients with viral RNA below 500 copies/mL in serum, and mean changes in
CD4 cell counts, during 24 weeks of randomized, double-blinded therapy are summarized
in Figures 5, 6, and 7, respectively. A limited number of patients remained
on randomized, double-blind treatment for longer periods; based on this extended
treatment experience, it appears that a greater number of subjects randomized
to CRIXIVAN plus zidovudine plus lamivudine demonstrated HIV RNA levels below
500 copies/mL during one year of therapy as compared to those in other treatment
groups.
Study 035: Figure 5: Indinavir Protocol 035 Zidovudine Experienced
Viral RNA - Mean Log 10 Change from Baseline in Serum
Study 035: Figure 6: Indinavir Protocol 035 Zidovudine Experienced
Viral RNA - Proportions Below 500 Copies/mL in Serum
Study 035: Figure 7: Indinavir Protocol 035 Zidovudine Experienced
CD4 Cell Counts - Mean Change from Baseline
Genotypic Resistance in Clinical Studies
Study 006 (10/15/93-10/12/94) was a dose-ranging study in which patients were initially treated with CRIXIVAN at a dose of < 2.4 g/day followed by 2.4 g/day. Study 019 (6/23/94-4/10/95) was a randomized comparison of CRIXIVAN 600 mg every 6 hours, CRIXIVAN plus zidovudine, and zidovudine alone. Table 6 shows the incidence of genotypic resistance at 24 weeks in these studies.
Table 6: Genotypic Resistance at 24 Weeks
| Treatment Group |
Resistanceto IDV n/N* |
Resistanceto ZDV n/N* |
| IDV |
— |
— |
| < 2.4 g/day |
31/37 (84%) |
— |
| 2.4 g/day |
9/21 (43%) |
1/17 (6%) |
| IDV/ZDV |
4/22 (18%) |
1/22 (5%) |
| ZDV |
1/18 (6%) |
11/17 (65%) |
| *N - includes patients with non-amplifiable virus at 24 weeks
who had amplifiable virus at week 0. |
Last updated on RxList: 11/2/2009