AGENERASE (amprenavir) in combination with other antiretroviral agents is indicated for the treatment of HIV-1 infection. This indication is based on analyses of plasma HIV RNA levels and CD4 cell counts in controlled studies of up to 24 weeks in duration. At present, there are no results from controlled trials evaluating long-term suppression of HIV RNA or disease progression with AGENERASE. DESCRIPTION: AGENERASE (amprenavir) is an inhibitor of the human immunodeficiency virus (HIV) protease. The chemical name of amprenavir is (3S)-tetrahydro-3-furyl N-[(1S,2R)-3-(4-amino-N- isobutylbenzenesulfonamido)-1-benzyl-2-hydroxypropyl]carbamate. Amprenavir is a single stereoisomer with the (3S)(1S,2R) configuration. It has a molecular formula of C25H35N3O6S and a molecular weight of 505.64. It has the following structural formula: Amprenavir is a white to cream-colored solid with a solubility of approximately 0.04 mg/mL in water at 25degC.
are available for oral administration in strengths of 50 and 150 mg. Each
capsule contains the inactive ingredients d-alpha tocopheryl polyethylene glycol 1000 succinate (TPGS), polyethylene glycol 400 (PEG 400), and propylene glycol. The capsule shell contains the inactive ingredients d-sorbitol and sorbitans solution, gelatin, glycerin, and titanium dioxide. The soft gelatin capsules are printed with edible red ink. Each 150-mg AGENERASE Capsule contains 109 IU vitamin E in the form of d-alpha tocopheryl polyethylene glycol 1000 succinate (TPGS). The total amount of vitamin E in the recommended daily adult dose of AGENERASE is 1744 IU.
is for oral administration. One milliliter (1 mL) of AGENERASE Oral Solution
contains 15 mg of amprenavir in solution and the inactive ingredients acesulfame potassium, artificial grape bubblegum flavor, citric acid (anhydrous), TPGS, menthol, natural peppermint flavor, polyethylene glycol 400 (PEG 400), propylene glycol, saccharin sodium, sodium chloride, and sodium citrate (dihydrate). Solutions of sodium hydroxide and/or diluted hydrochloric acid may have been added to adjust pH. Each mL of AGENERASE Oral Solution contains 46 IU vitamin E in the form of d-alpha tocopheryl polyethylene glycol 1000 succinate.
Amprenavir is an inhibitor of HIV-1 protease. Amprenavir binds to the active site of HIV-1 protease and thereby prevents the processing of viral gag and gag-pol polyprotein precursors, resulting in the formation of immature non-infectious viral particles.
The
antiviral activity of amprenavir was evaluated against HIV-1 IIIB in
both acutely and chronically infected lymphoblastic cell lines (MT-4, CEM-CCRF, H9) and in peripheral blood lymphocytes. The 50% inhibitory concentration (IC50) of amprenavir ranged from 0.012 to 0.08 mM in acutely infected cells and was 0.41 mM in chronically infected cells (1 mM = 0.50 mcg/mL). Amprenavir exhibited synergistic anti-HIV-1 activity in combination with abacavir, zidovudine, didanosine, or saquinavir, and additive anti-HIV-1 activity in combination with indinavir, nelfinavir, and ritonavir in vitro. These drug combinations have not been adequately studied in humans. The relationship between in vitro anti-HIV-1 activity of amprenavir and the inhibition of HIV-1 replication in humans has not been defined. Resistance: HIV-1 isolates with a decreased susceptibility to amprenavir have been selected in vitro and were also obtained from patients treated with amprenavir. Genotypic analysis of isolates from amprenavir-treated patients showed mutations in the HIV-1 protease gene resulting in amino acid substitutions primarily at positions M46I/L, I47V, I50V, I54L/V, and I84V as well as mutations in the viral protease p1/p6 cleavage site. Phenotypic analysis of HIV-1 isolates from some patients on amprenavir monotherapy for 8 to 12 weeks showed a 5- to 10-fold decrease in susceptibility to amprenavir in vitro compared to baseline. Phenotypic analysis of HIV-1 isolates from 28 patients treated with amprenavir in combination with zidovudine and lamivudine for 16 to 36 weeks identified isolates from six patients that exhibited a 5- to 11-fold decrease in susceptibility to amprenavir in vitro compared to wild-type virus. Clinical isolates that exhibited a decrease in amprenavir susceptibility harbored amprenavir-associated mutations. The clinical relevance of the genotypic and phenotypic changes associated with amprenavir therapy has not been established.
Varying degrees of HIV-1 cross-resistance among protease inhibitors have been observed. The potential for protease inhibitor cross-resistance in HIV-1 isolates from amprenavir-treated patients has not been fully evaluated.
The pharmacokinetic properties of amprenavir have been studied in asymptomatic, HIV-infected adult patients after administration of single oral doses of 150 to 1200 mg and multiple oral doses of 300 to 1200 mg twice daily.
Absorption and Bioavailability:
Amprenavir was rapidly absorbed after oral administration in
HIV-1-infected patients with a time to peak concentration (tmax) typically between 1 and 2 hours after a single oral dose. The absolute oral bioavailability of amprenavir in humans has not been established. Increases in the area under the plasma concentration versus time curve (AUC) after single oral doses between 150 and 1200 mg were slightly greater than dose-proportional. Increases in AUC were dose-proportional after 3 weeks of dosing with doses from 300 to 1200 mg twice daily. The pharmacokinetic parameters after administration of amprenavir 1200 mg b.i.d. for 3 weeks to HIV-infected subjects are shown in Table 1.
| C max (mcg/mL) | t max (hours) | AUC 0-12 (mcg * h/mL) | C avg (mcg/mL) | C min (mcg/mL) | CL/F (mL/min/kg) |
| 5.36 | 1.9 | 18.5 | 1.54 | 0.28 | 31 |
| (62%) | (51%) | (63%) | (63%) | (52%) | (132%) |
The relative bioavailability of AGENERASE Capsules and Oral Solution was assessed in healthy adults. AGENERASE Oral Solution was 14% less bioavailable compared to the capsules.
Effects of Food on Oral Absorption:
The relative bioavailability of AGENERASE Capsules was
assessed in the fasting and fed states in healthy volunteers (standardized high-fat meal: 967 kcal, 67 grams fat, 33 grams protein, 58 grams carbohydrate). Administration of a single 1200-mg dose of amprenavir in the fed state compared to the fasted state was associated with changes in Cmax (fed: 6.18 +- 2.92 mcg/mL, fasted: 9.72 +- 2.75 mcg/mL), tmax (fed: 1.51 +- 0.68, fasted: 1.05 +- 0.63), and AUC0-Y= (fed: 22.06 +- 11.6 mcg *h/mL, fasted: 28.05 +- 10.1 mcg *h/mL). AGENERASE may be taken with or without food, but should not be taken with a high fat meal (see DOSAGE AND ADMINISTRATION). Distribution: The apparent volume of distribution (Vz/F) is approximately 430 L in healthy adult subjects. In vitro binding is approximately 90% to plasma proteins. The high affinity binding protein for amprenavir is alpha1-acid glycoprotein (AAG). The partitioning of amprenavir into erythrocytes is low, but increases as amprenavir concentrations increase, reflecting the higher amount of unbound drug at higher concentrations.
Metabolism:
Amprenavir is metabolized in the liver by the cytochrome P450 CYP3A4 enzyme system.
The two major metabolites result from oxidation of the tetrahydrofuran and aniline moieties. Glucuronide conjugates of oxidized metabolites have been identified as minor metabolites in urine and feces.
Elimination:
Excretion of unchanged amprenavir in urine and feces is minimal. Approximately 14%
and 75% of an administered single dose of 14C-amprenavir can be accounted for as radiocarbon in urine and feces, respectively. Two metabolites accounted for >90% of the radiocarbon in fecal samples. The plasma elimination half-life of amprenavir ranged from 7.1 to 10.6 hours. Special Populations: Hepatic Insufficiency: AGENERASE has been studied in adult patients with impaired hepatic function using a single 600-mg oral dose. The AUC0-Y= was significantly greater in patients with moderate cirrhosis (25.76 +- 14.68 mcg *h/mL) compared with healthy volunteers (12.00 +- 4.38 mcg *h/mL). The AUC0-Y= and Cmax were significantly greater in patients with severe cirrhosis (AUC0-Y=: 38.66 +- 16.08 mcg *h/mL; Cmax: 9.43 +- 2.61 mcg/mL) compared with healthy volunteers (AUC0-Y=: 12.00 +- 4.38 mcg *h/mL; Cmax: 4.90 +- 1.39 mcg/mL). Patients with impaired hepatic function require dosage adjustment (see DOSAGE AND ADMINISTRATION).
Renal Insufficiency:
The impact of renal impairment on amprenavir elimination in adult patients has not been studied. The renal elimination of unchanged amprenavir represents <3% of the administered dose.
Pediatric Patients:
The pharmacokinetics of amprenavir have been studied after either single or
repeat doses of AGENERASE in 84 pediatric patients. Twenty HIV-1-infected children ranging in age from 4 to 12 years received single doses from 5 mg/kg to 20 mg/kg using 25-mg or 150-mg capsules. The Cmax of amprenavir increased less than proportionally with dose. The AUC0-Y= increased proportionally at doses between 5 and 20 mg/kg. Amprenavir is 14% less bioavailable from the liquid formulation than from the capsules; therefore AGENERASE Capsules and AGENERASE Oral Solution are not interchangeable on a milligram per milligram basis.
| Dose | n | C max (mcg/mL) | t max (hours) | AUC ss * (mcg * h/mL) | C avg (mcg/mL) | C min (mcg/mL) | CL/F (mL/min/kg) |
| 20 mg/kg | 20 | 6.77 | 1.1 | 15.46 | 1.29 | 0.24 | 29 |
| b.i.d. | (51%) | (21%) | (59%) | (59%) | (98%) | (58%) | |
| 15 mg/kg | 17 | 3.99 | 1.4 | 8.73 | 1.09 | 0.27 | 32 |
| t.i.d. | (37%) | (90%) | (36%) | (36%) | (95%) | (34%) |
*AUC is 0 to 12 hours for b.i.d. and 0 to 8 hours for t.i.d., therefore the Cavg is a better comparison of the exposures.
Geriatric Patients:
The pharmacokinetics of amprenavir have not been studied in patients over 65 years of age.
Gender:
The pharmacokinetics of amprenavir do not differ between males and females.
Race: The pharmacokinetics of amprenavir do not differ between Blacks and non-Blacks. Drug Interactions: See also CONTRAINDICATIONS, WARNINGS, and PRECAUTIONS: Drug Interactions. Amprenavir is metabolized in the liver by the cytochrome P450 enzyme system. Amprenavir inhibits CYP3A4. Caution should be used when coadministering medications that are substrates, inhibitors, or inducers of CYP3A4, or potentially toxic medications that are metabolized by CYP3A4. Amprenavir does not inhibit CYP2D6, CYP1A2, CYP2C9, CYP2C19, CYP2E1, or uridine glucuronosyltransferase (UDPGT). Drug interaction studies were performed with amprenavir and other drugs likely to be coadministered or drugs commonly used as probes for pharmacokinetic interactions. The effects of coadministration of amprenavir on the AUC, Cmax, and Cmin are summarized in Table 3 (effect of other drugs on amprenavir) and Table 4 (effect of amprenavir on other drugs). For information regarding clinical recommendations, see PRECAUTIONS.
| Co- administered Drug | Dose of Coadministered Drug | Dose of AGENERASE | n | % Change in Amprenavir Pharmacokinetic Parameters * (90% CI) | ||
| C max | AUC | C min | ||||
| Abacavir | 300 mg b.i.d. for 3 weeks | 900 mg b.i.d. for 3 weeks | 4 | a 47 ( a 15 to a 154) | a 29 ( a 18 to a 103) | a 27 ( a 46 to a 197) |
| Clarithromycin | 500 mg b.i.d. for 4 days | 1200 mg b.i.d. for 4 days | 12 | a 15 ( a 1 to a 31) | a 18 ( a 8 to a 29) | a 39 ( a 31 to a 47) |
| Indinavir | 800 mg t.i.d. for 2 weeks (fasted) | 750 or 800 mg t.i.d. for 2 weeks (fasted) | 9 | a 18 ( a 13 to a 58) | a 33 ( a 2 to a 73) | a 25 ( a 27 to a 116) |
| Ketoconazole | 400 mg single dose | 1200 mg single dose | 12 | a 16 ( a 25 to a 6) | a 31 ( a 20 to a 42) | NA |
| Lamivudine | 150 mg single dose | 600 mg single dose | 11 | = ( a 17 to a 9) | = ( a 15 to a 14) | NA |
| Nelfinavir | 750 mg t.i.d. for 2 weeks (fed) | 750 or 800 mg t.i.d. for 2 weeks (fed) | 6 | a 14 ( a 38 to a 20) | = ( a 19 to a 47) | a 189 ( a 52 to a 448) |
| Rifabutin | 300 mg q.d. for 10 days | 1200 mg b.i.d. for 10 days | 5 | = ( a 21 to a 10) | a 15 ( a 28 to 0) | a 15 ( a 38 to a 17) |
| Rifampin | 300 mg q.d. for 4 days | 1200 mg b.i.d. for 4 days | 11 | a 70 ( a 76 to a 62) | a 82 ( a 84 to a 78) | a 92 ( a 95 to a 89) |
| Saquinavir | 800 mg t.i.d. for 2 weeks (fed) | 750 or 800 mg t.i.d. for 2 weeks (fed) | 7 | a 37 ( a 54 to a 14) | a 32 ( a 49 to a 9) | a 14 ( a 52 to a 54) |
| Zidovudine | 300 mg single dose | 600 mg single dose | 12 | = ( a 5 to a 24) | a 13 ( a 2 to a 31) | NA |
*Based on total-drug concentrations. = Increase; - = Decrease; U = No change ( or -<10%); NA = Cmin not calculated for single-dose study.
| Co- administered Drug | Dose of Coadministered Drug | Dose of AGENERASE | n | % Change in Pharmacokinetic Parameters of Coadministered Drug (90% CI) | ||
| C max | AUC | C min | ||||
| Clarithromycin | 500 mg b.i.d. for 4 days | 1200 mg b.i.d. for 4 days | 12 | a 10 ( a 24 to a 7) | = ( a 17 to a 11) | = ( a 13 to a 20) |
| Ketoconazole | 400 mg single dose | 1200 mg single dose | 12 | a 19 ( a 8 to a 33) | a 44 ( a 31 to a 59) | NA |
| Lamivudine | 150 mg single dose | 600 mg single dose | 11 | = ( a 17 to a 3) | = ( a 11 to 0) | NA |
| Rifabutin | 300 mg q.d. for 10 days | 1200 mg b.i.d. for 10 days | 5 | a 119 ( a 82 to a 164) | a 193 ( a 156 to a 235) | a 271 ( a 171 to a 409) |
| Rifampin | 300 mg q.d. for 4 days | 1200 mg b.i.d. for 4 days | 11 | = ( a 13 to a 12) | = ( a 10 to a 13) | ND |
| Zidovudine | 300 mg single dose | 600 mg single dose | 12 | a 40 ( a 14 to a 71) | a 31 ( a 19 to a 45) | NA |
= Increase; - = Decrease; U = No change ( or -<10%); NA = Cmin not calculated for single-dose study, ND = Interaction cannot be determined as Cmin was below the lower limit of quantitation.
Nucleoside Reverse Transcriptase Inhibitors (NRTIs):
There was no effect of amprenavir on abacavir in subjects receiving both agents based on historical data.
HIV Protease Inhibitors:
The effect of amprenavir on total drug concentrations of other HIV protease
inhibitors in subjects receiving both agents was evaluated using comparisons to historical data. Indinavir steady-state Cmax, AUC, and Cmin were decreased by 22%, 38%, and 27%, respectively, by concomitant amprenavir. Similar decreases in Cmax and AUC were seen after the first dose. Saquinavir steady-state Cmax, AUC, and Cmin were increased 21%, decreased 19%, and decreased 48%, respectively, by concomitant amprenavir. Nelfinavir steady-state Cmax, AUC, and Cmin were increased by 12%, 15%, and 14%, respectively, by concomitant amprenavir. For information regarding clinical recommendations, see PRECAUTIONS: Drug Interactions.
AGENERASE (amprenavir) in combination with other antiretroviral agents is indicated for the treatment of HIV-1 infection. This indication is based on analyses of plasma HIV RNA levels and CD4 cell counts in controlled studies of up to 24 weeks in duration. At present, there are no results from controlled trials evaluating long-term suppression of HIV RNA or disease progression with AGENERASE (see Description of Clinical Studies).
PROAB3001, an ongoing, randomized, double-blind, placebo-controlled, multicenter study, compared treatment with AGENERASE (1200 mg twice daily) plus lamivudine (150 mg twice daily) plus zidovudine (300 mg twice daily) versus lamivudine (150 mg twice daily) plus zidovudine (300 mg twice daily) in 232 patients, median age 37 years (range 18
to 63 years), 75% Caucasian, 89% male, with a median CD4 cell count of 416 cells/mm3 (range 139 to 1800 cells/mm3) and a median plasma HIV-1 RNA of 4.67 log10 copies/mL (range 3.06 to 6.31 log10 copies/mL) at baseline. Through 24 weeks of therapy, there was no significant difference in the median CD4 cell count between the treatment arms. Figure 1 shows the proportions of patients with plasma HIV-1 RNA levels <400 copies/mL through 24 weeks.
HIV-1 RNA status and reasons for discontinuation of randomized treatment at 24 weeks are summarized (Table 5).
| Outcome | AGENERASE (n = 116) | Placebo (n = 116) |
| HIV RNA <400 copies/mL * | 53% | 11% |
| HIV RNA >= 400 copies/mL +,++ CDC Class C event ++ | 13% 0 | 62% 0 |
| Discontinued due to adverse events ++ | 15% | 3% |
| Discontinued due to other reasons ++,SS | 19% | 22% |
| On treatment with missing HIV RNA value ++ | 0% | 1% |
| TOTAL | 100% | 100% |
*Corresponds to rates at Week 24 in Figure 1.
+
Includes discontinuations due to virological failure at or before Week 24.
++
Treatment failure in the analysis.
SS
Consent withdrawn, lost to follow-up, and protocol violation.
Therapy-Experienced Adults:
PROAB3006, an ongoing, randomized, open-label multicenter study, compared treatment with AGENERASE (1200 mg twice daily) plus NRTIs versus indinavir (800 mg every 8 hours) plus NRTIs in 504 NRTI- and non-nucleoside reverse transcriptase inhibitor- (NNRTI) experienced, protease inhibitor-naive patients, median age 37 years (range 20 to 71 years), 72%
Caucasian, 80% male, with a median CD4 cell count of 399 cells/mm3 (range 9 to 1706 cells/mm3) and a median plasma HIV-1 RNA level of 3.93 log10 copies/mL (range 2.60 to 7.01 log10 copies/mL) at baseline. Through 24 weeks of therapy, there was a smaller increase in median CD4 cell count from baseline for the amprenavir group than for the indinavir group. Figure 2 shows the proportions of patients with plasma HIV-1 RNA levels <400 copies/mL through 24 weeks.
HIV-1 RNA status and reasons for discontinuation of randomized treatment at 24 weeks are summarized (Table 6).
| Outcome | AGENERASE (n = 254) | Indinavir (n = 250) |
| HIV RNA <400 copies/mL * | 43% | 53% |
| HIV RNA >= 400 copies/mL +,++ CDC Class C event ++ | 22% <1% | 18% 2% |
| Discontinued due to adverse events ++ | 16% | 8% |
| Discontinued due to other reasons ++,SS | 14% | 12% |
| On treatment with missing HIV RNA value ++ | 4% | 7% |
| TOTAL | 100% | 100% |
*Corresponds to rates at Week 24 in Figure 2.
+
Includes discontinuations due to virological failure at or before Week 24.
++
Treatment failure in the analysis.
SS
Consent withdrawn, lost to follow-up, and protocol violation.
AGENERASE should not be administered concurrently with astemizole, bepridil, cisapride, dihydroergotamine, ergotamine, midazolam, and triazolam. Although these drugs have not been specifically studied, coadministration may result in competitive inhibition of metabolism of these products and may cause serious or life-threatening adverse events. (See WARNINGS for agents whose coadministration may result in competitive inhibition of metabolism but for which concentration monitoring is recommended.) AGENERASE is contraindicated in patients with previously demonstrated clinically significant hypersensitivity to any of the components of this product.
Rifampin should not be used in combination with amprenavir because it reduces plasma concentrations and AUC of amprenavir by about 90%. Particular caution should be used when prescribing sildenafil in patients receiving amprenavir. Coadministration of AGENERASE with sildenafil is expected to substantially increase sildenafil concentrations and may result in an increase in sildenafil-associated adverse events, including hypotension, visual changes, and priapism. (see PRECAUTIONS: Drug Interactions and Information for Patients, and the complete prescribing information for sildenafil).
Acute hemolytic anemia has been reported in a patient treated with AGENERASE. New onset diabetes mellitus, exacerbation of pre-existing diabetes mellitus, and hyperglycemia have been reported during post-marketing surveillance in HIV-infected patients receiving protease inhibitor therapy. Some patients required either initiation or dose adjustments of insulin or oral hypoglycemic agents for treatment of these events. In some cases, diabetic ketoacidosis has occurred. In those patients who discontinued protease inhibitor therapy, hyperglycemia persisted in some cases. Because these events have been reported voluntarily during clinical practice, estimates of frequency cannot be made and causal relationships between protease inhibitor therapy and these events have not been established.
(see CLINICAL PHARMACOLOGY: Pediatric Patients).
Amprenavir is a sulfonamide. The potential for cross-sensitivity between drugs in the sulfonamide class and amprenavir is unknown. Patients with a known sulfonamide allergy should be treated with caution. AGENERASE is principally metabolized by the liver; therefore caution should be exercised when administering this drug to patients with hepatic impairment (see DOSAGE AND ADMINISTRATION). Formulations of AGENERASE provide high daily doses of vitamin E (see Information for Patients, DESCRIPTION, and DOSAGE AND ADMINISTRATION). The effects of long-term, high-dose vitamin E administration in humans is not well characterized and has not been specifically studied in HIV-infected individuals. High vitamin E doses may exacerbate the blood coagulation defect of vitamin K deficiency caused by anticoagulant therapy or malabsorption.
There have been reports of spontaneous bleeding in patients with hemophilia
A and B treated with protease inhibitors. In some patients, additional factor VIII was required. In many of the reported cases, treatment with protease inhibitors was continued or restarted. A causal relationship between protease inhibitor therapy and these episodes has not been established.
: Redistribution/accumulation of body fat including central obesity, dorsocervical fat
enlargement (buffalo hump), peripheral wasting, breast enlargement, and "cushingoid appearance" have been observed in patients receiving protease inhibitors. The mechanism and long-term consequences of these events are currently unknown. A causal relationship has not been established.
Because the potential for HIV cross-resistance among protease inhibitors has not been fully explored, it is unknown what effect amprenavir therapy will have on the activity of subsequently administered protease inhibitors (see MICROBIOLOGY).
A Patient Package Insert (PPI) for AGENERASE is available for patient
information. Patients should be informed that AGENERASE is not a cure for HIV infection and that they may continue to develop opportunistic infections and other complications associated with HIV disease. The long-term effects of AGENERASE (amprenavir) are unknown at this time. Patients should be told that there are currently no data demonstrating that therapy with AGENERASE can reduce the risk of transmitting HIV to others through sexual contact. Patients should remain under the care of a physician while using AGENERASE. Patients should be advised to take AGENERASE every day as prescribed. AGENERASE must always be used in combination with other antiretroviral drugs. Patients should not alter the dose or discontinue therapy without consulting their physician. If a dose is missed, patients should take the dose as soon as possible and then return to their normal schedule. However, if a dose is skipped, the patient should not double the next dose. Patients should inform their doctor if they have a sulfa allergy. The potential for cross-sensitivity between drugs in the sulfonamide class and amprenavir is unknown. Some drugs should not be used with AGENERASE. Therefore, patients should be advised that they must report to their doctor the use of any other prescription or nonprescription medication. Patients taking antacids (or didanosine) should take AGENERASE at least 1 hour before or after antacid (or didanosine) use. Patients receiving sildenafil should be advised that they may be at an increased risk of sildenafil-associated adverse events including hypotension, visual changes, and priapism, and should promptly report any symptoms to their doctor. Patients receiving hormonal contraceptives should be instructed that alternate contraceptive measures should be used during therapy with AGENERASE. High fat meals may decrease the absorption of AGENERASE and should be avoided. AGENERASE may be taken with meals of normal fat content. Patients should be informed that redistribution or accumulation of body fat may occur in patients receiving protease inhibitors and that the cause and long-term health effects of these conditions are not known at this time. Adult and pediatric patients should be advised not to take supplemental vitamin E since the vitamin E content of AGENERASE Capsules and Oral Solution exceeds the Reference Daily Intake (adults 30 IU, pediatrics approximately 10 IU).
Drug Interactions. AGENERASE is an inhibitor of cytochrome P450 CYP3A4 metabolism and therefore should not be administered concurrently with medications with narrow therapeutic windows that are substrates of CYP3A4. There are other agents that may result in serious and/or life-threatening drug interactions (see CONTRAINDICATIONS and WARNINGS).
| Drug Class | Drug Within Class Not To Be Coadministered |
| Antihistamines | Astemizole |
| Antimycobacterials | Rifampin * |
| Benzodiazepines | Midazolam, triazolam |
| Cardiovascular | Bepridil |
| Ergot derivatives | Dihydroergotamine, ergotamine |
| GI motility agents | Cisapride |
Decreases plasma concentrations of amprenavir and should not be coadministered as it is likely to reduce antiviral activity.
| Drug Class | Drug Within Class to Monitor |
| Antiarrhythmics | Amiodarone, lidocaine (systemic), quinidine |
| Anticoagulants | Warfarin * |
| Antidepressants | Tricyclic antidepressants |
*Monitor INR (International Normalized Ratio).
| Drug Class | Drug Within Class Requiring a Dosage Adjustment |
| Antimycobacterials | Rifabutin (reduce dose to at least half that recommended) * |
*
A complete blood count should be performed weekly and as clinically indicated in order to monitor for neutropenia in patients receiving amprenavir and rifabutin.
| Anticonvulsants: phenobarbital, phenytoin, carbamazepine | Induce CYP3A4 and may decrease amprenavir concentrations. |
| Cholesterol-lowering agents: atorvastatin, cerivastatin, lovastatin, pravastatin, and simvastatin | May have their serum concentrations increased by AGENERASE, which could increase their activity or toxicity. |
| Erectile dysfunction agents: sildenafil | Expected to substantially increase sildenafil concentrations (consult sildenafil prescribing information for dose reduction of sildenafil in patients receiving ritonavir) |
Antimycobacterials: Rifampin:
Rifampin should not be used in combination with amprenavir since it reduces plasma concentrations and AUC of amprenavir by about 90%.
Rifabutin:
Coadministration of amprenavir with rifabutin results in a 15% decrease in amprenavir
plasma AUC and a 193% increase in rifabutin plasma AUC. A dosage reduction of rifabutin to at least half the recommended dose is required when AGENERASE and rifabutin are coadministered (see CLINICAL PHARMACOLOGY: Drug Interactions). A complete blood count should be performed weekly and as clinically indicated in order to monitor for neutropenia in patients receiving amprenavir and rifabutin.
Other Potentially Significant Drug Interactions:
Other medications that interact at CYP3A4, either
as substrates, inhibitors, or inducers of the enzyme, could have potential interactions when used concomitantly. The clinical significance of these potential interactions is unknown and has not been studied.
Antibiotics:
Dapsone and erythromycin may have their plasma concentrations increased by
AGENERASE. Erythromycin may also increase amprenavir serum concentrations.
Antifungals:
Itraconazole may have its plasma concentrations increased by AGENERASE. Itraconazole may increase serum concentrations of amprenavir.
Benzodiazepines:
Alprazolam, clorazepate, diazepam, and flurazepam may have their serum
concentrations increased by AGENERASE, which could increase their activity.
Calcium Channel Blockers:
Diltiazem, nicardipine, nifedipine, and nimodipine may have their serum concentrations increased by AGENERASE, which could increase their activity.
Cholesterol-Lowering Agents:
Atorvastatin, cerivastatin, lovastatin, pravastatin, and simvastatin
may have their serum concentrations increased by AGENERASE, which could increase their activity or toxicity.
Erectile Dysfunction Agents:
Particular caution should be used when prescribing sildenafil in
patients receiving amprenavir. Because amprenavir is a cytochrome P4503A4 inhibitor, coadministration of AGENERASE with sildenafil is likely to result in an increase of sildenafil concentrations by competitive inhibition of metabolism. The magnitude of this interaction has not been determined. Results from drug interaction studies in healthy volunteers indicate that coadministration of saquinavir soft gelatin capsules (1200 mg t.i.d.) increases sildenafil (100 mg single dose) AUC by 210% (3.1-fold) and coadministration of ritonavir (500 mg b.i.d.) increases sildenafil (100 mg single dose) AUC by 1000% (11-fold). Providers should consult the sildenafil prescribing information for dose reductions of sildenafil in patients receiving ritonavir. Patients receiving amprenavir and sildenafil should be advised that they may be at an increased risk for sildenafil-associated adverse events, including hypotension, visual changes, and priapism, and should report these symptoms promptly to their doctor.
NNRTIs:
NNRTIs have the potential to increase (delavirdine) or decrease (efavirenz, nevirapine)
serum concentrations of amprenavir.
Steroids:
Estrogens, progestogens, and some glucocorticoids may have an interaction with AGENERASE but there is insufficient information to predict the nature of the interaction. Because of this potential for metabolic interactions with amprenavir, the efficacy of hormonal contraceptives may be reduced. Alternate or additional reliable barrier methods of contraception are recommended for women of childbearing potential.
Other Agents:
There are other agents that may have their plasma concentrations increased by
AGENERASE, and include but are not limited to: clozapine, carbamazepine, loratadine, pimozide, and warfarin. Cimetidine and ritonavir may increase amprenavir plasma concentrations. Antacids (and didanosine secondary to the antacid content) have not been specifically studied. Based upon data with other protease inhibitors, it is advisable that antacids not be taken at the same time as AGENERASE because of potential interference with absorption. It is recommended that their administration be separated by at least an hour. Carcinogenesis and Mutagenesis: Long-term carcinogenicity studies of amprenavir in rodents are in progress. Amprenavir was not mutagenic or genotoxic in a battery of in vitro and in vivo assays including bacterial reverse mutation (Ames), mouse lymphoma, rat micronucleus, and chromosome aberrations in human lymphocytes.
The effects of amprenavir on fertility and general reproductive performance were investigated in
male rats (treated for 28 days before mating, at doses producing up to twice the expected clinical exposure based on AUC comparisons) and female rats (treated for 15 days before mating through day 17 of gestation at doses producing up to 2 times the expected clinical exposure). Amprenavir did not impair mating or fertility of male or female rats and did not affect the development and maturation of sperm from treated rats. The reproductive performance of the F1 generation born to female rats given amprenavir was not different from control animals.
Pregnancy Category C. Embryo/fetal development studies were
conducted in rats (dosed from 15 days before pairing to day 17 of gestation) and rabbits (dosed from day 8 to day 20 of gestation). In pregnant rabbits, amprenavir administration was associated with abortions and an increased incidence of three minor skeletal variations resulting from deficient ossification of the femur, humerus trochlea, and humerus. Systemic exposure at the highest tested dose was approximately one-twentieth of the exposure seen at the recommended human dose. In rat fetuses, thymic elongation and incomplete ossification of bones were attributed to amprenavir. Both findings were seen at systemic exposures that were one half of that associated with the recommended human dose. Pre- and post-natal developmental studies were performed in rats dosed from day 7 of gestation to day 22 of lactation. Reduced body weights (10% to 20%) were observed in the offspring. The systemic exposure associated with this finding was approximately twice the exposure in humans following administration of the recommended human dose. The subsequent development of these offspring, including fertility and reproductive performance, was not affected by the maternal administration of amprenavir. There are no adequate and well-controlled studies in pregnant women. AGENERASE should be used during pregnancy only if the potential benefit justifies the potential risk to the fetus.
Antiretroviral Pregnancy Registry:
To monitor maternal-fetal outcomes of pregnant women
exposed to AGENERASE, an Antiretroviral Pregnancy Registry has been established. Physicians are encouraged to register patients by calling 1-800-258-4263.
Although it is
not known if amprenavir is excreted in human milk, amprenavir is secreted into the milk of lactating rats. Because of both the potential for HIV transmission and any possible adverse effects of amprenavir, mothers should be instructed not to breastfeed if they are receiving AGENERASE.
One hundred eighteen patients 4 to 17 years of age have received amprenavir as single or multiple doses in studies. An adverse event profile similar to that seen in adults was seen in pediatric patients.
The safety, effectiveness, and pharmacokinetics of amprenavir have not been evaluated in pediatric patients below the age of 4 years (see CLINICAL PHARMACOLOGY and DOSAGE AND ADMINISTRATION).
Clinical studies of AGENERASE did not include sufficient numbers of patients aged 65
and over to determine whether they respond differently from younger adults. In general, dose selection for an elderly patient should be cautious, reflecting the greater frequency of decreased hepatic, renal, or cardiac function, and of concomitant disease or other drug therapy.
Rates of discontinuation of randomized therapy due to adverse events were 15% in amprenavir vs 3% in placebo recipients from Study 3001, and 16% in amprenavir vs 8% in indinavir recipients from Study 3006. In these studies, adverse events leading to amprenavir discontinuation included gastrointestinal events (11%), rash (3%), and paresthesias (<1%).
Most gastrointestinal events (nausea, vomiting, diarrhea, and abdominal pain) that led to amprenavir discontinuation were graded as mild or moderate in severity. In all multidose studies in HIV-infected patients, skin rash occurred in 28% of patients treated with amprenavir. Rashes were usually maculopapular and of mild or moderate intensity, some with pruritus. Rashes had onsets ranging from 7 to 73 days (median: 10 days) after amprenavir initiation. With mild or moderate rash, amprenavir dosing was often continued without interruption; if interrupted, reintroduction of amprenavir generally did not result in rash recurrence (Phase 3 studies).
Severe or life-threatening rash, including Stevens-Johnson syndrome, occurred in 1% of
recipients of AGENERASE (4% of recipients who developed rash) (see WARNINGS). Amprenavir therapy should be discontinued for severe or life-threatening rashes and for moderate rashes accompanied by systemic symptoms.
Table 8: Selected Clinical Adverse Events Grades 1-4 (35% Frequency)
| Adverse Event | PROAB3001 Therapy-Naive Patients | PROAB3006 NRTI-Experienced Patients | ||
| AGENERASE/ Lamivudine/ Zidovudine (n = 113) | Lamivudine/ Zidovudine (n = 109) | AGENERASE/ NRTI (n = 245) | Indinavir/NRTI (n = 241) | |
| Digestive | 73% | 50% | 38% | 26% |
| Nausea | ||||
| Vomiting | 29% | 17% | 20% | 11% |
| Diarrhea or loose stools | 33% | 34% | 56% | 32% |
| Taste disorders | 10% | 5% | 1% | 7% |
| Skin | ||||
| Rash | 25% | 6% | 18% | 10% |
| Nervous | ||||
| Paresthesia, oral/perioral | 26% | 5% | 30% | 2% |
| Paresthesia (including peripheral) | 8% | 3% | 12% | 9% |
| Psychiatric | ||||
| Depressive or mood disorders | 15% | 4% | 4% | 6% |
In Phase 3 studies, one patient experienced diabetes mellitus de novo, and another developed a dorsocervical fat enlargement (buffalo hump).
Table 9: Selected Laboratory Abnormalities Grades 1-4 Reported in 35% of Patients
| Laboratory Abnormality (non-fasting specimens) | PROAB3001 Therapy-Naive Patients | PROAB3006 NRTI-Experienced Patients | ||
| AGENERASE/ Lamivudine/ Zidovudine (n = 113) | Lamivudine/ Zidovudine (n = 109) | AGENERASE/ NRTI (n = 245) | Indinavir/NRTI (n = 241) | |
| Hyperglycemia (>160 mg/L) | 37% | 29% | 41% | 44% |
| Hypertriglyceridemia (>399 mg/dL) | 36% | 22% | 47% | 40% |
| Hypercholesterolemia (>260 mg/dL) | 4% | 3% | 9% | 10% |
In studies 3001 and 3006, no increased frequency of Grade 3 or 4 AST, ALT, amylase, or bilirubin elevations was seen compared to controls.
Pediatric Patients:
An adverse event profile similar to that seen in adults was seen in pediatric patients.
There is no known antidote for AGENERASE. It is not known whether amprenavir can be removed by peritoneal dialysis or hemodialysis. If overdosage occurs, the patient should be monitored for evidence of toxicity and standard supportive treatment applied as necessary.
Adult and pediatric patients should be advised not to take supplemental vitamin E since the vitamin E content of AGENERASE Capsules and Oral Solution exceeds the Reference Daily Intake (adults 30 IU, pediatrics approximately 10 IU) (see DESCRIPTION).
AGENERASE may be taken with or without food, however, a high fat meal decreases the absorption of amprenavir and should be avoided (see CLINICAL PHARMACOLOGY: Effect of Food On Oral Absorption).
The recommended oral dose of AGENERASE Capsules for adults is 1200 mg (eight 150-mg
capsules) twice daily in combination with other antiretroviral agents.
For adolescents (13 to 16 years), the recommended oral dose of AGENERASE Capsules is 1200 mg (eight 150-mg capsules) twice daily in combination with other antiretroviral agents. For patients between 4 and 12 years of age or for patients 13 to 16 years of age with weight of <50 kg, the recommended oral dose of AGENERASE Capsules is 20 mg/kg twice daily or
15 mg/kg three times daily (to a maximum daily dose of 2400 mg) in combination with other antiretroviral agents.
AGENERASE Oral Solution:
The recommended oral dose of AGENERASE Oral Solution for patients between 4 and 12 years of age or for patients 13 to 16 years of age with weight <50 kg is 22.5 mg/kg
(1.5 mL/kg) twice daily or 17 mg/kg (1.1 mL/kg) three times daily (to a maximum daily dose of 2800 mg) in combination with other antiretroviral agents.
AGENERASE should be used with caution in patients with moderate or severe hepatic impairment. Patients with a Child-Pugh score ranging from 5 to 8 should receive a reduced dose of AGENERASE Capsules of 450 mg twice daily, and patients with a Child-Pugh score ranging from 9 to 12 should receive a reduced dose of AGENERASE Capsules of 300 mg twice daily (see CLINICAL PHARMACOLOGY: Hepatic Insufficiency).
AGENERASE Capsules, 50 mg, are oblong, opaque off-white to cream-colored soft gelatin capsules printed with "GX CC1" on one side.
Bottles of 480 with child-resistant closures (NDC 0173-0679-00). AGENERASE Capsules, 150 mg, are oblong, opaque off-white to cream-colored soft gelatin capsules printed with "GX CC2" on one side. Bottles of 240 with child-resistant closures (NDC 0173-0672-00).
AGENERASE Oral Solution, a clear, pale yellow to yellow, grape bubblegum peppermint-flavored liquid, contains 15 mg of amprenavir in each 1 mL. Bottles of 240 mL with child-resistant closures (NDC 0173-0687-00). This product does not require reconstitution.
US Patent No. 5,585,397 AGENERASE Capsules are manufactured by R.P. Scherer Beinheim, France for Licensed from Glaxo Wellcome Inc. Vertex Pharmaceuticals Incorporated Research Triangle Park, NC 27709 Cambridge, MA 02139 AGENERASE is a trademark of the Glaxo Wellcome group of companies.
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Copyright 1999, Glaxo Wellcome Inc. All rights reserved.
April 1999 RL-708 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _