Amprenavir
Pronouncation: (am-PREN-ah-veer)Class: Protease inhibitor
Trade Names:
Agenerase
- Capsules 50 mg
- Oral solution 15 mg/mL
Pharmacology
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Inhibits HIV protease, the enzyme required to form functional proteins in HIV-infected patients.
Pharmacokinetics
Absorption
Rapidly absorbed. T max is 1 to 2 h. C max is approximately 7.66 mcg/mL. AUC 0-12 is approximately 17.7 mcg•h/mL. Oral solution is 14% less bioavailable than the capsules. Food high in fat decreased C max and AUC, and increased T max . Do not take with high-fat meals.
Distribution
Vd is approximately 430 L; approximately 90% protein bound (primarily alpha- 1 -acid glycoprotein).
Metabolism
Metabolized in the liver by CYP3A4.
Elimination
Less than 3% excreted unchanged by the kidney; approximately 14% of dose excreted in urine and approximately 75% excreted in the feces (more than 90% as metabolites). The t ½ is 7.1 to 10.6 h.
Special Populations
Renal Function ImpairmentOral solution contraindicated because of propylene glycol excipient.
Hepatic Function ImpairmentModerate cirrhosis increased AUC; severe cirrhosis increased AUC and C max . Dosage reduction required for capsules. Oral solution is contraindicated in those with hepatic failure.
ChildrenOral solution contraindicated in infants and children younger than 4 yr of age because of propylene glycol excipient.
Indications and Usage
Treatment of HIV-1 infections in combination with other antiretroviral agents.
Contraindications
Concomitant therapies with cisapride, dihydroergotamine, ergotamine, ergonovine, methylergonovine, or pimozide; midazolam and triazolam; drugs that are highly dependent on CYP3A4 for Cl and for which elevated plasma levels are associated with serious or life-threatening events; when administered in combination with ritonavir, flecainide and propafenone are contraindicated; hypersensitivity to any component of the product; because of the propylene glycol content, the oral solution is contraindicated in infants and children younger than 4 yr of age, pregnant women, patients with renal or hepatic failure, and patients treated with disulfiram or metronidazole.
Dosage and Administration
Amprenavir capsules and oral solution are not interchangeable on a mg-to-mg basis.
Adults and children 13 to 16 yr of agePO (capsules) 1,200 mg twice daily in combination with other antiretroviral agents.
Adults and Children 13 to 16 yr of age weighing 50 kg or morePO 1,400 mg twice daily.
Children 4 to 16 yr of age weighing less than 50 kgPO (capsules) 20 mg/kg twice daily or 15 mg/kg 3 times daily (max, 2,400 mg/day) in combination with other antiretroviral agents.
Children 4 to 16 yr of age weighing less than 50 kgPO (oral solution) 22.5 mg/kg (1.5 mL/kg) twice daily or 17 mg/kg (1.1 mL/kg) 3 times daily (max, 2,800 mg) in combination with other antiretroviral agents.
Storage/Stability
Store capsules and oral solution at controlled room temperature (77°F).
Drug Interactions
Abacavir, aldesleukin, azole antifungal agents (eg, itraconazole), cimetidine, delavirdine, dexamethasone, didanosine, ethanol, indinavir, itraconazole, macrolide antibiotics, nelfinavir, ritonavir, zidovudineMay increase amprenavir plasma levels.
Benzodiazepines (eg, alprazolam)Amprenavir may increase blood levels of these drugs, which may produce extreme sedation and respiratory depression.
Amiodarone, cisapride, ergot derivatives, lidocaine (systemic), quinidine, rifabutin, sildenafil, tricyclic antidepressantsAmprenavir may elevate blood levels of these drugs, which may increase the risk of arrhythmias, hematologic abnormalities, seizures, or other potentially serious adverse reactions.
Calcium channel blockers (eg, felodipine), carbamazepine, clozapine, cylcosporine, dapsone, erythromycin, fentanyl, HMG-CoA reductase inhibitors (eg, atorvastatin), itraconazole, ketoconazole, loratadine, oral contraceptives, pimozide, rifabutin, sildenafil, tacrolimus, tricyclic antidepressants (eg, amitriptyline), zidovudineMay have their plasma concentrations increased, which could increase activity or toxicity.
Antacids, carbamazepine, didanosine (buffered formulation), efavirenz, methadone, nevirapine, oral contraceptives, phenobarbital, phenytoin, rifabutin, saquinavir, rifampin, St. John's wortMay decrease plasma levels of amprenavir, which may reduce antiviral activity.
Cisapride, dihydroergotamine, disulfiram, ergotamine, ergonovine, methylergonovine, midazolam, pimozide, triazolamUse with amprenavir is contraindicated.
RitonavirPlasma levels may be decreased by amprenavir.
WarfarinRisk of bleeding may be increased.
Laboratory Test Interactions
None well documented.
Adverse Reactions
CNS
Depressive or mood disorder, paresthesia (greater than 5%).
Dermatologic
Rash (greater than 5%; life-threatening [about 1%]).
GI
Nausea, vomiting, diarrhea, taste disorder (greater then 5%).
Precautions
WarningsOral solution Propylene glycol excipientRisk of toxicity from large amount of excipient contraindicates use in children younger than 4 yr of age and in certain other populations; use with caution in others. Only use when capsules or other protease inhibitors are not therapeutic options. |
Pregnancy
Category C .
Lactation
HIV-infected mothers should not breast-feed their infants.
Children
Safety and efficacy not established in children younger than 4 yr of age.
Elderly
Select dose with caution, reflecting greater frequency of decreased hepatic, renal, or cardiac function and comorbidity.
Hepatic Function
Use with caution; decreased amprenavir Cl may occur.
Fat redistribution
Redistribution/accumulation of body fat, including central obesity, dorsocervical fat enlargement (buffalo hump), peripheral wasting, facial wasting, breast enlargement, and cushingoid appearance, have occurred.
Hemophilia
Spontaneous bleeding in patients with hemophilia A and B has been reported.
Lipid levels
Increases in total cholesterol and triglyceride concentrations may occur.
Skin reactions
Life-threatening skin reactions, including Stevens-Johnson syndrome, have occurred.
Patient Information
- Advise patient to read the patient information leaflet before starting therapy and with each refill.
- Warn patient that this drug is not to be used by itself but is combined with other antiviral agents and not to change the dose or stop taking any other antiviral agents unless advised by health care provider.
- Instruct patient to take amprenavir exactly as prescribed and not to change the dose or discontinue therapy unless advised by health care provider.
- Advise patient to take prescribed dose without regard to meals. Advise patient that amprenavir can be taken with food (other than high-fat) if stomach upset occurs.
- Advise patient that if a dose is missed to take the dose as soon as possible and then return to their normal schedule. However, if a dose is skipped, caution patient not to double the dose to catch up but to continue with their normal schedule.
- Instruct patient taking antacids or Videx chewable/dispersible buffered tablets to take amprenavir 1 h before or 1 h after these medicines.
- Caution patient taking amprenavir capsules not to switch to amprenavir oral solution because of increased risk of adverse reactions from the large amount of propylene glycol in the oral solution.
- Inform women, Asians, Eskimos, Native Americans, and patients with renal or hepatic function impairment taking amprenavir solution that they may be at increased risk of adverse reactions from the propylene glycol in the oral solution. Advise such patients to report immediately any of the following to health care provider: seizures, stupor, rapid heart rate, profound or unexplained weakness or tiredness, paleness, dark urine.
- Caution patient using amprenavir oral solution to avoid ingestion of alcoholic beverages.
- Instruct patient or caregiver to avoid using vitamin E supplements, because amprenavir contains large amounts of vitamin E and excessive vitamin E intake may cause problems such as increased risk of bleeding.
- Instruct patient to report these symptoms immediately to health care provider: rash, depression or change in mood, abnormal skin sensations, dizziness, lightheadedness, rapid heart beat, dark urine, yellowing of the skin or eyes, persistent nausea or vomiting, profound weakness or tiredness, unexpected stomach discomfort, trouble breathing or unexplained shortness of breath.
- Advise patient that medication may cause changes in body fat distribution (eg, increased amount of fat in upper back and neck, breasts, around the back, chest, and stomach area; or loss of fat from arms, legs, and face) and that the cause and long-term health effects of these changes are not known at this time. Advise patient to report changes in body fat distribution to health care provider.
- Inform patient that drug does not completely eliminate HIV virus and therefore does not reduce risk of transmitting HIV to others. Appropriate precautions (eg, practicing safer sex using a latex or polyurethane condom to lower chance of sexual contact with semen, vaginal secretions, or blood; not using or sharing dirty needles) must still be followed.
- Advise patient that drug is not a cure for HIV infection and that they may continue to acquire illnesses associated with HIV infection, including opportunistic infections, and that they should remain under the care of a health care provider.
- Caution patient not to start any new medication or dietary supplement, particularly St. John's wort, without talking to health care provider first.
- Advise patient using a PDE5 inhibitor (eg, sildenafil, tadalafil, vardenafil) that they may be at greater risk of experiencing PDE5-associated adverse reactions and to discuss dosage modifications with health care provider. Instruct patient to promptly report low BP, visual changes, or prolonged penile erection to health care provider.
- Instruct diabetic patient to monitor blood glucose more frequently when drug is started or dose is changed and to inform health care provider of significant changes in readings.
- Advise women not to use hormonal contraceptives because some hormonal contraceptives reduce the effectiveness of amprenavir. Advise such patients to use a nonhormonal form of contraception.
- Caution HIV-infected mother that breast-feeding their baby could cause HIV infection in the baby.
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Amprenavir - Includes detailed dosage instructions.
