What is Agenerase (amprenavir)?

Agenerase (amprenavir) is a protease inhibitor used to treat human immunodeficiency virus (HIV) infection. The HIV virus multiplies within the body’s cells. Viruses are released from the cells and spread throughout the body where they infect other cells.

During the production of the viruses, new proteins, some of which are enzymes, manufacture DNA and other components for the new viruses. Protease is the enzyme that forms the new structural proteins and enzymes. 

Agenerase blocks the activity of protease and results in the formation of defective viruses unable to infect the body's cells. As a result, the viral load decreases. Agenerase does not prevent transmission of HIV, and it does not cure HIV or AIDS. Agenerase was discontinued in October 2007. 

Common side effects of Agenerase include:

Serious side effects of Agenerase include:

The propylene glycol in the oral solution can cause: 

Drug interactions of Agenerase include:

  • rifampin because it reduces plasma concentrations of Agenerase.
  • Systemic corticosteroid combined with Agenerase can produce effects including:
    • Cushing's syndrome
    • and adrenal suppression.
  • Agenerase used with St. John's wort substantially decreases protease inhibitor concentrations.
  • Agenerase combined with HMG-CoA reductase inhibitors increases the risk of:
  • Agenerase and sildenafil used together substantially increases sildenafil concentrations and may result in:

Other drug interactions of Agenerase include:

It is unknown Agenerase is secreted in breast milk. HIV-infected mothers should not breastfeed because of the potential risk of transmitting HIV to a nursing infant.

What are the important side effects of Agenerase (amprenavir)?

The most frequent side effects are:

Amprenavir may also cause severe skin reactions and breakdown of red blood cells.

The propylene glycol in the oral solution can cause:

Like other protease inhibitors, use of amprenavir may be associated with:

  • redistribution or accumulation of body fat,
  • increased cholesterol
  • and worsening of diabetes.

Agenerase (amprenavir) side effects list for healthcare professionals

  • In clinical studies, adverse events leading to amprenavir discontinuation occurred primarily during the first 12 weeks of therapy, and were mostly due to: gastrointestinal events (nausea, vomiting, diarrhea, and abdominal pain/discomfort), which were mild to moderate in severity.
  • Skin rash occurred in 22% of patients treated with amprenavir in studies PROAB3001 and PROAB3006.
  • Rashes were usually maculopapular and of mild or moderate intensity, some with pruritus.
  • Rashes had a median onset of 11 days after amprenavir initiation and a median duration of 10 days.
  • Skin rashes led to amprenavir discontinuation in approximately 3% of patients.
  • In some patients with mild or moderate rash, amprenavir dosing was often continued without interruption; if interrupted, reintroduction of amprenavir generally did not result in rash recurrence.

Severe or life-threatening rash (Grade 3 or 4), including cases of Stevens -Johnson syndrome, occurred in approximately 1% of recipients of Agenerase. Amprenavir therapy should be discontinued for severe or life-threatening rashes and for moderate rashes accompanied by systemic symptoms.

Table 9. Selected Clinical Adverse Events of All Grades Reported in > 5% of Adult Patients

Adverse EventPROAB 3001 Therapy-Naive PatientsPROAB 3006 NRTI-Experienced Patients
Agenerase/
Lamivudine/ Zidovudine
(n = 113)
Lamivudine/
Zidovudine
(n = 109)
Agenerase/
NRTI
(n = 245)
Indinavir/
NRTI
(n = 241)
Digestive
  Nausea74%50%43%35%
  Vomiting34%17%24%20%
  Diarrhea or loose stools 39%35%60%41%
  Taste disorders10%6%2%8%
Skin
  Rash27%6%20%15%
Nervous
  Paresthesia, oral/perioral26%6%31%2%
  Paresthesia, peripheral10%4%14%10%
Psychiatric
  Depressive or mood disorders16%4%9%13%

Among amprenavir-treated patients in Phase 3 studies, 2 patients developed de novo diabetes mellitus, 1 patient developed a dorsocervical fat enlargement (buffalo hump), and 9 patients developed fat redistribution.

In studies PROAB3001 and PROAB3006, 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.

Concomitant Therapy with Ritonavir: Tables 10 and 11 present adverse clinical events and laboratory abnormalities observed in subjects who received Agenerase plus ritonavir. Since the trials were small, open-label, of varying duration, and often included different patient populations, direct comparisons to the frequency of events with Agenerase alone (see Table 9) cannot be made.

Table 10. Selected Clinical Adverse Events of All Grades Reported in Adult Patients in Open-Label Clinical Trials of Agenerase in Combination With Ritonavir

Adverse EventAgenerase 1,200 mg
plus Ritonavir 200 mg q.d.*
(n = 101)
Agenerase 600 mg
plus Ritonavir 100 mg b.i.d.†
(n = 239)
Nausea31%23%
Diarrhea/loose stools30%28%
Headache16%12%
Abdominal symptoms14%14%
Vomiting11%9%
Rash10%9%
Paresthesias9%11%
Fatigue7%14%
Depressive & mood disorders4%9%
*Data from 2 open- label studies in treatment- naive patients also receiving abacavir/lamivudine.
Data from 3 open- label studies in treatment- naive and treatment-experienced patients receiving combination antiretroviral therapy.

Table 11. Grade 3/4 Laboratory Abnormalities Reported in ≥ 2% of Adult Patients in Open-Label Clinical Trials of Agenerase in Combination With Ritonavir

Laboratory Abnormality
(non- fasting specimens)
Agenerase 1,200 mg
plus Ritonavir 200 mg q.d.*
(n = 101)
Agenerase 600 mg
plus Ritonavir 100 mg b.i.d.†
(n = 239)
Hypertriglyceridemia ( > 750 mg/dL)8%13%
Hyperglycemia ( > 251 mg/dL)2%3%
AST ( > 5 x ULN)3%5%
ALT ( > 5 x ULN)4%4%
Amylase ( > 2 x ULN)4%3%
*Data from 2 open- label studies in treatment- naive patients also receiving abacavir/lamivudine.
Data from 3 open- label studies in treatment- naive and treatment-experienced patients receiving combination antiretroviral therapy.

What drugs interact with Agenerase (amprenavir)?

Agenerase is an inhibitor of cytochrome P450 3A4 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.

Table 7. Drugs That Should Not Be Coadministered With Agenerase

Drug Class/Drug Name Clinical Comment
Antimycobacterials: Rifampin* May lead to loss of virologic response and possible resistance to Agenerase or to the class of protease inhibitors.
Ergot derivatives: Dihydroergotamine, ergonovine, ergotamine, methylergonovine CONTRAINDICATED due to potential for serious and/or life-threatening reactions such as acute ergot toxicity characterized by peripheral vasospasm and ischemia of the extremities and other tissues.
GI motility agents: Cisapride CONTRAINDICATED due to potential for serious and/or life-threatening reactions such as cardiac arrhythmias.
Herbal products: St. John's wort (hypericum perforatum) May lead to loss of virologic response and possible resistance to Agenerase or to the class of protease inhibitors.
HMG Co-reductase inhibitors: Lovastatin, simvastatin Potential for serious reactions such as risk of myopathy including rhabdomyolysis.
Neuroleptic: Pimozide CONTRAINDICATED due to potential for serious and/or life-threatening reactions such as cardiac arrhythmias.
Non-nucleoside reverse transcriptase inhibitor: Delavirdine* May lead to loss of virologic response and possible resistance to delavirdine.
Oral contraceptives: Ethinyl estradiol/norethindrone May lead to loss of virologic response and possible resistance to Agenerase. Alternative methods of non-hormonal contraception are recommended.
Sedative/hypnotics: Midazolam, triazolam CONTRAINDICATED due to potential for serious and/or life-threatening reactions such as prolonged or increased sedation or respiratory depression.

Table 8. Established and Other Potentially Significant Drug Interactions: Alteration in Dose or Regimen May Be Recommended Based on Drug Interaction Studies or Predicted Interaction

Concomitant Drug Class: Drug Name Effect on Concentration of Amprenavir or Concomitant Drug Clinical Comment
HIV-Antiviral Agents
Non-nucleoside reverse transcriptase inhibitors: Efavirenz, nevirapine ↑Amprenavir Appropriate doses of the combinations with respect to safety and efficacy have not been established.
Nucleoside reverse transcriptase inhibitor: Didanosine (buffered formulation only) ↑Amprenavir Take Agenerase at least 1 hour before or after the buffered formulation of didanosine.
HIV proteaseinhibitors: Indinavir*, lopinavir /ritonavir,nelfinavir* ↓Amprenavir Amprenavir's effect on other protease inhibitors is not well established. Appropriate doses of the combinations with respect to safety and efficacy have not been established.
HIV protease inhibitor:Ritonavir* ↓Amprenavir The dose of amprenavir should be reduced when used in combination with ritonavir. Also, see the full prescribing information for NORVIR for additional drug interaction information.
HIV protease inhibitor: Saquinavir* ↑Amprenavir Amprenavir's effect on saquinavir is not well established. Appropriate doses of the combination with respect to safety and efficacy have not been established.
Other Agents

Antacids ↓Amprenavir Take Agenerase at least 1 hour before or after antacids.
Antiarrhythmics: Amiodarone, lidocaine (systemic), and quinidine ↑Antiarrhythmics Caution is warranted and therapeutic concentration monitoring is recommended for antiarrhythmics when coadministered with Agenerase, if available.
Antiarrhythmic: Bepridil ↑Bepridil Use with caution. Increased bepridil exposure may be associated with life-threatening reactions such as cardiac arrhythmias.
Anticoagulant: Warfarin   Concentrations of warfarin may be affected. It is recommended that INR (international normalized ratio) be monitored.
Anticonvulsants: Carbamazepine, phenobarbital, phenytoin ↓ Amprenavir Use with caution. Agenerase may be less effective due to decreased amprenavir plasma concentrations in patients taking these agents concomitantly.
Antidepressant: Trazodone ↑ Trazodone Concomitant use of trazodone and Agenerase with or without ritonavir may increase plasma concentrations of trazodone. Adverse events of nausea, dizziness, hypotension, and syncope have been observed following coadministration of trazodone and ritonavir. If trazodone is used with a CYP3A4 inhibitor such as Agenerase, the combination should be used with caution and a lower dose of trazodone should be considered.
Antifungals: Ketoconazole, itraconazole ↑ Ketoconazole
↑ Itraconazole
Increase monitoring for adverse events due to ketoconazole or itraconazole. Dose reduction of ketoconazole or itraconazole may be needed for patients receiving more than 400 mg ketoconazole or itraconazole per day.
Antimycobacterial: Rifabutin* ↑ Rifabutin and rifabutin metabolite A dosage reduction of rifabutin to at least half the recommended dose is required when Agenerase and rifabutin are coadministered.* A complete blood count should be performed weekly and as clinically indicated in order to monitor for neutropenia in patients receiving amprenavir and rifabutin.
Benzodiazepines: Alprazolam, clorazepate, diazepam, flurazepam ↑ Benzodiazepines Clinical significance is unknown; however, a decrease in benzodiazepine dose may be needed.
Calcium channel blockers: Diltiazem, felodipine, nifedipine, nicardipine, nimodipine, verapamil, amlodipine, nisoldipine, isradipine ↑ Calcium channel blockers Caution is warranted and clinical monitoring of patients is recommended.
Corticosteroid: Dexamethasone ↓ Amprenavir Use with caution. Agenerase may be less effective due to decreased amprenavir plasma concentrations in patients taking these agents concomitantly.
Erectile dysfunction agent: Sildenafil ↑ Sildenafil Use with caution at reduced doses of 25 mg every 48 hours with increased monitoring for adverse events.
HMG-CoA reductase inhibitors: Atorvastatin ↑ Atorvastatin Use lowest possible dose of atorvastatin with careful monitoring or consider other HMG-CoA reductase inhibitors such as pravastatin or fluvastatin in combination with Agenerase.
Immunosuppressants: Cyclosporine, tacrolimus, rapamycin ↑ Immunosup-pressants Therapeutic concentration monitoring is recommended for immunosuppressant agents when coadministered with Agenerase.
Inhaled/nasal steroid: Fluticasone Agenerase
↑ Fluticasone
Concomitant use of fluticasone propionate and Agenerase (without ritonavir) may increase plasma concentrations of fluticasone propionate. Use with caution. Consider alternatives to fluticasone propionate, particularly for long-term use.
  Agenerase/ ritonavir
↑ Fluticasone
Concomitant use of fluticasone propionate and Agenerase/ritonavir may increase plasma concentrations of fluticasone propionate, resulting in significantly reduced serum cortisol concentrations. Coadministration of fluticasone propionate and Agenerase/ritonavir is not recommended unless the potential benefit to the patient outweighs the risk of systemic corticosteroid side effects.
Narcotic analgesics: Methadone* ↓ Amprenavir Agenerase may be less effective due to decreased amprenavir plasma concentrations in patients taking these agents concomitantly. Alternative antiretroviral therapy should be considered.
  ↓ Methadone Dosage of methadone may need to be increased when coadministered with Agenerase.
Tricyclic antidepressants: Amitriptyline, imipramine ↑ Tricyclics Therapeutic concentration monitoring is recommended for tricyclic antidepressants when coadministered with Agenerase.
 

Summary

Agenerase (amprenavir) is a protease inhibitor used to treat human immunodeficiency virus (HIV) infection. The HIV virus multiplies within the body’s cells. Viruses are released from the cells and spread throughout the body where they infect other cells. During the production of the viruses, new proteins, some of which are enzymes, manufacture DNA and other components for the new viruses. Protease is the enzyme that forms the new structural proteins and enzymes. Common side effects of Agenerase include headache, weakness, diarrhea, nausea, stomach pain, and redistribution or accumulation of body fat. Agenerase has many drug interactions. It is unknown Agenerase is secreted in breast milk.

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Medically Reviewed on 3/18/2020
References
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