Fosamprenavir Calcium
Pronunciation: (foe-sam-PREN-a-veer).
- Generic name
- fosamprenavir calcium
- Brand names
- Lexiva, Fosavir, Amprena, Telzir, Fosam
- Drug class
- Antiretroviral, Protease Inhibitor
Availability and supply rules vary by country
Trade names by country: Canada
Australia: · Full directory
What fosamprenavir calcium is and how it works
Uses, formulations, monitoring, and supply rules can differ by patient, product, and country. Follow the exact local product information and professional advice.
Mechanism of action: how fosamprenavir calcium works
Fosamprenavir is a prodrug of amprenavir, a protease inhibitor. After oral administration, it is rapidly hydrolyzed to amprenavir, which inhibits the HIV-1 protease enzyme. This prevents the cleavage of viral polyproteins, resulting in the production of immature, non-infectious viral particles. (1) (2)
What fosamprenavir calcium is used for
Treatment of HIV-1 infection in adults
Treatment of HIV-1 infection in adults (2)
Treatment of HIV-1 infection in pediatric patients (aged 6 years and older)
Treatment of HIV-1 infection in pediatric patients (aged 6 years and older) (2)
Part of highly active antiretroviral therapy (HAART)
Part of highly active antiretroviral therapy (HAART) (2)
Before taking fosamprenavir calcium
Do not take / not appropriate for
- Contraindicated in patients with known hypersensitivity to fosamprenavir, amprenavir, or any excipients. (Contraindication) (2)
- Contraindicated in severe hepatic impairment and with drugs that are highly dependent on CYP3A4 for clearance (e.g., rifampin, St. (Contraindication) (2)
- John's wort, certain statins). (Contraindication) (2)
Tell your clinician about
(2)How to take fosamprenavir calcium
- General Instructions: Take fosamprenavir exactly as prescribed by your healthcare provider. Do not change your dose or stop taking it without consulting your doctor.. Adult Dosing: Typical adult dose: 1400 mg orally twice daily, or 1400 mg once daily with ritonavir 200 mg once daily. Dosing may vary based on other antiretrovirals used.. Pediatric Dosing: Dosing in children is based on weight and age. Pediatric patients should use the oral suspension or tablets as directed by a pediatric HIV specialist.. Administration: Fosamprenavir tablets can be taken with or without food. The oral suspension should be shaken well before use and measured with a dosing syringe or cup.. When To Stop: Do not stop taking fosamprenavir unless instructed by your healthcare provider. Stopping suddenly can cause your HIV to become harder to treat.. Storage: Store at room temperature, away from moisture and heat. Keep the oral suspension in its original container and use within the recommended time after opening.
- This page does not provide a dose calculator. Dosing must follow the prescriber, pharmacist, or product label.
Procedures and treatment changes
Tell the treating team before surgery, procedures, or any medicine change. Do not alter treatment without the responsible clinician. (2)
Missed dose
If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and resume your regular schedule. Do not take two doses at once.
Overdose
In case of overdose, seek emergency medical attention or contact a poison control center immediately. Symptoms may include nausea, vomiting, and abdominal discomfort. Supportive care is recommended as there is no specific antidote. (2)
Side effects
Side effects and their urgency vary; report severe, persistent, or concerning symptoms to a healthcare professional.
Nausea
Incidence: Reported in the clinician-authored database; frequency not established
Diarrhea
Incidence: Reported in the clinician-authored database; frequency not established
Vomiting
Incidence: Reported in the clinician-authored database; frequency not established
Rash
Incidence: Reported in the clinician-authored database; frequency not established
Headache
Incidence: Reported in the clinician-authored database; frequency not established
Increased triglycerides
Incidence: Reported in the clinician-authored database; frequency not established
Increased cholesterol
Incidence: Reported in the clinician-authored database; frequency not established
Serious warnings
Serious skin reactions, including Stevens-Johnson syndrome, have been reported — serious
Symptoms: Serious skin reactions, including Stevens-Johnson syndrome, have been reported. May cause liver problems; monitor liver function regularly. Can interact with many other medications, including statins and anticonvulsants. May increase blood sugar and lipid levels.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Fosamprenavir contains a sulfonamide (sulfa) moiety — serious
Symptoms: Fosamprenavir contains a sulfonamide (sulfa) moiety; use with caution in patients with a known sulfonamide allergy, since cross-sensitivity potential is unknown.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Contraindicated in patients with previously demonstrated clinically significant hypersensitivity (e — serious
Symptoms: Contraindicated in patients with previously demonstrated clinically significant hypersensitivity (e.g., Stevens-Johnson syndrome) to fosamprenavir, amprenavir, or any excipients, and with drugs that are highly dependent on CYP3A4 for clearance where elevated levels risk serious/life-threatening events (examples: flecainide, propafenone, ergot derivatives, cisapride, St. John's wort, lovastatin, simvastatin, pimozide, delavirdine, midazolam, triazolam). (Corrected: an earlier version also listed severe hepatic impairment as a contraindication — FDA labeling instead provides a specific reduced dose for severe hepatic impairment rather than avoiding the drug entirely; see Professional Information for the regimen.) Use caution in patients with liver disease, diabetes, or hemophilia.
Action: Follow the urgency stated and seek prompt or emergency care when indicated. (2)
Interactions
| Medicine or test | Effect | Action |
|---|---|---|
| Recorded interactions | Fosamprenavir interacts with many medications, including other antiretrovirals, statins, anticonvulsants, and herbal supplements like St. John's wort. Some interactions can cause serious or life-threatening effects. Always inform your healthcare provider about all medicines you are taking. | (1) |
Pregnancy, breastfeeding, kidney/liver function, age
Pregnancy
Use during pregnancy only if the potential benefit justifies the potential risk to the fetus, as judged by the treating clinician. An Antiretroviral Pregnancy Registry monitors outcomes; ask the prescriber about registering. (2)
Breastfeeding
HIV-infected mothers should not breastfeed, to avoid the risk of postnatal HIV transmission to the infant, and mothers taking fosamprenavir specifically should not breastfeed because of transmission risk and the potential for serious adverse reactions in a nursing infant. (2)
Children
Frequency: Not applicable. Weight Based: Not recommended for pediatric use. Max Daily Dose: Not applicable. Max Single Dose: Not applicable. Age Restrictions: Safety not established in children (2)
Renal_impairment
Renal: only about 1% of amprenavir is eliminated unchanged by the kidneys, so renal impairment is not expected to significantly affect elimination and no dose adjustment is recommended. Hepatic: dose is reduced by Child-Pugh class — mild (5-6): 700 mg twice daily (with or without ritonavir 100 mg once daily); moderate (7-9): 700 mg twice daily without ritonavir, or 450 mg twice daily with ritonavir 100 mg once daily; severe (10-15): 350 mg twice daily without ritonavir, or 300 mg twice daily with ritonavir 100 mg once daily. All adjustments are made by the treating clinician. (2)
Hepatic_impairment
Renal: only about 1% of amprenavir is eliminated unchanged by the kidneys, so renal impairment is not expected to significantly affect elimination and no dose adjustment is recommended. Hepatic: dose is reduced by Child-Pugh class — mild (5-6): 700 mg twice daily (with or without ritonavir 100 mg once daily); moderate (7-9): 700 mg twice daily without ritonavir, or 450 mg twice daily with ritonavir 100 mg once daily; severe (10-15): 350 mg twice daily without ritonavir, or 300 mg twice daily with ritonavir 100 mg once daily. All adjustments are made by the treating clinician. (2)
Monitoring
(2)Storage
Store at controlled room temperature, 25C (77F), with excursions permitted between 15-30C (59-86F); keep the container tightly closed. Keep the oral suspension in its original container and use within the recommended time after opening.
Professional information
Clinician-facing context only. This section does not replace current product labeling.
General
Indication: Treatment of HIV-1 infection in adults
Dose summary: 700 mg orally twice daily with food or 1400 mg once daily with food
Renal context: No dose adjustment is recommended for renal impairment; only about 1% of amprenavir is eliminated unchanged via the kidneys. (1) (2)
Frequently asked questions
What is fosamprenavir used for?
Fosamprenavir is used to treat HIV-1 infection in adults and children as part of combination antiretroviral therapy.
Can fosamprenavir cure HIV or AIDS?
No, fosamprenavir does not cure HIV or AIDS. It helps control the virus and improves immune function when taken as prescribed.
What should I do if I miss a dose?
Take the missed dose as soon as you remember. If it is almost time for your next dose, skip the missed dose and continue your regular schedule. Do not take an extra dose.
Are there foods or drinks I should avoid while taking fosamprenavir?
Avoid grapefruit juice and do not take antacids or mineral supplements within 2 hours of your dose.
Can I take fosamprenavir during pregnancy?
Discuss with your doctor if you are pregnant or planning to become pregnant. Fosamprenavir may be used if the benefits outweigh the risks, but close monitoring is required.
What are the most serious side effects?
Serious side effects include severe skin reactions, liver problems, and allergic reactions. Seek immediate medical attention if you experience symptoms such as rash, jaundice, or difficulty breathing.
Can children take fosamprenavir?
Yes, fosamprenavir can be used in children, but dosing is based on weight and age. It should be prescribed and monitored by a pediatric HIV specialist.
What happens if I take too much Fosamprenavir?
Taking too much Fosamprenavir can lead to an exacerbation of side effects, potentially including severe gastrointestinal issues, skin reactions, or liver problems. If you suspect an overdose, it is crucial to seek immediate emergency medical attention. Do not attempt to self-treat or wait for symptoms to worsen, as prompt intervention may be necessary.
Can I drink alcohol while taking Fosamprenavir?
It is generally advisable to limit or avoid alcohol consumption while taking Fosamprenavir. Alcohol can increase the risk of liver toxicity, a potential side effect of protease inhibitors. Additionally, alcohol may worsen gastrointestinal side effects such as nausea and diarrhea, which are common with Fosamprenavir. Consult your healthcare provider for personalized advice regarding alcohol intake.
Is Fosamprenavir safe during pregnancy?
Fosamprenavir's safety during pregnancy falls under a category that requires careful consideration. The decision to use Fosamprenavir during pregnancy should be made in consultation with a healthcare provider, weighing the potential benefits against any risks to the mother and fetus. Your doctor can provide the most accurate and personalized guidance based on your individual health circumstances.
What is the mechanism of action of fosamprenavir calcium?
Fosamprenavir is a prodrug of amprenavir, a protease inhibitor. After oral administration, it is rapidly hydrolyzed to amprenavir, which inhibits the HIV-1 protease enzyme. This prevents the cleavage of viral polyproteins, resulting in the production of immature, non-infectious viral particles. (1) (2)
What is the generic name of Fosamprenavir Calcium?
The generic name is fosamprenavir calcium. It is sold under brand names including Lexiva, Fosavir, Amprena, Telzir, Fosam.
What class of drug is fosamprenavir calcium?
Fosamprenavir Calcium is classed as: Antiretroviral, Protease Inhibitor.
References
- Fosamprenavir — MedGuideGlobal Clinician-Authored Medicine RecordMedGuideGlobal · Global (internal) · accessed 2026-08-06 · source 1
- LEXIVA (fosamprenavir calcium) tablet, film coated — prescribing informationU.S. Food and Drug Administration · United States · accessed 2026-08-06 · source 2
- FOSAMPRENAVIR CALCIUM TABLET, COATED [SUN PHARMACEUTICAL INDUSTRIES, INC.] — US prescribing information (DailyMed SPL)U.S. National Library of Medicine (DailyMed) · US · accessed 2026-08-14 · source 3
- Fosamprenavir Calcium — FDA approval record (Drugs@FDA ANDA204060)U.S. Food and Drug Administration · US · accessed 2026-08-14 · source 4
- fosamprenavir calcium — RxNorm normalized drug concept (RXCUI 402365)U.S. National Library of Medicine (RxNorm) · US · accessed 2026-08-14 · source 5
Brand names by country
Single-ingredient fosamprenavir calcium names are shown separately by country. Product availability, strengths, and supply rules can change; combination products are not included here.
Priority countries
Canada
- TELZIR