Fostemsavir is an HIV-1 gp120-directed attachment inhibitor. It is indicated for use in adult patients with multiply drug-resistant HIV-1 infection, in combination with other antiretroviral drugs.
How to Use Fostemsavir
Dosage and Administration Frequency
The recommended dosage of Fostemsavir is 600 mg (1 tablet) each time, taken orally twice daily. It can be administered with or without food.
The tablets must be swallowed whole; they should not be chewed, crushed, or split. Doing so may damage the extended-release structure and affect the drug's efficacy.
Medication Timing and Adherence
It is recommended to take the medication at fixed times (e.g., once in the morning and once in the evening) to maintain a stable plasma drug concentration.
If a dose is missed, take it as soon as possible. However, do not take a double dose to make up for the missed one.
Requirements for Combination Therapy
Fostemsavir must be used in combination with other active antiretroviral drugs to optimize efficacy and reduce the risk of drug resistance.
Commonly used clinical combinations include dolutegravir or darunavir, among others.
Dosage Adjustment of Fostemsavir
Situations Not Requiring Dosage Adjustment
Renal Impairment: No dosage adjustment is needed for patients with mild to severe renal impairment or those undergoing hemodialysis.
Hepatic Impairment: Patients with Child-Pugh Class A, B, or C hepatic impairment should use the regular dosage.
Absolute Contraindications
Contraindicated in patients with a known hypersensitivity to Fostemsavir or any of its components.
Concomitant use with strong CYP3A inducers (such as rifampicin, carbamazepine, St. John's wort, etc.) is prohibited. This is because such combinations can significantly reduce the plasma concentration of temsavir (the active component of Fostemsavir), leading to treatment failure.
Drugs Requiring Cautious Concomitant Use
QT Interval-Prolonging Drugs: High doses of Fostemsavir (2400 mg per dose) may prolong the QT interval. When used concomitantly with other arrhythmogenic drugs, close monitoring of the electrocardiogram (ECG) is required.
Statins: Treatment with statins should start at the lowest dose, and monitoring for muscle toxicity is necessary (for example, the exposure to rosuvastatin may increase by 69%).
Fostemsavir Use in Special Populations
Pregnancy and Lactation
Pregnancy: Existing animal studies have not shown teratogenicity, but data in humans are limited. It is recommended to use the Antiretroviral Pregnancy Registry (APR) to monitor fetal outcomes.
Lactation: HIV-1-infected individuals should avoid breastfeeding to prevent virus transmission to the infant.
Patients Coinfected with Hepatitis Viruses
Patients coinfected with HBV (hepatitis B virus) or HCV (hepatitis C virus) may experience elevated liver enzymes. Regular monitoring of ALT (alanine transaminase) and AST (aspartate transaminase) is required.
Discontinuation of anti-HBV drugs may lead to HBV reactivation; therefore, effective anti-HBV treatment should be maintained.
Pediatric and Adolescent Patients
The efficacy of Fostemsavir in patients under 18 years of age has not been established, and its use is not recommended for this population at this time.
