As an HIV-1 treatment drug, Fostemsavir requires strict adherence to dosage adjustments, drug interactions, and management of special populations to ensure efficacy and safety.

Basic medication requirements

(1) The recommended dosage is 600mg twice daily and should be swallowed whole without chewing. If the missed dose exceeds 20 hours, the dose should be skipped and double supplementation is prohibited.

Drug interactions

(2) Enzyme inducers should not be used in combination with potent CYP3A inducers (such as rifampicin and carbamazepine), as it can significantly reduce blood drug concentrations and should not be used in combination. Caution should be exercised and dosage adjustments should be considered for intermediate acting inducers.

(3) The impact of gastric acid regulators

Antacids should be taken at intervals of 4 hours, H2 receptor antagonists should be used 12 hours before or 2 hours after fossavir, and PPI drugs should be avoided in combination.

Monitoring requirements

(4) Liver function monitoring: ALT/AST should be tested before treatment and at 4 and 12 weeks. Patients with cirrhosis need to be monitored more frequently. If there is grade 3 or above liver damage, the medication should be permanently discontinued.

(5) Immune reconstitution monitoring

In the early stage of treatment, it is necessary to be alert to immune reconstitution syndrome, which manifests as activation of latent infections (such as tuberculosis and CMV), and to screen in advance and prepare emergency plans.

special populations

(6) During pregnancy and lactation, use only when the benefits outweigh the risks. Breastfeeding should be stopped during the lactation period as medication may be secreted into breast milk.

(7) Liver and kidney dysfunction

Severe liver damage (Child Pugh C) is contraindicated, and dosage adjustment is necessary for mild to moderate cases. Renal function may require adjustment, but it should be carefully monitored in the end-stage.

Special precautions

(8) After opening, the tablets should be used immediately after being taken out of the blister pack. If dispersed administration is required, the mixed solution should be used within 2 hours and cannot be stored for future use.

(9) Environmental control

Prohibit refrigeration or freezing storage, extreme temperatures can cause the decomposition of drug components. The storage area should be kept dry with a relative humidity not exceeding 60%.