raltegravir

Raltegravir is an antiretroviral medication used in the treatment of HIV-1 infection in adults and certain pediatric patients. It belongs to the class of integrase strand transfer inhibitors (INSTIs) and is sold under the brand name Isentress by Merck.

Mechanism of action: Raltegravir inhibits HIV integrase, the viral enzyme that inserts viral DNA into the host genome. By blocking integration, it prevents replication of new virus.

Raltegravir is administered orally. The usual adult dosing is 400 mg taken twice daily, with or without food. Dosing may be adjusted in the setting of certain drug interactions, such as rifampin.

Pharmacokinetics and metabolism: Raltegravir is primarily metabolized by UGT1A1-mediated glucuronidation and is excreted in feces and urine. It is not extensively metabolized by cytochrome P450 enzymes.

Drug interactions: Avoid coadministration with polyvalent cations (calcium, magnesium, iron) close to dosing; separate by at least 2 hours. Rifampin lowers raltegravir levels and often requires dosing adjustments under medical guidance.

Adverse effects: The medication is generally well tolerated. Common adverse events include insomnia, headache, nausea, and fatigue. Serious reactions such as hypersensitivity or severe skin reactions are rare.

Resistance and safety: HIV strains may acquire mutations in the integrase gene, reducing susceptibility to raltegravir. Cross-resistance with other INSTIs can occur, so regimen changes are guided by resistance testing. Raltegravir has a long track record of safety in adults and in pediatric populations.

Society and availability: Raltegravir is marketed as Isentress by Merck, with generic versions available in some markets. It is included in many HIV treatment guidelines as part of INSTI-based regimens.