Integrase inhibitors (INIs) are a class of antiretroviral drug designed to block the action of integrase, a viral enzyme that inserts the viral genome into the DNA of the host cell. Since integration is a vital step in retroviral replication, blocking it can halt further spread of the virus. Integrase inhibitors were initially developed for the treatment of HIV infection, but have been applied to other retroviruses. The class of integrase inhibitors called integrase strand transfer inhibitors (INSTIs) are in established medical use. Other classes, such as allosteric integrase inhibitors (ALLINIs) or integrase binding inhibitors (INBIs), are still experimental.
The development of integrase inhibitors led to a first approval for the class by the U.S. Food and Drug Administration (FDA) on October 12, 2007, for raltegravir (brand name Isentress).[1] Research published at the time supported the conclusion that "[for people living with HIV,] raltegravir plus optimized background therapy provided better viral suppression than optimized background therapy alone for at least 48 weeks."[2]
Since integrase inhibitors target a distinct step in the retroviral life cycle, they may be taken in combination with other types of HIV drugs to minimize adaptation by the virus.[3] They are also useful in salvage therapy for patients whose virus has mutated and acquired resistance to other drugs.[citation needed]