What Is an Integrase Strand Transfer Inhibitor (INSTI)?

What it means

Integrase strand transfer inhibitors, often called INSTIs or integrase inhibitors, are a class of antiretroviral medicine. HIV needs an enzyme called integrase to insert its genetic material into the DNA of human immune cells. INSTIs block that step, so the virus cannot make new copies of itself in those cells.

This class name appears on HIV medicine labels in the description of how the medicine works and in interaction warnings. Some products containing minerals, such as certain antacids and iron or calcium supplements, can reduce how much of an INSTI is absorbed, so labels give advice on timing. Labels also list other side effects and interactions to discuss with a pharmacist.

INSTIs are one of several HIV medicine classes, alongside nucleoside analogues (NRTIs), protease inhibitors and others. They are usually used together with other HIV medicines in a combination regimen.

Where you may see it

• The 'Mechanism of Action' and 'Clinical Pharmacology' sections of HIV medicine labels
• Drug interaction warnings about antacids and mineral supplements
• HIV clinic medication lists