Abstract

Dolutegravir (DTG; S/GSK1349572) is a potent HIV-1 integrase inhibitor with a distinct resistance profile and a once daily dose regimen that does not require pharmacokinetic boosting. This work investigated the in vitro drug transport and metabolism of DTG and assessed the potential for clinical drug-drug interactions. DTG is a substrate for the efflux transporters P glycoprotein (Pgp) and Breast Cancer Resistance Protein (BCRP). Its high intrinsic membrane permeability limits the impact these transporters have on DTG's intestinal absorption. UDP-glucuronosyltransferase (UGT) 1A1 is the main enzyme responsible for the metabolism of DTG in vivo, with cytochrome P450 (CYP) 3A4 being a notable pathway and UGT1A3 and UGT1A9 being only minor pathways. DTG demonstrated little or no inhibition (IC₅₀ values > 30 μM) in vitro of the transporters Pgp, BCRP, multidrug resistance protein (MRP) 2, organic anion transporting polypeptide (OATP) 1B1/3, organic cation transporter (OCT) 1, or the drug metabolizing enzymes CYP1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 3A4, UGT1A1 or 2B7. Further, DTG did not induce CYP1A2, 2B6, or 3A4 mRNA in vitro using human hepatocytes. DTG does inhibit the renal OCT2 (IC₅₀ = 1.9 μM) transporter, which provides a mechanistic basis for the mild increases in serum creatinine observed in clinical studies. These in vitro studies demonstrate a low propensity for DTG to be a perpetrator of clinical drug interactions, and provide a basis for predicting when other drugs could result in a drug interaction with DTG.