eng Science and Education Publishing American Journal of Medical Case Reports 2374-216X 2015-06-10 3 7 201 204 10.12691/ajmcr-3-7-5 AJMCR2015375 article Amedeo Capetti capame@hotmail.com 1 Laura Carenzi 1 Noemi Astuti 1 Valeria Cozzi 2 Valeria Micheli 3 Maria Vittoria Cossu 3 1st Division of Infectious Diseases, Luigi Sacco University Hospital, Milano, Italy Clinical Pharmacology Unit, Luigi Sacco University Hospital, Milano, Italy Clinical Microbiology Unit, Luigi Sacco University Hospital, Milano, Italy HIV-infected patients have a higher burden of comorbidities than the general population and drug-drug interactions limit the choice of antiretroviral compounds, also limiting the possibility of drug sequencing in case of toxicity or failure. In our patient, affected by HIV-related pulmonary hypertension (HIV-PAH), the use of sildenafil and ambrisentan excluded the possibility of using two of the main classes of antiretrovirals, protease inhibitors (PIs) and non-nucleoside reverse transcriptase inhibitors (NNRTIs). Having failed a combination regimen based on raltegravir, while awaiting the results of genotypic testing for drug resistance she was switched to dolutegravir, a brand new integrase strand transfer inhibitor (INSTI) with high genetic barrier, and in one month her HIV-1 viremia dramatically dropped to undetectable levels. The genotypic test revealed resistance to all the drugs she was taking including dolutegravir. The backbone was changed to a dual regimen including rilpivirine and viral suppression was maintained at three months. Unprecedented pharmacokinetic data are provided for the two antiviral drugs in combination with sildenafil and ambrisentan. http://pubs.sciepub.com/ajmcr/3/7/5/ajmcr-3-7-5.pdf HIV PAH dolutegravir sildenafil ambrisentan resistance