Background Drug interactions between protease inhibitors and treatment prescribed in primary care may compromise the efficacy of antiretroviral treatment or cause serious adverse reactions.

Purpose To identify potential interactions that may occur in patients treated with protease inhibitors (PIs) and other prescription drugs from Primary Care (PC).

Materials and methods All patients treated with PIs in the hospital pharmacy department were included. Each patient was checked to see if they were taking regular medicines that interact with PIs. Data were obtained by auditing the PC Digital Health Record. Based on the available literature, 3 types of interactions were established: drug combination contraindicated or not recommended (type A), potential interaction that may require close monitoring or changing dose (type B) and no clinically significant interactions (type C).

Results At the time of the study, 285 patients were treated with PIs. 89% showed no clinically relevant interactions with drugs prescribed from PC. Type A interactions were detected in 17 patients (6%), and type B in 13 patients (5%). The interaction most often observed was the combination of atazanavir and proton pump inhibitors in 8 patients (type A interaction that can cause reduction in plasma levels of atazanavir over 70%). Another type A interaction observed was salmeterol/fluticasone with various PIs in 3 patients (FDA has contraindicated this combination because of risk of QT prolongation).

Conclusions There were some disagreements between the hospital and PC treatment, several interactions found may compromise the efficacy of antiretroviral treatment or cause serious adverse reactions. In an effort to improve the situation, The authors are going to consult the specialists in the most serious cases and promote communication between PC and Hospital regarding HIV patients.