TREATMENT
Based on clinical history, laboratory and radiological findings, he was diagnosed with true gynecomastia. The patient was discussed at the HIV service’s multidisciplinary clinic and anastrozole was proposed as an alternative to tamoxifen to avoid the possible drug-drug interaction with rilpivirine. He was started an oral dose of anastrozole 1 mg once daily. After 10 days from the start of anastrozole, he presented a significant symptom improvement with visible reduction of breast enlargement and decreased discomfort. After six weeks of use of anastrozole, complete resolution of the gynecomastia occurred and the patient stopped anastrozole.
In the meantime (19/05/2023), the patient referred weight gain of 3 kilograms (in a span of 11months) and opted for switching back to oral antiretroviral treatment containing tenofovir + lamivudine + doravirine, while he was still on anastrazole. The latter provided a benefit (versus the most commonly used tamoxifen) with this ARV combination as well, as a drug-drug interaction between tamoxifen and doravirine, although not studied, may occur and again lead to a decrease in doravirine concentrations through CYP3A4 induction9.