Young men who have sex with men (MSM) experience a modest decline in bone density during their first year on Truvada (tenofovir/emtricitabine) as PrEP, a shift that is reversible after they go off the drug, aidsmap reports. Researchers from the ATN 110 study enrolled 200 MSM 18 to 22 years old and offered them PrEP for 48 weeks.

Findings from an extension study of bone density among the ATN 110 participants were presented at the 21st International AIDS Conference in Durban, South Africa (AIDS 2016).

In a yearlong extension phase of the study, the researchers enrolled those participants who had not seen an increase in their bone density if they were younger than 20 or a decrease of 1 percent or more in those older than 20, as well as anyone who developed kidney impairment. The purpose was to observe bone density changes after the men stopped Truvada at the end of the 48 weeks of the previous phase of the study.

As was previously reported, during the participants’ first 24 weeks on Truvada, they experienced a modest decline in bone density. This decline mostly stabilized by the 48-week mark. There was no difference in bone loss based on levels of adherence to the daily drug regimen.

A total of 135 of the men completed the 48-week initial phase of the study. Out of that group, 102 men met the criteria for entry into the observation phase. Seventy-two of them stopped PrEP and had their bone density tested during the 48 weeks of the extension phase. The researchers also analyzed 16 men who had bone or kidney problems who preferred to keep receiving PrEP; however, one of these men contracted HIV.

The men who stopped PrEP saw their bone density return to levels near those from the beginning of the first phase of the study. Men who continued on the drug saw their bone loss stabilize, but did not experience the bone density gains of the men who stopped.

As seen in other studies, none of the men experienced bone pain or fractures.

To read the aidsmap article, click here.

To read the bone mass conference abstract, click here.

To read the kidney conference abstract, click here.