Drug-Drug Interactions Appear No Worse in Older People Living With HIV

By Scott Baltic

February 28, 2020

NEW YORK (Reuters Health) - Drug-drug interactions (DDIs) are more common in older people, but a new study from Switzerland suggests they are no more severe in people living with HIV (PLWH) who are 55 years or older than in their younger peers.

As a result, researchers write in the journal AIDS, "the clinical management of DDIs in aging PLWH can be similar" to that in younger patients.

The risk of DDIs is known to be elevated in older people because of age-related comorbidities and polypharmacy, but there is a lack "of knowledge concerning the magnitude and clinical management of DDIs in aging PLWH," Dr. Dr. Felix Stader of University Hospital Basel and colleagues write.

"The lack of clinical data leads to missing guidance on how to clinically manage DDIs in the elderly," Dr. Stader told Reuters Health by email.

To investigate, they followed PLWH who were at least 55 years old and were enrolled in the Swiss HIV Cohort Study and were receiving amlodipine, atorvastatin and/or rosuvastatin with an HIV regimen containing dolutegravir or boosted darunavir. Patients with severe comorbidities such as advanced kidney disease, heart failure or cirrhosis were excluded, as were those receiving co-medications with inhibitory or inducing properties.

The three drugs in question were chosen, Dr. Stader explained, because statins and antihypertensives are the most commonly prescribed drugs in aging PLWH in the Swiss HIV Cohort.

The study included 21 white PLWH (four women) aged 56-80; as a control, the researchers used data from earlier studies of DDIs in patients who were typically under 50.

Comparing individual patients' use of any of the three cardiovascular medications with the historical controls, the researchers found no significant increase of DDIs in the former.

"DDI magnitudes were comparable to those reported in young individuals supporting that the clinical management of DDIs in aging PLWH can be similar," the researchers write.

Dr. Stader noted cautioned, "We studied only drug pairs, but in clinical reality polypharmacy (concomitant use of more than five drugs) is highly prevalent and therefore drugs might interact mutually."

Dr. Giovanni Guaraldi, an HIV expert at the University of Modena and Reggio Emilia, in Italy, told Reuters Health by email that the study "brings a reassuring contribution," though this is the glass-half-full part of the story. The glass-half-empty part, he continued, is that DDIs do exist and need to be managed carefully.

In an older PLWH, explained Dr. Guaraldi, who was not involved in the study, management requires an individualized approach, integrating HIV care with primary care and limiting polypharmacy.

Dr. Carl J. Fichtenbaum of the University of Cincinnati College of Medicine, in Ohio, who has studied DDIs involving antiretrovirals, called the Swiss study "timely and important," especially given the lack of data on aging PLWH.

He added, however, that he considers the study flawed, in part for having included few people older than 65 and partly from the use of historical controls.

Based on the study's design, he concluded, "I don't think we can say whether or not aging changes the risk for DDIs in older persons with HIV."

The study did not have commercial funding. Several of Dr. Stader's co-authors report ties to companies selling antiretrovirals.

SOURCE: https://bit.ly/2T1J6lY AIDS, online February 5, 2020.