Dose-schedule adherence is emphasized to patients on anti-HIV combination antiretroviral therapy, but no clinical guidance is available for patients who must take medication during international travel across multiple time-zones. In response to patient groups’ calls for “clear, practical and evidence-based guidance,” experts have published a review of what’s known about antiretroviral therapy dosing during international travel.

Combination antiretroviral therapy (cART) for HIV suppression long required “very high levels of adherence in the early days of combination therapy,” reflecting HIV’s “high replicating burden and the ease with which the virus mutated to develop drug resistance,” according to Professor of Translational Medicine Saye H. Khoo, MBBS, MD, FRCP, DTM&H, at the University of Liverpool, in England.

“For years the message has been going out to patients: they could not miss treatment doses, and should not even be late in taking their tablets,” Dr. Khoo said. “However, modern regimens are now far more potent and forgiving for late dosing—drugs hang around for much longer in the body.”

As a result, treatment failure due to resistance has become much less common. “Patients not only live longer, but they remain healthier and, like everybody else, enjoy holidays or working trips abroad,” he noted.

But air travel across time zones can “present challenges in the optimum timing of medication administration,” Professor Khoo noted. Delayed dosing can result in subtherapeutic drug levels, while early dosing can cause elevated drug levels, resulting in toxicity.

Further complicating dosing during travel, antiretroviral drugs like rilpivirine, efavirenz, tenofovir, elvitegravir, and boosted protease inhibitors, should be taken with food—and that can be a challenge on long-haul commercial flights with fixed meal-service times, Dr. Khoo and colleagues have pointed out.1

That can be a source of concern for patients who have long been counseled about the importance of sticking to their dosing schedule to avoid resistance and toxicity issues. Patients worry about missed or delayed doses during airplane travel.