Enhanced control in dosing may reduce adverse effects of drugs, author says
An October 2015 Reuters/FoxNews.com article reported that “a new matchstick-size implant that dispenses antiretroviral drugs may aid in HIV prevention.” The article cited early-stage findings published in the journal Antimicrobial Agents and Chemotherapy.
Compliance with a regimen of antiretroviral drugs is imperative in the suppression of HIV and the reduction of drug resistance risk. As FoxNews.com reported, though, “Following a drug regimen can be difficult when most patients take about three different drugs daily.” So says study author Marc Baum, President and Founder of the Oak Crest Institute of Science, whose team designed the implantable device that dispenses the antiretroviral medication.
The device may be of particular interest in areas with vulnerable populations. The Reuters/FoxNews.com piece notes that “The risk of contracting HIV is higher in sub-Saharan Africa, where in some countries, life expectancies for patients has fallen below 40 years, according to the World Health Organization (WHO).” While quantities and types of drugs available for HIV patients and HIV-vulnerable populations vary, compliance problems are universal.
Dr. Baum told FoxNews.com, “We wanted to take adherence out of the equation.” The device Baum’s team designed is similar to the contraceptive implant, measuring about 40 millimeters long and 2 millimeters in diameter. The subdermal implant is made of a PVA-coated silicone cylinder, which is approved by the U.S. Food and Drug Administration (FDA).
To test the safety of the device with a new HIV medication, study authors surgically implanted the device in four healthy dogs and collected plasma samples over a 40-day period, according to the Reuters/FoxNews.com article. They analyzed their blood and measured the drug, tenofovir alafenamide (TAF), in the animals’ immune cells to analyze its potency. Gilead Sciences Inc. is testing TAF for FDA approval and announced phase 3 results in February 2015. It filed a New Drug Application with the FDA in November 2014, according to the biopharmaceutical company’s website.
“In the end, we were delighted to see that this can work and that we can scale back on how much drug we’re delivering, which of course will make the implant last longer,” Baum told FoxNews.com. “Once we redesign the implant, we’re shooting for an implant that will last six months or even a year.”
Baum added that his team’s findings are the first to prove sustained-release nucleoside reverse transcriptase inhibitors (NRTIs)— drugs that block viral DNA production, a first-line defense against the virus— may be a viable option for HIV prevention. He noted that previous challenges to introducing a long-acting form of HIV drugs via an implantable device included finding the proper medication.
“You’re very limited with the range of drugs that are amenable to this technology,” he said. “They have to be potent, have a long half-life in the body and be very soluble.”
Based on his team’s preliminary findings, sustained release of the drug didn’t appear to have adverse effects on the dogs in the study, Baum told the news site.
“A lot of side effects from the same drug go away when you do sustained release because you’re maintaining therapeutically active levels without delivering an enormous amount of drug,” he said.
“Over 7,000 people a day are contracting HIV … mostly in sub-Saharan Africa,” Baum told FoxNews.com. “If we can make a dent in that with our technology, it would make an enormous impact.”