Scientists design implantable device for long-acting HIV Prevention

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A new implantable device that dispenses antiretroviral drugs may aid in HIV prevention. A new study from author and designer of implant – Marc Baum (president and founder of the Oak Crest Institute of Science) shows strict adherence to antiretroviral drugs is imperative to suppress HIV and reduce the risk of drug resistance. 

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But following a drug regimen can be difficult when most patients take about three different drugs daily. The risk of contracting HIV is especially high in vulnerable populations, including in sub-Saharan Africa (over 7,000 people a day are contracting HIV).

In some countries, life expectancies for patients has fallen below 40 years, according to the World Health Organizationz

This new implant technology would make an enormous impact.

While the number and type of drugs for HIV patients and HIV-vulnerable populations vary, adherence is a universal problem. The device is similar to the contraceptive implant. It measures about 40 millimeters long and 2 millimeters in diameter, and can be inserted into the upper arm. 

The subdermal implant is made of a PVA-coated silicone cylinder, which is approved by the FDA.

To test the safety of the device with a new HIV medication:

  • Surgically implanted the device in 4 healthy dogs and collected plasma samples over a 40-day period. 
  • Analyzed their blood and measured the drug, tenofovir alafenamide (TAF), in the animals’ immune cells to analyze its potency. 
  • Evaluated the device’s ability to release TAF over time. 

Gilead Sciences Inc. is testing TAF for FDA approval.

Why dogs and not mice? 

 The study authors wanted to stay consistent with Gilead’s preclinical work of TAF, which involved dogs. Researchers needed to collect at least 3 mLof blood to measure drug content in subjects’ immune cells and rodents aren’t large enough to draw that amount of plasma. Study authors observed that the medication sustained release through the device, and successfully treated the healthy dogs at a potency rate about 30 times the concentration that would be needed to prevent HIV infection in a healthy person.

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. 

Previous challenges to introducing a long-acting form of HIV drugs via an implantable device included finding the proper medication. Device needs to be redesigned to sustain release of a smaller amount of the drug for human use and future clinical trials

However, sustained release of the drug didn’t appear to have adverse side effects on the dogs in the study. Alot 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.

Common side effects to currently available HIV medication include nausea and vomiting, anemia, diarrhea, dizziness, fatigue, pain and nerve problems, and rash. Research team is currently waiting for funding to conduct a mice study, which they are aiming to begin in 2015. 

Researchers will be filing an application with the FDA to begin clinical trials within the next four or five years, after fine-tuning implant design.