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Refillable HIV Prevention Implant in Development

HIV particles infecting human T cell

Scanning electron micrograph of HIV particles infecting a human T cell (

14 July 2016. A device implanted under the skin that provides 60 days of antiretroviral drugs to prevent HIV infection is in development at Houston Methodist Research Institute. Tests of the refillable device with animals to prepare for human clinical trials are funded by a 5-year, $4 million grant from National Institute of Allergy and Infectious Diseases, or NIAID, part of National Institutes of Health.

A team led by Houston Methodist nanomedicine engineering professor Alessandro Grattoni is seeking to solve a continuing problem with adherence to drugs that prevent HIV infection among some individuals at high risk. Antiretroviral drugs can be taken by people to prevent HIV infection, but for various reasons (including side effects), taking HIV medicines every day and exactly as prescribed is sometimes difficult to sustain.

Grattoni and colleagues in the institute’s nanomedicine department developed a device, implanted under the skin, with nanoscale channels that diffuse drug compounds through membranes into the blood stream. Early versions of the device, known as a nanochannel delivery system, can sustain delivery of drugs in lab animals without pumps, valves, or a power supply. Among the early tests, the device delivered the drug tenofovir alafenamide for treating HIV for 21 days.

In the new project, the Houston Methodist team — with colleagues from University of Texas Medical School, M.D. Anderson Cancer Center, University of Houston, Baylor College of Medicine, and University of Colorado in Denver — will reconfigure the nanochannel delivery system to sustain delivery of an HIV prevention drug, including refills, for 60 days in monkeys. The drug is a combination of tenofovir alafenamide fumarate and emtricitabine, marketed as Truvada by Gilead Sciences as a pre-exposure prevention medication for HIV.

In addition, the team will test the ability of the sustained-release drugs to prevent infection of simian-human immunodeficiency virus, similar to HIV, in monkeys. The researchers will also test a remote-control feature that deactivates the device, as well as document chemical responses in the animals’ bodies to the implant and delivered drugs.

The developers already demonstrated that the nanochannel delivery system can administer more than HIV drugs. Grattoni’s lab is testing the device with hormone replacement, cancer prevention and treatment, mental disorders, drug abuse, and metabolic syndrome. NanoMedical Systems in Austin, Texas licenses the technology from Houston Methodist for commercialization.

A similar nanochannel delivery system is being tested as well aboard the International Space Station, evaluating nanoscale drug diffusion in microgravity conditions. The device was part of a resupply payload launched on 8 April 2016 with a SpaceX rocket.

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