Credit: Andrew Syred/Photo Researchers, Inc.

Lack of patient compliance with treatment regimens that require daily injections or multiple medicines taken over long periods can hinder effective treatment, but help is at hand. Drug delivery from an implantable microchip wirelessly controlled by your doctor may sound like science fiction, but the first human trial of such a device is now reported by Farra et al. (Sci. Transl. Med. doi: 10.1126/scitranslmed.3003276).

A microchip no bigger than a watch face was implanted subcutaneously into eight osteoporotic post-menopausal women and programmed to deliver intermittent microgram doses of the anabolic osteoporosis drug human parathyroid hormone fragment (hPTH) (1–34) once daily for 20 days. This drug is the only anabolic agent approved for osteoporosis treatment, but it requires burdensome daily injections.

The microchip is refined from an earlier prototype that was tested in dogs, allowing its use in humans. The drug is stored in individual reservoirs covered with a thin metallic membrane. When a current is applied, the membrane melts, releasing the drug. Instructions concerning dosing schedules are wirelessly transmitted to the device.

Despite the fact that a fibrous capsule had formed around the implant, the microchips produced similar pharmacokinetic profiles of hPTH (1–34) to those obtained by multiple injections. Serum concentrations of the bone formation marker type I collagen propeptide increased and were consistent with the levels reported with daily injections, serving as an indicator of increased bone formation.

The microchips were implanted in a doctor's office under local anesthetic and were well tolerated, with no toxic or adverse effects from the implant. What's next: implants delivering hundreds of drug doses per microchip and over longer periods.