[stickydink]

Like the contraceptive implant? Without know a thing about drug delivery, it seems like it'd be pretty feasible already. There's probably a reason it's not done for more drugs, but I can't think of a good one. Perhaps the fear of someone pulling out 6 months worth of drug X from their arm, and selling/abusing it?

[thetylerhayes]

http://gigaom.com/2013/05/01/company-behind-digital-pill-wit...

http://www.proteus.com/technology/digital-health-feedback-sy...

[dragonwriter]

Accidental breakage and overdose would seem likely to be a concern, as well. Breakage has been observed in contraceptive implants, but the resulting changes in drug release have not, AFAIK, resulted in particularly significant health effects. However, with other drugs that could be a bigger risk.

[rokhayakebe]

Here: http://pubs.acs.org/doi/abs/10.1021/ja211148a?journalCode=ja...