The in vitro and in vivo studies reported here demonstrate feasibility of the adherence monitoring approach and device; however, there are a number of development and regulatory hurdles associated with successful incorporation of the monitoring device in a combination product delivering one or more antiretroviral agents for HIV prophylaxis. The next steps in device development will focus on miniaturization of the electronics module and long term (≥28 days) in vitro and in vivo studies. The current devices are capable of this longer monitoring time. With a memory capacity of 2048 values, logging with a 30 min data interval allows continuous adherence monitoring for more than 42 days, and a 1 h interval increases this time to 85 days.