In vitro dissolution studies

Rings containing tenofovir or maraviroc were placed into DI water in a Distek dissolution system. Samples were taken daily for analysis by UV spectrophotometry. Release was approximately linear (pseudo-zero order) for the 30 days of testing for tenofovir and for maraviroc.

In vivo release of tenofovir

In vitro release of maraviroc

The release rate can be “tuned” by changing the number of pods in the ring, the thickness and composition of the drug delivery polymers or the size of the drug delivery window.

In vitro Release of tenofovir from ten pod ring

Drug delivery window size dependence for tenofovir (single pods)

The above data demonstrates that silicone IVRs are capable of sustained and controlled delivery of tenofovir and maraviroc as shown by in vitro release studies over one month. A method for fabrication of rings containing drug pods has been developed, and allows the production of IVRs with a defined drug loading and with the ability to modulate the release of the drug over 2.5 orders of magnitude (10-4000 µg/day for tenofovir).