Fluid-filled silastic capsules : a new approach to a more constant steroidal drug delivery system

A new approach to a more constant steroid delivery system was made in which 7,9 mg of norethisterone acetate was shaped into a cylindrical pellet (diameter 1.47 mm, length 4 mm) and placed inside a silastic capsule (i.d. 1.57 mm, o.d. 3.18 mm) of 5 mm effective length. The extra space available around the pellet was filled with physiological saline. For the sake of comparison, the same amount of crystalline norethisterone acetate was packed up to 5 mm length inside a silastic capsule of the same dimensions. The incorporation of fluid (saline) in the system not only caused a marked decrease in the initial high release but also a more constant release. Varying the pellet diameter showed that release of the steroid increases with the increase in surface area of the pellet.