Fabrication of a Reservoir Ring for Sustained and Prolonged Release of Levonorgestrel for Vaginal Administration

Introduction: More than one-third of women experience abnormal uterine bleeding (AUB) during their lifetime. One of the treatment methods of this disease is hormone therapy. Vaginal rings (VRs) containing progesterone hormones could be a good choice for treatment. In this study, the design and construction of a reservoir ring with the ability to release levonorgestrel hormone has been investigated. Methods: In this experimental study, to make vaginal rings containing levonorgestrel, biocompatible silicone fibers were used, the two ends of which were connected with special caps. Different amounts of LNG including 0.1, 0.2 and 0.4 weight percent relative to paraffin were loaded into the fibers. These three prototypes were named RSC1, RSC2, and RSC3, respectively. The daily and cumulative release of LNG from these rings was measured by spectrophotometer and compared using SPSS software version 16 and analyzed by one-way ANOVA method. Results: On the first day, there was a burst release that was different for these three prototypes depending on the drug loading percentage. From the second until thirtieth day for RSC3 and from forth until thirtieth day for RSC1 and RSC2, prolonged release was achieved and average daily release for RSC1, RSC2, and RSC3 were 24.10 ± 8.22, 41.77 ± 9.02 and 83.29 ± 5.07µg, respectively. Conclusion: According to the findings, it is possible to design VRs capable of prolonged and sustained release of LNG for up to 30 days and control their daily release rate based on initial drug loading. This method may be a suitable alternative to oral hormonal pills in the treatment of AUB.