Silicone vaginal ring

At the laboratory scale, silicone vaginal rings are usually obtained by injection molding, where poly(dimethylsiloxane) is mixed with a polymerization catalyst and the drug, being subsequently injected in ring-shaped molds. The mixture is allowed to cure for a period of time at a preestablished temperature, which can range from... 

Fig. 10 (A) Serum concentrations of medroxyprogesterone acetate after a daily oral administration of a medroxyprogesterone acetate tablet (10 mg) taken by a healthy woman before breakfast for five consecutive days. (B) Daily serum concentrations of medroxyprogesterone acetate in women wearing medicated silicone vaginal rings (2% medroxyprogesterone acetate) for 20 days. (From Ref. l)...

Spilman, C. Roseman, T. Luteolytic and abortifacient effects in rhesus monkeys of silicone vaginal rings containing 15(S) 15-methyl-prostaglandin F2 alpha methyl ester. Contraception 1975, 11, 409-18. 

Fig. 11 Comparative in vitro release rate profile of levonor-gestrel from a vaginal ring containing a homogeneous dispersion of drug in a silicone-based polymer matrix (O) and from one containing an inert overcoat covering the drug reservoir layer ( and ). The effect of overcoat thickness fijii on the release rate of levonorgestrel is also shown. (From RefP l)...

Prolonged retention of the drag is possible, if the appropriate delivery system such as vaginal silicone ring is used, thereby allowing a reduction in the dosing frequency. 

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