Intravaginal & Intrauterine Drug Delivery Systems

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Chapter: Biopharmaceutics and Pharmacokinetics : Controlled Release Medication

Controlled-release intravaginal systems are used for delivery of contraceptive steroid hormones.


Controlled-release intravaginal systems are used for delivery of contraceptive steroid hormones. The advantage of this route includes—no first-pass effect, improved bioavailability and lesser drug dose in comparison to that required by oral route. Two types of devices have been developed—a matrix diffusion controlled device e.g. medroxy progesterone acetate dispersed in viscous silicone elastomer, and the other, dissolution controlled device e.g. dispersion of a progestin and an estrogen in an aqueous solution of PEG 400 to form microscopic drug reservoir in a mixture of silicone elastomers. 

Fig. 14.21 Schematic representation of a vaginal ring

The device is generally prepared by extrusion of the resultant composition into a doughnut shaped vaginal ring (Fig. 14.21). The system releases the medicament for 21 days to achieve a cyclic intravaginal contraception.

Intrauterine route is also used for fertility control. Two types of medicated intrauterine devices (IUDs) have been developed to produce effective contraception for 12 months or more.

1. Copper Medicated IUD

It consists of a polypropylene or polyethylene plastic support of number 7 or letter T with certain amount of copper wire wound around them. T shape IUD is popular since its shape conforms to the uterine cavity and resists displacement and rotation within the cavity as well as expulsion from the cavity (see Fig. 14.22a). The copper wire of surface area 200 mm2 shows maximum contraceptive activity. Oxidation of copper in the body fluids releases its ion slowly and exert its effect locally. The device is effective for more than 3 years.

2. Progesterone Releasing IUD (Progestasert)

It is also a T shaped polyethylene device with a progesterone reservoir dispersed in a silicone polymer placed in the vertical arm which is enclosed in a sleeve of rate-controlling membrane of ethylene-vinyl acetate copolymer (Fig. 14.22b). The device releases progesterone at a rate of 65 mcg/day for a period of one year.

Fig. 14.22 Contraceptive IUDs—(a) Copper T located in the uterus, and (b) Progestasert

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