Progestins subdermal implants

Progestin-only contraceptives (Fig. 4) contain low-doses of progestins (e.g. 350 pg norethindrone or 75 pg norgestrel) that have to be administered daily without interruption. The lowest expected failure rate during the first year of use is 0.5%, while the typical failure rate amounts to 3%. Subdermal implants of norgestrel (216 mg) for sustained release provides for long-term (for up to 5 years) contraceptive effects characterized by failure rates of only 0.05%. Reliable contraception for 3 months can be achieved by an intramuscular injection of a crystalline suspension of 150 mg medroxyprogesterone acetate (Fig. 3) (failure rate 0.3%). 

Impiant Contraceptive Systems (Progestins) levonorgestrel 6 capsules, each containing 36 mg levonorgestrel for subdermal implantation... 

Fig. 17 Syncro-Mate-C implant, a subdermal implant fabricated from the microreservoir dissolution-controlled drug-delivery system, and subcutaneous controlled release of nor-gestomet, a potent synthetic progestin, at constant rate for 20 days. The open ends on the implant do not affect the zero-order in vivo drug release profile. (Adapted from Ref. . )...

Several subdermal implants are available that provide contraceptive efficacy for 1 to 5 years depending on the formulation (Table 46.10). These implants consist of progestins contained within individual rods that are surgically implanted into the upper arm. As indicated in Table 46.10, varying durations of action can be expected depending on the number of rods implanted. Currently, Norplant is not available in the United States, and Implanon has only received approval" status by the U.S. FDA. These formulation is subject to the same adverse effects as other progestin-only methods. 

IMPLANT CONTRACEPTIVE SYSTEM. Levonorgestrel, a progestin, is available as an implant contraceptive system (Norplant System). Six capsules, each containing levonorgestrel, are implanted under local anestiiesia in die subdermal (below the skin) tissues of the mid-portion of die upper arm. The capsules provide contraceptive protection for 5 years but may be removed at any time at die request of the patient. See Table 52-3 for more information on ways to promote an optimal response when taking die contraceptive hormones. 

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