Contraception injectable contraceptives

As of 1994, there were approximately 47 progestin-containing contraceptive dmg formulations sold in the United States for use as oral contraceptives (Table 3). In addition, there are three nonoral contraceptive formulations containing progestins ie, one injectable (Depo-Provera), one as an intrauterine device (lUD) (Progestasert), and one implantable (Norplant). Of the oral formulations, all but two also contain an estrogen component, ethynylestradiol. 

Injected formulation of leuptoleine and triptoreline [57773-63 ] ate used to treat metastasized cancer of the prostrate, whereas an encapsulated formulation of bromocryptin [25614-03-3] is used to inhibit milk production in women after pregnancy. The performance of encapsulated hormonal polypeptides is weU documented (47). Injectable biodegradable mictocapsules loaded with fertUity control agents have been under development for a number of years and have been carried to various stages of clinical development (48) (see Contraceptives). 

An example of such a product is Sterile Medroxyprogestrone Acetate Suspension used for its contraceptive property. Such an injection is designed to provide up to three months of contraceptive activity. Another such product is a depot injection of leuprolode acetate, an analogue of gonadatropin-releasing hormone (see Drug delivery systems). In this case, the product is a sterilized powder of microspheres to be suspended upon the addition of an appropriate diluent and intended for monthly injection. 

The currendy (ca 1992) marketed injectable and implantable contraceptives are designed to be effective for maximum periods of three months and five years, respectively. There is Htde evidence from programmatic or health reasons that an injectable formulation with a longer effective life span, eg, six months, would not be equally effective. The acceptabiUty and effectiveness of long-acting contraceptives may be determined by the means by which a community deUvers contraceptive products to the pubHc the active life of a product may be determined by economic rather than programmatic or health related factors. 

Injectable Contraceptives. Injections of contraceptive dmgs must be sufficiendy spaced to make the approach attractive to the user. The average contraceptive user is not willing to endure daily injections or injection intervals of one or two weeks the minimum acceptable injection interval has been found to be at least four weeks. 

Long-acting activity of injectable contraceptives can be accompHshed via a number of different approaches. Steroid activity can be extended over a... 

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%). 

Another form of contraception should be used if the monthly dosage is late (more than 33 days since the last injection). 

Long-term injectable contraceptive administered IM every 3 months. The injection is given only during the first 5 days after the onset of a normal menstrual period, within 5 days postpartum if not breastfeeding, or at 6 weeks postpartum. 

As an alternative to oral contraceptive pills, which must be taken daily in order to reliably prevent pregnancy, non-oral contraceptives in the form of transdermal, transvaginal, and injectable preparations are available and offer patients safe and effective alternatives to the pills for prevention of pregnancy. These formulations also do not require daily administration, making them more convenient than the pill formulations. 

Women who particularly benefit from progestin-only methods, including minipills, are those who are breast-feeding, those who are intolerant to estrogens, and those with concomitant medical conditions in which estrogen is not recommended. Also injectable and implantable contraceptives are beneficial for women with compliance issues. 

DMPA 150 mg administered by deep intramuscular injection in the gluteal or deltoid muscle within 5 days of the onset of menstrual bleeding inhibits ovulation for more than 3 months, and the dose should be repeated every 12 weeks to ensure continuous contraception. A new formulation contains 104 mg of DMPA (Depo-SubQ Provera 104), which is injected subcutaneously into the thigh or abdomen. The manufacturer recommends excluding pregnancy in women more than 1 week late for repeat injection of the intramuscular formulation or 2 weeks late for repeat injection of the subcutaneous formulation. 

In 1992, the US FDA approved a long-acting contraceptive device containing synthetic progestin medroxyprogesterone acetate (MPA) hormones. Manufactured by Pfizer, Inc., it is sold under the trade name Depo-Provera . It is typically injected into a woman s buttocks or upper arm, and renders her temporarily sterile for up to 3 months. ... 

Depo-Provera An Injectable Contraceptive (Last updated 2003, March). American Academy of Family Physicians. Retrieved April 8, 2004 from http //www.familydoctor.org/handouts/043.html... 

Prevention of pregnancy It is a long-term injectable contraceptive in women when administered at 3-month intervals. 

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