Recommendations for Contraceptive Use
		Combined Injectable Contraceptives

Combined Injectable Contraceptives

The name of Combined Injectable Contraceptives (CICs) is given to a group of hormonal contraceptives administered by intramuscular injection. The term "combined" indicates that these injectables contain both a progestin and an estrogen. At present there are 3 main types of CICs on the market:

The first 2 are new products approved by World Health Organization (WHO), which are becoming more widely used throughout the world; the latter is mostly used in some Latin American countries. The 3 formulations provide very effective pregnancy protection for a 30-day period, therefore, they are also referred to as "monthly injectables".

CICs have some similarities with progestin-only injectables: the 2 new CICs contain precisely the same progestin as the 2 most widely used progestin-only injectables (Depo Provera^® and Noristerat); however, the progestin dose received over time is much lower with the new CICs. The basic difference between CICs and progestin-only injectables is the presence of estrogen in the CICs; the estrogen was incorporated mostly to improve the regularity of the menstrual cycle.

Although CICs and combined oral contraceptives (COCs) are combined hormonal contraceptives, they have several differences. Besides the different route of administration, from a safety point of view, the most important difference is the presence of a "natural" estrogen in the CICs versus a "synthetic" estrogen in the COCs. It is now recognized that natural estrogens have very favorable effects on lipid metabolism and cardiovascular function. The use of natural estrogens in post-menopausal women has actually shown to have a protective effect against cardiovascular disease, including both cerebrovascular and cardiac problems. Estradiol has direct effects on the arterial wall and on various stages of the atherosclerotic plaque formation, resulting in an increase in tissue blood flow, and in an anti-atherosclerotic effect. The addition of a progestin to the estradiol (in CICs) has not been shown to lessen these beneficial effects.

Based on the above evidence, CICs might actually be considered safer than COCs. However, due to the recent introduction of the 2 new CICs, no long-term safety information on the use of these CICs is available yet. Therefore, the current medical criteria for CIC use are mostly derived from the information existing on COC use.

Citations:

1. World Health Organization, Task Force on Long-acting Systemic Agenda for Fertility Regulation, Special Programme of Research,Development and Research Training in Human Reproduction. A multicentered phase III comparative study of 2 hormonal contraceptive preparations given once-a-month by intramuscular injection: I. contraceptive efficacy and side-effects. Contraception 1988;37:1-20.
2. Garza-Flores J. Pharmacokinetics of once-a-month injectable contraceptives. Contraception 1994;49(4):347-59.
3. Lobo RA, Speroff L. International consensus conference on post menopausal hormone therapy and the cardiovascular system. Fertility and Sterility 1994;61(4):592-5.
4. Chester AH, Jiang C, Borland JA, Yacoub MH, Collins P. Oestrogen relaxes human epicardial coronary arteries through non-endothelium-dependent mechanisms. Coronary Artery Disease 1995;6(5):417-22.

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Any part of Recommendations for Updating Selected Practices in Contraceptive Use may be reproduced or adapted to meet local needs without prior permission from the TG/CWG Secretariat, provided the TG/CWG is acknowledged and the material is made available free of charge or at cost.