Combined injectable contraceptive

Combined injectable contraceptive (CIC) is a form of birth control that is administered through an injection. It contains two types of hormones, progestogen and estrogen, which work together to prevent ovulation, thicken cervical mucus to block sperm, and thin the lining of the uterus to prevent a fertilized egg from implanting.

Composition

The CIC typically contains a progestogen component and an estrogen component. The progestogen may be a derivative of 17α-hydroxyprogesterone, such as medroxyprogesterone acetate or norethisterone enanthate, or a derivative of 19-nortestosterone, such as nandrolone decanoate. The estrogen is usually estradiol valerate or estradiol cypionate.

Mechanism of action

The combined injectable contraceptive works by suppressing ovulation, altering the cervical mucus to inhibit sperm penetration, and changing the endometrium to prevent implantation of a fertilized egg. The progestogen component primarily prevents ovulation and thickens cervical mucus, while the estrogen component stabilizes the endometrium and may help to prevent the breakthrough bleeding that can sometimes occur with progestogen-only contraceptives.

Usage

CICs are administered by intramuscular injection once a month. They are an effective method of birth control, with a typical-use failure rate of less than 1% per year. However, they do not protect against sexually transmitted infections.

Side effects

Possible side effects of CICs include menstrual irregularities, weight gain, breast tenderness, and headaches. In rare cases, they may cause serious health problems such as blood clots, heart attack, and stroke.

See also

• Contraceptive patch
• Contraceptive vaginal ring
• Intrauterine device
• Oral contraceptive pill

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