Combined Oral Contraception available in Ireland

Table 1: Combined Oral Contraception (COC) available in Ireland

*All combination birth control pills contain oestrogen (typically ethinyloestradiol, except for Qlaira and Zoely where it is oestradiol) and a progestin. The term progestin is used for any natural or man-made substance that has properties similar to natural progesterone. In contrast to oestrogen, there are many types of progestin found in various oral contraceptive brands. The older progestin types are usually referred to as first- and second-generation while the newer ones are called third- and fourth generation.

The progestogen component of Dianette, the anti-androgen cyproterone acetate, supresses ovulation and therefore also has a contraceptive effect, but due to known risk of thromboembolism Dianette is now indicated solely in the treatment of moderate to severe acne related to androgen sensitivity or hirsutism in women of reproductive age.

Classification of progestins

Most of these synthetic progestins are chemical derivatives of testosterone (known as 19-nortestosterone derivatives) and can be divided into two families: estrane and gonane. They include:

First generation progestins which consist of norethindrone and other progestins that metabolize to norethindrone (not marketed in Ireland). They belong to the estrane family.

Second generation progestins, which include levonorgestrel, have varying degrees of androgenic and oestrogenic activities. They are more androgenic than the first-generation progestins, which are in turn more androgenic than newer progestins, like desogestrel. They belong to the gonane family.

Newer gonanes, or third generation progestins include desogestrel, gestodene and norgestimate, which also belong to the gonane family. They are reported to have fewer androgenic effects.

The newest (fourth) generation include drospirenone, dienogest, and nomegestrol. Drospirenone is a unique progestin as it differs from the others because it is derived from 17a-spirolactone, not from the 19-nortestosterone derivatives.

Typically the third and fourth generation progestins tend to be highly selective and possess minimal androgenic properties.

NB: Higher androgenic activity may increase the chances of androgen-related side effects which mainly include acne and hirsutism. Also, progestins with less androgenic activity tend to have little to no effect on carbohydrate metabolism. A higher amount of oestrogenic activity helps to decrease androgen-related side effects.

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