All combination birth control pills contain estrogen (typically ethinyl estradiol) and a progestin. The expression progestin is used for any man-made or natural substance which has properties very similar to natural progesterone. Compared to estrogen, there are various kinds of progestin found in several oral contraceptive brands. The elderly progestin forms are often referred to as first- and second-generation while the more recent ones are known as third-generation (and fourth).
Comparing estrogen is rather simple since all blend birth control pills utilize the identical type of estrogen; this makes it feasible to compare doses simply by quantity. On the other hand, because tablets utilize different types of progestin (each of which has a different strength), it’s significantly more difficult to compare progestin levels across tablets. The quantity of progestin found in birth control pills is rather small and is usually denoted in milligrams (mg). This signifies is that even if two brands have the same progestin dose, they may have different kinds of progestin, or so the potency can vary widely.
Types of Progestin:
There are various kinds of progestins, and each has a distinct profile in terms of progestational, estrogenic, and androgenic activity and/or impacts. The result of the effects is dependent on the combination of this type and level of progestin and the level of estrogen.
Because the hormones contained in every type of pill are different, and because every woman responds differently to the tablet computer, these general guidelines may not apply to all girls. To better understand the way the progestin may be categorized, it is helpful to clarify what effects a progestin may have on the female body.
- Progestational Effects: Progestational effects refer to how the progestin stimulates the progesterone receptors (thus helping to prevent ovulation and to lessen menstrual bleeding). A similar term is progestational selectivity, that’s the degree to which progestational effects are maximized and androgenic effects are reduced. Normally, the goal of a birth control pill is to achieve a high level of progestational selectivity.
- Androgenic Effects: Androgenic effects refer to the chance that the progestin can cause unpleasant side effects. Progestins with greater androgenic activity might increase the chances of androgen-related side effects which mostly consist of acne and hirsutism (female unwanted hair growth).
Also, progestins with less androgenic activity generally have little to no impact on carbohydrate metabolism, which is the way the body breakdowns and synthesizes easy sugars into smaller components which can then be employed by the body for energy.
- Estrogenic Effects: Estrogenic activity has to do with ethinyl estradiol, the kind of artificial estrogen found in birth control pills. A greater number of micrograms of ethinyl estradiol lead to more powerful estrogenic effects. A higher amount of estrogenic action helps to reduce androgen-related side effects. But, progestins tend to counter some of the estrogenic effects of ethinyl estradiol.
Classification of Progestins:
Combination birth control pills include an estrogen and a single progestin. There are eight types of progestins. Most of these artificial progestins are chemical derivatives of testosterone (called 19-nortestosterone derivatives).
The available birth control pills that are classified under 19-nortestosterone can be further split into two families: estrane and gonane.
- The estrane household (generally, first generation progestins) consist of norethindrone and other progestins that metabolize to norethindrone. These include norethindrone acetate and ethynodiol diacetate.
- The gonane household : This classification is further subdivided into two groups:
Secondly generation progestins, that have varying degrees of androgenic and estrogenic activities. These include levonorgestrel and norgestrel.
Newer gonanes, or third generation progestins; those are reported to have the least side effects and contain desogestrel and norgestimate.
- Drospirenone, the last progestin, is also the newest (4th) generation. 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 are usually extremely selective and possess minimal androgenic properties. These include norgestimate, desogestrel, and drospirenone. There’s been some evidence to suggest that the third generation progestins may carry a higher risk of blood clots.