Understanding Androgenic Effects in Contraceptives
Androgens are a group of hormones, like testosterone, that are responsible for male characteristics but are also present in females in smaller amounts. In the context of hormonal contraceptives, the progestin component can sometimes interact with androgen receptors in the body [1.6.6]. This interaction can lead to androgenic side effects such as acne, oily skin, and unwanted hair growth (hirsutism) [1.3.1]. Conversely, some progestins have an 'anti-androgenic' effect, meaning they block these receptors, which can help improve such conditions [1.6.3]. The specific type of progestin in a birth control pill determines its androgenic or anti-androgenic potential [1.6.6].
The Unique Composition of Zoely
Zoely is a monophasic combined oral contraceptive (COC) that is distinct from many others on the market [1.2.2]. It combines 2.5 mg of nomegestrol acetate (NOMAC) with 1.5 mg of estradiol (E2) [1.2.2].
Nomegestrol Acetate (NOMAC): The Key Player
Nomegestrol acetate is a highly selective progestogen derived from the naturally occurring hormone progesterone [1.2.3]. Its high selectivity is a crucial aspect of its pharmacological profile. NOMAC binds strongly to the progesterone receptor, which is its intended target for providing contraception by suppressing ovulation [1.2.6].
Crucially, sources state that NOMAC is devoid of androgenic activity [1.2.3, 1.4.1]. In fact, it exhibits moderate anti-androgenic activity [1.2.3, 1.4.3]. This means it does not stimulate androgen receptors; instead, it can help block them [1.9.2]. This profile makes it a potentially favorable option for individuals concerned about androgenic side effects [1.6.4]. Its anti-androgenic activity is estimated to be between 5% and 30% of the potent anti-androgen cyproterone acetate [1.4.4].
Estradiol (E2): A Natural Estrogen
Unlike many COCs that use the synthetic estrogen ethinylestradiol (EE), Zoely contains estradiol, a form of estrogen that is identical to what the human body produces naturally [1.2.2, 1.2.4]. The use of natural estrogen is another factor that differentiates Zoely's formulation.
Clinical Implications of Zoely's Anti-Androgenic Profile
The anti-androgenic nature of Zoely's progestin, NOMAC, has several clinical implications, particularly for skin health.
- Acne and Skin: Because it can block androgen receptors, NOMAC may be useful in alleviating androgen-dependent symptoms like acne and seborrhea (oily skin) [1.9.2]. However, it's important to note that acne is still listed as a possible side effect, as individual responses can vary [1.3.2, 1.3.5]. In a large-scale study, no differential effect on acne was observed between Zoely users and users of a levonorgestrel-containing pill after 24 months [1.9.5].
- Hair Growth: Anti-androgenic medications can be used to treat hirsutism (excessive hair growth) [1.6.3]. Due to its anti-androgenic properties, Zoely may be beneficial for this purpose, although this is not its primary indication.
- Weight: While weight gain is a common concern with hormonal contraceptives, studies on Zoely and NOMAC suggest body weight generally remains unchanged [1.9.2, 1.9.5].
Comparison with Other Oral Contraceptives
To understand Zoely's profile, it's helpful to compare it to other common birth control pills. The androgenic activity of a COC depends almost entirely on its progestin.
| Progestin | Common Brand(s) | Androgenic Profile | Clinical Notes |
|---|---|---|---|
| Nomegestrol Acetate (NOMAC) | Zoely | Anti-androgenic (moderate) [1.2.3] | Derived from progesterone; highly selective. Does not bind to androgen receptors [1.2.3, 1.5.3]. May improve acne [1.9.2]. |
| Drospirenone | Yaz, Yasmin | Anti-androgenic [1.6.2] | Often prescribed for PCOS and acne due to its anti-androgenic and antimineralocorticoid properties [1.6.2, 1.6.4]. |
| Levonorgestrel (LNG) | Various, Mirena IUD | Androgenic [1.6.6] | An older progestin, known for its androgenic activity, which can sometimes cause or worsen acne [1.6.6]. |
| Desogestrel | Desogen, Ortho-Cept | Low Androgenic Activity [1.6.2] | A third-generation progestin with high selectivity for progesterone receptors and minimal androgenic effects [1.6.2]. |
| Cyproterone Acetate | Diane-35 (not available in US) | Strongly Anti-androgenic [1.6.2] | One of the most potent anti-androgens, highly effective for severe hirsutism and acne but carries a higher risk of side effects [1.6.2]. |
Conclusion
So, is Zoely androgenic? The scientific evidence clearly indicates that it is not. The progestin in Zoely, nomegestrol acetate, is devoid of androgenic activity and possesses moderate anti-androgenic properties [1.2.3, 1.4.3]. This makes Zoely a unique oral contraceptive that may be particularly suitable for individuals who are sensitive to the androgenic side effects of other birth control pills or those seeking potential benefits for conditions like acne. As with any medication, individual experiences can differ, and it is essential to consult with a healthcare provider to determine the most appropriate contraceptive option.
For more detailed product information, you can refer to the official patient information leaflet from the European Medicines Agency.
