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    Puberty Blockers: How Hormone Blockers Suppress Sexual Characteristics in Teens

    Published 20 April 2020
    Fact Checked
    Reviewed by Marina Savchenko, MD, Pediatric Neurologist, Medical Consultant at Flo
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    Did you know it’s possible to decrease gender-defining hormonal activity and hit the pause button on adolescent development? Today, Flo reveals exactly how puberty blockers work.

    What are puberty blockers?

    Let’s first define the phase in life that every individual must go through regardless of gender. Puberty is a process in which the body begins its journey towards adulthood and becomes sexually mature enough to reproduce. It’s also marked by accompanying physical growth and brain development. 

    It all starts with the brain’s stimulation of the pituitary gland to release certain hormones, like follicle-stimulating hormone (FSH) and luteinizing hormone (LH). The spike triggers testosterone production in male testicles and estrogen production in female ovaries. (Note that FSH and LH are not responsible for adolescent acne or the growth of underarm and pubic hair.)

    Puberty blocker medications inhibit the activity of hormones that normally guide the body through puberty, and are also known as GnRH analogs.

    How do puberty blockers work?

    The physical changes associated with puberty may create significant distress in gender-nonconforming young adults. When taken regularly, GnRH analogs suppress the secretion of sex hormones like estrogen and testosterone which, in turn, impact the following:

    • Primary sexual characteristics

    These include the sex organs present at birth such as the penis, testicles, and scrotum or the uterus, vagina, and ovaries.

    • Secondary sexual characteristics

    These include various physical signs of maturity during puberty like the appearance of facial hair or breast development.

    What are androgen blockers?

    Androgen proteins can be found in prostate gland cells and certain prostate cancer cells. Any substance designed to stop the binding of androgens (or male sex hormones) to androgen receptors are known as androgen blockers. Also referred to as antiandrogens or androgen receptor antagonists, they include apalutamide, enzalutamide, bicalutamide, nilutamide, and flutamide. 

    Androgen blockers impede the usual effects of these hormones on the body and even stem the growth of prostate cancer cells. Health care providers use androgen blockers to treat numerous hyperandrogenic conditions (i.e., when there’s an excessive amount of androgens present), including hirsutism, paraphilias, and acne. 

    Chemically speaking, androgen blockers may be classified as follows:

    • Steroidal (e.g., cyproterone acetate)
    • Nonsteroidal (e.g., bicalutamide, nilutamide, and flutamide)

    Despite undergoing multiple trials, cyproterone has yet to receive approval from the Food and Drug Administration (FDA) as it’s likely to be toxic to the liver. On the contrary, bicalutamide, nilutamide, and flutamide have been approved for clinical treatment of prostate cancer.

    Abiraterone is one of the most recently developed steroid androgen blockers for battling this disease. It inhibits CYP17 (an enzyme involved in androgen production) and is successful at prolonging overall relapse-free survival in men with castration-resistant, metastatic prostate cancer.

    If you were born male, taking hormone blockers might limit or completely stop the following things:

    • Body or facial hair growth
    • Voice deepening
    • Development of an Adam’s apple
    • Shoulder broadening
    • Maturation of the gonads or sex organs (e.g., penis, testes, erectile tissue, etc.) 

    What are estrogen blockers?

    Antiestrogens or estrogen blockers contain either steroidal or nonsteroidal compounds that interfere with estrogen-induced hormonal activity. Once in the body, the antiestrogens tamoxifen, U23, 469, and C1628 activate into forms with a greater attraction to estrogen receptors. This way, estrogens are blocked from reaching receptors of the cells, including cancer ones which is pivotal in breast cancer treatment. The body still makes estrogens, but their effects are absent in some cells.

    Other estrogen blockers utilize aromatase inhibitors to prevent the synthesis of estradiol. They constitute a rapidly growing class of steroidal and nonsteroidal based inhibitor drugs. The former includes testolactone, formestane, exemestane, and atamestane, while the latter includes fadrozole, letrozole, anastrozole, vorozole, and finrazole.

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