Antiandrogens and their Importance

By: | Tags: | Comments: 0 | April 27th, 2019

-Definition:

An antiandrogen or androgenic antagonist is a group of drugs that exert an antagonistic action or hormonal suppression capable of preventing or inhibiting the biological effects of androgens or male sex hormones on the normal responses of body tissues to these hormones.
Antiandrogens normally act by blocking androgen receptors, competing with binding sites on the surface of cells, nullifying the function of androgens, except in those cases that inhibit the conversion of testosterone to dihydrotestosterone, which is more potent than dihydrotestosterone and therefore are partially antiandrogenics.

-Various Uses:

Antiandrogens are indicated and used in multiple diseases and non-medical situations respectively:
Antineoplastic agents either palliative, adjuvant or hormonal adjuvant treatment in prostate cancer.
Benign prostatic hyperplasia.
Acne.
Androgenic alopecia.
Hirsutism.
Combined therapy in sex reassignment, gender dysphoria.
Occasionally they are also used in men as a contraceptive method.
To prevent or counteract masculinization in cases of preoperative transsexual women.
To prevent symptoms associated with testosterone deficiency, such as hot flashes, after castration, whether physical or chemical.
Antiandrogens are often indicated to treat serious sexual disorders, such as hypersexuality or excessive sexual desire and sexual deviations, especially paraphilias.
The administration of antiandrogens to men may cause a decrease or increase in the development or involution of secondary sexual characteristics in men, reducing the activity or function of accessory sexual organs, and hyposexuality, with decreased sexual desire or libido.
The term antiandrogen withdrawal response describes the medical situation that occurs when cancer cells adapted to antiandrogen administration and which no longer respond, begin to suffer antiandrogenic effects after the antiandrogen administration ceases.

The complete or maximum androgenic block is the association of antiandrogen with gonadotropin-releasing factor analogue.
Of all cancers, prostate cancer is the most hormone sensitive: therefore, it is very important to take advantage of this unique property and always use the optimal androgenic block when hormone therapy is the appropriate treatment.
A fundamental observation is that the concentration of testosterone in serum only reflects the amount of testosterone of testicular origin that is released into the blood from which it reaches all tissues.
Recent data show, however, that approximately equal amounts of testosterone are made from dehydroepiandrosterone (DHEA) directly in peripheral tissues, including the prostate, and do not appear in the blood.
The combination of castration (surgical or medical with a gonadotropin releasing hormone (GnRH) agonist with a pure antiandrogen has been the first treatment shown to prolong life.
More importantly, when applied at the localized stage, the same combined androgenic blockade (CAB) can provide long-term control or cure of the disease in more than 90% of cases.
Because prostate cancer usually grows and metastasizes without signs or symptoms, screening with prostate-specific antigen (PSA) is absolutely necessary to diagnose prostate cancer at an “early” stage before metastasis occurs and the cancer becomes uncured.

Although it was believed that the role of androgens was not significant in the progression of cancer under any form of androgenic blockade, recent data have shown an increase in androgen receptor expression (AR) in treatment-resistant diseases benefiting from increased androgen blockade.
Since available antiandrogens have low affinity for AR and cannot completely block the action of androgens, especially in the presence of elevated AR levels, it is important to discover more potent and purely antagonistic AR blockers.
The data obtained with the compounds under development are promising. While awaiting these new antiandrogens, combined treatment with castration and a pure antiandrogen (bicalutamide, flutamide or nilutamide) is the only available and the best scientifically based means of treating prostate cancer with hormonal therapy at any stage of the disease, with the optimal chance of success and even cure of the disease at its early stage.
We do not recommend the use of alpha reductase inhibitors, such as finasteride and dutasteride, in androgenic alopecia and prostatic hypertrophy.

-Types of anti-androgenic drugs:

There are multiple antiandrogenic drugs such as:
Degarelix of ethyl
Bicalutamide.
Cyproterone acetate.
Finasteride.
Dutasteride.
Flutamide.
Enzalutamide.
Nilutamide.
Spironolactone.
ketoconazole at toxic doses orally.

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