What is Testosterone?
Testosterone is a hormone of sex naturally produced in a man’s testicles and in a woman’s ovaries and adrenals (in lower concentration) [1]. It’s a steroid hormone that forms male sexual traits and functions and the homeostasis of many organ systems throughout life [2]. Testosterone is also a source of male exogenous genitals and secondary sexual characteristics [3].
What Does Testosterone Do?
Testosterone functions in a range of physiological processes. It is also the cause of the development and maturation of testicles and prostate, as well as of the production of sperm in men [4]. It also increases secondary characteristics like hair growth, muscle mass, voice expansion, bone density, and red blood cell production [5].
Testosterone in women occurs in much smaller quantities; it’s involved in hormone secretion, bone, breast, menstrual and vaginal health, fertility, and sexual desire [5]. It also acts as a woman’s sexual stimulant and secretes hormones involved in a woman’s cycle [4].
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Testosterone is also a significant driver of body fat and muscle in men. Low testosterone levels have been linked to high body fat, low insulin sensitivity, poor glucose control, high triglycerides and cholesterol levels, and low HDL cholesterol—all risk factors for cardiovascular disease [6].
What is the Structure of Testosterone?
The prominent male anabolic-androgenic steroid is testosterone (17β-Hydroxyandrost-4-en-3-one). It’s a 19-carbon steroid and the most potent endogenous androgen [7]. Testosterone’s chemistry is exceptionally sophisticated, and it has been examined by different techniques like X-ray single crystal diffraction, powder X-ray diffraction, and high-resolution rotational spectroscopy [8, 9, 10].
Testosterone’s molecule is made up of a cyclopentanone ring (A) that’s joined to two subsequent rings of cyclohexane (B and C) and a cyclohexanone ring (D). The three rings are all slightly bent-over boat shapes, and the cyclopentanone ring is a bent half-chair [11].
Testosterone’s crystal packing is maintained by weak intermolecular C-HO interactions between O atoms from both rings of cyclohexanone and cyclopentanone and H atoms from each one [11].
The testosterone-isolated molecule takes on a longer axis, revealed by high-resolution rotational spectroscopy [10].
Pharmaceutically, the water solubility of testosterone and esterified forms has been studied to deliver the hormone in medicine [8, 9].
What is Finasteride?
Finasteride is a prescription medicine delivered as an oral tablet. It is available under the brand names Proscar and Propecia and as a generic. Finasteride is a type II selective 5-reductase inhibitor; that is, it blocks testosterone’s breakdown to the active form of testosterone, dihydrotestosterone (DHT), in its target organs, including the skin, scalp, liver, and prostate [12, 13, 14].
What Does Finasteride Do?
Finasteride works by cutting your body’s production of DHT. DHT is a hormone that usually makes your prostate significant and can be the cause of hair loss in some men. Because finasteride suppresses DHT, it helps prevent your prostate from growing larger; you start to grow more hair and shed less on your head. But hair growth on the rest of the body doesn’t suffer [14].
Finasteride helps patients who suffer from a protruding prostate or benign prostatic hyperplasia (BPH). You can take it as a combination therapy, that is to say, taken with other medications. It can also be used in combination with doxazosin to prevent the progression of symptoms of a large prostate [14, 15].
Besides BPH, finasteride can be prescribed for male pattern hair loss (androgenetic alopecia). It’s been reported to result in visible hair growth in up to 66% of men with mild to moderate alopecia and has stopped hair loss in 91% of patients [16].
What is the Structure of Finasteride?
Finasteride is a 4-azasteroid artificial medication that reduces type II 5-reductase, an enzyme that turns androgen testosterone into 5-dihydrotestosterone [17]. It is a specific steroid 5-reductase inhibitor, an intracellular enzyme responsible for testosterone conversion into 5-dihydrotestosterone (DHT) [18].
We know the crystal structures of two enantiotropic polymorphs of finasteride. These two polymorphs’ solid-state nuclear magnetic resonance spectra, infrared spectra and physical property data are compared with solid-state structures and hydrogen-bonding networks [19].
The AKR1D1.NADP(+)*finasteride complex, solved at 1.7 A resolution NADPH cannot reduce finasteride’s Delta(1-2)-ene because the cofactor and steroid are not within proximal proximity [20].
The C3-ketone of finasteride binds to hydrogen bonds on the catalytic residues Tyr-58 and Glu-120 in the AKR1D1 active site, which is why competitive inhibition occurred [20].
We know the dioxane, IPA, and THF solvates' crystal structures from single-crystal X-ray diffraction. All the solvates (except acetic acid) are hemihydrates, have finasteride: solvent molar ratio of 2:1, and are the same shape [21].
Does Testosterone Have The Same Effect on Hair Growth as Finasteride?
Testosterone and Finasteride don’t both have the same effect on hair growth because they have very different actions. Finasteride is a type II 5-reductase inhibitor that prevents testosterone from converting into dihydrotestosterone (DHT), a man’s hair loss hormone [22, 23]. Finasteride decreases DHT, slows hair loss, and even increases hair regrowth in men with androgenetic alopecia or male pattern baldness [24, 25, 26, 27, 28, 29].
In contrast, testosterone, another hormone that finasteride targets has a somewhat complicated relationship with hair. It’s required for average hair growth, but when converted into DHT, it shrinks the hair follicle and causes hair loss in men susceptible to androgenetic alopecia [23].
Intriguingly, some research has demonstrated that testosterone therapy can enhance hair regrowth in androgen-deficient women, indicating that hair growth may be affected by the hormone depending on your hormone levels and other factors [30].
However, keep in mind that finasteride was found to be ineffective in encouraging hair growth in postmenopausal women with androgenetic alopecia, so that it could be more assertive in women with higher testosterone levels [31].
Overall, both testosterone and finasteride are hair growth-influencing drugs but do it in different ways and to various extents, depending on one’s sex and hormone levels.