Three-Dimensional Proteome-Wide Scale Screening for the 5-Alpha Reductase Inhibitor Finasteride: Identification of a Novel Off-Target.

Finasteride, a 5-alpha reductase (5α-R) inhibitor, is a widely used drug for treating androgen-dependent conditions. However, its use is associated with sexual, psychological, and physical complaints, suggesting that other mechanisms, in addition to 5α-R inhibition, may be involved. Here, a multidisciplinary approach has been used to identify potential finasteride off-target proteins. SPILLO-PBSS software suggests an additional inhibitory activity of finasteride on phenylethanolamine N-methyltransferase (PNMT), the limiting enzyme in formation of the stress hormone epinephrine. The interaction of finasteride with PNMT was supported by docking and molecular dynamics analysis and by in vitro assay, confirming the inhibitory nature of the binding. Finally, this inhibition was also confirmed in an in vivo rat model. Literature data indicate that PNMT activity perturbation may be correlated with sexual and psychological side effects. Therefore, results here obtained suggest that the binding of finasteride to PNMT might have a role in producing the side effects exerted by finasteride treatment.

Detection of 5α-reductase inhibitors by UPLC-MS/MS: Application to the definition of the excretion profile of dutasteride in urine.

An analytical procedure based on ultra-performance liquid chromatography-mass spectrometry was developed to screen and to confirm dutasteride and its metabolites in human urine. Sample preparation included an enzymatic hydrolysis followed by solid-phase extraction using the strong cation exchange cartridges OASIS® MCX. The chromatographic separation was carried out on C18 column, employing as mobile phases ultra purified water and acetonitrile, both containing 0.1% formic acid. Detection was achieved using a triple quadrupole as a mass spectrometric analyzer, with positive ion electrospray ionization and multiple reaction monitoring as acquisition mode. The analytical procedure developed was validated according to ISO 17025 and World Anti-Doping Agency guidelines. The extraction efficiency was estimated to be greater than 75% for both dutasteride and its hydroxylated metabolites. Detection capability was determined in the range of 0.1-0.4 ng/mL. Specificity and repeatability of the relative retention times (CV% < 0.5) and of the relative abundances of the characteristic ion transitions selected (CV% < 10) were confirmed to be fit for purpose to ensure the unambiguous identification of dutasteride and its metabolites in human urine. The developed method was used to characterize the urinary excretion profile of dutasteride after both chronic and acute administration of therapeutic doses. After chronic administration, dutasteride and its hydroxylated metabolites were easily detected and confirmed. After acute administration, instead, only the two hydroxylated metabolites were detected for 3-4 days.

A Systematic Review of Topical Finasteride in the Treatment of Androgenetic Alopecia in Men and Women.

INTRODUCTION: Currently, only topical minoxidil (MNX) and oral finasteride (FNS) are approved by the Food and Drug Administration (FDA) and the European Medicines Agency (EMA) for the treatment of androgenetic alopecia. Although FNS is efficacious for hair regrowth, its systemic use is associated with side effects limiting long-term utilization. Exploring topical FNS as an alternative treatment regimen may prove promising. METHODS: A search was conducted to identify studies regarding human in vivo topical FNS treatment efficacy including clinically relevant case reports, randomized controlled trials (RCTs), and prospective studies. RESULTS: Seven articles were included in this systematic review. In all studies, there was significant decrease in the rate of hair loss, increase in total and terminal hair counts, and positive hair growth assessment with topical FNS. Both scalp and plasma DHT significantly decreased with application of topical FNS; no changes in serum testosterone were noted. CONCLUSION: Preliminary results on the use of topical FNS are limited, but safe and promising. Continued research into drug-delivery, ideal topical concentration and application frequency, side effects, and use for other alopecias will help to elucidate the full extent of topical FNS' use.

J Drugs Dermatol. 2018;17(4):457-463.

Equine 5α-reductase activity and expression in epididymis.

The 5α-reductase enzymes play an important role during male sexual differentiation, and in pregnant females, especially equine species where maintenance relies on 5α-reduced progesterone, 5α-dihydroprogesterone (DHP). Epididymis expresses 5α-reductases but was not studied elaborately in horses. Epididymis from younger and older postpubertal stallions was divided into caput, corpus and cauda and examined for 5α-reductase activity and expression of type 1 and 2 isoforms by quantitative real-time polymerase chain reaction (qPCR). Metabolism of progesterone and testosterone to DHP and dihydrotestosterone (DHT), respectively, by epididymal microsomal protein was examined by thin-layer chromatography and verified by liquid chromatography tandem mass spectrometry (LC-MS/MS). Relative inhibitory potencies of finasteride and dutasteride toward equine 5α-reductase activity were investigated. Pregnenolone was investigated as an additional potential substrate for 5α-reductase, suggested previously from in vivo studies in mares but never directly examined. No regional gradient of 5α-reductase expression was observed by either enzyme activity or transcript analysis. Results of PCR experiments suggested that type 1 isoform predominates in equine epididymis. Primers for the type 2 isoform were unable to amplify product from any samples examined. Progesterone and testosterone were readily reduced to DHP and DHT, and activity was effectively inhibited by both inhibitors. Using epididymis as an enzyme source, no experimental evidence was obtained supporting the notion that pregnenolone could be directly metabolized by equine 5α-reductases as has been suggested by previous investigators speculating on alternative metabolic pathways leading to DHP synthesis in placenta during equine pregnancies.

Conversion of abiraterone to D4A drives anti-tumour activity in prostate cancer.

Prostate cancer resistance to castration occurs because tumours acquire the metabolic capability of converting precursor steroids to 5α-dihydrotestosterone (DHT), promoting signalling by the androgen receptor and the development of castration-resistant prostate cancer. Essential for resistance, DHT synthesis from adrenal precursor steroids or possibly from de novo synthesis from cholesterol commonly requires enzymatic reactions by 3ß-hydroxysteroid dehydrogenase (3ßHSD), steroid-5α-reductase (SRD5A) and 17ß-hydroxysteroid dehydrogenase (17ßHSD) isoenzymes. Abiraterone, a steroidal 17α-hydroxylase/17,20-lyase (CYP17A1) inhibitor, blocks this synthetic process and prolongs survival. We hypothesized that abiraterone is converted by an enzyme to the more active Δ(4)-abiraterone (D4A), which blocks multiple steroidogenic enzymes and antagonizes the androgen receptor, providing an additional explanation for abiraterone's clinical activity. Here we show that abiraterone is converted to D4A in mice and patients with prostate cancer. D4A inhibits CYP17A1, 3ßHSD and SRD5A, which are required for DHT synthesis. Furthermore, competitive androgen receptor antagonism by D4A is comparable to the potent antagonist enzalutamide. D4A also has more potent anti-tumour activity against xenograft tumours than abiraterone. Our findings suggest an additional explanation-conversion to a more active agent-for abiraterone's survival extension. We propose that direct treatment with D4A would be more clinically effective than abiraterone treatment.

Consideraciones sobre el valor del antígeno prostático específico en los pacientes tratados con 5-alpha reductasa / Considerations about the value of prostate specific antigen in patients treated with 5-alpha reductase

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5α-Reduced glucocorticoids: a story of natural selection.

5α-Reduced glucocorticoids (GCs) are formed when one of the two isozymes of 5α-reductase reduces the Δ(4-5) double bond in the A-ring of GCs. These steroids are largely viewed inert, despite the acceptance that other 5α-dihydro steroids, e.g. 5α-dihydrotestosterone, retain or have increased activity at their cognate receptors. However, recent findings suggest that 5α-reduced metabolites of corticosterone have dissociated actions on GC receptors (GRs) in vivo and in vitro and are thus potential candidates for safer anti-inflammatory steroids. 5α-Dihydro- and 5α-tetrahydro-corticosterone can bind with GRs, but interest in these compounds had been limited, since they only weakly activated metabolic gene transcription. However, a greater understanding of the signalling mechanisms has revealed that transactivation represents only one mode of signalling via the GR and recently the abilities of 5α-reduced GCs to suppress inflammation have been demonstrated in vitro and in vivo. Thus, the balance of parent GC and its 5α-reduced metabolite may critically affect the profile of GR signalling. 5α-Reduction of GCs is up-regulated in liver in metabolic disease and may represent a pathway that protects from both GC-induced fuel dyshomeostasis and concomitant inflammatory insult. Therefore, 5α-reduced steroids provide hope for drug development, but may also act as biomarkers of the inflammatory status of the liver in metabolic disease. With these proposals in mind, careful attention must be paid to the possible adverse metabolic effects of 5α-reductase inhibitors, drugs that are commonly administered long term for the treatment of benign prostatic hyperplasia.

Development and characterization of dutasteride bearing liposomal systems for topical use.

Dutasteride loaded liposomal system were developed for topical application in order to avoid the side effects associated with the oral administration of the drug. Drug-loaded multilamellar liposomes were prepared using thin-film hydration method followed by sonication and optimized with respect to entrapment efficiency, drug payload, size and lamellarity. The vesicular systems consisting of egg phosphatidylcholine (100 mg), cholesterol (50 mg), and dutasteride (5 mg) showed highest drug entrapment efficiency (94.6%) and drug payload (31.5 µg/mg of total lipids). Mean vesicle size of these liposomes was noted to be 1.82 ± 0.15 µm. Significantly higher skin permeation of dutasteride through excised abdominal mouse skin was achieved via the developed liposomal formulations as compared to hydro-alcoholic solution and conventional gels. The formulation exhibited about seven fold higher deposition of drug in skin. Stability studies indicated that the liposomal formulations were quite stable in the refrigerated conditions for 10 weeks with negligible drug leakage or vesicle size alteration. Results of the current studies exhibited improved and localized drug action in the skin and thus could be formulated as a better option to cure androgenetic alopecia.

In vivo investigation in pigs of intestinal absorption, hepatobiliary disposition, and metabolism of the 5α-reductase inhibitor finasteride and the effects of coadministered ketoconazole.

The overall aim of this detailed investigation of the pharmacokinetics (PK) and metabolism of finasteride in pigs was to improve understanding of in vivo PK for this drug and its metabolites. Specific aims were to examine the effects of ketoconazole coadministration on the PK in three plasma compartments (the portal, hepatic, and femoral veins), bile, and urine and to use these data to study in detail the intestinal absorption and the liver extraction ratio and apply a semiphysiological based PK model to the data. The pigs received an intrajejunal dose of finasteride (0.8 mg/kg) either alone (n = 5) or together with ketoconazole (10 mg/kg) (n = 5) or an intravenous dose (0.2 mg/kg) (n = 3). Plasma, bile, and urine (collected from 0 to 6 h) were analyzed with ultraperformance liquid chromatography-tandem mass spectrometry. Ketoconazole increased the bioavailability of finasteride from 0.36 ± 0.23 to 0.91 ± 0.1 (p < 0.05) and the terminal half-life from 1.6 ± 0.4 to 4.0 ± 1.1 h (p < 0.05). From deconvolution, it was found that the absorption rate from the intestine to the portal vein was rapid, and the product of the fraction absorbed and the fraction that escaped gut wall metabolism was high (f(a) · F(G) ∼ 1). Interestingly, the apparent absorption rate constant (k(a)) to the femoral vein was lower than that to the portal vein, probably because of binding and distribution within the liver. The liver extraction ratio was time-dependent and varied with the two routes of administration. After intrajejunal administration, from 1 to 6 h, the liver extraction ratio was significantly (p < 0.05) reduced by ketoconazole treatment from intermediate (0.41 ± 0.21) to low (0.21 ± 0.10).

Finasteride metabolism and pharmacogenetics: new approaches to personalized prevention of prostate cancer.

Incidences of prostate cancer in most countries are increasing owing to better detection methods; however, prevention with the use of finasteride, a very effective steroid 5α-reductase type II inhibitor, has been met with mixed success. A wide interindividual variation in response exists and is thought to be due to heritable factors. This article summarizes the literature that attempts to elucidate the molecular mechanisms of finasteride in terms of its metabolism, excretion and interaction with endogenous steroid molecules. We describe previously reported genetic variations of steroid-metabolizing genes and their potential association with finasteride efficacy. Based on the literature, we outline directions of research that may contribute to understanding the interindividual variation in finasteride prevention and to the future development of personalized medicine.