Finasteride is a potent 5 alpha-reductase inhibitor that has shown limited success in men treated for benign prostatic hyperplasia (success is defined as a decrease in the symptoms associated with urinary tract obstruction, and as increases in the urinary flow rate). 5 alpha-reductase is necessary for the prostatic conversion of testosterone to dihydrotesterone (DHT), the specific steroid that stimulates prostate transitional zone growth. Finasteride reduces the size of the prostate gland by 20%, but this does not correlate well with improvement in symptoms. Finasteride is well absorbed after oral administration and, while the rate of absorption may be slowed postprandially, the presence of food has no effect on the total bioavailability. Finasteride is widely distributed, but since its pharmacological effects are very specific to inhibition of 5 alpha-reductase, and since only the prostate gland, the scalp, and the genital skin contain high concentrations of this enzyme, few adverse reactions will be seen in other organ systems. Finasteride undergoes extensive hepatic metabolism to essentially inactive metabolites, which are eliminated through the bile and urine. The terminal elimination half-life (t1/2z) is 4.7 to 7.1 hours; but despite this, slow accumulation occurs with multiple doses. Values of t1/2z are higher in elderly men, but no dosage adjustments are necessary. Likewise, no dosage adjustments are necessary for patients with renal dysfunction, since the metabolites which accumulate are relatively inactive and well tolerated, and because greater faecal excretion of the metabolites occurs in these patients. The effect of hepatic dysfunction on the metabolism of finasteride is unknown. Therapeutic doses of finasteride produce a rapid and pronounced effect in reducing both plasma and prostate tissue levels of DHT. Doses below 0.5 mg/day do not produce much suppression of DHT levels, and doses above 5 mg/day have little additional benefit. A single dose of finasteride suppresses serum DHT levels for up to 4 days, longer than would be expected from the serum terminal elimination half-life (t1/2z) of the drug: this is probably due to the high affinity that finasteride has for the 5 alpha-reductase enzyme. Serum testosterone levels increase in patients receiving finasteride, but are not normally outside the upper limits of the normal range. Serum prostate-specific antigen (PSA) levels decrease with finasteride administration; the baseline for investigation of prostate cancer with elevated PSA levels should be one-half of the normal range. In responders to finasteride, the prostate gland shrinks in volume by about 20%, urinary flow rate improves by approximately 3 ml/s, and symptoms are relieved. The response to finasteride appears to be maximal at doses of 5 mg/day. For most men receiving finasteride, these effects will persist for at least the 5 years that long term studies have been conducted. Serum DHT levels increase again when finasteride therapy is discontinued, probably resulting in the return of the hyperplasia, decreased urine flow and obstructive symptoms. Finasteride is well tolerated, with loss of libido and sexual potency being the most commonly reported adverse reactions. No drug interactions with finasteride have been reported.

Clinical Pharmacokinetics and Pharmacodynamics of Finasteride

Extract from fruit of Sabal serrulata are used in the treatment of human benign prostate hyperplasia (BPH). Therefore, it is of interest whether this phytopharmacon has any influence on the androgen metabolism in the human prostate. It was found that the extract IDS 89 of Sabal serrulata inhibited dose dependently 5 alpha-reductase activity in the epithelium and stroma of human BPH, the mean inhibition being 29% and 45%, respectively. This inhibitory effect is mainly due to the saponifiable subfraction of IDS 89 showing a mean 5 alpha-reductase inhibition of 39% and 38% in epithelium and stroma, respectively. The inhibition was dose dependent and noncompetitive. At a testosterone concentration of 580 nM as substrate for 5 alpha-reductase, the main fatty acids of the extract IDS 89 gave rise to a percentual enzyme inhibition in the epithelium and stroma as follows: 51% and 42% (lauric acid), 5% and 0% (oleic acid), 43% and 34% (myristic acid), 2% and 0% (palmitic acid), respectively. The inhibitory effect of lauric acid was noncompetitive and dose dependent up to a concentration of 0.2 nM, the maximal inhibition in the epithelium and stroma being 52% and 45%, respectively. The nonsaponifiable subfraction, consisting mainly of phytosterols, showed a mean inhibition of 5 alpha-reductase in the epithelium and stroma of 15% and 10%, respectively. Finally, the hydrophilic subfraction, containing carbohydrates, amino acids, and polysaccharides, showed no inhibitory effect. The present in vitro studies suggest that the Sabal serrulata extract IDS 89 has an inhibitory effect on 5 alpha-reductase in the epithelium and stroma of human BPH. This inhibition is mainly due to the fatty acids of the saponifiable subfraction.

Effects of the Sabal serrulata extract IDS 89 and its subfractions on 5α‐reductase activity in human benign prostatic hyperplasia

Pathogenic role of HIF-1α in prostate hyperplasia in the presence of chronic inflammation

Potential activities of androgen metabolizing enzymes in human prostate.

Androgens are known to play an important role in normal prostate development, benign prostatic hyperplasia, established prostate cancer, and in prostate carcinogenesis. However, despite convincing experimental and clinical evidence, the epidemiologic data correlating sex steroid levels with disease risk is inconsistent. More recent work has focused on studies of polymorphisms in germ-line DNA in an effort to develop polygenic models of prostate cancer susceptibility and prognosis. Such models have the potential to aid in the selection of men for specific chemopreventive interventions and to help determine which men with localized prostate cancer are most likely to benefit from aggressive therapy. In this review, we will provide a brief summary of androgen metabolic pathways followed by an assessment of the epidemiology literature addressing the relationship between androgens and prostate cancer. Finally, we will address the two major questions that have arisen in response to the recently published results...

Prevention of Hormone-Related Cancers: Prostate Cancer

5α-Reductase inhibition by finasteride (proscar®) in epithelium and stroma of human benign prostatic hyperplasia

Background: A majority of oncological patients apply add-on white-berry European mistletoe (Viscum album L., VA) extracts to reduce disease- and treatment-related symptoms and to improve health-related quality of life (HRQL). VA extracts exert various antitumor, pro-apoptotic, anti-proliferative, and immunomodulatory effects. Two current meta-analyses attribute life-prolonging and HRQL-improving properties to additive VA therapy. The aim of the present update was to review the current knowledge on VA extracts in clinical oncology. Hereby, we concentrated on studies with the highest clinical relevance in the field of lung, gastric, colorectal and pancreatic, gynaecological, as well as breast cancer applying the anthroposophical mistletoe preparations. Summary: The present update provides a brief overview regarding the use of VA preparations in clinical oncology reviewing current guidelines, systematic reviews, randomized controlled and real-world data studies. We have searched the pubmed.gov database of the National Library of Medicine with the search terms “mistletoe” and “cancer.” We found good evidence of add-on VA therapy to improve the HRQL of patients with breast cancer (American Society of Clinical Oncology – endorsed Society for Integrative Oncology guideline) and of HRQL-improving and survival-prolonging properties of VA therapy in pancreatic cancer. In the field of gastrointestinal, gynaecological, and lung cancer, new or updating integrative and/or oncological guidelines should consider clear recommendations on integrative therapies including VA therapy. Nevertheless, further clinical and real-world data trials need to be performed in this field. Key Messages: Evidence for add-on VA treatment for the improved management of cancer and cancer-related side effects is accumulating. Patients with breast cancer: good evidence for add-on VA therapy to improve the HRQL of oncological patients. Patients with pancreatic cancer: good evidence for add-on VA to improve HRQL and prolong survival. Patients with gastrointestinal, gynaecological, and lung cancer: update of guidelines is recommended with regards to integrative oncological therapies including add-on VA.

https://refubium.fu-berlin.de/bitstream/fub188/31079/3/2021_Thronicke_etal.pdf

Viscum album L. Therapy in Oncology: An Update on Current Evidence

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5α-Reductase inhibition by finasteride (proscar®) in epithelium and stroma of human benign prostatic hyperplasia

Viscum album L. Therapy in Oncology: An Update on Current Evidence