The Effects of Chronic 5‐Alpha‐Reductase Inhibitor (Dutasteride) Treatment on Rat Erectile Function

Analysis of diurnal variation in serum testosterone levels in men with symptoms of testosterone deficiency

BACKGROUND

Testosterone (T) plays a crucial role in various physiological functions in men, and understanding the variations in T levels during the day is essential for diagnosing and treating testosterone deficiency (TD).

AIM

We sought to evaluate the reduction in serum total T (TT) levels throughout the day in men with symptoms of testosterone deficiency and to determine the variables having an impact on the extent of this decline.

METHODS

The study population consisted of a group of men who within 3 months of each other had all undergone both early morning and afternoon TT level measurements. We did not include patients with a history of a prior orchiectomy, testosterone levels below 100 ng/dL or above 1000 ng/dL, a history of androgen deprivation therapy, or patients on T therapy. Statistical analyses were conducted using descriptive statistics, t-tests, chi-square tests, and correlation calculations. Liquid chromatography-tandem mass spectrometry was used to measure TT, and a change in TT levels greater than 100 ng/dL was considered significant. Using multivariable and univariable analysis, we attempted to define predictors of a decrease in afternoon TT levels.

OUTCOMES

The majority of men showed no significant difference in T levels between morning and afternoon.

RESULTS

In total, 506 men with a median age of 65 years were analyzed. The most common comorbidities were hypertension and hyperlipidemia. Levels of TT were measured in the morning and afternoon, and no significant differences in mean T levels based on the time of the test were found. Age was not significantly associated with T levels.

CLINICAL IMPLICATIONS

There was a weak negative correlation between age and the difference between morning and afternoon T levels, with younger men showing more significant variations in T levels. The most considerable differences in T levels were observed in men younger than 30 years. There were no predictors of the magnitude of the T decrease in the afternoon.

STRENGTHS AND LIMITATIONS

Strengths of the study include the number of subjects and the use of liquid chromatography-tandem mass spectrometry for T measurement. Limitations include failure to measure morning and afternoon T levels on the same day, the retrospective nature of the study, and a smaller sample size of patients younger than 30 years.

CONCLUSION

In this study we found no strong link between age and daily T fluctuation, but we observed a decrease in the magnitude of variation with aging. The group experiencing the most significant decline in daily T had higher morning and consistently normal afternoon T levels.

Exploring rat corpus cavernosum alterations induced by finasteride treatment and withdrawal

Despite its efficacy for treating androgenetic alopecia, finasteride, an inhibitor of 5α-reductase (i.e., the enzyme converting testosterone, T, into dihydrotestosterone, DHT), is associated with several side effects including sexual dysfunction (e.g., erectile dysfunction). These side effects may persist after drug suspension, inducing the so-called post-finasteride syndrome (PFS). The effects of subchronic treatment with finasteride (i.e., 20 days) and its withdrawal (i.e., 1 month) in rat corpus cavernosum have been explored here. Data obtained show that the treatment was able to decrease the levels of the enzyme 5α-reductase type II in the rat corpus cavernosum with increased T and decreased DHT levels. This local change in T metabolism was linked to mechanisms associated with erectile dysfunction. Indeed, by targeted metabolomics, we reported a decrease in the nitric oxide synthase (NOS) activity, measured by the citrulline/arginine ratio and confirmed by the decrease in NO2 levels, and a decrease in ornithine transcarbamylase (OTC) activity, measured by citrulline/ornithine ratio. Interestingly, the T levels are negatively correlated with NOS activity, while those of DHT are positively correlated with OTC activity. Finasteride treatment also induced alterations in the levels of other molecules involved in the control of penile erection, such as norepinephrine and its metabolite, epinephrine. Indeed, plasma levels of norepinephrine and epinephrine were significantly increased and decreased, respectively, suggesting an impairment of these mediators. Interestingly, these modifications were restored by suspension of the drug. Altogether, the results reported here indicate that finasteride treatment, but not its withdrawal, affects T metabolism in the rat corpus cavernosum, and this alteration was linked to mechanisms associated with erectile dysfunction. Data here reported could also suggest that the PFS sexual side effects are more related to dysfunction in a sexual central control rather than peripheral compromised condition.

A review of experimental techniques for erectile function researches and development of medical technology using animal erectile dysfunction models in sexual and reproductive medicine

Background

Erectile dysfunction (ED) is one of the causes of male infertility and is a disease that requires treatment. The first-line drugs for ED are phosphodiesterase 5 (PDE-5) inhibitors, and further treatment options are currently limited. Medical technologies, such as genetic control and regenerative medicine, are developing rapidly. Research on erectile function is progressing rapidly, coupled with technological innovations in other areas.

Methods

A PubMed search using the keywords "animal (rat, mouse, rabbit, dog, and monkey)" and "erectile" was conducted, and all relevant peer-reviewed English results were evaluated.

Main findings

The methods for evaluating erectile function include intracavernous pressure (ICP) measurements, isometric tension studies, and dynamic infusion cavernosometry. Papers also reported various disease model animals for the study of diabetes mellitus, cavernous nerve injury, and drug-induced ED.

Conclusion

Basic research on ED treatment has progressed rapidly over the past 20 years. In particular, research on the mechanism of ED has been accelerated by the publication of a study on the evaluation of erectile function using ICP measurements in rats. In addition, molecular biological experimental methods such as polymerase chain reaction (PCR) and western blotting have become relatively easy to perform due to technological progress, thus advancing research development.

Dihydrotestosterone through blockade of TGF-β/Smad signaling mediates the anti-fibrosis effect under hypoxia in canine Sertoli cells

The hypoxic microenvironment of cryptorchidism is an important factor to induce the impairment of the structure and function of Sertoli cells and thus lead to spermatogenesis loss or tumorigenesis. Dihydrotestosterone (DHT), as a potent nonaromatizable 5α-reduced androgen, has both positive and negative effect on pathological fibrosis process. However, it is still unknown whether DHT can regulate hypoxia-induced fibrosis of Sertoli cells. Herein, in this study, we evaluate the DHT level, two 5α-reductase isoforms, 5α-red1 and 5α-red2, as well as HIF-1α expression pattern in canine cryptorchidism and contralateral normal testis. Results showed that the abdominal testes presented low DHT levels and 5α-red1 and 5α-red2 expression, while significantly higher HIF-1α expression and ECM production compared with the scrotum. Moreover, we established a hypoxia-induced fibrosis model in canine Sertoli cells induced by cobalt chloride (CoCl₂), and found that DHT inhibited the fibrosis of Sertoli cells in a dose-dependent manner. Meanwhile, DHT interfered with the TGF-β signaling by reducing the expression of TGF-βRI and TGF-βRII and inhibiting the expression and phosphorylation of Smad2 and Smad3, while flutamide (androgen receptor inhibitor) inhibited these effects of DHT. Furthermore, use of LY2109761 (TGF-β receptor type I/II inhibitor) to interfere with the TGF-β/Smad pathway showed a similar effect with DHT suppression of the fibrosis in Sertoli cells. Our research data demonstrated that cryptorchidism is located in a hypoxic and DHT deficiency microenvironment. Moreover, supplementing DHT can alleviate the fibrosis process of Sertoli cells caused by hypoxia, which is associated with AR regulating the inhibition of TGF-β/Smad signaling.

Does treatment with dutasteride or finasteride has impact on renal morphology? Experimental study

PURPOSE

To investigate whether renal modifications occur following treatment with dutasteride or finasteride.

METHODS

Twenty-four male rats were divided into three groups: control (that received distilled water), dutasteride (0.5 mg/kg/day), and finasteride (5 mg/kg/day) groups. All administrations were given by gavage for 40 consecutive days. After inducing euthanasia, blood was collected for urea and creatinine analyses, and both the kidneys were collected for stereological analyses of kidney morphology.

RESULTS

Serum urea and creatinine levels were increased in both the finasteride and the dutasteride groups compared with those in the control group. In addition, kidney weight, kidney volume, cortical volume, glomerular volumetric density, and mean glomerular volume were reduced in both treatment groups. Finally, the number of glomeruli per kidney was reduced by 26.8% in the finasteride group and by 51.6% in the dutasteride group compared with that in the control group.

CONCLUSIONS

The 5-ARIs finasteride and dutasteride promoted morphological and functional damages in rat kidneys. In addition, rats in the dutasteride group showed more severe renal modifications than those in the finasteride group.

Restorative effects of red onion (Allium cepa L.) juice on erectile function after-treatment with 5α-reductase inhibitor in rats

Benign prostatic hyperplasia (BPH) is one of the most prevalent conditions among aged men. The use of 5α-reductase inhibitors (5-ARIs) to treat BPH was linked to erectile dysfunction (ED). Many medicinal plants and secondary metabolites are used in the management of ED. Onion (Allium cepa L.) is an economically affordable vegetable with vital phytochemicals and biological functions. The study aimed to identify the beneficial effects of onion juice on dutasteride (a 5-ARI)-induced ED. Rats were divided into two groups (n = 5 per group): control and dutasteride-treated rats (0.5 mg/kg/day). Dutasteride was administered in drinking water for 12 weeks. Experiments were performed at the end of the 12th week. In vivo erectile responses were measured before and after intracavernosal injection of onion. Relaxant responses to onion juice were examined in the corpus cavernosum (CC). Acetylcholine (ACh)-, electrical field stimulation (EFS)-, sodium nitroprusside (SNP)-induced relaxation responses in CC tissues were evaluated in the absence and presence of onion juice. Total intracavernosal pressure (ICP) and ICP/ mean arterial pressure were significantly reduced in dutasteride-treated rats (1881.14 ± 249.72 mmHg, P < 0.001;0.26 ± 0.03, P < 0.01) as compared to control rats (4542.60 ± 429.19 mmHg, 0.51 ± 0.05), which was normalized after the intracavernous administration of onion (3288.60 ± 185.45 mmHg, 0.58 ± 0.04). Onion markedly induced relaxant responses in control (72.5 ± 4.7) and dutasteride-treated (66.5 ± 2.7) groups after precontraction with phenylephrine. Relaxation responses to onion were partially inhibited after precontraction with KCl (32.5 ± 3.1, P < 0.001). The relaxant responses to ACh (14.9 ± 4.2, P < 0.01) were diminished in dutasteride-treated CC) compared to control CC (59.8 ± 3.4), which was enhanced after the incubation with onion (36.6 ± 4.8). There were no differences in relaxation response to SNP among all groups. However, relaxation response to SNP was reduced in dutasteride-treated CC at 1 μM (P < 0.05) and 10 μM dosages (P < 0.001), which was partially increased after the incubation with onion at 10 μM dosage (P < 0.01). The presence of onion did not change the reduction in EFS-caused relaxation in the dutasteride-treated group. The current data suggest that red onion juice has a restorative effect on erectile function and endothelium-dependent relaxation response following the treatment of dutasteride.

Beneficial Effects of Human Umbilical Cord Blood Mononuclear Cells on Persistent Erectile Dysfunction After Treatment of 5-Alpha Reductase Inhibitor in Rats

BACKGROUND

Effects of human umbilical cord blood (HUCB) as a valuable source for stem cell-based therapies have not been studied in persistent post-5-alpha reductase inhibitors (5ARI) erectile dysfunction (PPED).

AIM

To determine the effect of intracavernosal injection of HUCB mononuclear cells (MNCs) on ED associated with dutasteride treatment.

METHODS

Twenty five adult male Sprague-Dawley rats were divided into 5 groups (n = 5 per group): (i) control, (ii) 8-week dutasteride (0.5 mg/kg/day, in drinking water), (iii) 12-week dutasteride, (iv) 8-week dutasteride+HUCB-MNCs (1 × 10⁶) and (v) 12-week dutasteride+HUCB-MNCs. HUCB-MNCs were administered intracavernosally after eight weeks of dutasteride treatment. Experiments were performed at 4 weeks following the injection of HUCB-MNCs. Erectile responses and isometric tension of corpus cavernosum (CC) were measured. The protein expressions of phosphodiesterase type 5 (PDE5), endothelial nitric oxide synthase (eNOS), neuronal NOS (nNOS), hypoxia-inducible factor (HIF)-1α and smooth muscle/collagen contents in penile tissue were evaluated by Western blotting, immunohistochemistry, and Masson's trichrome staining, respectively.

MAIN OUTCOME

In vivo erectile function, in vitro relaxant and contractile responses of CC, protein expression and localization of PDE5, eNOS, nNOS, HIF-1α, and smooth muscle content in penile tissue.

RESULTS

Erectile responses in the dutasteride-treated groups were significantly decreased compared with controls (P < .001), persisting after 4-wk of washout. HUCB-MNCs restored diminished intracavernosal pressure responses, acetylcholine-, sodium nitroprusside-, sildenafil-induced relaxations, and increased phenylephrine and electrical field stimulation (EFS)-induced contractions. Decreased EFS-induced relaxations in dutasteride-treated groups were not restored by HUCB-MNCs. Increased PDE5 and reduced nNOS expressions in dutasteride groups were restored by HUCB-MNCs in the 12-week dutasteride group. eNOS and HIF-1α protein expression and serum total and free testosterone  levels were similar among groups. HUCB-MNCs reversed the decreased smooth muscle/collagen ratio in dutasteride-treated tissues. There was a significant increase in PDE5 and HIF-1α staining in 8-week dutasteride animals.

CLINICAL TRANSLATION

This study demonstrates the corrective potential of HUCB-MNCs on some persistent structural and functional deterioration caused by 5ARI treatment in rats, which may encourage further evaluation of HUCB-MNCs in men with PPED.

STRENGTHS AND LIMITATIONS

Therapeutic application of intracavernosal HUCB-MNCs is a novel approach for the rat model of post-5ARI ED. Lack of serum and tissue dihydrotestosterone measurements, vehicle injections and characterization of the cells remain limitations of our study.

CONCLUSION

The persistent ED after prolonged administration of dutasteride in rats is reversed by HUCB-MNC treatment, which holds promise as a realistic therapeutic modality for this type of ED. Oztekin CV, Yilmaz-Oral D, Kaya-Sezginer E, et al. Beneficial Effects of Human Umbilical Cord Blood Mononuclear Cells on Persistent Erectile Dysfunction After Treatment of 5-Alpha Reductase Inhibitor in Rats. J Sex Med 2021;18:889-899.

Effects of the dutasteride and sildenafil association in the penis of a benign prostatic hyperplasia animal model

OBJECTIVE

The aim of this study was to investigate whether concomitant treatment of dutasteride and sildenafil could prevent structural changes in the penis of a BPH rodent model.

METHODS

Thirty-two adult male rats were divided into the following groups: Ctrl, untreated control rats; BPH, untreated spontaneously hypertensive rats (SHRs); BPH + D, SHRs treated with dutasteride; and BPH + DS, SHRs treated with dutasteride and sildenafil. All treatments were performed during 40 days, following which the penises were collected for histomorphometrical analysis. The results were compared via one-way ANOVA with Bonferroni's post-test, considering p values <.05 as significant.

RESULTS

The smooth muscle density decreased by 28.6% and 21.4% in BPH + D and BPH + DS, respectively, when compared to the BPH group. The sinusoid space density reduced by 32.2% in BPH, when compared to the Ctrl group; this density was also reduced by 22.6% in BPH + D, when compared to the BPH group. The density of the elastic fibers increased 51.6% and 65.6% in BPH + D and BPH + DS, when compared to the BPH group.

CONCLUSION

Treatment with dutasteride promoted morphological changes in the corpus cavernous of this BPH model. Concomitant treatment with sildenafil did not prevent the morphological changes caused by dutasteride; on the contrary, it also promoted a further increase in elastic fibers.

Post-finasteride syndrome: a surmountable challenge for clinicians

Post-finasteride syndrome (PFS) is a constellation of serious adverse side effects manifested in clinical symptoms that develop and persist in patients during and/or after discontinuing finasteride treatment in men with pattern hair loss (androgenetic alopecia) or benign prostatic hyperplasia. These serious adverse side effects include persistent or irreversible sexual, neurological, physical and mental side effects. To date, there are no evidence-based effective treatments for PFS. Although increasing number of men report persistent side effects, the medical community has yet to recognize this syndrome nor are there any specific measures to address this serious and debilitating symptoms. Here we evaluate the scientific and clinical evidence in the contemporary medical literature to address the very fundamental question: Is PFS a real clinical condition caused by finasteride use or are the reported symptoms only incidentally associated with but not caused by finasteride use? One key indisputable clinical evidence noted in all reported studies with finasteride and dutasteride was that use of these drugs is associated with development of sexual dysfunction, which may persist in a subset of men, irrespective of age, drug dose or duration of study. Also, increased depression, anxiety and suicidal ideation in a subset of men treated with these drugs were commonly reported in a number of studies. It is important to note that many clinical studies suffer from incomplete or inadequate assessment of adverse events and often limited or inaccurate data reporting regarding harm. Based on the existing body of evidence in the contemporary clinical literature, the author believes that finasteride and dutasteride induce a constellation of persistent sexual, neurological and physical adverse side effects, in a subset of men. These constellations of symptoms constitute the basis for PFS in individuals predisposed to epigenetic susceptibility. Indeed, delineating the pathophysiological mechanisms underlying PFS will be of paramount importance to the understanding of this syndrome and to development of potential novel therapeutic modalities.

Effect of tadalafil on penile nitric oxide synthase and corporal smooth muscle in rats under dutasteride treatment

Aim: To investigate the effect of tadalafil in rats administered with daily dutasteride.Methods: Twenty-four Sprague-Dawley male rats were allocated to three groups as control (group C), dutasteride (group D) and dutasteride plus tadalafil (group D + T). After a month of treatment, serum samples were obtained from rats to measure dihydrotestosterone and total testosterone. Nitric oxide (NO) synthase (NOS) immunoreactivity and levels of NOS enzyme isoforms, NO and cyclic guanosine monophosphate (cGMP) were evaluated in the harvested penile tissues. Also, corporal smooth muscle and collagen were examined.Results: Staining intensities of neuronal NOS and endothelial NOS were significantly lower in group D (p < .05). They were similar between group C and group D + T. Immunoreactivity of inducible NOS was observed higher in group D than group C (p  =  .01) whereas group D + T had the highest iNOS (p<.001). ELISA revealed similar outcomes in terms of NOS enzyme isoform levels. The mean of smooth muscle to collagen ratio was the lowest in group D (p < .001) and it was similar among group C and group D + T (p = .072). Group D had the lowest cGMP and NO levels (p  <  .05) and they did not differ between group C and group D + T (p>.05). Group D and group D + T had significantly decreased dihydrotestosterone and increased testosterone, compared to group C (p < .001). They were similar between group D and group D + T.Conclusion: Daily treatment with tadalafil improves dutasteride-induced changes in rat penis.

Consequences of steroid-5α-reductase deficiency and inhibition in vertebrates

In 1974, a lack of 5α-dihydrotestosterone (5α-DHT), the most potent androgen across species except for fish, was shown to be the origin of a type of pseudohermaphrodism in which boys have female-like external genitalia. This human intersex condition is linked to a mutation in the steroid-5α-reductase type 2 (SRD5α2) gene, which usually produces an important enzyme capable of reducing the Δ⁴-ene of steroid C-19 and C-21 into a 5α-stereoisomer. Seeing the potential of SRD5α2 as a target for androgen synthesis, pharmaceutical companies developed 5α-reductase inhibitors (5ARIs), such as finasteride (FIN) and dutasteride (DUT) to target SRD5α2 in benign prostatic hyperplasia and androgenic alopecia. In addition to human treatment, the development of 5ARIs also enabled further research of SRD5α functions. Therefore, this review details the morphological, physiological, and molecular effects of the lack of SRD5α activity induced by both SRD5α mutations and inhibitor exposures across species. More specifically, data highlights 1) the role of 5α-DHT in the development of male secondary sexual organs in vertebrates and sex determination in non-mammalian vertebrates, 2) the role of SRD5α1 in the synthesis of the neurosteroid allopregnanolone (ALLO) and 5α-androstane-3α,17β-diol (3α-diol), which are involved in anxiety and sexual behavior, respectively, and 3) the role of SRD5α3 in N-glycosylation. This review also features the lesser known functions of SRD5αs in steroid degradation in the uterus during pregnancy and glucocorticoid clearance in the liver. Additionally, the review describes the regulation of SRD5αs by the receptors of androgens, progesterone, estrogen, and thyroid hormones, as well as their differential DNA methylation. Factors known to be involved in their differential methylation are age, inflammation, and mental stimulation. Overall, this review helps shed light on the various essential functions of SRD5αs across species.

Health Risks Associated with Long-Term Finasteride and Dutasteride Use: It's Time to Sound the Alarm

5α-dihydrotestosterone (5α-DHT) is the most potent natural androgen. 5α-DHT elicits a multitude of physiological actions, in a host of tissues, including prostate, seminal vesicles, hair follicles, skin, kidney, and lacrimal and meibomian glands. However, the physiological role of 5α-DHT in human physiology, remains questionable and, at best, poorly appreciated. Recent emerging literature supports a role for 5α-DHT in the physiological function of liver, pancreatic β-cell function and survival, ocular function and prevention of dry eye disease and kidney physiological function. Thus, inhibition of 5α-reductases with finasteride or dutasteride to reduce 5α-DHT biosynthesis in the course of treatment of benign prostatic hyperplasia (BPH) or male pattern hair loss, known as androgenetic alopecia (AGA) my induces a novel form of tissue specific androgen deficiency and contributes to a host of pathophysiological conditions, that are yet to be fully recognized. Here, we advance the concept that blockade of 5α-reductases by finasteride or dutasteride in a mechanism-based, irreversible, inhabitation of 5α-DHT biosynthesis results in a novel state of androgen deficiency, independent of circulating testosterone levels. Finasteride and dutasteride are frequently prescribed for long-term treatment of lower urinary tract symptoms in men with BPH and in men with AGA. This treatment may result in development of non-alcoholic fatty liver diseases (NAFLD), insulin resistance (IR), type 2 diabetes (T2DM), dry eye disease, potential kidney dysfunction, among other metabolic dysfunctions. We suggest that long-term use of finasteride and dutasteride may be associated with health risks including NAFLD, IR, T2DM, dry eye disease and potential kidney disease.

Post-finasteride syndrome: An emerging clinical problem

The presence of side effects during pharmacological treatment is unfortunately a quite common problem. In this review, we focused our attention on adverse events related to 5 alpha-reductase (5α-R) inhibitors (i.e., finasteride and dutasteride), approved for the treatment of benign prostatic hyperplasia and androgenetic alopecia (AGA). Although these drugs are generally well tolerated, many reports described adverse effects in men during treatment, such as sexual dysfunction and mood alteration. In addition, it has been also reported that persistent side effects may occur in some AGA patients. This condition, termed post-finasteride syndrome (PFS) is characterized by sexual side effects (i.e., low libido, erectile dysfunction, decreased arousal and difficulty in achieving orgasm), depression, anxiety and cognitive complaints that are still present despite drug withdrawal. Indeed, some national agencies (e.g., Swedish Medical Products Agency, the Medicines and Healthcare Products Regulatory Agency of UK and the U.S. Food and Drug Administration) required to include multiple persistent side effects within the finasteride labels. As here reported, these observations are mainly based on self-reporting of the symptomatology by the patients and few clinical studies have been performed so far. In addition, molecular mechanisms and/or genetic determinants behind such adverse effects have been poorly explored both in patients and animal models. Therefore, results here discussed indicate that PFS is an emerging clinical problem that needs to be further elucidated.

The corpus cavernosum after treatment with dutasteride or finasteride: A histomorphometric study in a benign prostatic hyperplasia rodent model

Erectile dysfunction is a common side effect of finasteride and dutasteride treatments. The objective of this study was to investigate the structural changes in the penis using a benign prostatic hyperplasia (BPH) rodent model treated with dutasteride or finasteride. Sixty male rats were divided into the following groups: C, untreated control rats; C + D, control rats receiving dutasteride; C + F, control rats receiving finasteride; H, untreated spontaneously hypertensive rats (SHRs); H + D, SHRs treated with dutasteride; and H + F, SHRs treated with finasteride. Treatments were performed for 40 days, and penises were collected immediately thereafter. The organs were analyzed using histomorphometric methods to determine the cross-sectional penile area, as well as the surface density (Sv) of smooth muscle fibers, connective tissue, elastic system fibers, and sinusoidal spaces of the corpus cavernosum. The results were compared using a one-way ANOVA with Bonferroni's posttest. Groups C + D and C + F had a significantly smaller penile cross-sectional area, but more elastic system fiber Sv compared to Group C. Group C + D showed less smooth muscle Sv, and Group H showed more connective tissue but a smaller sinusoidal space Sv in the corpus cavernosum compared to Group C. Groups H + D and H + F had less smooth muscle Sv than Group H. Group H + D also had more connective tissue and elastic system fiber Sv than Group H. Both dutasteride and finasteride promoted penile modifications in the control rat penis, although this affect was greater in Group H animals. In this rodent model, dutasteride was the drug that most affected the corpus cavernosum.

The efficacy and safety of dutasteride compared with finasteride in treating men with androgenetic alopecia: a systematic review and meta-analysis

Aim

We performed a meta-analysis to evaluate the efficacy and safety of dutasteride and finasteride in treating men with androgenetic alopecia (AGA) during a 24-week treatment cycle.

Methods

Randomized controlled trials of dutasteride and finasteride for treating AGA were searched using MEDLINE, EMBASE, and the Cochrane Controlled Trials Register. The data were calculated using Rev Man v5.3.0. The reference lists of retrieved studies were also investigated.

Results

Three articles including 576 participants which compared dutasteride with finasteride were selected for our analysis. The mean change in total hair count (mean difference [MD], 28.57; 95% CI, 18.75–38.39; P<0.00001), investigator’s assessment of global photographs for the vertex (MD, 0.68; 95% CI, 0.13–1.23; P=0.02) and frontal (MD, 0.63; 95% CI, 0.13–1.13; P=0.01) views, panel global photographic assessment for the vertex (MD, 0.17; 95% CI, 0.09–0.24; P<0.00001) and frontal (MD, 0.25; 95% CI, 0.18–0.31; P<0.00001) views, and subjects’ assessment (MD, 0.56; 95% CI, 0.18–0.94; P=0.003) suggested that dutasteride provided a better efficacy in treating men with AGA compared with finasteride. With regard to the assessment of safety, altered libido (P=0.54), erectile dysfunction (P=0.07), and ejaculation disorders (P=0.58), dutasteride did not show a significant difference compared with finasteride.

Conclusion

Dutasteride seems to provide a better efficacy compared with finasteride in treating AGA. The two drugs appear to show similar rates of adverse reactions, especially in sexual dysfunction.

Current evidence for the involvement of sex steroid receptors and sex hormones in benign prostatic hyperplasia

Benign prostatic hyperplasia (BPH) is a pathology that affects 50% of men over 50 years of age and 90% of men develop BPH in their eighth decade of life. In 2018, more than 1 billion men will be affected by this disease worldwide. However, the progression of BPH is highly complex and has been debated and studied for approximately four decades. Recent studies indicate that BPH can originate from the alteration of different hormone synthesis pathways, and that it is also linked to the function of hormone receptors. There is a close relationship between the progression of BPH and sexual hormones, such as progesterone, testosterone, dihydrotestosterone, and estrogen. The focus of this study was to characterize the interactions of these hormones and investigate the direct or indirect role of each sex hormone receptor in the progression of BPH. Although several studies have described the effects of these hormones on BPH, no conclusions have been drawn regarding their role in disease progression. Here, we present a literature review on the sexual receptors possibly involved in the progression of BPH.

Persistent Erectile Dysfunction after Discontinuation of 5-Alpha Reductase Inhibitor Therapy in Rats Depending on the Duration of Treatment

Purpose

The current study is aimed to assess whether a longer duration of 5α-reductase inhibitor (5α-RI) exposure was associated with higher rate of permanent erectile dysfunction (ED) in a rat model.

Materials and Methods

Male Sprague-Dawley rats (n=76) were assigned to five groups: (i) normal control group; (ii) dutasteride (0.5 mg/rat/d) for 4-weeks group; (iii) dutasteride for 4-weeks plus 2-weeks of resting group; (iv) dutasteride for 8-weeks group; and (v) dutasteride for 8-weeks plus 2-weeks of resting group. In vivo erectile responses to electrical stimulation, and changes of fibrotic factors and smooth muscle/collagen contents in the corpus cavernosum were evaluated in each group.

Results

Dutasteride administration for 4 and 8 weeks significantly decreased erectile parameters compared with the control group. Reduced erectile responses were recovered during 2 weeks of drug-free time in the 4-week treatment group, but were not in the 8-week group. Protein levels of fibrosis-related factors transforming growth factor (TGF)-β1, TGF-β2, and p-Smad/Smad (Smad 2/3) in the corpus cavernosum showed no significant change after 4 weeks of dutasteride oral administration, but were enhanced after 8 weeks. Dutasteride markedly decreased smooth muscle content and increased collagen after 4 and 8 weeks of use, but no nuclear size changes; however, neither group showed significant improvement in the smooth muscle to collagen ratio after the rest period.

Conclusions

Our study showed that recovery from ED depended on the duration of medication, and administration of dutasteride for more than 8-weeks in rats could result in irreversible ED even after discontinuation of medication.

Long-term dutasteride therapy in men with benign prostatic hyperplasia alters glucose and lipid profiles and increases severity of erectile dysfunction

Background Dutasteride has been successfully used in treatment of lower urinary tract symptoms (LUTS) secondary to benign prostatic hyperplasia (BPH). However, dutasteride inhibits 5α-reductase type 1 and type 2 enzymes and may compromises glucocorticoids and androgen metabolism and alters metabolic function resulting in undesirable metabolic and sexual adverse side effects. Aim The aim of this study was to investigate the long-term adverse effects of dutasteride therapy in men with BPH on: i) blood glucose, ii) glycated hemoglobin (HbA1c), iii) low density lipoprotein-cholesterol (LDL-C); high density lipoprotein-cholesterol (HDL-C) and total cholesterol (TC), iv) testosterone (T), v) liver alanine and aspartate aminotransferases (ALT and AST) and vi) erectile dysfunction (ED). Methods A retrospective registry study, with a cohort of 230 men aged between 47 and 68 years (mean 57.78 ± 4.81) were treated with dutasteride (0.5 mg/day) for LUTS, secondary to BPH. A second cohort of 230 men aged between 52 and 72 years (mean 62.62 ± 4.65) were treated with tamsulosin (0.4 mg). All men were followed up for 36-42 months. At intervals of 3-6 months, and at each visit, plasma glucose, HbA1c, TC, LDL-cholesterol, T levels and liver alanine amino transferase (ALT) and aspartate aminotransferase (AST) were determined. Further patient assessment was made by the International Index of Erectile Function (IIEF-EF) questionnaire, the Aging Male Symptom (AMS) and International Prostate Symptom Scores (IPSS). Results Long-term treatment with dutasteride therapy is associated with significant improvements in LUTS, as assessed by reduction in prostate volume, IPSS and prostate specific antigen (PSA). Long-term dutasteride therapy, however, resulted in increased blood glucose, HbA1c, TC and LDL levels, ALT and AST activities, AMS Score and reduced T levels and worsened ED as assessed by the IIEF-EF scores. No worsening of ED, glucose, HbA1c, ALT, AST, AMS were observed in men treated with tamsulosin. Most importantly, long-term dutasteride therapy resulted in reduction in total T levels, contributing to a state of hypogonadism. Conclusion Our findings suggest that long-term dutasteride therapy produces worsening of ED, reduced T levels and increased glucose, HbA1c and alters lipid profiles, suggesting induced imbalance in metabolic function. We strongly recommend that physicians discuss with their patients these potential serious adverse effects of long-term dutasteride therapy prior to instituting this form of treatment.

Challenges in Testosterone Measurement, Data Interpretation, and Methodological Appraisal of Interventional Trials

INTRODUCTION

Male hypogonadism is a common condition, with an increasing body of literature on diagnosis, implications, and management. Given the significant variability in testosterone (T) from a physiologic and assay perspective, a thorough understanding of factors affecting T values and study methodology is essential to interpret reported study outcomes appropriately. However, despite the large number of publications on T, there are no reference materials consolidating all relevant and potentially confounding factors necessary to interpret T studies appropriately.

AIMS

To create a resource document that reviews sources of T variability, free vs total T, assay techniques and questionnaires, and study methodology relevant to interpreting outcomes.

METHODS

A PubMed search was performed of all the T literature published on T variability, assay techniques, and T-specific questionnaires. Results were summarized in the context of their impact on interpreting T literature outcomes and methodology.

MAIN OUTCOME MEASURES

Effect of various factors on T variability and their relevance to study methodology and outcomes.

RESULTS

Several factors affect measured T levels, including aging, circadian rhythms, geography, genetics, lifestyle choices, comorbid conditions, and intraindividual daily variability. The utility of free T over total T is debatable and must be compared using appropriate threshold levels. Among various assay techniques, mass spectrometry and equilibrium dialysis are gold standards. Calculated empirical estimates of free T also are commonly used and accepted. Hypogonadism-specific questionnaires have limited utility in screening for hypogonadism, and their role as objective end points for quantifying symptoms remains unclear. Numerous aspects of study methodology can directly or indirectly affect reported outcomes, including design (randomized, prospective, retrospective), duration, populations studied (age, comorbid conditions), low T threshold, therapeutic agent used, objective measurements and end points selected, and statistical interpretation.

CONCLUSION

Critical appraisal of the T literature requires an understanding of numerous factors resulting in T variability, study design and methodology, and limitations of assay techniques and objective measurement scales.

A prospective longitudinal survey of erectile function status in symptomatic benign prostatic hyperplasia patients treated with dutasteride

We prospectively evaluated erectile function (EF) using the Sexual Health Inventory for Men (SHIM) and the erectile hardness score (EHS) as well as urinary statuses using the International Prostate Symptom Score (IPSS) and Overactive Bladder Symptom Score (OABSS) before and 3, 6, and 12 months after a daily treatment with 0.5 mg dutasteride (DUT). Significant improvements were observed in IPSS and OABSS in 98 patients with the DUT treatment, and the effects were similar between 28 patients with potency with baseline SHIM of 8 or greater and 70 severe erectile dysfunction (ED) patients at baseline. In the 28 patients with potency, significant decreases were observed in SHIM and EHS after 3, 6, and 12 months of the DUT treatment, with the severity of ED according to SHIM deteriorating in half of these patients after 12 months of the DUT treatment. Eighteen out of 28 patients (64.3%) with potency at baseline had awareness of the occurrence of ED before the DUT treatment, were younger, and had higher SHIM and EHS just before the DUT treatment than their counterparts. Regular assessments of EF may be needed, especially in younger patients and those with higher levels of EF before the administration of DUT.

Side Effects of 5-Alpha Reductase Inhibitors: A Comprehensive Review

INTRODUCTION

5α-reductase inhibitors (5ARI) include finasteride and dutasteride, and are commonly prescribed in the treatment of benign prostatic hyperplasia and androgenic alopecia. 5ARIs are associated with several known adverse effects (AEs), with varying reported prevalence rates.

AIM

The aim was to review and summarize findings from published literature detailing AEs associated with 5ARI use. A secondary aim was to review potential mechanisms of action, which may account for these observed and reported AEs.

METHODS

A PubMed search was conducted on articles published from 1992 to 2012, which reported AEs with 5ARIs. Priority was given to randomized, placebo-controlled trials. Studies investigating potential mechanisms of action for 5ARIs were included for review.

MAIN OUTCOME MEASURES

AE data reported from available trials were summarized and reviewed.

RESULTS

Reported AEs with 5ARIs include sexual dysfunction, infertility, mood disorders, gynecomastia, high-grade prostate cancer, breast cancer, and cardiovascular morbidity/risk factors, although their true association, prevalence, causality, and clinical significance remain unclear. A pooled summary of all randomized, placebo-controlled trials evaluating 5ARIs (N = 62,827) revealed slightly increased rates over placebo for decreased libido (1.5%), erectile dysfunction (ED) (1.6%), ejaculatory dysfunction (EjD) (3.4%), and gynecomastia (1.3%). The limited data available on the impact of 5ARIs on mood disorders demonstrate statistically significant (although clinically minimal) differences in rates of depression and/or anxiety. Similarly, there are limited reports of reversible, diminished fertility among susceptible individuals. Post-marketing surveillance reports have questioned the actual prevalence of AEs associated with 5ARI use and suggest the possibility of persistent symptoms after drug discontinuation. Well-designed studies evaluating these reports are needed.

CONCLUSIONS

5ARIs are associated with slightly increased rates of decreased libido, ED, EjD, gynecomastia, depression, and/or anxiety. Further studies directed at identifying prevalence rates and persistence of symptoms beyond drug discontinuation are required to assess causality. Trost L, Saitz TR, and Hellstrom WJG. Side effects of 5-alpha reductase inhibitors: A comprehensive review. Sex Med Rev 2013;1:24-41.

Adverse effects of 5α-reductase inhibitors: What do we know, don't know, and need to know?

Steroids are important physiological orchestrators of endocrine as well as peripheral and central nervous system functions. One of the key processes for regulation of these molecules lies in their enzymatic processing by a family of 5α-reductase (5α-Rs) isozymes. By catalyzing a key rate-limiting step in steroidogenesis, this family of enzymes exerts a crucial role not only in the physiological control but also in pathological events. Indeed, both 5α-R inhibition and supplementation of 5α-reduced metabolites are currently used or have been proposed as therapeutic strategies for a wide array of pathological conditions. In particular, the potent 5α-R inhibitors finasteride and dutasteride are used in the treatments of benign prostatic hyperplasia (BPH), as well as in male pattern hair loss (MPHL) known as androgenetic alopecia (AGA). Recent preclinical and clinical findings indicate that 5α-R inhibitors evoke not only beneficial, but also adverse effects. Future studies should investigate the biochemical and physiological mechanisms that underlie the persistence of the adverse sexual side effects to determine why a subset of patients is afflicted with such persistence or irreversible adverse effects. Also a better focus of clinical research is urgently needed to better define those subjects who are likely to be adversely affected by such agents. Furthermore, research on the non-sexual adverse effects such as diabetes, psychosis, depression, and cognitive function are needed to better understand the broad spectrum of the effects these drugs may elicit during their use in treatment of AGA or BPH. In this review, we will summarize the state of art on this topic, overview the key unresolved questions that have emerged on the pharmacological targeting of these enzymes and their products, and highlight the need for further studies to ascertain the severity and duration of the adverse effects of 5α-R inhibitors, as well as their biological underpinnings.

Safety concerns regarding 5α reductase inhibitors for the treatment of androgenetic alopecia

PURPOSE OF REVIEW

To examine the clinical and basic studies regarding persistent adverse effects associated with 5α reductase inhibitor treatment for androgenetic alopecia.

RECENT FINDINGS

Recent postmarketing reports and a US Food and Drug Administration analysis have documented uncommon persistent sexual and nonsexual side-effects in a subset of younger men who have taken finasteride 1 mg for androgenic alopecia. While the mechanisms of the sexual side-effects in humans is incompletely understood, one study found lower cerebrospinal fluid concentrations of dihydrotestosterone, progesterone, dihydroprogesterone and allopregnanolone, and higher levels of testosterone, 5α-androstane-3α,17β-diol and pregnenolone. Another study found up-regulation of the androgen receptor in the human foreskin with a mean of 5 years after finasteride discontinuation. Studies of erectile dysfunction in finasteride-treated rats showed fewer autophagosomes in smooth muscle on transmission electron microscopy, increased apoptosis, decreased smooth muscle, increased collagen deposition and decreased endothelial nitric oxide synthase. Finally, 5α reductase inhibitors have also been found to alter semen parameters in healthy men.

SUMMARY

Multiple animal studies provide a biological basis for many of the persistent effects seen in humans such as erectile dysfunction, depression and decreased alcohol consumption. Prescribers of 5α reductase inhibitors should discuss the potential risks with their patients seeking treatment for androgenetic alopecia.

A synopsis of drugs currently in preclinical and early clinical development for the treatment of benign prostatic hyperplasia

INTRODUCTION

Benign prostatic hyperplasia (BPH) is a common disease among men and significantly impacts quality of life by causing lower urinary tract symptoms (LUTS). Current medical therapies are not always adequate in controlling LUTS or slowing disease progression, and there is unmet need for new effective therapeutic options.

AREAS COVERED

The authors review the standard current medical therapies for BPH which include the use of α-1 blockers, 5-α reductase inhibitors, combination therapy and PDE inhibitors. Following this, the authors then discuss new therapies that are currently undergoing preclinical and clinical investigation.

EXPERT OPINION

Existing preclinical and clinical trials have highlighted many promising therapies to treat BPH. Further investigation with larger clinical trials is needed to establish these drugs as standard therapies. As the number of drugs in the arsenal against BPH continues to grow, providers and patients will have to engage in a discussion that weighs the risks and benefits of each therapy.

L-arginine and tetrahydrobiopterin, but not sodium nitrite partially restored erectile dysfunction in aged rats

Aging is associated with erectile dysfunction (ED), in which nitric oxide synthase (NOS) activity and NO bioavailability are reduced due to deficiencies of NOS cofactor (tetrahydrobiopterin, BH(4)) and substrate (L-arginine). We determined whether the prolonged treatment with sodium nitrite (NaNO(2)) as a storage form of NO ameliorates ED in aged rats. Male Sprague-Dawley rats were divided: younger, aged and NaNO(2)-treated (20 mg/kg per day) aged groups. The erectile (intracavernosal pressure [ICP]/mean arterial pressure [MAP]) and corpus cavernous (CC) responses were evaluated after 12 weeks. The ICP/MAP in aged rats was lower than in young controls, which was not improved by the NaNO(2) treatment. Immunohistochemical (IHC) staining for endothelial NOS and collagen deposition was performed. We assayed NO indirectly by measuring the level of its stable end products, nitrite/nitrate, using the Griess reagent. The relaxations to ACh and EFS in the aged group were considerably less than in the younger group, which were normalized by acute incubations of l-arginine or BH(4) of aged CC. In conclusion, NaNO(2) treatment did not restore erectile response while nitrate levels were enhanced in aged penis. The cofactor or substrate administrations, but not chronic exogenous modulation of NO system may be beneficial in aged men with ED.

Immunohistochemical evaluation of androgen receptor and nerve structure density in human prepuce from patients with persistent sexual side effects after finasteride use for androgenetic alopecia

Finasteride is an inhibitor of 5-α-reductase used against male androgenetic alopecia (AGA). Reported side effects of finasteride comprise sexual dysfunction including erectile dysfunction, male infertility, and loss of libido. Recently these effects were described as persistent in some subjects. Molecular events inducing persistent adverse sexual symptoms are unexplored. This study was designed as a retrospective case-control study to assess if androgen receptor (AR) and nerve density in foreskin prepuce specimens were associated with persistent sexual side effects including loss of sensitivity in the genital area due to former finasteride use against AGA. Cases were 8 males (aged 29–43 years) reporting sexual side effects including loss of penis sensitivity over 6 months after discontinuation of finasteride who were interviewed and clinically visited. After informed consent they were invited to undergo a small excision of skin from prepuce. Controls were 11 otherwise healthy matched men (aged 23–49 years) who undergone circumcision for phimosis, and who never took finasteride or analogues. Differences in AR expression and nerve density in different portions of dermal prepuce were evaluated in the 2 groups. Density of nuclear AR in stromal and epithelial cells was higher in cases (mean 40.0%, and 80.6% of positive cells, respectively) than controls (mean 23.4%, and 65.0% of positive cells, respectively), P = 0.023 and P = 0.043, respectively. Conversely, percentage of vessel smooth muscle cells positive for AR and density of nerves were similar in the 2 groups. The ratio of AR positive stromal cells % to serum testosterone concentrations was 2-fold higher in cases than in controls (P = 0.001). Our findings revealed that modulation of local AR levels might be implicated in long-term side effects of finasteride use. This provides the first evidence of a molecular objective difference between patients with long-term adverse sexual effects after finasteride use versus drug untreated healthy controls in certain tissues.

The dark side of 5α-reductase inhibitors' therapy: sexual dysfunction, high Gleason grade prostate cancer and depression

With aging, abnormal benign growth of the prostate results in benign prostate hyperplasia (BPH) with concomitant lower urinary tract symptoms (LUTS). Because the prostate is an androgen target tissue, and transforms testosterone into 5α-dihydrotestosterone (5α-DHT), a potent androgen, via 5α-reductase (5α-R) activity, inhibiting this key metabolic reaction was identified as a target for drug development to treat symptoms of BPH. Two drugs, namely finasteride and dutasteride were developed as specific 5α-reductase inhibitors (5α-RIs) and were approved by the U.S. Food and Drug Administration for the treatment of BPH symptoms. These agents have proven useful in the reducing urinary retention and minimizing surgical intervention in patients with BPH symptoms and considerable literature exists describing the benefits of these agents. In this review we highlight the adverse side effects of 5α-RIs on sexual function, high grade prostate cancer incidence, central nervous system function and on depression. 5α-Rs isoforms (types 1-3) are widely distributed in many tissues including the central nervous system and inhibition of these enzymes results in blockade of synthesis of several key hormones and neuro-active steroids leading to a host of adverse effects, including loss of or reduced libido, erectile dysfunction, orgasmic dysfunction, increased high Gleason grade prostate cancer, observed heart failure and cardiovascular events in clinical trials, and depression. Considerable evidence exists from preclinical and clinical studies, which point to significant and serious adverse effects of 5α-RIs, finasteride and dutasteride, on sexual health, vascular health, psychological health and the overall quality of life. Physicians need to be aware of such potential adverse effects and communicate such information to their patients prior to commencing 5α-RIs therapy.

A critical analysis of the role of testosterone in erectile function: from pathophysiology to treatment-a systematic review

CONTEXT

Androgen modulation of erectile function (EF) is widely accepted. However, the use of testosterone replacement therapy (TRT) in men with erectile dysfunction (ED) has generated an unprecedented debate.

OBJECTIVE

To summarize the relevant data on the incidence, diagnosis, and management of ED coexisting with hypogonadism and to develop a pathophysiology-based treatment algorithm.

EVIDENCE ACQUISITION

We reviewed the relevant medical literature, with a particular emphasis on original molecular studies, prospective observational data, and randomized controlled trials performed in the past 20 yr.

EVIDENCE SYNTHESIS

Testosterone modulates nearly every component involved in EF, from pelvic ganglions to smooth muscle and the endothelial cells of the corpora cavernosa. It also regulates the timing of the erectile process as a function of sexual desire, coordinating penile erection with sex. Epidemiologic studies confirm the significant overlap of hypogonadism and ED; however, most guidelines do not consider the differential diagnosis of hypogonadism or the relevance of subclinical disease. Various clinical tools can help the physician to assess and restore androgen levels in men with ED. Special attention is given to fertility-sparing treatments, due to the increasing number of older men desiring fatherhood. The simultaneous use of phosphodiesterase type 5 inhibitors (PDE5-Is) and TRT has recently been questioned. Originally proposed as a salvage therapy for nonresponders to PDE5-Is, this approach has been inappropriately transformed into a combination therapy. Clinical data are consistent when reinterpreted in the proper framework, whereas molecular evidence remains controversial.

CONCLUSIONS

A body of molecular and clinical evidence supports the use of TRT in hypogonadal patients with ED, although the benefit-risk ratio is uncertain in advanced age. Critical appraisal of this evidence enabled the development of a pathophysiology-oriented algorithm designed to avoid inappropriate treatments and support whether to start with TRT, PDE5-I only, or both. Apparently divergent findings are reconciled when TRT is correctly indicated. An improved diagnosis and individualized management is desirable in light of the many available options.

5α-reductases in human physiology: an unfolding story

OBJECTIVE

5α-reductases are a family of isozymes expressed in a wide host of tissues including the central nervous system (CNS) and play a pivotal role in male sexual differentiation, development and physiology.

METHODS

A comprehensive literature search from 1970 to 2011 was made through PubMed and the relevant information was summarized.

RESULTS

5α reductases convert testosterone, progesterone, deoxycorticosterone, aldosterone and corticosterone into their respective 5α-dihydro-derivatives, which serve as substrates for 3α-hydroxysteroid dehydrogenase enzymes. The latter transforms these 5α-reduced metabolites into a subclass of neuroactive steroid hormones with distinct physiological functions. The neuroactive steroid hormones modulate a multitude of functions in human physiology encompassing regulation of sexual differentiation, neuroprotection, memory enhancement, anxiety, sleep and stress, among others. In addition, 5α -reductase type 3 is also implicated in the N-glycosylation of proteins via formation of dolichol phosphate. The family of 5α-reductases was targeted for drug development to treat pathophysiological conditions, such as benign prostatic hyperplasia and androgenetic alopecia. While the clinical use of 5α-reductase inhibitors was well established, the scope and the magnitude of the adverse side effects of such drugs, especially on the CNS, is still unrecognized due to lack of knowledge of the various physiological functions of this family of enzymes, especially in the CNS.

CONCLUSION

There is an urgent need to better understand the function of 5α-reductases and the role of neuroactive steroids in human physiology in order to minimize the potential adverse side effects of inhibitors targeting 5α-reductases to treat benign prostatic hyperplasia and androgenic alopecia.

Inhibitors of 5α-reductase-related side effects in patients seeking medical care for sexual dysfunction

BACKGROUND

Despite their efficacy in the treatment of benign prostatic hyperplasia (BPH) the popularity of inhibitors of 5α-reductase (5ARI) is limited by their association with adverse sexual side effects. However, the real impact of 5ARI on sex hormones and sexual function is controversial.

AIM

To investigate the role of 5ARI therapy on hormonal parameters and sexual function in men already complaining of sexual problems.

MATERIALS AND METHODS

A consecutive series of 3837 men (mean age 63.5±12.8 yr) attending our outpatient clinic for sexual dysfunction was retrospectively studied. Several clinical, biochemical, and instrumental (penile color doppler ultrasound) factors were evaluated.

RESULTS

Among the patients studied, 78.7% reported erectile dysfunction, 51.1% hypoactive sexual desire (HSD), 86.7% perceived reduced sleep-related erections (PR-SRE) and 19.1% premature ejaculation. The use of 5ARI was associated with an increased risk of HSD and PR-SR whereas no relationship was found with erectile dysfunction and ejaculation disturbances. Subjects using 5ARI also more frequently had gynecomastia along with reduced SHBG and higher calculated free testosterone levels. All these associations were confirmed in a case-control study comparing 5ARI users with age-body mass index-smoking status and total testosterone-matched controls.

CONCLUSIONS

Our data indicates that use of 5ARI in men with sexual dysfunction does not significantly exacerbate pre-existing ejaculatory or erectile difficulties, but can further impair their sexual life by reducing sexual drive and spontaneous erection.

Incomplete recovery of erectile function in rat after discontinuation of dual 5-alpha reductase inhibitor therapy

AIM

The association of 5-alpha reductase inhibitor (5ARI) therapy and sexual dysfunction has been reported. Some patients claim persistent erectile dysfunction despite long-term discontinuation of 5ARI treatment. The aim of this study was to assess erectile function after cessation of 5ARI therapy using a rat model.

METHODS

Twenty-six adult male Sprague-Dawley rats were randomized into three groups: (i) control (N = 10); (ii) 8-week dutasteride treatment (0.5 mg/rat/day, in drinking water, N = 8); and (iii) 6-week dutasteride treatment followed by a 2-week washout period (N = 8). The experiments were performed after 8 weeks from the initiation of treatment in all groups. In vivo erectile activity and in vitro contractile and relaxant responses of cavernosal smooth muscle were investigated.

RESULTS

In vivo erectile activity (intracavernosal pressure [ICP]/mean arterial pressure [MAP] and total ICP) in treatment groups were significantly decreased compared with controls (ICP/MAP: P < 0.001 for 2.5 v, 5 v, and 7.5 v; total ICP: P < 0.001 for 5 v and P < 0.01 for 7.5 v). Acetylcholine-induced relaxations were diminished in treatment groups (P < 0.05). Relaxant responses to electrical field stimulation (EFS) were decreased in the 8-week treatment group (P < 0.05) but were similar to controls in the washout group. Sodium nitroprusside (SNP)-induced endothelium-independent relaxations were reduced in the 8-week dutasteride treatment group (P < 0.01), while these responses were restored in the washout group. The contractile responses to the alpha1-adrenergic agonist phenylephrine were decreased in treatment groups compared with controls (P < 0.01). Direct neurogenic contractile responses in the dutasteride groups were significantly lower than controls between 1 and 15 Hz frequencies (but not at 20 Hz) and washout partially restored the responses at 10 and 15 Hz.

CONCLUSION

Discontinuation of dutasteride improved the relaxant responses to EFS and SNP, while cholinergic and adrenergic responses remained depressed. Our findings suggest a time-dependent detriment of dutasteride on erectile function. The withdrawal/washout effect of 5ARIs on parameters of human sexual function warrants further investigation.

Effects of oral finasteride on erectile function in a rat model

INTRODUCTION

Many clinical studies reported finasteride-related erectile dysfunction, but to date, few animal experiments have focused on it.

AIM

To investigate the effects of oral finasteride on erectile function in a rat model.

MAIN OUTCOME MEASURES

Erectile responses and morphological changes.

METHODS

Adult, male Sprague-Dawley rats were divided into four groups (25/group): (i) control; (ii) castration; (iii) castration with testosterone (T) replacement; and (iv) oral finasteride treatment. Four weeks later, erectile function was measured by the ratio of intracavernosal pressure and mean arterial blood pressure upon electrical stimulation of the cavernous nerve. Serum T and dihydrotestosterone (DHT) and intraprostatic DHT were measured. The weights and histopathological features of the penile corpus cavernosum and prostate were examined.

RESULTS

Serum T and DHT and intraprostatic DHT concentrations, erectile function, and mean weights of the corpus cavernosum and prostate were lowest in group 2. There was no significant difference in the serum T concentration and erectile function between groups 4 and 1. However, the serum and intraprostatic DHT concentrations were significantly lower in group 4 than in group 1 (both P < 0.001). The tissue weights of the corpus cavernosum and prostate were reduced by 25.9% and 92.3% in group 4 compared with group 1 (both P < 0.001). Histopathology revealed a significant atrophy of the prostate in groups 2 and 4. There was a significant decrease in the smooth muscle content in group 2, but not in groups 3 and 4.

CONCLUSIONS

In a rat model, finasteride treatment for 4 weeks reduces the weight of the corpus cavernosum but appears not to affect the erectile responses to electrical stimulation of the cavernous nerve. As erection is a complex process involving important signaling in the brain, further studies are necessary to demonstrate the long-term effects of finasteride on both central and peripheral neural pathways of erection.