Testosterone Restoration by Enclomiphene Citrate in Men with Secondary Hypogonadism: Pharmacodynamics and Pharmacokinetics

Efficacy of Clomiphene Citrate Versus Enclomiphene Citrate for Male Infertility Treatment: A Retrospective Study

Introduction Infertility and hypogonadism in males can greatly affect their reproductive health and overall well-being. Since exogenous testosterone administration for hypogonadism management may disrupt the normal hormonal cascade necessary for spermatogenesis, clomiphene citrate (CC) and enclomiphene citrate (EC) are medications often used to manage hypogonadism and male infertility. This study aims to directly compare the effects of CC and EC on serum testosterone levels and semen parameters in men to determine which medication may have an advantage in managing these conditions. Materials and methods We retrospectively analyzed ≥18-year-old men presenting with primary infertility, abnormal semen parameters, or hypogonadism who received CC or EC monotherapy for at least three months between January 2021 and December 2022. We compared baseline and follow-up hormone levels, semen parameters, and demographics. Variables were compared using paired and unpaired t-tests. Significance was assessed at p<0.05. Results A total of 46 men received EC and 32 men received CC. The median age was 42 (IQR: 34-47.75) years in men who received EC and 41 (IQR: 36-44) years in men who received CC (p=0.450). The two treatment groups exhibited a significant increase in serum total testosterone, while only EC had a statistically significant increase in FSH and LH. Semen volume and concentration did not significantly change with either treatment. Sperm motility increased in both groups, but total motile sperm count (TMSC) only significantly increased in men who received EC.  Conclusions Our study found that EC and CC are effective treatments in increasing total testosterone without negatively affecting spermatogenesis. EC demonstrated to be more effective in raising gonadotropin levels and TMSC.

Prediction of Drug-Drug-Gene Interaction Scenarios of (E)-Clomiphene and Its Metabolites Using Physiologically Based Pharmacokinetic Modeling

Clomiphene, a selective estrogen receptor modulator (SERM), has been used for the treatment of anovulation for more than 50 years. However, since (E)-clomiphene ((E)-Clom) and its metabolites are eliminated primarily via Cytochrome P450 (CYP) 2D6 and CYP3A4, exposure can be affected by CYP2D6 polymorphisms and concomitant use with CYP inhibitors. Thus, clomiphene therapy may be susceptible to drug-gene interactions (DGIs), drug-drug interactions (DDIs) and drug-drug-gene interactions (DDGIs). Physiologically based pharmacokinetic (PBPK) modeling is a tool to quantify such DGI and DD(G)I scenarios. This study aimed to develop a whole-body PBPK model of (E)-Clom including three important metabolites to describe and predict DGI and DD(G)I effects. Model performance was evaluated both graphically and by calculating quantitative measures. Here, 90% of predicted C_max and 80% of AUC_last values were within two-fold of the corresponding observed value for DGIs and DD(G)Is with clarithromycin and paroxetine. The model also revealed quantitative contributions of different CYP enzymes to the involved metabolic pathways of (E)-Clom and its metabolites. The developed PBPK model can be employed to assess the exposure of (E)-Clom and its active metabolites in as-yet unexplored DD(G)I scenarios in future studies.

Testosterone kinetics on hypogonadal men under clomiphene

OBJECTIVE

To evaluate total testosterone (TT) kinetics and its predictors 6 months after the discontinuation of clomiphene citrate (CC) in patients with hypogonadism.

MATERIALS AND METHODS

Consecutive patients with normal testicles and male hypogonadism defined by TT < 300 ng/dl in the presence of signs or symptoms according to the previous consensus were prospectively evaluated in a urologic outpatient clinic by TT levels at baseline (T₀), after a daily dose of 50 mg CC for 40 days (T₁), and after the washout period of 6 months of CC discontinuation (T₂).

RESULTS

Among 75 patients, mean age 56.8 years, testosterone at T₁ > 300 ng/dl was achieved by 69 (92%), 450-600 ng/dl by 32 (42.6%), and > 600 ng/dl by 27 (36.0%). 18 subjects (24%) maintained asymptomatic and TT levels over 300 ng/dl at T₂. Age negatively related to testosterone response and T₁ response > 810 ng/dl predicts a median gain of 166.5 ng/dl at 6 months of CC discontinuation.

CONCLUSIONS

CC is a compelling option to treat male hypogonadism, although a chronic treatment is needed in most patients. About one in every four patients respond to a CC short trial to "reboot" the physiology. Further understanding of TT kinetics in these patients in the long term is warranted.

An update on male infertility and intratesticular testosterone-insight into novel serum biomarkers

Intratesticular testosterone is vital for spermatogenesis, male fertility, and virility. Currently the only method to assess levels of intratesticular testosterone is to perform testicular biopsy which is invasive and can lead to several complications. Approaches to assess intratesticular testosterone have been understudied but hold promise as future male contraceptive agents and may grant the ability to monitor patients undergoing hormonal changes from therapeutic and diagnostic perspectives. Previous studies have sought to assess the utility of 17-hydroxyprogesterone (17-OHP) and insulin-like factor 3 (INSL3) as accurate surrogate biomarkers of intratesticular testosterone. The aim of this review is thus to highlight the importance of intratesticular testosterone and the consequent advances that have been made to elucidate the potential of biomarkers for intratesticular testosterone in the context of male infertility.

Clomiphene Citrate for Men with Hypogonadism - A Systematic Review & Meta-analysis

BACKGROUND

Male hypogonadism is a clinical and biochemical androgen insufficiency syndrome, becoming more prevalent with age. Exogenous testosterone is first choice therapy, with several side-effects, including negative feedback of the hypothalamic-pituitary-gonadal axis, resulting in suppression of intratesticular testosterone production and spermatogenesis. To preserve these testicular functions while treating male hypogonadism clomiphene citrate (CC) is used as off-label therapy. This systematic review and meta-analysis aimed to evaluate the effectiveness and safety of CC therapy for men with hypogonadism.

METHODS

The EMBASE, PubMed, Cochrane databases were searched in May 2021, for effectiveness studies of men with hypogonadism treated with CC. Both intervention and observational studies were included. The Effective Public Health Practice Project Quality Assessment Tool, a validated instrument was used to assess methodological study quality. The primary outcome measure was the evaluation of serum hormone concentration. Secondary outcomes were symptoms of hypogonadism, metabolic- and lipid profile, side-effects, safety aspects.

RESULTS

We included 19 studies, comprising four randomized controlled trials and 15 observational studies, resulting in 1642 patients. Seventeen studies were included in the meta-analysis, with a total of 1279 patients. Therapy and follow-up duration varied between one and a half and 52 months. Total testosterone (TT) increased with 2.60 (95% CI 1.82 - 3.38) during CC treatment. An increase was also seen in free testosterone, luteinizing hormone, follicle stimulating hormone, sex hormone-binding globulin and estradiol. Different symptom scoring methods were used in the included studies. The most frequently used instrument was the Androgen Deficiency in Aging Males-questionnaire, which score improved during treatment. Reported side-effects were only prevalent in less than 10% of the study populations and no serious adverse events were reported.

CONCLUSION

CC is an effective therapy for improving both biochemical as well as clinical symptoms of males suffering from hypogonadism. CC has few reported side-effects and good safety aspects. This article is protected by copyright. All rights reserved.

Diagnosis and Management of Testosterone Deficiency in men: A review of the European and American Urology Associations

Ambiguous data on both terminology, diagnostics, and treatment of testosterone deficiency in men prompted us to attempt a critical analysis of existing knowledge on this subject. Current guidelines of both American and European Association of Urology (AUA, EUA) define testosterone therapy as effective and safe. However, media reports and some scientific reports indicating negative effects of the abovementioned therapy arouse aversion to its use by doctors and potential patients for fear of developing prostate cancer or cardiovascular incidents. The peak of scepticism about testosterone therapy was observed after the publication in 2013 and 2014, respectively, two retrospective data analysis on this topic, which resulted in the discontinuation of therapy in many patients with long histories of benefits from testosterone therapy. In addition, in many men with indications for testosterone therapy, this treatment was not used for fear of patient safety. However, the latest data on these concerns do not confirm any negative effects. More than 100 recently published scientific studies have shown the beneficial effects of testosterone therapy on many aspects of health. The American Society of Clinical Endocrinologists (AACE) and the American College of Endocrinology (ACE) have jointly developed their own literature assessment, stating that there is no convincing evidence that testosterone therapy increases the risk of cardiovascular incidents. The same conclusions can be drawn from the current EAU and AUA guidelines.

Enclomiphene citrate: A treatment that maintains fertility in men with secondary hypogonadism

Hypogonadism is an important issue among the male population. Treatments such as exogenous testosterone have become very popular. One of the adverse effects of testosterone is its suppression of fertility. This has lead to the use of alternative therapies such as selective estrogen receptor modulators (SERMs) that aim to correct hypogonadism without reducing fertility. Areas covered: The SERM, clomiphene citrate, which is approved by the FDA for the treatment of ovarian dysfunction, has been shown to have beneficial effects on male hypogonadism. Clomiphene citrate exists as a mixture of both the cis-isomer (zuclomiphene) and the trans-isomer (enclomiphene). The literature has suggested that most of the beneficial effects of clomiphene are due to the trans-isomer enclomiphene. Zuclomiphene contributes little to the intended outcomes. The purpose of this drug profile is to examine the available literature on the trans-isomer enclomiphene. Expert opinion: Enclomiphene has been shown to increase testosterone levels while stimulating FSH and LH production. Initial studies demonstrated that enclomiphene maintains the androgenic benefit of clomiphene citrate without the undesirable effects attributable to zuclomiphene. This article reviews the difficulties associated with the FDA approval of a new molecular entity related to the treatment of hypogonadism.

Hypothalamic-Pituitary-Testicular Axis Effects and Urinary Detection Following Clomiphene Administration in Males

CONTEXT

Clomiphene is a performance-enhancing drug commonly abused by males in sport, but the extent to which testosterone increases in healthy males following its use is unknown. In addition, evidence suggests that clomiphene, a mixture of cis- and trans-isomers zuclomiphene and enclomiphene, is detectable in urine for months following use; the isomer-specific urinary detection window has yet to be characterized in a controlled study.

OBJECTIVE

To determine the effect of once-daily, 30-day clomiphene treatment on serum testosterone and gonadotropin levels in the subject population studied and the urinary clearance and detection window of clomiphene isomers following administration for antidoping purposes.

PARTICIPANTS AND DESIGN

Twelve healthy males aged 25 to 38 years, representing a recreational athlete population, participated in this open-label, single-arm study.

INTERVENTION

Oral clomiphene citrate (50 mg) was self-administered once daily for 30 days. Serum and urine samples were collected at baseline and at days 7, 14, 21, 28, 30, 32, 35, 37, 44, 51, and 58; urine collections continued periodically up to day 261.

RESULTS

Mean testosterone, LH, and FSH levels increased 146% (SEM, ±23%), 177% (±34%), and 170% (±33%), respectively, during treatment compared with baseline. Serum drug concentrations and urinary excretion were nonuniform among individuals as isomeric concentrations varied. The zuclomiphene urinary detection window ranged from 121 to >261 days.

CONCLUSIONS

Clomiphene significantly raised serum testosterone and gonadotropin levels in healthy men and thus can be abused as a performance-enhancing drug. Such abuse is detectable in urine for ≥4 months following short-term use.

Clomiphene citrate treatment for late onset hypogonadism: rise and fall

Objective:

Previous series have demonstrated that Clomiphene Citrate (CC) is an effective treatment to increase Total Testosterone (TT) in Late Onset Hypogonadism (LOH) patients. However, what happens to TT levels after ending CC treatment is still debatable. The objective of this study is to evaluate TT levels 3 months after the discontinuation of CC in patients with LOH who were previously successfully treated with the same drug.

Materials and Methods:

Twenty-seven patients with LOH that were successfully treated (achieved TT levels >11nmol/l) with CC 50mgs daily for 50 days were prospectively recruited in our Andrological outpatient clinic. CC was then stopped for 3 months and TT levels were measured at the end of this period.

Results:

Mean TT level before discontinuation of CC was 22.7±8.1nmol/L (mean±SD). Three months after discontinuation, mean TT level significantly decreased in all patients, 10.2±3.9nmol/l (p<0.01). Twenty-one patients (78%) decreased TT levels under 11nmol/L. Six patients (22%) had TT levels that remained within the normal recommended range (≥11nmol/l). No statistical significant differences were observed between both groups.

Conclusion:

In the short term LOH does not seem to be a reversible condition in most patients after CC treatment. More studies with longer follow-up are needed to evaluate the kinetics of TT in LOH.

Recovery of spermatogenesis following testosterone replacement therapy or anabolic-androgenic steroid use

The use of testosterone replacement therapy (TRT) for hypogonadism continues to rise, particularly in younger men who may wish to remain fertile. Concurrently, awareness of a more pervasive use of anabolic-androgenic steroids (AAS) within the general population has been appreciated. Both TRT and AAS can suppress the hypothalamic-pituitary-gonadal (HPG) axis resulting in diminution of spermatogenesis. Therefore, it is important that clinicians recognize previous TRT or AAS use in patients presenting for infertility treatment. Cessation of TRT or AAS use may result in spontaneous recovery of normal spermatogenesis in a reasonable number of patients if allowed sufficient time for recovery. However, some patients may not recover normal spermatogenesis or tolerate waiting for spontaneous recovery. In such cases, clinicians must be aware of the pathophysiologic derangements of the HPG axis related to TRT or AAS use and the pharmacologic agents available to reverse them. The available agents include injectable gonadotropins, selective estrogen receptor modulators, and aromatase inhibitors, but their off-label use is poorly described in the literature, potentially creating a knowledge gap for the clinician. Reviewing their use clinically for the treatment of hypogonadotropic hypogonadism and other HPG axis abnormalities can familiarize the clinician with the manner in which they can be used to recover spermatogenesis after TRT or AAS use.

Estrogens and Body Weight Regulation in Men

Our understanding of the metabolic roles of sex steroids in men has evolved substantially over recent decades. Whereas testosterone once was believed to contribute to metabolic risk in men, the importance of adequate androgen exposure for the maintenance of metabolic health has been demonstrated unequivocally. A growing body of evidence now also supports a critical role for estrogens in metabolic regulation in men. Recent data from clinical intervention studies indicate that estradiol may be a stronger determinant of adiposity than testosterone in men, and even short-term estradiol deprivation contributes to fat mass accrual. The following chapter will outline findings to date regarding the mechanisms, whereby estrogens contribute to the regulation of body weight and adiposity in men. It will present emergent clinical data as well as preclinical findings that reveal mechanistic insights into estrogen-mediated regulation of body composition. Findings in both males and females will be reviewed, to draw comparisons and to highlight knowledge gaps regarding estrogen action specifically in males. Finally, the clinical relevance of estrogen exposure in men will be discussed, particularly in the context of a rising global prevalence of obesity and expanding clinical use of sex steroid-based therapies in men.

Testosterone replacement in the infertile man

Hypogonadism is a common clinical condition affecting men of different age groups. In addition to its sexual consequences, it has several implications posing significant concerns for a man’s health and well-being. Recent advances in testosterone (T) supplementation have facilitated hypogonadism treatment. Despite that, patients complaining of infertility or seeking conception are still hindered by the unfavorable effects supplemental T has on testicular function. Consequently, alternative approaches that can stimulate endogenous T production are favored. Selective estrogen receptor modulators, gonadotropins and aromatase inhibitors (AIs) can be successful in restoring serum T levels, preserving fertility, and providing symptomatic relief.

Clomiphene and Its Isomers Block Ebola Virus Particle Entry and Infection with Similar Potency: Potential Therapeutic Implications

The 2014 outbreak of Ebola virus (EBOV) in Western Africa highlighted the need for anti-EBOV therapeutics. Clomiphene is a U.S. Food and Drug Administration (FDA)-approved drug that blocks EBOV entry and infection in cells and significantly protects EBOV-challenged mice. As provided, clomiphene is, approximately, a 60:40 mixture of two stereoisomers, enclomiphene and zuclomiphene. The pharmacokinetic properties of the two isomers vary, but both accumulate in the eye and male reproductive tract, tissues in which EBOV can persist. Here we compared the ability of clomiphene and its isomers to inhibit EBOV using viral-like particle (VLP) entry and transcription/replication-competent VLP (trVLP) assays. Clomiphene and its isomers inhibited the entry and infection of VLPs and trVLPs with similar potencies. This was demonstrated with VLPs bearing the glycoproteins from three filoviruses (EBOV Mayinga, EBOV Makona, and Marburg virus) and in two cell lines (293T/17 and Vero E6). Visual problems have been noted in EBOV survivors, and viral RNA has been isolated from semen up to nine months post-infection. Since the clomiphene isomers accumulate in these affected tissues, clomiphene or one of its isomers warrants consideration as an anti-EBOV agent, for example, to potentially help ameliorate symptoms in EBOV survivors.

Enclomiphene citrate for the treatment of secondary male hypogonadism

INTRODUCTION

Hypogonadism is a growing concern in an aging male population. Historically treated using exogenous testosterone, concerns about possible adverse effects of testosterone have led physicians to seek alternative treatment approaches.

AREAS COVERED

Enclomiphene citrate is the trans isomer of clomiphene citrate, a non-steroidal estrogen receptor antagonist that is FDA-approved for the treatment of ovarian dysfunction in women. Clomiphene citrate has also been used off-label for many years to treat secondary male hypogonadism, particularly in the setting of male infertility. Here we review the literature examining the efficacy and safety of enclomiphene citrate in the setting of androgen deficiency.

EXPERT OPINION

Initial results support the conclusion that enclomiphene citrate increases serum testosterone levels by raising luteinizing hormone (LH) and follicle stimulating hormone (FSH) levels, without negatively impacting semen parameters. The ability to treat testosterone deficiency in men while maintaining fertility supports a role for enclomiphene citrate in the treatment of men in whom testosterone therapy is not a suitable option.

Preserving fertility in the hypogonadal patient: an update

An increasing number of young and middle-aged men are seeking treatment for symptoms related to deficient levels of androgens (hypogonadism) including depression, loss of libido, erectile dysfunction, and fatigue. The increase in prevalence of testosterone supplementation in general and anabolic steroid-induced hypogonadism specifically among younger athletes is creating a population of young men who are uniquely impacted by the testicular end-organ negative consequences of exogenous steroid use. Exogenous testosterone therapy can alter the natural regulation of the hypothalamic-pituitary-gonadal axis leading to impaired spermatogenesis with azoospermia being a serious possible result, thus rendering the individual infertile. For men of reproductive age who suffer from hypogonadal symptoms, preservation of fertility is an important aspect of their treatment paradigm. Treatment with human chorionic gonadotropin (hCG) has shown the ability not only to reverse azoospermia brought on by testosterone supplementation therapy but also to help maintain elevated intratesticular testosterone levels. In addition, selective estrogen receptor modulators, often used with hCG have been shown both to elevate total testosterone levels and to maintain spermatogenesis in hypogonadal men.

Treatment of hypogonadotropic male hypogonadism: Case-based scenarios

The aim of this study is to review four case-based scenarios regarding the treatment of symptomatic hypogonadism in men. The article is designed as a review of published literature. We conducted a PubMed literature search for the time period of 1989-2014, concentrating on 26 studies investigating the efficacy of various therapeutic options on semen analysis, pregnancy outcomes, time to recovery of spermatogenesis, as well as serum and intratesticular testosterone levels. Our results demonstrated that exogenous testosterone suppresses intratesticular testosterone production, which is an absolute prerequisite for normal spermatogenesis. Cessation of exogenous testosterone should be recommended for men desiring to maintain their fertility. Therapies that protect the testis involve human chorionic gonadotropin (hCG) therapy or selective estrogen receptor modulators (SERMs), but may also include low dose hCG with exogenous testosterone. Off-label use of SERMs, such as clomiphene citrate, are effective for maintaining testosterone production long-term and offer the convenience of representing a safe, oral therapy. At present, routine use of aromatase inhibitors is not recommended based on a lack of long-term data. We concluded that exogenous testosterone supplementation decreases sperm production. It was determined that clomiphene citrate is a safe and effective therapy for men who desire to maintain fertility. Although less frequently used in the general population, hCG therapy with or without testosterone supplementation represents an alternative treatment.

Alternative treatment modalities for the hypogonadal patient

Testosterone (T) deficiency syndrome (TDS) is a prevalent condition, commonly managed with exogenous T. Despite an abundance of T formulations, alternative treatments are often sought for various reasons. To evaluate outcomes of alternative therapies, a PubMed search was performed of all publications that included men with TDS from 1990 through October 2013, with results summarized. Proposed mechanisms of action were also reviewed to provide a pathophysiologic basis for reported outcomes. Nonpharmacologic therapies that increase endogenous T are weight loss, exercise, and varicocelectomy, while medications used off-label include aromatase inhibitors, human chorionic gonadotropin, and selective estrogen receptor modulators. All reported therapies increase T, while changes in estradiol and adverse events vary by therapeutic class. Although limited data preclude direct comparisons between therapies, exercise and weight loss alone or in combination with medications may be considered first line. The role for surgical therapy in TDS remains undefined and requires further study.

Enclomiphene citrate stimulates testosterone production while preventing oligospermia: a randomized phase II clinical trial comparing topical testosterone

OBJECTIVE

To determine the effect of enclomiphene citrate in men with secondary hypogonadism.

DESIGN

Phase II clinical trial.

SETTING

Community dwelling men making visits to physician offices.

PATIENT(S)

Men with secondary hypogonadism.

INTERVENTION(S)

Oral administration of enclomiphene citrate or 1% topical T gel.

MAIN OUTCOME MEASURE(S)

Luteinizing hormone, FSH, T, and semen analysis.

RESULT(S)

Treatment with enclomiphene citrate resulted in increased morning serum T, E2, and LH levels similar to those obtained with a topical T gel in men with secondary hypogonadism. Follicle-stimulating hormone and LH were increased with enclomiphene, and sperm counts were conserved.

CONCLUSION(S)

Enclomiphene citrate reverses the two hallmarks of secondary hypogonadism, namely, low serum total T and low or inappropriately normal LH while preserving sperm production.

CLINICAL TRIAL REGISTRATION NUMBER

NCT01270841 (ClinicalTrials.gov Identifier NCT01270841).