Pharmacokinetic Profile of Subcutaneous Testosterone Enanthate Delivered via a Novel, Prefilled Single-Use Autoinjector: A Phase II Study

A prospective comparison study of subcutaneous and intramuscular testosterone injections in transgender male adolescents

OBJECTIVES

This prospective study compares testosterone injection type and effects on biochemical changes, clinical effects, and quality of life amongst transgender and gender diverse (TGD) adolescents assigned female at birth (AFAB) over the first 6 months of subcutaneous (SQ) vs. intramuscular (IM) testosterone injections as part of their gender affirming care.

METHODS

Subjects were testosterone-naïve transgender adolescents, AFAB, ages 14-18 years old. Subjects were either randomized to injection type or selected a preferred injection type. At enrollment, subjects completed baseline labs and PedsQL™ quality of life questionnaire. At 3 month and 6 month follow up, subjects completed peak and trough testosterone levels, PedsQL™, masculinizing effects, and medication experience questionnaires.

RESULTS

Twenty-six subjects participated with a median age 15.5 years. By 6-month follow up, trough testosterone levels were comparable between the two groups. Peak testosterone levels were higher in the IM group at 3-month follow up. Mild adverse effects were rare (12 %, all in SQ subjects) and limited to skin reaction only. Self-reported masculinization effects and quality of life were not statistically different between injection groups. A total of 92 % of participants was self-injecting by 3-month follow up.

CONCLUSIONS

In this prospective study, clinical and biochemical effects are similar between SQ and IM testosterone injections for transgender adolescents. Subjects expressed preference for both injection types. Both SQ and IM injection modalities are safe and effective for TGD youth initiating testosterone and both options should be offered to patients.

Allometric Scaling of Testosterone Enanthate Pharmacokinetics to Adolescent Hypogonadal Males (IM and SC Administration)

Context

Intramuscular (IM) testosterone enanthate (TE) and testosterone pellets were US Food and Drug Administration approved before 1962 for pediatric use but not studied in controlled trials in adolescents.

Objective

An analysis using nonlinear mixed effect (NLME) modeling was designed to evaluate the adult pharmacokinetics (PK) of subcutaneous (SC) and IM TE. This model was used to simulate SC and IM TE administration in adolescents of different weight groups.

Methods

Data from adult male patients in a phase 2 trial were used to characterize the PK of TE using population PK modeling for SC and IM administration: Allometry was used to scale PK parameters from the adult model to simulate adolescent (aged 12 to < 18 years) serum testosterone levels at body weights of 30, 40, 50, and 60 kg after weekly, every-other-week (EOW), and monthly SC and IM administration of 12.5, 25, 50, 75, and 100 mg TE regimens.

Results

The final data set included 714 samples from 15 patients receiving 100 mg SC TE and 123 samples from 10 patients receiving 200 mg IM TE. In simulated populations, average serum concentration SC:IM ratios were 0.783, 0.776, and 0.757 at steady state for weekly, EOW, and monthly dosing groups, respectively. Simulated regimens of 12.5 mg SC TE monthly produced serum testosterone levels representative of early puberty and simulated pubertal stage progression following multiple subsequent testosterone dose increases.

Conclusion

SC TE administration achieved a testosterone exposure-response relationship similar to IM TE in simulated adolescent hypogonadal males, which may reduce size of fluctuations in serum T and related symptoms.

Misadventures in Toxicology: Concentration Matters for Testosterone-Induced Neurotoxicity

Testosterone is the predominant androgen in men and has important physiological functions. Due to declining testosterone levels from a variety of causes, testosterone replacement therapy (TRT) is increasingly utilized, while testosterone is also abused for aesthetic and performance-enhancing purposes. It has been increasingly speculated that aside from more well-established side effects, testosterone may cause neurological damage. However, the in vitro data utilized to support such claims is limited due to the high concentrations used, lack of consideration of tissue distribution, and species differences in sensitivity to testosterone. In most cases, the concentrations studied in vitro are unlikely to be reached in the human brain. Observational data in humans concerning the potential for deleterious changes in brain structure and function are limited by their inherent design as well as significant potential confounders. More research is needed as the currently available data are limited; however, what is available provides rather weak evidence to suggest that testosterone use or abuse has neurotoxic potential in humans.

Long vs Short Acting Testosterone Treatments: A Look at the Risks

Prescriptions for testosterone therapy (TT) to treat testosterone deficiency have increased in recent years. The purpose of this review was to evaluate the risks of several treatment modalities to better counsel patients. Both short-acting and long-acting TT has been shown to restore normal serum testosterone levels and improve symptoms of testosterone deficiency. Short-acting pharmacology mimics normal physiology more closely than long-acting TT but requires multiple doses per day. Long-acting TT has a higher rate of patient adherence but is more likely to create supraphysiologic serum testosterone and pathologic sequelae.

New and Consolidated Therapeutic Options for Pubertal Induction in Hypogonadism: In-depth Review of the Literature

Delayed puberty (DP) defines a retardation of onset/progression of sexual maturation beyond the expected age from either a lack/delay of the hypothalamo-pituitary-gonadal axis activation or a gonadal failure. DP usually gives rise to concern and uncertainty in patients and their families, potentially affecting their immediate psychosocial well-being and also creating longer term psychosexual sequelae. The most frequent form of DP in younger teenagers is self-limiting and may not need any intervention. Conversely, DP from hypogonadism requires prompt and specific treatment that we summarize in this review. Hormone therapy primarily targets genital maturation, development of secondary sexual characteristics, and the achievement of target height in line with genetic potential, but other key standards of care include body composition and bone mass. Finally, pubertal induction should promote psychosexual development and mitigate both short- and long-term impairments comprising low self-esteem, social withdrawal, depression, and psychosexual difficulties. Different therapeutic options for pubertal induction have been described for both males and females, but we lack the necessary larger randomized trials to define the best approaches for both sexes. We provide an in-depth and updated literature review regarding therapeutic options for inducing puberty in males and females, particularly focusing on recent therapeutic refinements that better encompass the heterogeneity of this population, and underlining key differences in therapeutic timing and goals. We also highlight persistent shortcomings in clinical practice, wherein strategies directed at "the child with delayed puberty of uncertain etiology" risk being misapplied to older adolescents likely to have permanent hypogonadism.

Testosterone Replacement Therapy in Hypogonadal Men

All approved testosterone replacement methods, when used according to recommendations, can restore normal serum testosterone concentrations, and relieve symptoms in most hypogonadal men. Selection of the method depends on the patient's preference with advice from the physician. Dose adjustment is possible with most delivery methods but may not be necessary in all hypogonadal men. The use of hepatotoxic androgens must be avoided. Testosterone treatment induces reversible suppression of spermatogenesis; if fertility is desired in the near future, human chronic gonadotropin, selective estrogen receptor modulator, estrogen antagonist, or an aromatase inhibitor that stimulates endogenous testosterone production may be used.

Testosterone Therapy With Subcutaneous Injections: A Safe, Practical, and Reasonable Option

CONTEXT

Injections with intramuscular (IM) testosterone esters have been available for almost 8 decades and not only result in predictable serum testosterone levels but are also the most inexpensive modality. However, they are difficult to self-administer and associated with some discomfort. Recently, subcutaneous (SC) administration of testosterone esters has gained popularity, as self-administration is easier with this route. Available data, though limited, support the feasibility of this route. Here we review the pharmacokinetics and safety of SC testosterone therapy with both long- and ultralong-acting testosterone esters. In addition, we provide guidance for clinicians on how to counsel and manage their patients who opt for the SC route.

EVIDENCE ACQUISITION

Systematic review of available literature on SC testosterone administration including clinical trials, case series, and case reports. We also review the pharmacology of testosterone absorption after SC administration.

EVIDENCE SYNTHESIS

Available evidence, though limited, suggests that SC testosterone therapy in doses similar to those given via IM route results in comparable pharmacokinetics and mean serum testosterone levels. With appropriate training, patients should be able to safely self-administer testosterone esters SC with relative ease and less discomfort compared with the IM route.

CONCLUSION

Although studies directly comparing the safety of SC vs IM administration of testosterone esters are desirable, clinicians should consider discussing the SC route with their patients because it is easier to self-administer and has the potential to improve patient adherence.

Society for Endocrinology guidelines for testosterone replacement therapy in male hypogonadism

Male hypogonadism (MH) is a common endocrine disorder. However, uncertainties and variations in its diagnosis and management exist. There are several current guidelines on testosterone replacement therapy that have been driven predominantly by single disciplines. The Society for Endocrinology commissioned this new guideline to provide all care providers with a multidisciplinary approach to treating patients with MH. This guideline has been compiled using expertise from endocrine (medical and nursing), primary care, clinical biochemistry, urology and reproductive medicine practices. These guidelines also provide a patient perspective to help clinicians best manage MH.

Testosterone therapy in children and adolescents: to whom, how, when?

Male production of testosterone is crucial for the development of a wide range of functions. External and internal genitalia formation, secondary sexual characteristics, spermatogenesis, growth velocity, bone mass density, psychosocial maturation, and metabolic and cardiovascular profiles are closely dependent on testosterone exposure. Disorders in androgen production can present during all life-stages, including childhood and adolescence, and testosterone therapy (TT) is in many cases the only treatment that can correct the underlying deficit. TT is controversial in the pediatric population as hypoandrogenism is difficult to classify and diagnose in these age groups, and standardized protocols of treatment and monitorization are still lacking. In pediatric patients, hypogonadism can be central, primary, or a combination of both. Testosterone preparations are typically designed for adults' TT, and providers need to be aware of the advantages and disadvantages of these formulations, especially cognizant of supratherapeutic dosing. Monitoring of testosterone levels in boys on TT should be tailored to the individual patient and based on the anticipated duration of therapy. Although clinical consensus is lacking, an approximation of the current challenges and common practices in pediatric hypoandrogenism could help elucidate the broad spectrum of pathologies that lie behind this single hormone deficiency with wide-ranging implications.

Subcutaneous Testosterone Is Effective and Safe as Gender-Affirming Hormone Therapy in Transmasculine and Gender-Diverse Adolescents and Young Adults: A Single Center's 8-Year Experience

Purpose: To describe our Center's 8-year experience with subcutaneous testosterone (SC-T) as gender-affirming hormone therapy (GAHT) in transmasculine and gender-diverse (TM/GD) youth.

Methods: An Institutional Review Board (IRB)-approved retrospective study for 119 TM/GD subjects who started SC-T at age 13–19 and received SC-T for >6 months between 2012 and 2020.

Results: SC-T was typically started at 25–50 mg biweekly and dose was escalated at provider's discretion. Over 96% of subjects were on 100–320 mg monthly (divided weekly or biweekly) at last follow-up. There was an overall increase in mean total and free testosterone (T) over the dose range (p=0.003), with mean total and free T levels of 460 ng/dL and 92 pg/mL, respectively, at a monthly SC-T dose of 200 mg. For subjects on SC-T without additional menstrual suppression, 54% had cessation of menses at 140 mg monthly and 97% at 200 mg monthly. On average, menses stopped 4.7 (standard deviation 3.0) months after starting SC-T. There was a decrease in high-density lipoprotein and increase in hematocrit from baseline to follow-up. Body mass index Z-scores did not change significantly with treatment. Mild acne was common; severe acne and significant injection site reactions were uncommon. Sustained hypertension, transaminitis, and dyslipidemia were infrequent.

Conclusions: SC-T is well tolerated and effective in reaching recommended T levels and stopping menses in TM/GD youth. Occurrence of serious adverse effects is low and inability to tolerate injections is very uncommon. SC-T is a safe and effective alternative to intramuscular testosterone in initiation and maintenance of GAHT in TM/GD youth.

Hypogonadism in Male Infants and Adolescents: New Androgen Formulations

BACKGROUND

Male hypogonadism may be associated with micropenis and cryptorchidism in newborn, absent or incomplete pubertal development when it occurs during childhood. During puberty, androgen replacement therapy plays a pivotal role in subjects with hypogonadism to induce sexual maturation, growth acceleration, anabolic effects on fat-free mass growth increasing muscle strength, directly and indirectly on the attainment of peak bone mass in young men. Moreover, in newborns with congenital hypogonadism, androgen therapy could be effective to increase genital size.

SUMMARY

Testosterone replacement therapy (TRT) represents the cornerstone of the management of hypogonadism in boys. During puberty, replacement therapy needs to be modulated with gradual dosing increase to better mimic the physiologic pubertal development. Currently, intramuscular testosterone (T) esters (in particular testosterone enanthate) and subcutaneous T pellets are the only formulations approved by the US Food and Drug Administration for delayed puberty, while no preparation is approved for long-term use in the adolescent age. Several new T formulations (as transdermal, nasal, subcutaneous, and oral formulation) are recently developed to improve the pharmacokinetic profile and to ease the administration route increasing patient compliance in adult males with hypogonadism. All these formulations are not approved for pediatric age, although some of them are used as "off-label" regimens. This special issue is aimed to illustrate new T formulations and their potential role as replacement therapy in the pediatric population, as well as to highlight investigational areas to contribute to health care improvement in these patients.

KEY MESSAGES

Despite the lack of evidence-based guidelines regarding the choice of T formulation in the pediatric population, new formulations appear to have a potential role for TRT in adolescent age. They have been designed for adult age with a little flexibility of dosage, although a few formulations may be attractive for pubertal induction and penile enlargement thanks to their greater flexibility and easing of administration. On the other hand, long-acting and stable formulations could meet post-pubertal needs, increasing TRT compliance in a critical phase as the adolescent age. Further controlled, long-term safety, and efficacy studies for all these new T formulations within the pediatric population are needed.

Pharmacokinetics of testosterone therapies in relation to diurnal variation of serum testosterone levels as men age

Background

To improve symptoms associated with testosterone deficiency, many testosterone therapies are available that aim to restore serum testosterone (T) levels to the normal physiologic range. The magnitude, frequency, and duration between peak and trough T concentrations vary with route of administration, and none reflect normal endogenous daily diurnal T variations.

Objective

To compare pharmacokinetic profiles of serum T from approved T formulations with endogenous diurnal T variations in young and older men, and to consider whether there may be value in mimicking the diurnal T rhythmicity with exogenous testosterone therapies as men age.

Materials and methods

A literature search of studies examining the diurnal variation of endogenous T in healthy men and men with testosterone deficiency was performed using PubMed in January 2020. Additional searches for serum T pharmacokinetic profiles of various testosterone therapy formulations were also conducted. Prescribing information for various T formulations was also reviewed.

Discussion and conclusion

Endogenous diurnal T variation is well described and appears to be blunted naturally as men age. Men with testosterone deficiency lack diurnal T variation and exhibit a flatter T profile compared with eugonadal men. Some T replacement options provide intraday T level variations similar to normal circadian secretion, and others provide a flatter exposure profile reflective of depot release. Others provide profiles that exceed the frequency and physiologic range of the natural diurnal variation of T. All exogenous T replacement dosing targets an increase in average T levels to within the normal physiologic range and improves symptoms associated with low T, but no single testosterone therapy can exactly mimic the normal diurnal T patterns seen in younger men and the blunted circadian T secretion of older men.

Post-market safety and efficacy profile of subcutaneous testosterone enanthate-autoinjector: a cohort analysis

A subcutaneous testosterone enanthate-autoinjector (SCTE-AI) was recently approved by the Food and Drug Administration for patient-administered weekly testosterone replacement therapy (TRT). From January 2019 to October 2019, 110 hypogonadal men were treated with SCTE-AI at two institutions. Patients were assessed in a pretherapy visit prior to receiving SCTE-AI and re-assessed 6 weeks after treatment initiation. Patients with a history of prostate cancer were excluded. Trough serum total testosterone (TT), estradiol (E2), prostate-specific antigen (PSA), and hematocrit (HCT) levels were collected at clinic visits. Therapeutic phlebotomy was recommended for HCT > 54%, and treatment was discontinued for significant increases in PSA as well as for significant treatment-related adverse events. Values from each visit were compared with univariate analysis. 110 patients completed the 6 weeks of observation with a mean age of 40.3 (SD: 10.5). TT significantly rose from 246.6 ng/dL (SD:113.3) pretherapy to 538.4 ng/dL (SD: 209.3) at 6 weeks (p < 0.001). Post-therapy, 101/110 (91.8%) of patients had TT > 300 ng/dL. No patients had HCT > 54%. 74 patients (70.5%) had PSA increase with only 3 (2.9%) experiencing an increase >1.0 ng/dL. There was a significant increase in mean PSA from 1.07 ng/dL (SD: 0.8) pretherapy to 1.18 ng/dL (SD: 0.9) at 6 weeks (p = 0.01). One patient had immediate treatment cessation following diagnosis of prostate cancer. This is the largest non-industry sponsored safety and efficacy profile of SCTE-AI application in urology clinics. After 6 weeks of observation, TT levels increased significantly without any reports of adverse events. SCTE-AI is a safe and effective alternative delivery system of TRT.

Late-onset hypogonadism: Clinical evidence, biological aspects and evolutionary considerations

The growing life expectancy in modern societies has raised scientific interest in identifying medical interventions to alleviate age-associated pathologies such as vascular calcification, cognitive decline, sarcopenia, osteoporosis and sexual dysfunction. Although no such single treatment has thus far been established in humans, some clinicians and patients have set their hopes on testosterone replacement therapy (TRT) as a potential "fountain of youth" for aging men. While TRT has proven effective in ameliorating distinct symptoms of late-onset hypogonadism (LOH), its safety remains to be demonstrated. Besides humans, multiple other species exhibit age-related reductions in circulating testosterone levels, raising the question whether such changes are an inherent, pathological feature of growing organismal age or rather reflect an adaptive response. In this manuscript, we apply key principles of evolutionary medicine to testosterone biology and LOH to provide a novel perspective on these two fields. Additionally, we discuss insightful data derived from the animal kingdom to illustrate the plasticity of individual testosterone trajectories across the lifespan, outline cost-benefit-considerations of TRT in LOH and highlight potential caveats of such therapies.

Testosterone Use in Adolescent Males: Current Practice and Unmet Needs

Testosterone replacement therapy (TRT) is routinely prescribed in adolescent males with constitutional delay of growth and puberty (CDGP) or hypogonadism. With many new testosterone (T) formulations entering the market targeted for adults, we review current evidence and TRT options for adolescents and identify areas of unmet needs. We searched PubMed for articles (in English) on testosterone therapy, androgens, adolescence, and puberty in humans. The results indicate that short-term use of  T enanthate (TE) or oral  T undecanoate is safe and effective in inducing puberty and increasing growth in males with CDGP. Reassuring evidence is emerging on the use of transdermal  T to induce and maintain puberty. The long-term safety and efficacy of TRT for puberty completion and maintenance have not been established. Current  TRT regimens are based on consensus and expert opinion, but evidence-based guidelines are lacking. Limited guidance exists on when and how  T should be administered and optimal strategies for monitoring therapy once it is initiated. Only  TE and  T pellets are US Food and Drug Administration approved for use in adolescent males in the United States. Despite the introduction of a wide variety of new  T formulations, they are designed for adults, and their metered doses are difficult to titrate in adolescents. In conclusion, TRT in adolescent males is hindered by lack of long-term safety and efficacy data and limited options approved for use in this population. Additional research is needed to identify the route, dose, duration, and optimal timing for TRT in adolescents requiring androgen therapy.

Testosterone Therapy and Cardiovascular Risk: A Critical Analysis of Studies Reporting Increased Risk

BACKGROUND

Treatment of "adult-onset hypogonadism" (AOH) with exogenous testosterone therapy (TTh) to raise serum testosterone (T) levels may influence cardiovascular (CV) risk factors in patients with AOH, whereas low endogenous T levels are associated with an increased CV risk and mortality.

AIM

To critically evaluate studies reporting increased CV risk associated with TTh and to provide an overview of the risks and benefits of restoring T levels through exogenous TTh.

METHODS

A review of publications focusing on the association between TTh and increased CV risk was conducted, and the study methodologies and conclusions of each were critically evaluated. Further, recent clinical and epidemiological studies associating AOH or TTh with a change in CV risk, and pertinent hematologic and vascular effects noted in animal studies and in vitro, as well as in clinical practice were also reviewed.

OUTCOMES

A review of the literature shows that untreated testosterone deficiency and/or low T is associated with an increase in CV risk and adverse outcomes, with numerous studies and meta-analyses to support a positive association between exogenous TTh and an improvement in CV risk factors in men with AOH.

RESULTS

Numerous studies in the literature demonstrate the positive benefits of using TTh; however, since 2013, some publications have suggested a link to increased CV risk associated with TTh. A number of these studies retrospectively analyzed insurance claims databases using diagnosis codes, procedures codes, and prescription information. Many reviews published since have pointed out the methodological flaws and debatable conclusions of these studies.

CLINICAL IMPLICATIONS

A careful assessment of the patient's current health status and CV risk factors should be weighed against the benefits and possible risks resulting from TTh, and consideration should be given to deferring treatment pending resolution or stabilization of CV disease or risk factors.

STRENGTHS & LIMITATIONS

In this review, we provide an in-depth analysis of studies reporting increased CV risk with TTh. Many of the studies were not well-designed, randomized, double-blind, prospective clinical trials but rather post hoc analyses of cohort data. These studies may reflect bias in how treatment and nontreatment decisions are made or reflect conclusions based on widely cited methodological flaws.

CONCLUSION

Appropriate patient selection supported by low pre-treatment T levels and monitoring T levels during treatment with the goal of achieving and maintaining physiologic levels all contribute to the safe and effective use of TTh in men with AOH. Khera M, Miner M, Jaffe J, et al. Testosterone Therapy and Cardiovascular Risk: A Critical Analysis of Studies Reporting Increased Risk. J Sex med 2021;18:83-98.

Pharmacokinetics and Acceptability of Subcutaneous Injection of Testosterone Undecanoate

Context

Can injectable testosterone undecanoate (TU) be administered effectively and acceptably by the subcutaneous (SC) route?

Objective

To investigate the acceptability and pharmacokinetics (PK) of SC injection of TU.

Design

Randomized sequence, crossover clinical study of SC vs IM TU injections.

Setting

Ambulatory clinic of an academic andrology center.

Participants

Twenty men (11 hypogonadal, 9 transgender men) who were long-term users of TU. injections. Intervention: Injection of 1000 mg TU (in 4 mL castor oil vehicle) by SC or IM route. Main Outcome Measures: Patient-reported pain, acceptability, and preference scales. PK by measurement of serum testosterone, dihydrotestosterone (DHT), and estradiol (E₂) concentrations with application of population PK methods and dried blood spot (DBS) sampling.

Results

Pain was greater after SC compared with IM injection 24 hours (but not immediately) after injection but both routes were equally acceptable. Ultimately 11 preferred IM, 6 preferred SC, and 3 had no preference. The DBS-based PK analysis of serum testosterone revealed a later time of peak testosterone concentration after SC vs IM injection (8.0 vs 3.3 days) but no significant route differences in model-predicted peak testosterone concentration (8.4 vs 9.6 ng/mL) or mean resident time (183 vs 110 days). The PK of venous serum testosterone, DHT, and E₂ did not differ according to route of injection.

Conclusions

We conclude that SC TU injection is acceptable but produces greater pain 24 hours after injection that may contribute to the overall majority preference for the IM injection. The PK of testosterone, DHT, or E₂ did not differ substantially between SC and IM routes. Hence whereas further studies are required, the SC route represents an alternative to IM injections without a need to change dose for men for whom IM injection is not desired or recommended.

Clinical Management of Congenital Hypogonadotropic Hypogonadism

The initiation and maintenance of reproductive capacity in humans is dependent on pulsatile secretion of the hypothalamic hormone GnRH. Congenital hypogonadotropic hypogonadism (CHH) is a rare disorder that results from the failure of the normal episodic GnRH secretion, leading to delayed puberty and infertility. CHH can be associated with an absent sense of smell, also termed Kallmann syndrome, or with other anomalies. CHH is characterized by rich genetic heterogeneity, with mutations in >30 genes identified to date acting either alone or in combination. CHH can be challenging to diagnose, particularly in early adolescence where the clinical picture mirrors that of constitutional delay of growth and puberty. Timely diagnosis and treatment will induce puberty, leading to improved sexual, bone, metabolic, and psychological health. In most cases, patients require lifelong treatment, yet a notable portion of male patients (∼10% to 20%) exhibit a spontaneous recovery of their reproductive function. Finally, fertility can be induced with pulsatile GnRH treatment or gonadotropin regimens in most patients. In summary, this review is a comprehensive synthesis of the current literature available regarding the diagnosis, patient management, and genetic foundations of CHH relative to normal reproductive development.

Pharmacokinetics, safety, and patient acceptability of subcutaneous versus intramuscular testosterone injection for gender-affirming therapy: A pilot study

PURPOSE

Results of a study comparing testosterone exposure and tolerability with subcutaneous versus i.m. administration are presented.

METHODS

In a prospective, open-label, crossover study, adult participants already on stable i.m. testosterone gender-affirming therapy self-injected testosterone cypionate or enanthate i.m. for 3 weeks followed by subcutaneous injections for 8 weeks. Trough serum testosterone concentrations were determined weekly, and serial total serum testosterone (TST) concentrations were determined on postinjection days 1, 3, and 5 of weeks 3 and 11. Hemoglobin and alanine transaminase (ALT) levels were measured at week 3 (the first visit), with repeat measurements at week 11 (the final visit). The dose-normalized area under the time-concentration curve (AUC) was calculated during weeks 3 and 11.

RESULTS

Fourteen transgender males (mean age, 30 ± 10 years) participated in the study. The mean hemoglobin values at the first and final visits were 160 ± 9 and 153 ± 9 g/L, respectively (p > 0.05); the mean ALT values were 18 ± 6 and 21 ± 10 IU/L (p > 0.05). Total testosterone exposure was comparable with subcutaneous versus i.m. injection (mean AUC, 1.7 ± 0.6 nmol·days/L/mg versus 1.9 ± 0.6 nmol·days/L/mg; p > 0.05). Information collected via weekly questionnaires indicated that the subcutaneous route was more tolerable, with lower self-reported scores for preinjection anxiety, pain during injection, and postinjection pain.

CONCLUSION

The subcutaneous route for the injection of testosterone was well tolerated and appeared to be as effective as i.m. injection in delivering equivalent TST levels, although there was wide intrapatient and interpatient variability.

Serum Testosterone Concentrations Remain Stable Between Injections in Patients Receiving Subcutaneous Testosterone

Purpose:

Intramuscular (IM) testosterone is the most common modality for testosterone therapy of both male hypogonadism and female-to-male (FTM) gender transition. However, IM injections can be painful and often are not self-administered by the patient. The objective of this study was to further characterize subcutaneous (SC) administration of testosterone as an effective and safe alternative to IM injections by evaluating the pharmacodynamics of serum total and free testosterone concentrations between weekly testosterone injections.

Methods:

Eleven FTM transgender patients already receiving weekly SC testosterone cypionate with documented therapeutic levels prior to enrollment had free and total serum testosterone levels measured at eight different time points during a 1-week dosing interval.

Results:

Mean levels of total and free testosterone were stable and remained well within the normal range between injections. Overall mean ± standard deviation levels for the seven samples taken between injections were 627 ± 206 ng/dL (range, 205 to 1410) for total testosterone and 146 ± 51 pg/mL (range, 38 to 348) for free testosterone. No adverse effects were encountered.

Conclusions:

The results of this study support use of SC testosterone to achieve therapeutic and stable serum testosterone levels for the purpose of gender transition. It is anticipated that these results can be extended to hypogonadal men. This route may be preferred over IM testosterone because it is relatively painless and easy to self-inject thus allowing for the convenience and economy of patient self-administration.

Subcutaneous Injection of Testosterone Is an Effective and Preferred Alternative to Intramuscular Injection: Demonstration in Female-to-Male Transgender Patients

CONTEXT

Testosterone (T) is commonly administered intramuscularly to treat hypogonadal males and female-to-male (FTM) transgender patients. However, these injections can involve significant discomfort and may require arrangements for administration by others.

OBJECTIVE

We assessed whether T could be administered effectively and safely subcutaneously as an alternative to intramuscular (IM) injections.

DESIGN

Retrospective cohort study.

SETTING

Outpatient reproductive endocrinology clinic at an academic medical center.

PATIENTS

Sixty-three FTM transgender patients aged >18 years electing to receive subcutaneous (SC) T therapy for sex transition were included. Fifty-three patients were premenopausal.

INTERVENTION

Patients were administered T cypionate or enanthate weekly at an initial dose of 50 mg. Dose was adjusted if needed to achieve serum total T levels within the normal male range.

MAIN OUTCOME MEASUREMENTS

Serum concentrations of free and total T and total estradiol (E2), masculinization, and surveillance for reactions at injection sites.

RESULTS

Serum T levels within the normal male range were achieved in all 63 patients with doses of 50 to 150 mg (median, 75/80 mg). Therapy was effective across a wide range of body mass index (19.0 to 49.9 kg/m2). Minor and transient local reactions were reported in 9 out of 63 patients. Among 53 premenopausal patients, 51 achieved amenorrhea and 35 achieved serum E2 concentrations <50 pg/mL. Twenty-two patients were originally receiving IM and switched to SC therapy. All 22 had a mild (n = 2) or marked (n = 20) preference for SC injections; none preferred IM injections.

CONCLUSIONS

Our observations indicate that SC T injections are an effective, safe, and well-accepted alternative to IM T injections.

Hormonal and Surgical Treatment Options for Transgender Men (Female-to-Male)

Untreated transgender men face serious negative health care outcomes. Effective medical, surgical, and mental health treatment ameliorates these risks. Although the research is not as robust as would be ideal, hormone treatment is effective and generally well tolerated with few serious medical risks. Surgeries carry serious risks; but for most transgender men, the benefits outweigh the risks. This review describes current evidence-based medical treatments for transgender men and provides an overview of surgical therapy to enable practitioners to discuss these options with their transgender male patients.