Pharmacokinetics and Acceptability of Subcutaneous Injection of Testosterone Undecanoate

Androgen Inhibition of Reproductive Neuroendocrine Function in Females and Transgender Males

Ovarian function is controlled by pituitary secretion of luteinizing hormone (LH) and follicle stimulating hormone (FSH), which in turn are governed by gonadotropin releasing hormone (GnRH) secreted from the brain. A fundamental principle of reproductive axis regulation is negative feedback signaling by gonadal sex steroids back to the brain to fine-tune GnRH and gonadotropin secretion. Endogenous negative feedback effects can be mimicked by exogenous steroid treatments, including androgens, in both sexes. Indeed, a growing number of clinical and animal studies indicate that high levels of exogenous androgens, in the typically male physiological range, can inhibit LH secretion in females, as occurs in males. However, the mechanisms by which male-level androgens inhibit GnRH and LH secretion still remain poorly understood, and this knowledge gap is particularly pronounced in transgender men (individuals designated female at birth but identifying as male). Indeed, many transgender men take long-term gender-affirming hormone therapy that mimics male-level testosterone levels. The impact of such gender-affirming testosterone on the reproductive axis, both at the ovarian and neuroendocrine level, is a long-understudied area that still requires further investigation. Importantly, the few concepts of androgen actions in females mostly come from studies of polycystic ovary syndrome, which does not recapitulate a similar androgen milieu or a pathophysiology of inhibited LH secretion as occurs in testosterone-treated transgender men. This review summarizes clinical evidence indicating that exogenous androgens can impair neuroendocrine reproductive function in both female individuals and transgender men and highlights emerging experimental data supporting this in recently developed transgender rodent models.

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.

Safety Aspects and Rational Use of Testosterone Undecanoate in the Treatment of Testosterone Deficiency: Clinical Insights

Testosterone deficiency is diagnosed by a serum total testosterone level below 300 ng/dL in combination with symptoms such as decreased energy and libido. These symptoms can be ameliorated by restoring serum testosterone to the physiologic range with testosterone therapy (TT). There are numerous forms of testosterone therapy, such as injectable, transdermal, nasal, and subcutaneous applications. There are also multiple formulations of injection, such as testosterone cypionate, testosterone enanthate, and testosterone undecanoate. Testosterone undecanoate (TU) is a long-acting ester formulation of testosterone that can be provided in an injectable or oral form. Oral testosterone undecanoate is marketed as Andriol, Jatenzo, Tlando, and Kyzatrex. Oral TU provides a convenient option for many patients, which may increase compliance with TT. Injectable testosterone undecanoate is marketed as Aveed and Nebido. Injectable TT remains the most cost-effective therapeutic option and is appropriate for most patients as an initial therapy. This review describes the pharmacokinetics of these testosterone undecanoate products and provides a guide for prescribers using these medications. While many forms of testosterone are appropriate for TT, a patient-centered discussion focused on goals of care should best guide physician prescription of these medications.

Is Oral Testosterone the New Frontier of Testosterone Replacement Therapy?

Male hypogonadism is a condition in which the body does not produce enough testosterone, resulting in symptoms such as depressed mood, decreased sex drive, decreased skeletal muscle, and increased fat mass. Male hypogonadism can be readily treated with many available treatments when clinically indicated. The advent of readily available testosterone therapy has increased the importance of finding the most efficacious and cost-efficient treatment modality to approach these patients. Testosterone is typically administered through intramuscular or subcutaneous injections, topical gels, and oral tablets. The efficacy of testosterone therapy on hypogonadal men has been widely studied. However, there has been little research done comparing each modality against each other. This paper seeks to compare the various modalities of testosterone replacement therapy using various parameters such as the beneficial effects on bone mineral density, skeletal muscle mass, fat mass, and libido while simultaneously weighing the distinct undesirable side effects of each form of administration. Our investigation analyzes the methodology and results of the existing research within this field. It aims to draw a nuanced conclusion about the current standard of care for testosterone replacement therapy. According to our research and statistical analyses, we have concluded that oral administration has shown to be as advantageous as other modalities for male hypogonadism. Currently, injectables are the modality of choice, but with the right improvements, oral administration can potentially overtake injectables and transdermal testosterone as the treatment of choice.

Occurrence of pulmonary oil microembolism (POME) with intramuscular testosterone undecanoate injection: literature review

Testosterone undecanoate injections (TU), an oil-based depot, is a universal hormonal-based treatment which has been associated with pulmonary oil microembolism (POME). However, the rate of POME during routine intramuscular (IM) TU injection is unknown. Here, we conduct a peer-reviewed literature review investigating POME incidents in the setting of TU injections. A total of 48 articles were selected in the literature review, which included 29 studies that used TU and reported its effects. Relatively few POME cases were reported across multiple published studies, including those that focused particularly on the occurrence rate of POME while administrating IM TU. Of the 29 individual studies, which included 7 978 patients, eight studies reported a total of 88 incidence of POME cases or cough. This included episodes of cough that were not originally declared as POME. One post market review reported 223 cases per 3,107,652 injections. When POME did occur, almost all cases resolved spontaneously within 60 min without intervention. Overall, POME was observed to be rare.

An Approach to the Patient With Delayed Puberty

Pediatric endocrinologists often evaluate and treat youth with delayed puberty. Stereotypically, these patients are 14-year-old young men who present due to lack of pubertal development. Concerns about stature are often present, arising from gradual shifts to lower height percentiles on the population-based, cross-sectional curves. Fathers and/or mothers may have also experienced later than average pubertal onset. In this review, we will discuss a practical clinical approach to the evaluation and management of youth with delayed puberty, including the differential diagnosis and key aspects of evaluation and management informed by recent review of the existing literature. We will also discuss scenarios that pose additional clinical challenges, including: (1) the young woman whose case poses questions regarding how presentation and approach differs for females vs males; (2) the 14-year-old female or 16-year-old young man who highlight the need to reconsider the most likely diagnoses, including whether idiopathic delayed puberty can still be considered constitutional delay of growth and puberty at such late ages; and finally (3) the 12- to 13-year-old whose presentation raises questions about whether age cutoffs for the diagnosis and treatment of delayed puberty should be adjusted downward to coincide with the earlier onset of puberty in the general population.

Point-of-Care Ultrasound Identifies Pyomyositis Secondary to Intramuscular Testosterone Injection: Report of Two Cases

BACKGROUND

Intramuscular (i.m.) injections are a commonly utilized route for medication delivery. Intramuscular-associated soft tissue infections are rare and can include pyomyositis and i.m. abscess. Intramuscular testosterone injections have not been previously implicated in causing pyomyositis. Point-of-care ultrasound is an important bedside tool that can identify pyomyositis and differentiate this infection from more common entities such as cellulitis.

CASE REPORTS

We present two cases of i.m. testosterone-associated pyomyositis. In both cases, the physical examination features were consistent with simple cellulitis. However, point-of-care ultrasound evaluation revealed changes consistent with pyomyositis in each case. WHY SHOULD AN EMERGENCY PHYSICIAN BE AWARE OF THIS?: Although uncommon, i.m. injections such as testosterone carry a risk of soft tissue infection. As demonstrated in the above cases, ultrasound can be helpful in making the differentiation between simple cellulitis and pyomyositis. The emergency physician should be cognizant of this complication of therapeutic i.m. injections, as well as the diagnostic efficacy of point-of-care ultrasound in evaluating the extent and location of the soft tissue infection.

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.

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.

Optimal injection interval for testosterone undecanoate treatment of hypogonadal and transgender men

OBJECTIVE

To define the optimized inter-injection interval of injectable testosterone undecanoate (TU) treatment for hypogonadal and transmen based on individual dose titration in routine clinical practice.

DESIGN AND METHODS

A prolective observational study of consecutive TU injections in men undergoing testosterone replacement therapy for pathological hypogonadism or masculinization of female-to-male transgender (transmen) subject to individual dosing titration to achieve a stable replacement regimen.

RESULTS

From 2006 to 2019, 6899 injections were given to 325 consecutive patients. After excluding the 6-week loading dose, 6300 injections were given to 297 patients who had at least three and a median of 14 injections. The optimal injection interval (mean of last three injection intervals) had a median of 12.0 weeks (interquartile range 10.4-12.7 weeks). The interval was significantly influenced by age and body size (body surface area, BSA) but not by diagnosis or trough serum LH, FSH, and SHBG. Longer (≥14 weeks; 68/297, 23%), but not shorter (≤10 weeks; 22/297, 7.4%), intervals were weakly correlated with age but not diagnosis or other covariables. Low blood hemoglobin increased with trough serum testosterone to reach plateau once testosterone was about 10 nmol/L or higher.

CONCLUSION

Optimal intervals between TU injection after individual titration resulted in the approved 12-week interval in 70% of patients with only minor influence for clinical application of BSA and not of trough serum LH, FSH, and SHBG. Individually optimized inter-injection interval did not differ between men with primary or secondary hypogonadism or transmen.

Androgen Treatment in Adolescent Males With Hypogonadism

During adolescence, androgens are responsible for the development of secondary sexual characteristics, pubertal growth, and the anabolic effects on bone and muscle mass. Testosterone is the most abundant testicular androgen, but some effects are mediated by its conversion to the more potent androgen dihydrotestosterone (DHT) or to estradiol. Androgen deficiency, requiring replacement therapy, may occur due to a primary testicular failure or secondary to a hypothalamic–pituitary disorder. A very frequent condition characterized by a late activation of the gonadal axis that may also need androgen treatment is constitutional delay of puberty. Of the several testosterone or DHT formulations commercially available, very few are employed, and none is marketed for its use in adolescents. The most frequently used androgen therapy is based on the intramuscular administration of testosterone enanthate or cypionate every 3 to 4 weeks, with initially low doses. These are progressively increased during several months or years, in order to mimic the physiology of puberty, until adult doses are attained. Scarce experience exists with oral or transdermal formulations. Preparations containing DHT, which are not widely available, are preferred in specific conditions. Oxandrolone, a non-aromatizable drug with higher anabolic than androgenic effects, has been used in adolescents with preserved testosterone production, like Klinefelter syndrome, with positive effects on cardiometabolic health and visual, motor, and psychosocial functions. The usual protocols applied for androgen therapy in boys and adolescents are discussed.

Dried blood spots in doping analysis

A series of dried blood spot (DBS) detection methods for doping agents have been developed in the last two decades. The DBS technique minimizes invasiveness and reduces storage and shipping costs. Recently, the World Anti-Doping Agency announced the use of DBS for the 2022 Beijing Winter Olympic Games and Paralympic Games owing to the advantages of the DBS application in routine doping control. Therefore the further development of detection methods for doping agents in DBS is important and urgent. This review summarizes five aspects of DBS application in doping analysis: sample collection, storage conditions, pretreatment, instrumentation and validation according to the Prohibited List issued by the World Anti-Doping Agency, and proposes some suggestions for future studies of DBS in doping analysis.

Medical transition for gender diverse patients

Purpose of review

The purpose of this review is to provide an up-to-date overview of gender-affirming hormone therapy, including the various hormone regimens available, the efficacy and potential risks of these treatments, and considerations for surveillance and long-term care.

Recent findings

Recent studies reaffirm that hormone therapy has positive physical and psychological effects for many transgender individuals. The overall risks of treatment are low. Transgender women may have an increased risk of venous thromboembolism and breast cancer based on recent cohort studies, but these findings have yet to be confirmed with randomized controlled trials. Important long-term considerations include metabolic, cardiovascular, and skeletal health.

Summary

High-quality, long-term studies on the effectiveness and safety of various gender-affirming hormone treatment regimens are lacking, but the currently available evidence suggests that it is overall safe and effective with appropriate oversight.