Skin reactions in a phase 3 study of a testosterone topical solution applied to the axilla in hypogonadal men

A new 2% testosterone gel formulation: a comparison with currently available topical preparations

Testosterone gel formulations have become a popular testosterone replacement therapy in patients with hypogonadism since their advent in the year 2000. The gel formulations restore testosterone levels to mid-normal physiological levels (14-17.5 nmol/L) as early as within 24 h, and help alleviate the signs and symptoms of testosterone deficiency, thereby leading to an improved quality of life. Although testosterone gels have a favourable efficacy and safety profile as compared to injectable and patch formulations, risk of secondary exposure poses a challenge. Approved testosterone topical formulations include Tostrex^® (Tostran^® , Fortesta^® ), Androgel^® (Testogel^® ), Testim^® and Axiron^® (solution), which have a favourable efficacy profile and positively impacted patient-reported outcome(s). Besides, Testavan, which is a 2% testosterone gel, is under registration in Europe and already approved in Australia in May 2017. Testavan uses a novel hydroalcoholic and highly viscous topical formulation. This product comes with a metered dose dispenser and a cap applicator that allows a hands-free application for precise dispensing and application. The present article provides a comprehensive review of pharmacokinetic, tolerability and safety profile of the testosterone gels available in the market along with the new 2% testosterone gel, Testavan.

Transdermal delivery of testosterone

Male hypogonadism has been treated with exogenous testosterone since the 1930s. The early transdermal patches of testosterone became available in the 1980s with gel and solution preparations following subsequent decades. This review focusses on the skin permeation characteristics of testosterone, pharmacokinetics following application of transdermal formulations and formulations currently available. At present, gels dominate the market for transdermal testosterone replacement therapy, presumably because of their greater patient acceptability and non-occlusive nature compared with patches. However, specific incidences of secondary transfer of gels to children with consequent unwanted effects such as precocious puberty have been reported. A regulatory review of all testosterone replacement therapies is currently underway which may have implications for future prescribing practices of transdermal testosterone products.

Pharmacological regulation of the cholesterol transport machinery in steroidogenic cells of the testis

Reduced serum testosterone (T), or hypogonadism, is estimated to affect about 5 million American men, including both aging and young men. Low serum T has been linked to mood changes, worsening cognition, fatigue, depression, decreased lean body mass and bone mineral density, increased visceral fat, metabolic syndrome, decreased libido, and sexual dysfunction. Administering exogenous T, known as T-replacement therapy (TRT), reverses many of the symptoms of low T levels. However, this treatment can result in luteinizing hormone suppression which, in turn, can lead to reduced sperm numbers and infertility, making TRT inappropriate for men who wish to father children. Additionally, TRT may result in supraphysiologic T levels, skin irritation, and T transfer to others upon contact; and there may be increased risk of prostate cancer and cardiovascular disease, particularly in aging men. Therefore, the development of alternate therapies for treating hypogonadism would be highly desirable. To do so requires greater understanding of the series of steps leading to T formation and how they are regulated, and the identification of key steps that are amenable to pharmacological modulation so as to induce T production. We review herein our current understanding of mechanisms underlying the pharmacological induction of T formation in hypogonadal testis.

Application site affects the pharmacokinetics of topical testosterone applied to the axilla compared with the inner arm

PURPOSE

This study compared the pharmacokinetics of a single dose of 1% testosterone solution after application to the inner arm or the axilla as application sites for transdermal testosterone therapy.

METHODS

Healthy, not pregnant, premenopausal women, 18 to 45 years of age with a body mass index of 20 to 28 kg/m(2) were enrolled into a single-center, open-label, randomized, 2-way crossover study. Serum total testosterone (TT), free testosterone (fT), and sex hormone binding globulin concentrations were measured. Pharmacokinetic parameters determined from serum TT and fT included area under the serum concentration versus time curve from time zero (pre-dose) until 72 hours post-dose (AUC0-72), Cmax, and Tmax. Descriptive statistics were performed on serum concentrations of TT and fT for each site. ANOVA was performed on AUC0-72 and Cmax.

FINDINGS

A single-dose application of 1% testosterone solution to the inner arm and the axilla produced clear increases in TT and fT. Slower and lower increases in TT and fT were observed after treatment to the inner arm. Based on baseline-corrected AUC versus time curves, the bioavailability of 1% testosterone solution was increased 2-fold for the axilla compared with the inner arm.

IMPLICATIONS

The absorption of a 1% testosterone solution was significantly greater after application to the axilla than to the inner arm. Study number DDS16; Australian Therapeutic Goods Administration, CTN 2005/158.

Effect of deodorant and antiperspirant use and presence or absence of axillary hair on absorption of testosterone 2% solution applied to men's axillae

INTRODUCTION

Testosterone 2% solution is applied to axillae and is indicated for testosterone replacement therapy in males deficient in endogenous testosterone.

AIM

This open-label crossover study evaluated the effect of deodorant/antiperspirant use and presence or absence of axillary hair on absorption of testosterone solution.

METHODS

Healthy males (N = 30; ≥50 years of age with baseline testosterone <400 ng/dL) were randomized to one of four treatment sequences involving six treatments. Each treatment consisted of one 1.5-mL dose of testosterone 2% solution (30 mg of testosterone) applied to each axilla. Axillae were unshaved or shaved, and were untreated or pretreated with deodorant/antiperspirant.

MAIN OUTCOME MEASURES

Blood samples were taken over 72 hours after each dose for measuring serum testosterone concentrations.

RESULTS

Profiles of mean testosterone concentrations were similar across treatments. For all treatments, area under the concentration-time curve through 24 hours (AUC[0-24] ) and 72 hours (AUC[0-72] ), and maximum total testosterone concentration (Cmax ) were similar except for 15% lower Cmax when treatment was applied after deodorant/antiperspirant to shaved vs. unshaved axillae (least squares mean, 531 ng/dL vs. 626 ng/dL, respectively; P = 0.011). This difference is not considered clinically significant. The 95% confidence intervals for AUC(0-24) , AUC(0-72) , and Cmax fell within the traditional bioequivalence limits of 0.8 to 1.25. Incidence of treatment-emergent adverse events (TEAEs) was low (<15%) in each treatment arm, and most TEAEs were mild.

CONCLUSIONS

Absorption of testosterone 2% solution was unaffected by use of deodorant/antiperspirant or by the presence or absence of axillary hair. Testosterone solution was generally well tolerated.

Diagnosis and treatment of late-onset hypogonadism: systematic review and meta-analysis of TRT outcomes

Late-onset hypogonadism (LOH) is a relatively common conditions affecting the aging male. The aim of this review is to summarize the available evidence regarding LOH and its interaction with general health. LOH is often comorbid to obesity and several chronic diseases. For this reason lifestyle modifications should be strongly encouraged in LOH subjects with obesity, type 2 diabetes mellitus (T2DM) and metabolic syndrome (MetS) and good treatment balance of chronic diseases. Medical therapy of LOH should be individualized depending on the etiology of the disease and the patient's expectations. Available evidence seems to suggest that testosterone replacement therapy is able to improve central obesity (subjects with MetS) and glycometabolic control (patients with MetS and T2DM), as well as to increase lean body mass (HIV, chronic obstructive pulmonary disease), along with insulin resistance (MetS) and peripheral oxygenation (chronic kidney diseases). However, it should be recognized that the number of studies on benefits of T supplementation is too limited to draw final conclusions. Longer and larger studies are needed to better clarify the role of TRT in such chronic conditions.