Androgen replacement in the male: recent studies:

Effects of skin washing on systemic absorption of testosterone in hypogonadal males after administration of 1.62% testosterone gel

OBJECTIVE

The impact of washing on the pharmacokinetics, systemic absorption and residual testosterone on the skin after application of a 1.62% testosterone gel was investigated in an open-label, randomized, three-way crossover study in hypogonadal men.

RESEARCH DESIGN AND METHODS

Twenty-four hypogonadal men (total testosterone <300 ng/dL) applied 5 g of 1.62% gel (81 mg testosterone) once daily to the shoulders/upper arms for 7 days during each of three consecutive treatment periods. On the 7th dosing day of each period, the skin was washed (soap/water) at one of the following times: 2, 6, or 10 hours post-dose. Pharmacokinetic serum samples were collected at baseline, and on days 6 (no washing) and 7 (with washing) of each treatment period. Skin stripping for determination of residual testosterone was also performed on days 6 and 7. A single location on the application site was stripped a total of 10 times. Testosterone was extracted from the tape strips using ethanol, and concentrations were determined using high performance liquid chromatography with diode array detection (HPLC-UV).

MAIN OUTCOME MEASURES

Testosterone C(max), AUC(0-24), average concentration over the dosing interval (C(av)), and safety were assessed.

RESULTS

Washing at 2 and 6 hours caused a 10-14% decrease in AUC(0-24) and C(av), but not C(max). Washing 10 hours after gel application had no effect on C(max), AUC(0-24), or C(av). Skin washing decreased the mean amount of testosterone remaining on the skin surface by at least 81%.

CONCLUSIONS

Washing the site of gel application as soon as 2 hours after application had little impact on bioavailability and was effective in reducing residual testosterone on the skin. This finding may be important to prevent secondary transfer.

STUDY LIMITATIONS

The experimental conditions using uniform timing and procedures for dose administration and washing may not fully reflect real world circumstances. CLINICAL TRIAL REGISTRATION NCT NUMBERS: Study was not registered (first subject enrolled 22 December 2006).

Effect of application site, clothing barrier, and application site washing on testosterone transfer with a 1.62% testosterone gel

OBJECTIVES

To evaluate the effect of application site location, clothing barrier, and application site washing on testosterone transfer from males dosed with 1.62% testosterone gel to female partners.

RESEARCH DESIGN AND METHODS

Open-label, randomized, parallel group, crossover study performed in 24 healthy male/female couples. 2.5 or 5.0 g of gel was applied to upper arms and shoulders or abdomens of male subjects. Skin contact occurred 2 hours after gel application between male and female subjects to compare the effect of wearing or not wearing a t-shirt, washing or not washing before contact, and the effect of differing application sites. Treatments were separated by a 1-week washout period. On each dosing day, 15 minutes of supervised skin contact occurred between the dosed male and female partner. Contact was either abdomen to abdomen (male to female), or upper arms/shoulders (male) to upper arms/shoulders, wrists and hands (female), depending on the male application site. Serum samples were collected from females at baseline and after contact to assess secondary testosterone exposure.

MAIN OUTCOME MEASURES

C(max) (maximum serum concentration), AUC(0-24) (area under serum concentration-time curve from 0-24 hours), and C(av) (time-averaged concentration over 24-hour post-contact period) were assessed. Subjects were monitored for adverse events.

RESULTS

Testosterone exposure (C(av) and C(max)) in females increased by up to 27% (2.5 g) or up to 280% (5.0 g) from baseline after direct skin contact at 2 hours after gel application, although C(av) remained within the female eugonadal range. Transfer from the abdomen was prevented when a t-shirt was worn (2.5-g dose). When the application site was washed before contact, mean C(av) was comparable to baseline, and C(max) was slightly higher (14%). Transfer was higher after direct skin-to-skin contact when the application and contact sites were upper arms/shoulders versus the abdomen. Testosterone concentrations returned to baseline within 48 hours after last skin contact.

CONCLUSIONS

There is a risk of testosterone transfer from males using 1.62% testosterone gel to others who come into direct skin contact with the application site. This can be prevented by covering the application site with a t-shirt (2.5-g dose), or washing the application site before contact.

STUDY LIMITATIONS

Women for these studies were not selected by menopausal status. The study was conducted under circumstances that were intended to simulate exaggerated conditions of contact and may not represent average contact under normal conditions. CLINICAL TRIAL REGISTRATION NCT NUMBERS: Study was not registered (first subject enrolled 28 November 2007).

Testosterone and the prostate: implications for the treatment of hypogonadal men

Late-onset hypogonadism (LOH) and testosterone replacement therapy (TRT) are subjects of much recent research. Because aging men are at risk for benign prostatic hyperplasia (BPH) and prostate cancer, elucidating the relationship between testosterone and these diseases is crucial to ensure its safe administration. It is known that testosterone supplementation may worsen active prostate cancer and that its blockade or removal slows the disease's progression. However, recent studies have attempted to show that, in individuals in whom prostate cancer has been ruled out, TRT may simply restore serum testosterone levels to within normal limits without significant adverse affects on the prostate. Patients undergoing TRT should be monitored carefully for any evidence of prostatic disease.

Testim® 1% testosterone gel for the treatment of male hypogonadism

OBJECTIVE

The aim of this work was to review the pharmacokinetic and clinical profile of Testim (Auxilium Pharmaceuticals, Norristown, Pennsylvania) 1% gel formulation of testosterone for the treatment of male hypogonadism.

METHODS

An English-language search of the medical literature was conducted using PubMed (1998-December 2004) and EMBASE (1998-December 2004). Search terms included ag(e)ing male, male hypogonadism, late-onset hypogonadism, testosterone, testosterone deficiency, testosterone therapy, testosterone replacement therapy, androgen therapy, testosterone gel, and Testim. Bibliographies of retrieved articles were also reviewed.

RESULTS

Five published clinical studies were reviewed. Testim 50 mg showed clear pharmacokinetic differences from AndroGel (known as Testogel in Europe; Unimed Pharmaceuticals, Inc., and Solvay Pharmaceuticals, Inc., Marietta, Georgia) 1% testosterone gel 50 mg, with increases of 30% (90% CI, 8%-57%) and 47% (90% CI, 20%-79%) versus AndroGel, respectively, in AUC(0-24h) for total serum testosterone and free testosterone. In a 30-day study of 638 men with hypogonadism, sexual desire scores and sexual motivation scores increased after Testim treatment at weeks 1, 2, 3, and 4 (each, P < 0.001). During 12 months of treatment with Testim 50 or 100 mg in 371 men with hypogonadism, total serum testosterone levels were raised to and maintained within the normal adult range, lean body mass increased by 2.2 kg (P < 0.001), fat mass fell by 2.1% (P < 0.001), and bone mineral density increased by 2.58% (P < 0.001). Mean scores for sexual desire, performance, motivation, and spontaneous erections were all significantly higher (all, P < 0.001) than at baseline for all time points during 12-month studies of Testim. In 2 studies comparing Testim with different testosterone patches, treatment with the gel resulted in 10-fold fewer application-site reactions than either patch.

CONCLUSIONS

In men with hypogonadism, Testim gel raised and maintained serum testosterone levels to within the normal adult range, alleviated signs and symptoms associated with hypogonadism, and was well tolerated.