Androgens play a crucial role in the development and maintenance of male reproductive and sexual functions, body composition, erythropoiesis, muscle and bone health, and cognitive functions. Low levels of circulating androgens in utero can cause disturbances in male sexual development, resulting in congenital abnormalities of the male reproductive tract, such as testicular dysfunction, testicular maldescensus and hypospadias.
Later in life, low testosterone levels may result in reduced male fertility, sexual dysfunction, decreased muscle formation and bone mineralisation, disturbances of fat metabolism and cognitive dysfunction, and overall reduction of quality of life. Testosterone levels decrease slightly as a process of ageing. Risk factors for developing adult-onset hypogonadism are:
- Chronic diseases
- Poor general health.
Testosterone deficiency has been reported to be associated with insulin resistance, inflammation, dyslipidaemia, metabolic syndrome and vascular risk.
The care of testosterone deficient patients should focus on accurate assessment of total testosterone levels, symptoms and signs, as well as proper on treatment monitoring to ensure therapeutic testosterone levels are reached and symptoms are ameliorated.
Transdermal delivery of testosterone represents safe and effective alternative to injectable androgens. Transdermal T normalises serum T levels and reverses the symptoms of androgen deficiency in hypogonadal men.
Testosterone gels restore serum T and E2 concentrations to physiological male ranges with fewer fluctuations of T concentrations. A study by Swerdloff et al examined the pharmacokinetic profiles after one, 30, 90, and 180 days of daily application of two doses of testosterone gel (50mg and 100 mg testosterone in 5g and 10g gel respectively). The 1% hydroalcoholic gel formulation when applied to the upper arms, shoulders and abdomen dried within a few minutes, and about 9%–14% of the testosterone applied was bioavailable.
It was shown that transdermal testosterone gel application can efficiently elevate serum T and free T levels in hypogonadal men into the mid to upper normal range within the first day of application, achieve steady state within a few days, and maintain serum T levels with once daily repeated application. Daily changes in testosterone concentrations are then of similar amplitude to those observed during the circadian rhythm of endogenous testosterone.
The authors conclude that transdermal testosterone gel provided flexibility in dosing with little skin irritation and a low discontinuation rate. When treatment is stopped, testosterone concentrations start decreasing approximately 24 hours after the last dose. Concentrations return to baseline approximately 72 to 96 hours after the final dose.
Similarly, Wang et al concluded that T gel replacement in hypogonadal men led to restoration of serum T and free T into the physiological for adult males range. Sexual function and mood improved rapidly and were sustained with long-term treatment., Increase in lean mass and muscle strength (principally in the legs), and decrease in fat mass, as well as improvement in serum bone markers suggesting increase in bone formation, were observed.
Simple and convenient to use, transdermal gels provide flexibility of dosing, ease of application, good skin tolerability and improvement in physical and metabolic markers in men with consistently low serum testosterone levels.
References available on request.