Androgens in Health and Disease.pdf - E Library

432 Anawalt
osterone levels achieved within 1–2 d after the injection. Intramuscular testosterone is
also the least expensive form of androgen therapy and can be safely administered to
virtually all hypogonadal men, even those patients with bleeding diatheses. Most men
can be taught how to self-administer the intramuscular injections although some men are
too fearful and require either a friend or a health professional to administer the injection.
Although many men tolerate intramuscular testosterone therapy, this regimen does not
provide physiological testosterone replacement, and many hypogonadal men would
strongly prefer a less invasive route of delivery.
Transdermal Testosterone Patch Systems
There are three testosterone patch systems available for hypogonadal men. All of the
patch systems are applied daily in the evening and produce a physiological circadian
rhythm of testosterone levels with peak levels in the early-morning hour and a gradual
decline in serum testosterone levels throughout the day (52). The first patch developed
was Testoderm (Alza, Palo Alto, CA), which is applied to shaved scrotal skin. Scrotal
skin is very thin and vascular and readily absorbs steroid hormones. However, the scrotal
patch has not proven to be a very popular therapy because men object to shaving their
scrota and because Testoderm does not adhere very well. Two nonscrotal systems have
been developed for application to the torso, arms and buttocks (Androderm from Watson,
Corona, CA, USA; Testoderm TTS from Alza, Palo Alto, CA). Both of these patches
may commonly cause a rash although Testoderm TTS might cause a rash less frequently
than Androderm (60).
Transdermal patch systems developed in the 1990s were a major advance for the
treatment of male hypogonadism because they provided a safe, noninvasive mode of
providing physiological androgen replacement. However, transdermal patch systems do
not always provide adequate serum testosterone levels for many hypogonadal men, and
it is very difficult to adjust the dosage. In contradistinction to intramuscular androgen
replacement, testosterone levels must be monitored in men using transdermal patches to
verify that adequate serum testosterone levels have been achieved.
Transdermal Testosterone Gel
A testosterone gel (Androgel; Unimed, Buffalo Grove) has recently been approved
for use in hypogonadal men (53). Its pharmacokinetics are similar to the nonscrotal
patches, but it causes significant skin irritation much less frequently (23,54). The chief
advantages of Androgel are that the dosage may be adjusted more easily than patches and
the gel raises serum testosterone levels formulation more reliably into the upper half of
the normal range. The major drawback of Androgel is the possibility of vicariously
transferring testosterone to female sexual partners and household contacts. This vicarious
transfer of exogenous testosterone to sexual partners and household contacts might
be avoided by showering shortly after applying the testosterone gel. In addition, the
current price of Androgel is exorbitant. As with transdermal testosterone patches, serum
testosterone levels must be monitored in hypogonadal men treated with Androgel.
Oral Androgen Therapy
Unmodified testosterone has a short half-life when ingested orally. Aklylated (at the
17α position), testosterone has a longer half-life. These alkylated androgens may cause
serious hepatoxicity and should not be used in the treatment of hypogonadal men.