Are there different types of testosterone therapy?
There are several different types of available testosterone therapies (Table 19).
Oral Testosterone Therapy
Currently, oral testosterone therapy is not used in the United States. In other countries, an oral form of testosterone (testosterone undecenoate) is available that is well-tolerated and provides more consistent testosterone levels.
Parenteral (Intramuscular) Testosterone Therapy
Parenteral testosterone is inexpensive and safe, but has several disadvantages. Use of parenteral testosterone requires periodic deep intramuscular (IM, into the muscle) injections, usually every 2 to 3 weeks. Use of testosterone injection therapy results in supraphysiologic (higher than normal) levels of testosterone, usually
Table 19. Comparison of Testosterone Replacement Therapies
within 3 days of the shot. These levels steadily decline over the next 10-14 days, with a low level occurring around the time of the next injection. This peak-and-trough effect can affect one's mood, well-being, and sexual interest; in some men, these fluctuations can be disturbing. The risk of developing erythrocytosis (increased number of red blood cells) is 44% with injection therapy compared to only 3-18% with transdermal (gel or patch) therapy. Lastly, high peaks in testosterone levels are associated with negative effects on sperm production, so caution is warranted when treating men who are interested in having children with IM testosterone therapy. The recommended dose of intramuscular testosterone is 200-400 mg every 10-21 days to maintain normal average testosterone levels.
A long-acting form of testosterone, testosterone undecanoate (Nebido, Endo) is approved for use in Europe and is in clinical trials in the United States, awaiting evaluation by the FDA. With this formulation, patients typically require only about four injections per year of 1000 mg/4ml. An advantage of the long-acting formulation is less variability in testosterone levels. Side effects are the same as the other IM testosterone formulations. The two most common side effects are acne and discomfort at the injection site.
Transdermal Testosterone Therapy
Two forms of transdermal testosterone therapy are available: patch and gel.
Transdermal testosterone patch therapy (Testoderm, Testoderm TTS, and Androderm) provides one of the most physiologic restorations of testosterone level— meaning that the therapy brings your testosterone level back to levels resembling the natural amount of testosterone that should be in your body throughout the day. Transdermal testosterone therapy (therapy that enters through the skin) can be given as a scrotal patch or a nonscrotal patch. The limitations of the scrotal patch (Testoderm) make it less appealing: Its use requires shaving the scrotum—and in some men, the scrotum may be too small to apply the patch. The nonscrotal patch (Androderm, Testoderm TTS) must be applied to a nonhairbearing skin surface and one to which pressure is not applied (i.e., you cannot put the patch on your buttocks because pressure would be applied when you sit down). Also, the site of patch placement must be rotated each day.
The testosterone patch is usually applied at bedtime and produces the highest testosterone level in the morning and the lowest level at the time of next patch application; this pattern matches the variation in testosterone levels normally seen over the course of a day. Unlike with the parenteral form of testosterone, the transdermal form has little effect on the blood cell count. The most common side effects of the patch are skin related and may vary from skin irritation to a chemical burn. Application of triamcinolone cream to the skin underneath the patch reservoir decreases the incidence of skin irritation.
The Androderm patch is available in 2.5 mg and 5 mg versions. The usual daily dose is 5 mg, but individual dosing will vary with testosterone levels. The skin patch achieves normal testosterone levels in 67 to 90% of men.
Another form of transdermal testosterone therapy is a topical gel applied to the skin (Androgel, Testim). Gel therapy produces normal testosterone levels in 87% of men. Androgel is available as a 5 g gel packet that delivers 5 mg of testosterone daily. The usual starting dose is 5 g, but the dose may be increased to 7.5 g or 10 g, depending on the individual's original serum testosterone levels. Testim is also a 5 g dose (the gel contains 50 mg of testosterone, but only 10% of it is delivered through the skin); its dose also may be increased to 10 g based on the individual's serum testosterone levels. A testosterone level is usually checked about 2 weeks after starting gel therapy.
Like the patch form of testosterone, the gel is applied once daily. Once applied, it is important to make sure that the gel has completely dried prior to wiping the affected area. You should not shower or swim shortly after the gel is applied. You must also be careful about physical contact when the gel is first applied because it may be absorbed by your partner if it gets onto your partner's skin. The gel therapy is easy to use and does not cause skin irritation, but it is more expensive than some other forms of testosterone therapy.
Striant, a transbuccal form of testosterone therapy has been approved by the FDA. This buccal system contains 30 mg of testosterone and is used twice each day, in the morning and in the evening. This method of testosterone administration most closely mimics the normal daily variation in testosterone levels. Although Striant is easy to use, it may cause some gum irritation. In one study, 97% of men had a normal testosterone level when taking transbuccal therapy.