Why AndroGel Absorption Varies: The Biology Behind Inconsistent Testosterone Levels
At a glance
- Share of a 1% gel dose that reaches the blood / about 9 to 14% of the testosterone applied [1]
- Site used in the 1% gel study / upper arms, shoulders and abdomen [1]
- Application sites in the Teva gel 1% label / shoulders, upper arms and/or abdomen only [2]
- Sites that label excludes / genitals, chest, armpits, knees or back [2]
- Dose steps in that label / 50, 75 or 100 mg once daily, adjusted by total serum testosterone [2]
- Steady state, per an earlier study cited in the 1% gel report / 48 to 72 hours after the first application [1]
- 1% versus 1.62% gel / different dosage and administration [2]
How much reaches the blood?
Swerdloff and colleagues gave 227 hypogonadal men a 1% hydroalcoholic testosterone gel at 50 mg or 100 mg (5 g or 10 g of gel, delivering 5 mg or 10 mg of testosterone a day), or a testosterone patch [1]. The gel went on the upper arms, shoulders and abdomen and dried within a few minutes, and about 9 to 14% of the testosterone applied was bioavailable [1].
The study reports average levels for treatment groups; it does not identify which skin factors account for an individual's result [1].
Serum testosterone rose into the normal adult male range on day 1, and average total and free testosterone were very similar on days 30, 90 and 180 of daily dosing [1]. The researchers reported that an earlier study had found steady state levels 48 to 72 hours after the first gel application [1].
What the 1% gel label says
The Teva testosterone gel 1% label is not AndroGel's. It says to apply the gel to clean, dry, intact skin of the shoulders and upper arms and/or abdomen, and not to the genitals, chest, armpits, knees or back [2]. It also states that dosage and administration for the 1% gel differ from testosterone gel 1.62%, and that topical testosterone products may have different doses, strengths or application instructions that may result in different systemic exposure [2].
Does raising the dose reliably raise levels?
In the same study, the dose was raised from 50 to 75 mg a day, or lowered from 100 to 75 mg, after 90 days when pre-application serum testosterone sat outside the normal adult male range [1]. Raising the dose from 50 to 75 mg a day did not significantly increase the average serum concentration, while lowering it from 100 to 75 mg reduced levels to the normal range for most men [1]. Average concentration in the 100 mg group was 1.4 times that of the 50 mg group and 1.9 times that of the patch group [1].
In TRAVERSE, the cardiovascular safety trial that used 1.62% testosterone gel, the dose was adjusted to keep serum testosterone between 350 and 750 ng/dL [3].
Frequently asked questions
Why might testosterone levels differ on the same AndroGel dose?
Is the 1.62% gel absorbed the same way as the 1% gel?
How fast does a 1% gel dose dry on the skin?
References
- Swerdloff RS, Wang C, Cunningham G, Dobs A, Iranmanesh A, Matsumoto AM, et al. Long-term pharmacokinetics of transdermal testosterone gel in hypogonadal men. J Clin Endocrinol Metab. 2000;85(12):4500-10. Long-term pharmacokinetics of transdermal testosterone gel in hypogonadal men
- U.S. National Library of Medicine, DailyMed. Testosterone gel 1% topical (Teva) prescribing information. Testosterone gel 1% topical (Teva) label
- Lincoff AM, Bhasin S, Flevaris P, Mitchell LM, Basaria S, Boden WE, et al. Cardiovascular Safety of Testosterone-Replacement Therapy. N Engl J Med. 2023;389(2):107-117. Cardiovascular Safety of Testosterone-Replacement Therapy