Non-scrotal patches solved an acceptability problem and inherited a dermatological one. Ordinary skin is far less permeable than scrotal skin, so getting a therapeutic dose through it required permeation enhancers and sustained occlusion — and both irritate skin.
A note on this page's slug: it names a 48% skin-problem rate. That figure is not stated in the sources cited here, so it is not asserted. It came from unverified material, and this hub drops numbers it cannot attribute rather than softening them. What the literature does establish is the direction of travel, and it is unambiguous.
What the record says
Gels dominate the market for transdermal testosterone replacement therapy, "presumably because of their greater patient acceptability and non-occlusive nature compared with patches."[1]
Read that as a verdict. The two named advantages of gels are both about the patch's failure mode: acceptability, and not being occlusive. A patch works by sealing a reservoir of drug against skin for hours at a time. That seal is the delivery mechanism and the irritation mechanism — they cannot be separated.
Why enhancers were necessary
Testosterone crosses skin poorly. On the scrotum, thin and permeable skin made a passive patch viable. Anywhere else, the flux is too low.
Permeation enhancers close that gap by disrupting the skin's barrier function — which is, by definition, doing something to the stratum corneum. A formulation whose mechanism is "temporarily compromise the barrier, under an occlusive seal, daily" has a predictable dermatological profile.
The pattern across all three generations
Each transdermal generation solved its predecessor's headline complaint and introduced its own:
Scrotal patch — worked pharmacologically; unacceptable site and preparation.
Non-scrotal patch — acceptable site; occlusion and enhancers meant skin reactions.
Gel — non-occlusive and acceptable; introduced the transfer problem, with documented incidences of secondary transfer to children and consequent unwanted effects such as precocious puberty.[1]
There is no free option. The guideline's framing is the right one: weigh pharmacokinetics, patient preference, formulation-specific adverse effects, treatment burden and cost together.[3] "Formulation-specific adverse effects" is doing a lot of work in that sentence, and this series is what it refers to.
Frequently asked questions
What was the actual patch irritation rate? Not asserted here — the specific figure in this page's slug is unverified in the sources cited. The documented point is that gels displaced patches partly because gels are non-occlusive.[1]
Do gels irritate skin? Less occlusion means less of that particular problem, which is the stated reason for their market dominance.[1] Their distinctive risk is transfer to other people.
Are patches still available? Gels dominate the transdermal market.[1] Availability varies by country and product.
Next in this series
Gels took the market. One product did most of the taking.
Continue with the gel that took over.
References
3 sources
- Hadgraft J, Lane ME. Transdermal delivery of testosterone. Eur J Pharm Biopharm. 2015;92:42–48. doi:10.1016/j.ejpb.2015.02.015 · PMID 25709060
- Grabner M, Hepp Z, Raval A, et al. Topical Testosterone Therapy Adherence and Outcomes Among Men With Primary or Secondary Hypogonadism. J Sex Med. 2018;15(2):148–158. doi:10.1016/j.jsxm.2017.11.225 · PMID 29425664
- Bhasin S, Brito JP, Cunningham GR, et al. Testosterone Therapy in Men With Hypogonadism: An Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2018;103(5):1715–1744. doi:10.1210/jc.2018-00229 · PMID 29562364
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