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Another method of administering testosterone is through transdermal absorption. Testosterone is available as a transdermal delivery system (TDS) in various concentrations for topical application. Testosterone is purchased in raw form (testosterone base) by compounding pharmacies and drug manufactures to be used to create various testosterone products. A specific concentration of testosterone base is then added to a transdermal delivery system either in the form of an alcohol-based gel or transdermal cream. A patient can apply a measured amount of the gel or cream to the skin where a small amount of the hormone penetrates through the skin, absorbing into circulation. When applied on a daily basis, topical testosterone provides 24-hour duration of action, which naturally mimics the rise and fall of testosterone throughout the day.
Types of transdermal delivery systems
Transdermal delivery systems are self-contained dosage forms that, when applied to unbroken skin, are designed to deliver the drug(s) through the skin to systemic circulation. TDS works by diffusion. The drug diffuses from the carrier through the skin into general circulation. Transdermal testosterone products are available in different types of TDS. The most common types of delivery systems used for hormones are in the form of a gel, lotion, cream, or patch. Although each type of delivery system has a different appearance and texture, all of them are designed to deliver the highest concentration of active ingredient deep into the dermis. There are transdermal creams and gels that are also designed to deliver multiple active ingredients at one time. A compounded hormone combination cream is an example of a multi-drug transdermal delivery system (ie. Testosterone 10%+DHEA 10% topical cream). Compounding pharmacies have the ability to compound testosterone using different delivery systems depending on which one is best for the patient. Manufactured brand-name transdermal testosterone products are available only as either a gel or transdermal patch.
Common transdermal testosterone delivery systems
Compounding pharmacies usually carry a variety of TDS bases that can be used to make a transdermal hormone. Many pharmacies manufacture their own TDS formulas and even make improvements to existing base formulas available at the pharmacy supplier. Here is a list of common TDS bases used in transdermal hormone products including testosterone.
Lipoderm®- Transdermal cream base that is designed to deliver multiple medications or hormones through the skin.
HRT Cream base-An oil-in-water emulsion developed for use as a topical or vaginal delivery system in Hormone Replacement Therapy. Primarily used for women, this versatile base can also be used for men. It's highly absorbent and is specially designed with an emollient to help soften skin. Alternatively, this base can be used in a wide variety of other medicated topical applications.
Versabase®- Cosmetic transdermal cream base that is designed to deliver fast absorption of medication. Due to its moisturizing effects on the skin, Versabase ® can be used for both cosmetic and pharmaceutical application.
Hydro-Alcohol Gel-Alcohol is used to solubilize the skin to allow for diffusion of the hormone. Hydro-alcohol gels dry faster than transdermal creams, but can also cause drying of the skin and irritation at the site of application.
All types of TDS listed are available at compounding pharmacies.
Transdermal Testosterone Absorption
Absorption can vary between individuals who apply transdermal testosterone to the skin. The standard measurement of predicted absorption used by compounding pharmacists is at 10%. Roughly 10% of the total dosage of topically applied hormone will penetrate the skin. This means that for every 100mg of testosterone applied only 10mg will actually be absorbed through the skin. Depending on the individual sometimes less is absorbed, therefore it is important to follow up with laboratory testing so that the testosterone dose might be titrated to maximize transdermal absorption.
Men require a daily supply of 7mg-10mg of testosterone to achieve a physiological level in the upper-quartile and to reverse the symptoms of hypogonadism. Using compounded transdermal testosterone appears to be more effective than brand name (manufactured) transdermal testosterone products (Androgel, Testim, etc) for a few reasons. Higher concentrations of testosterone can be achieved in a compounded transdermal. Common strengths found in compounded topical testosterone products range between 5%-20% testosterone. 5% equals a 50mg/ml concentration of testosterone; 7% equals 70mg/ml; 10% equals 100mg/ml; etc. The highest concentration available for most transdermal hormone creams and gels is 20%, or 200mg/ml. More than 20% concentration may result in poor distribution of the testosterone, ‘clumping’ of the ingredients, and reduced absorption of the medication. Most male patients respond best to dosages between 5%-20% applied topically to reach 5mg-10mg absorption. Another reason compounded transdermal testosterone might more effective is due to the ability to provide patients a transdermal delivery system that works best for them. For example, cream based delivery systems apply better to skin in sensitive areas, such as the scrotum or inner thighs. Using an alcohol based gel in these areas can irritate the skin, therefore using a compounded cream is preferred. Some patients who do not experience skin irritation may like the consistency and faster rate of absorption found in gels. Compounding pharmacies can compound either a gel or cream depending on what the prescription calls for. If the type of delivery system is not specified on the prescription, the pharmacy will usually default to either a cream or gel base.
Available transdermal delivery systems for testosterone
Common brand name testosterone products on the market include AndroGel® from AbbVie and Testim® from Endo Pharmaceuticals. AndroGel® is a very expensive, low dose 1% (10mg/ml), testosterone product on the market since July 2000, which provides a safe, alcohol based gel containing testosterone in low physiologic doses. Due to the low concentration, larger amounts are required for adequate testosterone replacement in men. Testim®, released in 2004, seems to have slightly better absorption rate than AndroGel, making it more efficient, but it also has a low concentration of testosterone (1%) therefore the increased absorption rate may not provide significant elevation of total testosterone. Patients have also reported a slight musky odor after applying Testim®. Clinical trials have also proven that testosterone patch called Androderm®, developed by Watson pharmaceuticals in 1985, is another safe form of testosterone replacement. Androderm® is available in two strengths, as either a 2mg or 4mg transdermal patch. Due to the low strength, two patches are often needed to adequately restore testosterone. Patients who use testosterone patches have reported negative experiences including problems with the patch falling off, often when they are physically active. Patients have also reported skin irritation including a rash at the site where the patch is applied. Testosterone is also available at compounding pharmacies who specialize in hormone preparations. Compounding pharmacies have the ability customize topically applied testosterone into different strengths and combinations using a variety of transdermal delivery systems (Lipoderm, HRT, Versabase, alcohol gel). Compounding pharmacies can be used to prescribe a higher concentrated transdermal testosterone which will allow enough of the hormone to be absorbed to maintain a good physiologic level of total testosterone. In addition, testosterone can be compounded using a custom delivery system which will result in minimal skin reactions. Lipoderm, Versabase, and HRT base are delivery systems that can provide maximum bio-availability and penetration of active ingredients while minimizing skin irritation that can occur with alcohol-based gels or transdermal patches.
The higher-dose compounded testosterone creams containing 5% to 20% testosterone have been available by physician’s prescription from any compounding pharmacy specializing in hormone preparations. The cost for compounded testosterone creams are far less expensive than 1% AndroGel® Likewise, cheaper generic alternatives to can be compounded by many pharmacists. A low dose dihydrotestosterone, DHT gel, labeled Andactrim™, also from Solvay, has been available in Europe for almost a decade. Doctors who specialize in bio-identical hormone replacement therapy have been using cream and gel delivery of female hormones for decades.
Compounded testosterone creams create more physiologic testosterone levels, skin reactions are minimal and short-term discontinuation of therapy is possible due to the longer half-life of up to 25 hours. Scrotal application is also convenient and discrete while theoretically producing more DHT than when applied to other locations on the body.
There are different containers that can be used to dispense transdermal hormones. Dispensing syringes of various sizes are commonly used for hormone gels and creams. The hormone is dispensed by depressing the plunger until a measured dose releases from the syringe. Plastic or glass jars can also be used to store medicated transdermal gels and creams. The jar may come with a measuring spoon or the patient can use their finger to apply an estimated amount of hormone. Another common dispensing container is called “Topi-Click”, which looks like a deodorant container. The patient twists the dial at the bottom of the container to dispense a measured dose of transdermal hormone out of the opening at the top. 1 twist (click) of the dial equals 1/4ml of medication. Other containers might be available depending on the pharmacy. If the prescription does not request a specific type of container, then the compounding pharmacy will usually default to one of the more commonly used containers.