Transdermal Dosing for Pain Management

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Tim Van Mol, RPh

There are several dosage forms that can be used for pain management.  One that I will share with you today is transdermal dosing, which has many advantages over the more familiar oral form.

Almost everything we swallow in the form of tablets or capsules are metabolized by the liver.  If your body receptor sites “are looking for the drug and seeing the metabolite”, then the drug may not be picked up by the receptor site, and we may not receive the desired therapeutic effect or the full effect we were anticipating.  There is also the potential problem of the stomach acid degrading the orally administered drug excessively, thus requiring us to use a higher dose.  Up to 90% of an oral dosage form may not be available to the body’s receptor sites because of metabolism by the liver.

Local topical application allows us to deliver more drug to the problem site.  We can use a lower dose than the oral dose because the drug is concentrated at the target site, and we are not dependent on a blood plasma concentration.  Since we are using a lower dose topically, we can avoid potential side effects such as GI upset and, most of the time, sedation.

Transdermal medications are also useful when patients have trouble taking medications orally.  The transdermal route can often eliminate the need for injectable therapy.  Since transdermal administration avoids the first pass hepatic (liver) metabolism, this is a great choice for patients with impaired liver function.

We can include multiple drugs in our transdermal cream/gel so that we can target the many factors that can contribute to chronic pain into one dosage application.  Some of the many meds that we can include in transdermal gel or cream dosing include antidepressants, anticonvulsants, antiarrhythmics, anesthetics, antiviral agents, NMDA receptor antagonists, and corticosteroids.

Some forms of chronic pain that transdermal medications are utilized for include: neuropathic (stinging, burning) pain, musculoskeletal pain, fibromyalgia, migraine, rheumatoid arthritis, osteoarthritis, shingles, nausea and vomiting, cancer pain, and Sports Medicine.  Transdermal meds can be used alone or in combination with oral therapy.  This gives a healthcare practitioner another tool in the quest for the treatment of both acute and chronic pain.

When properly compounded into an appropriate base such as a transdermal form, high concentrations in the subcutaneous tissues leads to a successful outcome.  The skills of the compounding pharmacist and the choice of an appropriate base are critical to the success of the compound.  Without a proper base, the compound, when applied, can leave a sticky, greasy feeling and may not absorb properly.

For more information on transdermal dosing, call Van Mol Family Pharmacy at (318) 443-7073.