Optimizing transdermal drug therapy.

PURPOSE: The pharmacokinetics, benefits, risks, and future of transdermal drug products are reviewed.
SUMMARY: Transdermal drug delivery capitalizes on an attractive route of drug delivery, as it avoids the need for painful i.v. drug administration, i.v. site access, and syringe disposal and is an option for drug delivery to patients who are unable to swallow oral medications. Specific transdermal drug designs have advantages and disadvantages, including the ability to alter the patch size or readily manipulate the products. Transdermal drug delivery systems currently available include drug reservoir and microreservoir membrane-modulated systems, drug-in-adhesive layer designs, and matrix patches. Maximizing patient response to transdermal drug formulations may also rely on a number of other practical concerns, including patient dexterity, dose reproducibility, storage and stability of the remaining portion, and decreased adhesive efficacy. Adhesives in transdermal precuts may be locally irritating, and prolonged use and high dosages have resulted in dermatological reactions to some patches. Patients may also develop contact sensitization or systemic sensitization to the transdermal formulation itself. When a transdermal product regimen is initiated, caregivers should be mindful of the product's primary features and educate patients accordingly, specifically addressing where and how to apply the patch, duration of patch use, and procedures for properly changing and storing patches.
CONCLUSION: The increasing complexity of transdermal drug products, the growing number of medications available in such dosage forms, and reports of potential safety concerns contribute to the need for clinicians to understand the principles of transdermal drug delivery, safe usage techniques, and proper patient counseling points.