Practical considerations for optimal transdermal drug delivery

PURPOSE

The properties of various transdermal drug delivery system (TDDS) products are reviewed, with safety recommendations and guidance on addressing questions frequently posed by patients and caregivers.

SUMMARY

Drug delivery via a TDDS can offer many advantages over other methods of administration, but those benefits can be compromised by improper use or alteration of medication patches or a lack of awareness of the properties of different patch types (reservoir, matrix, drug-in-adhesive). To assess current TDDS technologies and recommended practices for safe and effective use of medication patches, a literature search for articles on commonly used TDDS products available in the United States was conducted; supplemental information was obtained from package inserts and through direct communication with manufacturers. In addition to recommendations on the site and duration of TDDS application and proper patch disposal, clinicians must consider (1) potential problems with cutting patches as a method of dosage adjustment, (2) safety concerns related to the electric conductivity of metal-containing patches, (3) appropriate strategies for managing patch adhesion failures, and (4) the advisability of writing on patches for medication safety or compliance reasons. Clinicians should also be prepared to counsel patients about TDDS-specific recommendations on the avoidance of sunlight and other external heat sources during the use of a medication patch.

CONCLUSION

Practical considerations related to transdermal drug delivery include the appropriateness of cutting patches, the implications of their containing metallic components, and whether they may be covered with tape or written on. Manufacturers of patches provide some useful information on these topics.

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.