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ABSTRACT:
Transdermal therapeutic systems, or transdermal patches, facilitate controlled release of active ingredients through the skin and into the systemic circulation. Drugs administered through such systems escape first pass metabolism and steady state is maintained similar to a continuous intravenous infusion for up to several days. The transdermal route of drug delivery has attracted researchers due to many biomedical advantages associated with it. However, excellent impervious nature of skin is the greatest challenge that has to be overcome for successfully delivering drug molecules to the systemic circulation by this route. This article gives a brief overview over principles behind transdermal drug delivery, as well as the advantages and disadvantages of transdermal therapeutic systems and the recent innovations in the field of transdermal drug delivery and also describes the methods of preparation of different types of transdermal patches, evaluation parameters and some available marketed products.
KEY WORDS: Transdermal drug delivery system, transdermal patches, evaluation of Transdermal system, skin.
INTRODUCTION:
Transdermal therapeutic systems have been designed to provide controlled continuous delivery of drugs via the skin to the systemic circulation. oral treatment involves attainment and maintenance of drug concentration in the body within a therapeutically effective range by introduction of fixed dose at regular intervals due to which drug concentration in the body follow a peak and trough profile leading to a greater chance of adverse effects or therapeutic failure, large amount of drug is lost in vicinity of target organ and close attention is required to monitor therapy to avoid overdosing1-5.
Advantages of Transdermal Drug Delivery
It offers therapeutic benefits such as:
* Sustained delivery of drugs to provide a steady plasma profile, particularly for drugs with short half-lives, control input kinetics and hence reduced systemic side effects.
* Reducing the typical dosing schedule to once daily or even once weekly. * Potential for improved patient compliance.
* Avoidance of the first-pass metabolism effect for drugs with poor oral bioavailability.
* Convenient, patient-friendly option for drug delivery with the potential for flexibility, easily allowing dose changes according to patient needs and the capacity for self-regulation of dosing by the patient.
* Transdermal drug delivery can be used in situations requiring minimal patient cooperation, in situations involving administration of drugs by someone other than the patient.