The benefits, risks, and contraindications of the transdermal contraceptive patch are generally similar to those of combined hormonal oral contraceptives. Both methods offer highly effective, reversible, noncoital-based contraception, but are subject to adverse estrogen-related side effects. However, transdermal hormonal contraceptive systems offer several potential advantages to oral contraceptive pills:
- Therapeutic effects are achieved at lower peak doses since first-pass hepatic metabolism and enzymatic degradation in the gastrointestinal tract are avoided.
- Plasma hormone levels remain constant (peaks and troughs do not occur).
- Sustained drug delivery reduces the need for frequent self-administration, and thus may improve patient compliance.
- The nonoral route of administration is useful for patients who have difficulty swallowing pills.
- Immediate cessation of drug administration is possible with removal of the transdermal system.
Although data are limited, there is a possibility of an increased risk of venous thromboembolism (VTE) in patch users compared to users of estrogen-progestin oral contraceptives.
Of note, the US Food and Drug Administration (FDA) has issued a warning to providers and consumers about on-line sales of counterfeit contraceptive patches, as well as other drugs .
STRUCTURE AND PHARMACOLOGY
The transdermal contraceptive patch is a matrix system consisting of a thin 20 cm2 square. It is composed of three layers: the outer layer is water-resistant and protects the underlying layer from the environment, the middle layer is medicated and adhesive, and the inner layer is a clear release liner which is removed before patch application.