SPL Set ID: 7adfc439-e6d0-4593-87dd-0eef36d33c6d

Clonidine transdermal system, USP is a transdermal system providing continuous systemic delivery of clonidine for 7 days at an approximately constant rate. Clonidine is a centrally acting alpha-agonist hypotensive agent. It is an imidazoline derivative with the chemical name 2-[(2,6-Dichlorophenyl)imino]imidazolidine and has the following chemical structure: Meets USP Drug Release Test 3. System Structure and Components Clonidine transdermal system is a multi-layered film, 0.25 mm thick, containing clonidine as the active agent. The system areas are 3.33 cm 2 (0.1 mg/day), 6.67 cm 2 (0.2 mg/day), and 10.0 cm 2 (0.3 mg/day) and the amount of drug released is directly proportional to the area (see DESCRIPTION: Release Rate Concept ). The composition per unit area is the same for all three doses. Proceeding from the visible surface towards the surface attached to the skin, there are three consecutive layers: 1) a backing layer of pigmented polyethylene and polyester film, 2) a solid matrix reservoir of clonidine, mineral oil, polyisobutylene, and colloidal silicon dioxide, 3) an adhesive formulation of clonidine, mineral oil, polyisobutylene, and colloidal silicon dioxide. Prior to use, a protective slit release liner of polyester that covers the adhesive formulation layer is removed. Clonidine transdermal systems are packaged with additional pieces of protective film above and below the system within each pouch. These pieces of protective film are removed and discarded at the time of use. Cross Section of the System: Clonidine Cross Section Release Rate Concept Clonidine transdermal system is programmed to release clonidine at an approximately constant rate for 7 days. The energy for drug release is derived from the concentration gradient existing between the patch and the much lower concentration prevailing in the skin. Clonidine flows in the direction of the lower concentration at a constant rate. Following system application to intact skin, clonidine in the adhesive formulation layer saturates the skin site below the system. Clonidine from the patch then begins to flow into the systemic circulation via the capillaries beneath the skin. Therapeutic plasma clonidine levels are achieved 2 to 3 days after initial application of clonidine transdermal system. The 3.33, 6.67, and 10.0 cm 2 systems deliver 0.1, 0.2, and 0.3 mg of clonidine per day, respectively. To ensure constant release of drug for 7 days, the total drug content of the system is higher than the total amount of drug delivered. Application of a new system to a fresh skin site at weekly intervals continuously maintains therapeutic plasma concentrations of clonidine. If the clonidine transdermal system is removed and not replaced with a new system, therapeutic plasma clonidine levels will persist for about 8 hours and then decline slowly over several days. Over this time period, blood pressure returns gradually to pretreatment levels. Clonidine Structural Formula