Description
Nitroglycerin is 1,2,3-propanetriol, trinitrate, an organic nitrate whose structural formula is:
and whose molecular weight is 227.09. The organic nitrates are vasodilators, active on both arteries and veins.
The nitroglycerin transdermal system is a flat unit designed to provide continuous controlled release of nitroglycerin through intact skin.
The rate of release of nitroglycerin is linearly dependent upon the area of the applied system; each cm2 of applied system delivers approximately 0.026 mg of nitroglycerin per hour. Thus, the 4 cm2, 8 cm2, 16 cm2 and 24 cm2 systems deliver approximately 0.1 mg, 0.2 mg, 0.4 mg and 0.6 mg of nitroglycerin per hour, respectively.
The remainder of the nitroglycerin in each system serves as a reservoir and is not delivered in normal use. After 12 hours, for example, each system has delivered approximately 11% of its original content of nitroglycerin.
The nitroglycerin transdermal system comprises two layers as shown below. Proceeding from the visible surface towards the surface attached to the skin, these layers are: 1) a polyolefin film backing layer that is impermeable to nitroglycerin and is printed with the name of the drug and strength; 2) nitroglycerin in an acrylic pressure sensitive adhesive. Prior to use, a peelable polyester release liner, which is coated on one side with silicone, is removed from the adhesive surface. Each unit is sealed in a foil-lined pouch.
Cross section of the system: