Nitro-Dur® system

The Nitro-dur system, marketed by Key Pharmaceuticals, Inc., contains nitroglycerin in acryUc-based polymeric adhesives with a cross-linking agent for polymer stabiUty. This depot of dmg provides a continuous source of active ingredient. An impermeable backing prevents release of nitroglycerin away from the skin. The systems are individually sealed in a paper polyethylene-foil pouch (81). 

The Minitran system, by 3M Health Care, is a monolithic transdermal system that deUvers nitroglycerin at a continuous rate of 0.03 mg/(cm h) (81). The dmg flux through the skin is higher than the previous two systems thus the Minitran system is a smaller size for equivalent dosing. For example, the 0.1 mg/h dose is achieved with a 3.3 cm system rather than the 5 cm systems of Transderm-Nitro or Nitro-dur. Because the skin is rate-controlling in a monolithic system and the Minitran flux is higher than the similar monolithic Nitro-dur system flux, it appears that 3M Health Care has included an additive to increase the skin flux to 0.03 mg/(cm h). Whereas this information is not apparent in Reference 81, patent information supports the hypothesis (96). 

Fig. 9 Cross-sectional view of a unit of Nitro-Dur system, showing various structural components, and the plasma nitroglycerin concentration profiles in six human volunteers, each receiving 1 unit of Nitro-Dur system (20 cm, with a delivery rate of lOmg/day) for 24 h. (From RefsJ l)...

Passive transdermal dehvery systems on the market tend to be either matrix or membrane controUed. In matrix devices, the stmctural and molecular characteristics of the dmg-polymer matrix determine dmg release. Examples of polymer matrix-controUed diffusional systems for angina prophylaxis include Nitro-Dur and Nitrodisc, which provide transdermal dehvery of nitroglycerin [55-63-0], and Erandol, a tape that releases isosorbide dinitrate [87-33-2]. Matrix diffusional systems have been used for dehvering dmgs with a wide therapeutic index. 

Nitroglycerin Delivery Systems. Transderm-Nitro, Nitro-dur, and Minitran are all transdermal therapeutic systems that dehver nitroglycerin [55-63-0] mol wt 227.09, at a continuous, controlled rate through intact skin for treatment of angina (95). 

JX Sun, AJ Piraino, JM Morgan, JC Joshi, A Cipriano, K Chan, E Redalieu. Comparative pharmacokinetics and bioavailability of nitroglycerine and its metabolites from Transderm-Nitro, Nitodisc, and Nitro-Dur II systems using a stable-isotope technique. J Clin Pharmacol 35 390—397, 1995. 

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