In a study conducted by office-based cardiologists at eight sites, 115 patients using transdermal nitroglycerin for treatment of angina pectoris participated in a four-week comparison of two transdermal nitroglycerin patches: Transderm-Nitro (TDN) and Nitro-Dur II (ND II). Patients wore two patches, one of each brand, each with half their normal prescribed daily dose of 10 mg (release rate per 24 hours) to compare patch adherence properties, patient preference, and local side effects. More ND II than TDN patches fell off (5% versus 0.1%), and fewer TDN than ND II patches became loose (1.7% versus 8.4%); 98.2% of the TDN and 86.7% of the ND II patches adhered totally. Significantly more patients expressed a preference for TDN over ND II in four of eight assessment variables, including the choice of their next prescription. The frequency of problems at the site of patch application was similar with both patches.