An assessment of the clinical use of glyceryl trinitrate in a hospital outpatient population.

Despite the availability of information on the use of glyceryl trinitrate (GTN) in standard texts, in practice many patients fail to obtain maximum benefit from GTN. This study of an Outpatient population, documents the patients' knowledge of the use and precautions which should apply to GTN and records the ways in which these patients took the drug. Fifty patients who regularly took GTN (greater than 5 tablets per week) were asked a series of questions by the same interviewer. Forty-nine of the 50 patients took GTN for the relief of chest pain, but only 34 patients knew that the drug could be used to prevent chest pain. Although 48 patients kept their bulk supply of GTN in the original container, over 40% transferred some or all of the tablets to other containers and locations. Seventy per cent of patients knew that GTN tablets deteriorate with time. However, knowledge of the factors which influence the rate of deterioration was lacking. Less than half the patients knew that the prompt relief of pain or the local effects on the buccal mucosa could be used as simple tests of the activity of tablets. It is recommended that all physicians should take more time to explain to their patients how to use glyceryl trinitrate correctly.