ObjectiveTo determine the effect of an extended-release nitrate preparation on the arterial pulse wave and blood pressure of patients in whom systolic blood pressure was elevated in part by exaggerated pulse-wave reflectance.DesignA double-blind randomized placebo-controlled crossover study was carried out.Patients and methodsThe subjects were ten elderly patients with systolic hypertension resistant to conventional anti-hypertensive therapy. Pharmacodynamic responses to 2-week courses of placebo/isosorbide mononitrate (ISMN) were assessed in seven subjects by an ambulatory blood pressure monitor, and in all ten subjects by standard sphygmomanometry, arterial pulse- wave analysis and measurement of plasma nitrate concentration during peak and trough.ResultsAmbulatory systolic blood pressure was decreased by ISMN (P< 0.02) between 1000 and 2200 h. Ambulatory diastolic blood pressure fell with ISMN(P< 0.01) during the last 4 h of this period. At peak plasma nitrate levels, ISMN decreased the aortic systolic blood pressure (P< 0.01), ejection peak (P< 0.02) and augmentation component (P< 0.001) of the pulse wave; heart rate increased slightly (P< 0.03).ConclusionISMN has a role as an adjunct in the anti-hypertensive therapy of patients with refractory systolic hypertension due to exaggerated pulse-wave reflectance.