LOW-DOSE TRANSDERMAL SCOPOLAMINE DECREASES BLOOD-PRESSURE IN MILD ESSENTIAL-HYPERTENSION

Background Increasing cardiovascular parasympathetic nervous activity could have antihypertensive effects. Low-dose transdermal scopolamine increases vagal-cardiac modulation of sinus node and baroreflex sensit ivity in healthy subjects and in cardiac patients. Objective To study the short-term effects of transdermal scopolamine on blood pressure an d cardiovascular autonomic control in patients with mild essential hyp ertension. Design A randomized, double-blind, placebo-controlled cross over trial with 12 untreated middle-aged [aged 39 +/- 5 years (mean +/ - SD)] patients with mild essential hypertension. Methods We recorded the electrocardiogram, auscultatory sphygmomanometric and continuous p hotoplethysmographic finger arterial pressure, and spirometry signals with patients supine and 70 degrees tilted during controlled (0.25 Hz) breathing. Cardiovascular autonomic regulation was analyzed with powe r spectrum analysis of R-R interval and arterial pressure variability and a spontaneous sequence method for baroreflex sensitivity. In addit ion, a deep-breathing test was performed to assess maximal breathing-r elated sinus arrhythmia. Results Transdermal scopolamine treatment sig nificantly decreased blood pressure both when patients lay supine and when they were in the 70 degrees tilted position. Scopolamine also slo wed heart rate and increased baroreflex sensitivity and R-R interval h igh-frequency variability for both body positionings. In addition, sco polamine accentuated respiratory sinus arrhythmia during deep breathin g and blunted the tilt-induced increase in heart rate. Scopolamine did not affect blood pressure variability. Conclusions Transdermal scopol amine decreases arterial pressure, increases baroreflex sensitivity an d accentuates vagal-cardiac modulation of sinus node in patients with mild hypertension. Our study supports the hypothesis that increasing c ardiovascular parasympathetic activity could have antihypertensive eff ects in essential hypertension. (C) 1998 Rapid Science Ltd.