Increased Autonomic Dysfunction in Subjects Treated with Alpha-Methyldopa

Methyldopa is a catecholamine used as an antihypertensive agent. The purpose of this study was to evaluate the effect of a week treatment of a bi-daily dosage of αmethyldopa on the sympathetic nervous system of healthy volunteers as measured by four different techniques; (QT interval, heart rate variability (HRV), skin conductance and salivary cortisol). All volunteers received either 250mg α-methyldopa orally or a placebo tablet in a randomized, double blind, placebo controlled study design. The correlation between the following techniques was also evaluated: Skin conductance, QT interval on ECG and HRV measured with Viport apparatus. A salivary sample was collected to evaluate the effect of α-methyldopa on salivary cortisol using an ELISA kit. After a week treatment, the systolic blood pressure and heart rate were significantly decreased. In both the placebo and the treatment groups the cardio stress index (CSI) decreased. Within the groups only the treatment group had a statistically significant result. The study revealed a decreasing effect on blood pressure, heart rate, CSI, standard deviation of the RR interval (RRSD) and QTc, whilst an increasing effect on QRS complex, HRV, QT interval, skin conductance and salivary cortisol.