Guanabenz Combination Therapy Inhibits Sympathetic Nerve Activity and Regresses Left Ventricular Hypertrophy

The cardiovascular and sympatholytic effects of combination therapy with guanabenz were examined in 26 patients (48 ± 13 years old [mean ± SD]) with stage 2 and 3 hypertension. Included in the study were patients under treatment with conventional antihypertensive drugs whose systolic and diastolic blood pressure was above 140 and 90 mmHg, respectively. Blood pressure, heart rate, and sympathetic parameters such as plasma concentration of norepinephrine and muscle sympathetic nerve activity at rest as well as during ambulatory conditions, 24-hour urinary excretion of norepinephrine, and low frequency (LF: 0.04–0.15 Hz)/high frequency (HF: 0.15–0.4 Hz) power ratio as a marker of cardiac sympathetic activity during 24 hours were examined before and after guanabenz (4–8 mg/d) combination therapy with first-line antihypertensive drugs such as diuretics. Left ventricular mass index (LVMI) was also calculated by conventional echocardiography. After 32 weeks of guanabenz combination therapy, systolic and diastolic blood pressure, heart rate, plasma and urinary excretion of norepinephrine, muscle sympathetic nerve activity, and LF/HF power ratio were significantly decreased, while neither LF nor HF power was changed. LVMI was also significantly decreased (270 ± 81 vs. 236 ± 83 g/m², p < 0.005). These results indicate that guanabenz combination therapy inhibits sympathetic nerve activity under resting conditions as well as during ambulatory conditions and may accelerate regression of left ventricular hypertrophy in patients with moderate to severe hypertension.