Management of acute hypertensive crises with clonidine (Catapres)

Hypertension, alcohol drinking and stroke incidence: a population-based prospective cohort study among inner Mongolians in China

OBJECTIVES

The purpose of this study was to evaluate the effect of hypertension and alcohol drinking on stroke incidence and whether alcohol drinking would increase the risk of stroke in hypertension participants among Inner Mongolians.

METHODS

A prospective cohort study from June 2003 to July 2012 was conducted among 2535 people aged 20 years and older from Inner Mongolia, China. We categorized the participants into four subgroups according to blood pressure and drinking status. The cumulative risks of stroke among the four subgroups were estimated with the Kaplan-Meier curves and compared by log-rank test. Cox proportional hazards models and receiver operating characteristic (ROC) curves were employed to evaluate the association between hypertension, alcohol drinking and stroke incidence.

RESULTS

A total of 120 stroke patients were observed during the follow-up period. The multivariate-adjusted hazard ratios (95% confidential intervals) of stroke for nonhypertension/drinkers, hypertension/nondrinkers and hypertension/drinkers were 1.03 (0.48-2.22), 2.64 (1.45-4.81) and 2.89 (1.55-5.39), respectively, compared with nonhypertension/nondrinkers. The area under ROC curve (AUC) for a model containing hypertension and drinking status along with conventional factors (AUC = 0.684) was significantly (P = 0.005) larger than one containing only conventional factors (AUC = 0.660).

CONCLUSION

These findings suggest that hypertension is an independent risk factor of stroke in Inner Mongolians. Drinkers with hypertension seem to be more susceptible to stroke; larger-sample prospective cohort studies are still required to examine the cumulative effect of drinking and hypertension on stroke incidence.

Evaluation of intravenous clonidine in hypertensive emergencies

Nineteen patients with severe essential hypertension or hypertension due to renal parenchymal disease were treated with intravenous clonidine. In 14 patients the elevated blood pressure was complicated by one or more crises: left ventricular failure in seven patients, encephalopathy in six, and subarachnoid hemorrhage, cerebral hemorrhage, dissecting aortic aneurysm, acute renal failure, and severe epistaxis, one episode each. Clonidine 0.15 or 0.30 mg, was given intravenously every 40 minutes until the diastolic blood pressure was decreased to 120 mm Hg or below. Blood pressure was taken every 10 minutes. Both systolic and diastolic blood pressure were reduced significantly after intravenous clonidine, the former by 96 mm Hg (P less than 0.001), the latter by 52 mm Hg (P less than 0.001) within a period of 40 minutes to 2 1/2 hours. The clonidine dose varied from 0.15 to 0.90 mg, mean 0.52 mg. Heart rate was decreased significantly by 20 beats/minute (P less than 0.001) by the drug. Serious side effects were not observed except for an episode of transient sinoatrial block. Renal function was not affected. Patients who were on chronic diuretic therapy prior to treatment with intravenous clonidine showed a significantly greater decrease in both systolic (P less than 0.01) and diastolic (P less than 0.001) blood pressure after the first clonidine dose. In one patient intravenous clonidine was not effective (i.e., blood pressure remained 200/150 mm Hg) in spite of a total clonidine dose of 0.9 mg. Two patients died, one from severe cerebral hemorrhage, the other from an extensive dissecting aortic aneurysm, but the fatal outcome was not related to clonidine.

The use of clonidine by intramuscular injection in the treatment of hypertension

Clonidine (Catapres) administered intramuscularly in a dose of 150 microng produced a satisfactory reduction in blood pressure in 13 of 16 hypertensive patients. Its effect occurred within five minutes, was maximal at 75 minutes and persisted for five hours. In six patients who received two doses (150 microng and 300 microng), the response was shown to be dose-related. No serious side effects were noted. Intramuscular administration of clonidine thus appears to be safe and effective. It has a place in the management of uncontrolled hypertension when a rapid reduction in blood pressure is undesirable and in the maintenance of blood pressure control when oral therapy cannot be tolerated.