Clonidine Study

Clonidine is a centrally acting alpha-agonist antihypertensive drug that is used to suppress the sympathetic nervous system and plasma renin activity1. This allows blood vessels to relax, which leads to better blood flow throughout the body. It has been used since 1970s. Clonidine was initially only used to treat hypertension, but now it is used for various other conditions including ADHD, alcohol and opiate withdrawal, anxiety, smoking cessation, and many more. Clonidine comes in a tablet form (extended-release and immediate release), and transdermal patch2. Clonidine tablet has a half-life of 6-24 hours after being in a therapeutic range whereas clonidine patch has a half-life of 26-55 hours. The starting dose of clonidine is 0.1 mg twice

A prospective study was conducted in 14 hospitalized patients on chronic clonidine therapy to evaluate the frequency and pathophysiology of clonidine withdrawal syndrome1. All 14 patients were receiving a total 900ug of clonidine in six divided doses for essential hypertension. Patients were not given clonidine for 3 days and the blood pressure and heart rate were recorded to evaluate the frequency of withdrawal syndrome. The results of the study showed a significant increase in the blood pressure and heart rate. Increase in the blood pressure was more prominent as the time passed. 3 out of 14 patients had significant increase in their blood pressure, which required medical intervention. Furthermore, another study was conducted to see if this phenomenon was reproducible. Hansson and colleagues conducted a prospective study in five patients who already had experienced rebound hypertension after an abrupt discontinuation of clonidine. All 5 patients were on chronic treatment for essential hypertension and dose ranged from 0.3-2.4 mg daily. All patients experienced an increased in blood pressure. Both of the studies show a 100% incidence rate; however the study population is too small to generalize. In addition, both studies included a high dose of clonidine and this likely contributed to patients experiencing withdrawal

Hoobler and Kashima conducted a prospective study consisting of 16 patients that were taken off clonidine treatment for a shorter period of time. The patients were divided into two groups: one group included 6 patients that were receiving less than 1.2 mg of clonidine and a second group which included 10 patients that were receiving more than 1.2 mg of clonidine. Patients receiving less than 1.2 mg did not have a significant increase in blood pressure; however, patients receiving more than 1.2 mg of clonidine had significant increase in their blood pressure. This shows that withdrawal symptoms are more likely to occur in patients who are on a higher dose. Also, the incidence rate of withdrawal symptoms was 81.25%, but the study group is too small to