Which of the following statements is not true about the use of clonidine in the treatment of hypertension? (AIPG 2011)
|A||Reduction in central sympathetic outflow|
|B||Increase in LDL-cholesterol on prolonged use|
|C||Sedation and xerostomia are common side effects|
|D||It can also be controlled with vasodilators|
a. Clonidine is a partial alpha agonist with higher affinity and intrinsic activity at alpha-2 receptors. It stimulates alpha2 receptors present mainly post-junctionally at central sites primarily in medulla (vasomotor center).
b. This leads to decrease in sympathetic outflow; fall in blood pressure and heart rate (also due to enhanced vagal tone). On chronic administration decrease in cardiac output contributes more to the fall in blood pressure than decrease in total peripheral resistance.
c. Cardiovascular reflexes are affected little. Decreased sympathetic flow to the kidney results in reduced renin release. It does not alter plasma lipid levels. Sedation, depression, xerostomia and constipation are common and disturbing side effects.