Alpha-methyldopa is used most commonly in?
|A||Pregnancy induce hypertension|
|C||First line agent in hypertension|
a. Methyldopa has been a conventional ‘sympatholytic drug’. It is the member of family of alpha-2 agonists that act centrally and reduce sympathetic output.
b. Examples include, clonidine, guanabenz, guanfacine. Guanadrel and guanethidine are not centrally acting drugs and are complex ganglion blockers.
c. Clonidine is available in the form of patches and can be useful in patients where compliance remains to be particularly troublesome.
d. Methy-dopa has long been used for treatment of hypertension, gestational hypertension and pregnancy induced hypertension. The drug has a good safety record in pregnancy and is considered to be the drug of choice for hypertension in pregnancy (CMDT’2010, pp-723). (Others drug which is safe to be use in pregnancy induce hypertension is hydralazine)
e. Methyldopa undergoes active absorption and is a prodrug. In the in presynaptic vesicles the drug gets converted into alpha methyl norepinephrine.
f. It will lead to formation of a false neurotransmitter. It was believed that the drug can cause antihypertensive action due to formation of this neurotransmission.
g. It has now been demonstrated that antihypertensive action is due to alpha-2 agonistic action.
h. Usual side effects of the drug are sedation and dry mouth. Prolonged use can cause mental depression. hemolytic anemia (Coombs +ve), hepatitis and hyperprolactinemia are other side effects.
i. Sometimes, the drug can also cause extrapyramidal side effects. Due to a number of side effects associated with centrally acting alpha-2 agonists, these drugs are used as 2nd or 3rd line drugs in hypertension (CMDT’2010, pp-406).
j. Sudden withdrawal of alpha-2 agonists is associated with rebound hypertension (BG Katzung’ 10th Edition, 2010).
k. Several drugs are used in refractory hypertension. these include, reserpine, gaunethedine, gaunedrel, gaunebenz, gaunefacine, trimethophan etc. It is important to remember that refractory hypertension may need to be treated with the help of multiple drugs. For example, a patient require an alpha blocker, calcium channel blocker and beta blockers. This is a common scenario.