Methyldopa | Introduction | Classification | Mechanism | Indication | Side Effects

Introduction

methyldopa is a centrally acting sympatholytic drug used as an antihypertensive medication.altough methyldopa is not the first line therapy as anti hypertensives yet it is drug of choice in hypertension associated with pregnancy. the the classification of METHYLDOPA meets back to antihypertensives as..
METHYLDOPA--centrally acting sympathomyletic drugs---- sympathomyletic drugs---antihypertensive drugs
below is the structural formula of methyldopa

methyldopa structure

 methyldopa is available in market under trade name aldomet in 250 and 500 mg dose.

MECHANISM OF METHYLDOPA

Site of action of methyldopa of vassopressor centre in brain stem as direct acting and presynaptic alpha ii receptor as agonistic action.over all effect is directly on cns thats why it is called centrally acting sympathomyletics.below is an illustration of the overall mechanism of action of methyldopa.

pharmacodynamics of methyldopa

methyldopa first converts to pro drug which is inactive form of the drug.pro-drug then converts into alpha methyl dopamine and then alpha methyl noradrenaline.Here alpha methyl adrenaline has two sites of actions..pre synaptic alpha II receptor and vasomotor centre.the over all effect is the decreased sympathetic outflow.the final action is on heart and vessels.on heart the effect is a decreased cardiac outflow and on vascular system the effect is a decreased peripheral vascular resistance.The over all result is a decreased blood pressure and thus the blood pressure is reduced to normal. 

INDICATIONS

the drug is indicated in..

• mild to moderate hypertension
• as a preferred drug in pregnancy associated hypertension.

SIDE EFFECTS OF METHYLDOPA

following are the side effects of methyldopa

• sedation(dizziness)
• sleep disorders.
• night mares.
• depression
• extra pyramidal systems
• parkinson like symptoms
• xeromastia(dryness of mouth)
• gynacomastia
• male impotancy
• hemolytic anemia