3520 Methyldopa Methyldopa or alpha-methyldopa (brand names Aldomet, Apo-Methyldopa, Dopamet, Novomedopa) is a centrally-acting adrenergic antihypertensive medication. Its use is now deprecated following introduction of alternative safer classes of agents. However it continues to have a role in otherwise difficult to treat hypertension and gestational hypertension (formerly known as pregnancy-induced hypertension). Methyldopa is an aromatic-amino-acid decarboxylase inhibitor in animals and in man. Only methyldopa, the <i>L</i>-isomer of alpha-methyldopa, has the ability to inhibit dopa decarboxylase and to deplete animal tissues of norepinephrine. In man the antihypertensive activity appears to be due solely to the L-isomer. About twice the dose of the racemate (DL-alpha-methyldopa) is required for equal antihypertensive effect. Methyldopa has no direct effect on cardiac function and usually does not reduce glomerular filtration rate, renal blood flow, or filtration fraction. Cardiac output usually is maintained without cardiac acceleration. In some patients the heart rate is slowed. Normal or elevated plasma renin activity may decrease in the course of methyldopa therapy. Methyldopa reduces both supine and standing blood pressure. Methyldopa usually produces highly effective lowering of the supine pressure with infrequent symptomatic postural hypotension. Exercise hypotension and diurnal blood pressure variations rarely occur. Methyldopa, in its active metabolite form, is a central alpha-2 receptor agonist. Using methyldopa leads to alpha-2 receptor-negative feedback to sympathetic nervous system (SNS) (centrally and peripherally), allowing peripheral sympathetic nervous system tone to decrease. Such activity leads to a decrease in total peripheral resistance (TPR) and cardiac output. When introduced it was a mainstay of antihypertensive therapy, but its use has declined, with increased use of other safer classes of agents. One of its important present-day uses is in the management of pregnancy-induced hypertension, as it is relatively safe in pregnancy compared to other antihypertensive drugs (Wikipedia). 555-29-3 38853 C10H13NO4 211.084460 White powder. 300°C 10mg/mL at 25°C Oral Although the mechanism of action has yet to be conclusively demonstrated, the antihypertensive effect of methyldopa probably is due to its metabolism to alpha-methylnorepinephrine, which then lowers arterial pressure by stimulation of central inhibitory alpha-adrenergic receptors, false neurotransmission, and/or reduction of plasma renin activity. Methyldopa has been shown to cause a net reduction in the tissue concentration of serotonin, dopamine, norepinephrine, and epinephrine. Hepatic, extensively metabolized. The known urinary metabolites are: a-methyldopa mono-0-sulfate; 3-0-methyl-a-methyldopa; 3,4-dihydroxyphenylacetone; a-methyldopamine; 3-0-methyl-a-methyldopamine and their conjugates. LD50: > 1.5 g/kg( oral, mouse) LD50: > 1.5 g/kg( oral, rat) No indication of carcinogenicity to humans (not listed by IARC). Symptoms of overdose include bloating, constipation, diarrhea, dizziness, extreme drowsiness, gas, light-headedness, nausea, severely low blood pressure, slow heartbeat, vomiting, and weakness. 2009-07-30T17:58:37Z 2026-04-13T20:39:34Z http://en.wikipedia.org/wiki/Methyldopa C07194 61058 ALPHA-METHYLDOPA Methyldopa, alpha- DB00968 true C[C@](N)(CC1=CC=C(O)C(O)=C1)C(O)=O C10H13NO4 InChI=1S/C10H13NO4/c1-10(11,9(14)15)5-6-2-3-7(12)8(13)4-6/h2-4,12-13H,5,11H2,1H3,(H,14,15)/t10-/m0/s1 CJCSPKMFHVPWAR-JTQLQIEISA-N 211.2145 211.084457909 Exogenous Solid -1.79 HMDB11754 35562 <p><a href="http://www.drugsyn.org/Methyldopa.htm">DrugSyn.org</a></p> CHEM002504 DTXSID5023295 NS00007484 (2S)-2-amino-3-(3,4-dihydroxyphenyl)-2-methylpropanoic acid