Methyldopa
Title: Methyldopa
CAS Registry Number: 555-30-6
CAS Name: 3-Hydroxy-a-methyl-L-tyrosine
Additional Names: L-3-(3,4-dihydroxyphenyl)-2-methylalanine; L-a-methyl-3,4-dihydroxyphenylalanine; L-2-amino-2-methyl-3-(3,4-dihydroxyphenyl)propionic acid; a-methyldopa; AMD
Manufacturers' Codes: MK-351
Trademarks: Aldomet (Merck & Co.); Aldomin (Merck & Co.); Dopamet (Dumex); Dopegyt (Egis); Elanpres (Elan); Equibar (Aventis); Medopren (Malesci); Methoplain (Kowa Yakuhin); Sembrina (Orion); Presinol (Bayer)
Molecular Formula: C10H13NO4
Molecular Weight: 211.21
Percent Composition: C 56.87%, H 6.20%, N 6.63%, O 30.30%
Literature References: Exists as the sesquihydrate. Prepn: Pfister, Stein, US 2868818 (1959 to Merck & Co.). Resolution: Jones et al., US 3158648 (1964 to Merck & Co.); cf. Slates et al., J. Org. Chem. 29, 1424 (1964). Resolution and configuration: Tristram, ibid. 2053. Synthesis from asymmetric intermediates: Reinhold et al., J. Org. Chem. 33, 1209 (1968). Prepn of the ethyl ester hydrochloride: FR M2153 (1963 to Merck & Co.); of pharmaceutical dosage forms: Marcus, US 3230143 (1966 to Merck & Co.). Mode of action: Finch, Haeusler, Br. J. Pharmacol. 45, 167p (1972); Day et al., ibid. 168p. Review of pharmacology: A. Scriabine, Ed. in Pharmacology of Antihypertensive Drugs (Raven, New York, 1980) pp 43-54.
 
Derivative Type: L-Form sesquihydrate
Properties: Crystals from water. Minute anhydr crystals from methanol, considerably hygroscopic, dec ~300°. [a]D23 -4.0 ± 0.5° (c = 1 in 0.1N HCl). uv max: 281 nm (e 2780). Soly in water at 25°: ~10 mg/ml. pH of satd aq soln about 5.0. (Soly of D-form in water at 25°: ~10 mg/ml, of DL-form: ~18 mg/ml) Practically insol in the common organic solvents. Sol in dil mineral acids.
Optical Rotation: [a]D23 -4.0 ± 0.5° (c = 1 in 0.1N HCl)
Absorption maximum: uv max: 281 nm (e 2780)
 
Derivative Type: Ethyl ester hydrochloride
CAS Registry Number: 2508-79-4
Additional Names: Methyldopate hydrochloride
Molecular Formula: C12H18ClNO4
Molecular Weight: 275.73
Percent Composition: C 52.27%, H 6.58%, Cl 12.86%, N 5.08%, O 23.21%
Properties: After drying, mol wt 275.7 (1 mg = 0.77 mg of the free acid). Soluble in water to the extent of 10-300 mg/ml at pH 2-7. May be stabilized with sodium bisulfite and/or disodium EDTA.
 
Therap-Cat: Antihypertensive.
Keywords: Antihypertensive.

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