METHYLDOPA (Methyldopa; synonym: dopegit, Aldomet, Aldomin, Dopamet, Dopegyt, Hyperpax, Methyldopum etc.) — an antihypertensive. L - alpha Methyl - beta (3,4 dioxyphenyl) - alanine, or alpha Methyldopa; With 10 H 13 NO 4 :
The m reduces the peripheric resistance of vessels and at the expense of it the ABP reduces. The minute volume of heart under the influence of a single dose of M. does not change or slightly decreases. The m has also sedative effect.
Consider that in an organism alpha methylnoradrenaline is formed of M., to-ry stimulates in c. N of page presynaptic alpha adrenoceptors that leads to oppression of the vasculomotor centers. At the same time there is a reduction of a sympathetic tone and decrease in the ABP.
The m is well soaked up from went. - kish. a path and after intake collects in blood in the maximum concentration in 2 — 5 hour. Duration of action of M. apprx. the 6th hour. At normal function of kidneys apprx. 80 — 90% of M. it is allocated with urine during the first 2 days after administration of drug. M.'s metabolites (alpha methyldopamine and alpha methylnoradrenaline) are allocated with urine within 8 and more days. At M.'s use decrease in excretion with urine of catecholamines is observed (noradrenaline, etc.).
M apply as an antihypertensive, hl. obr. at an idiopathic hypertensia of IIA — IIB of a stage. At prolonged use of M. at patients, except decrease in the ABP, increase in glomerular filtering, decrease of the activity of a renin in a blood plasma, reduction of formation of angiotensin is noted. In general activity of system a renin — angiotensin — Aldosteronum decreases. At patients with an idiopathic hypertensia with the low maintenance of a renin of M. maloaktiven.
Appoint M. inside, in the first days of treatment — on 0,25 — 0,5 g a day, then each 2 — 3 days increase a dose by 0,25 — 0,5 g to the general daily dose of 0,75 — 1 g (on 0,25 g 3 — 4 times a day). If necessary the daily dose is increased to 1,5 — 2 g. The steady hypotensive effect occurs usually in 2 — 5 days. At insufficient efficiency of M. it is possible to combine with saluretics — dichlothiazide (see), furosemide (see), etc. It is necessary to appoint saluretics also in cases when at prolonged use of M. the volume of the circulating blood increases, sodium and water, and also in case of development of the phenomena of accustoming to action of M are late. During the accustoming to M. it is possible to appoint Reserpinum or Octadinum also.
Side effect of M. is shown by hl. obr. drowsiness, slackness, dryness in a mouth, dispeptic frustration. Less often at patients the depression, symptoms of parkinsonism, swelling of a mucous membrane of a nose, a leukopenia, fervescence, change funkts, tests of a liver are observed.
The m is contraindicated at acute diseases of a liver, a pheochromocytoma, parkinsonism, pregnancy. With M.'s care it is necessary to appoint the elderly patient (possibly development of an orthostatic collapse) and at a renal failure.
Form of release: tablets on 0,25 g
See also Antihypertensives .
Bibliography Valdman A. V., Diamonds B. And. and Tsyrlin V. A. Clinical neuropharmacology of antihypertensives, page 91, M., 1978; Clinical pharmacology, under the editorship of V. V. Zakusov, page 94, 177, M., 1978; Komissarov I. V. Medicinal regulation of adrenergic processes, page 78, 93, Kiev, 1976; Erina E. V. Treatment of an idiopathic hypertensia, page 145, M., 1973; The pharmacological basis of therapeutics, ed. by L. S. Goodman a. A. Gilman, p. 707, N. Y., 1975.
G. V. Kovalyov.