Methyldopa
Methyldopa (Aldomet)
Methyldopa/Methyldopate
(meth-ill- DOH-pah)
Pregnancy Category: B (PO) Aldomet Apo-Methyldopa Dopamet Novo-Medopa Nu-Medopa (Rx)
Methyldopate hydrochloride
Methyldopate hydrochloride (Aldomet Hydrochloride)
Methyldopa/Methyldopate
(meth-ill- DOH-payt)
Pregnancy Category: B (PO), C (IV) Aldomet Hydrochloride (Rx)

Classification: Antihypertensive, centrally acting antiadrenergic

See Also: See also Antihypertensive Agents .

Action/Kinetics: The active metabolite, alpha-methylnorepinephrine, lowers BP by stimulating central inhibitory alpha-adrenergic receptors, false neurotransmission, and/or reduction of plasma renin. Little change in CO. PO: Onset: 7-12 hr. Duration: 12-24 hr. All effects terminated within 48 hr. Absorption is variable. IV: Onset: 4-6 hr. Duration: 10-16 hr. Seventy percent of drug excreted in urine. Full therapeutic effect: 1-4 days. t 1/2: 1.7 hr. Metabolites excreted in the urine.

Uses: Moderate to severe hypertension. Particularly useful for clients with impaired renal function, renal hypertension, resistant cases of hypertension complicated by stroke, CAD, or nitrogen retention, and for hypertensive crisis (parenterally).

Contraindications: Sensitivity to drug (including sulfites), labile and mild hypertension, pregnancy, active hepatic disease, use with MAO inhibitors, or pheochromocytoma.

Special Concerns: Use with caution in clients with a history of liver or kidney disease. A decrease in dose in geriatric clients may prevent syncope.

Side Effects: CNS: Sedation (transient), weakness, headache, asthenia, dizziness, paresthesias, Parkinson-like symptoms, psychic disturbances, symptoms of CV impairment, choreoathetotic movements, Bell's palsy, decreased mental acuity, verbal memory impairment. CV: Bradycardia, orthostatic hypotension, hypersensitivity of carotid sinus, worsening of angina, paradoxical hypertensive response (after IV), myocarditis, CHF, pericarditis, vasculitis. GI: N&V;, abdominal distention, diarrhea or constipation, flatus, colitis, dry mouth, sore or ``black tongue,'' pancreatitis, sialoadenitis. Hematologic: Hemolytic anemia leukopenia, granulocytopenia, thrombocytopenia, bone marrow depression. Endocrine: Gynecomastia, amenorrhea, galactorrhea, lactation, hyperprolactinemia. GU: Impotence, failure to ejaculate, decreased libido. Dermatologic: Rash, toxic epidermal necrolysis. Hepatic: Jaundice, hepatitis, liver disorders, abnormal liver function tests. Miscellaneous: Edema, fever, lupus-like symptoms, nasal stuffiness, arthralgia, myalgia, septic shock-like syndrome.

Laboratory Test Alterations: False + or : Alkaline phosphatase, bilirubin, BUN, BSP, cephalin flocculation, creatinine, AST, ALT, uric acid, Coombs' test, PT. Positive lupus erythematosus cell preparation and antinuclear antibodies.

Overdose Management: Symptoms: CNS, GI, and CV effects including sedation, weakness, lightheadedness, dizziness, coma, bradycardia, acute hypotension, impairment of AV conduction, constipation, diarrhea, distention, flatus, N&V.; Treatment: Induction of vomiting or gastric lavage if detected early. General supportive treatment with special attention to HR, CO, blood volume, urinary function, electrolyte imbalance, paralytic ileus, and CNS activity. In severe cases, hemodialysis is effective.

Drug Interactions: Anesthetics, general / Additive hypotension Antidepressants, tricyclic / May block methyldopa hypotensive effects Haloperidol / Haloperidol toxic effects Levodopa / Effect of both drugs Lithium / Possibility of lithium toxicity MAO inhibitors / Accumulation of methyldopa metabolites may excessive sympathetic stimulation Methotrimeprazine / Additive hypotensive effect Phenothiazines / Possible BP Propranolol / Paradoxical hypertension Sympathomimetics / Potentiation of hypertensive drug effects Thiazide diuretics / Additive hypotensive effect Thioxanthenes / Additive hypotensive effect Tolbutamide / Hypoglycemia R/T liver breakdown Tricyclic antidepressants / Methyldopa effect Vasodilator drugs / Additive hypotensive effect Verapamil / Methyldopa effect

How Supplied: Methyldopa: Tablet: 125 mg, 250 mg, 500 mg. Methyldopate hydrochloride: Injection: 50 mg/mL

Dosage
?Methyldopa. Tablets Hypertension.
Initial: 250 mg b.i.d.-t.i.d. for 2 days. Adjust dose q 2 days. If increased, start with evening dose. Usual maintenance: 0.5-3.0 g/day in two to four divided doses; maximum: 3 g/day. Gradually transfer to and from other antihypertensive agents, with initial dose of methyldopa not exceeding 500 mg. NOTE: Do not use combination medication to initiate therapy. Pediatric, initial: 10 mg/kg/day in two to four divided doses, adjusting maintenance to a maximum of 65 mg/kg/day (or 3 g/day, whichever is less).
?Methyldopate HCl. IV Infusion Hypertension.
Adults: 250-500 mg q 6 hr; maximum: 1 g q 6 hr for hypertensive crisis.
Switch to PO methyldopa, at same dosage level, when BP is brought under control. Pediatric: 20-40 mg/kg/day in divided doses q 6 hr; maximum: 65 mg/kg/day (or 3 g/day, whichever is less).