methyldopa

Absorption: 50% absorbed from the GI tract.

Distribution: Crosses the blood-brain barrier.

Metabolism/Excretion: Partially metabolized by the liver, partially excreted unchanged by the kidneys.

Half-Life: 1.7 hr.

Time/Action Profile ⬆ ⬇

(antihypertensive effect)

ROUTE	ONSET	PEAK	DURATION
PO	4–6 hr	12–24 hr	24–48 hr

Contraind./Precautions ⬆ ⬇

Contraindicated in:

Hypersensitivity;
Active liver disease.

Use Cautiously in:

Previous history of liver disease;
Geri: Appears on Beers list. risk of adverse reactions in older adults; consider age-related impairment of hepatic, renal and cardiovascular function as well as other chronic illnesses.

Adv. Reactions/Side Effects ⬆ ⬇

CV: bradycardia, edema, MYOCARDITIS, orthostatic hypotension

EENT: nasal stuffiness

GI: diarrhea, dry mouth, HEPATITIS

GU: erectile dysfunction

Hemat: eosinophilia, hemolytic anemia

Neuro: sedation, ↓mental acuity, depression

Misc: fever

Interactions ⬆ ⬇

Drug-drug:

Additive hypotension with other antihypertensives, acute ingestion of alcohol, anesthesia, and nitrates.
Amphetamines, barbiturates, tricyclicantidepressants, NSAIDs, and phenothiazines may ↓ antihypertensive effect of methyldopa.
↑effects and risk of psychoses with haloperidol.
Excess sympathetic stimulation may occur with concurrent use of MAO inhibitors or other adrenergics.
May ↑ lithium toxicity.
Additive hypotension and CNS toxicity with levodopa.
Additive CNS depression may occur with alcohol, antihistamines, sedative/hypnotics, some antidepressants, and opioid analgesics.
Concurrent use with nonselective beta blockers may rarely cause paradoxical hypertension.

Route/Dosage ⬆ ⬇

PO (Adults ): 250–500 mg 2–3 times daily (not to exceed 500 mg/day if used with other agents); may be ↑ every 2 days as needed; usual maintenance dose is 500 mg–2 g/day (not to exceed 3 g/day).
PO (Children ): 10 mg/kg/day (300 mg/m²/day); may be ↑ every 2 days up to 65 mg/kg/day in divided doses (not to exceed 3 g/day).

Availability ⬆ ⬇

(Generic available)

Tablets: 250 mg; 500 mg

Assessment ⬆ ⬇

Monitor BP and pulse frequently during initial dose adjustment and periodically during therapy. Report significant changes.
Monitor intake and output ratios and weight and assess for edema daily, especially at beginning of therapy. Report weight gain or edema; sodium and water retention may be treated with diuretics.
Assess patient for depression or other alterations in mental status. Notify health care professional promptly if these symptoms develop.
Monitor temperature during therapy. Drug fever may occur shortly after initiation of therapy and may be accompanied by eosinophilia and hepatic function changes. Monitor hepatic function test if unexplained fever occurs.

Lab Test Considerations:

Monitor renal and hepatic function and CBC before and periodically during therapy.
- Monitor direct Coombs’ test before and after 6 and 12 mo of therapy. May cause a positive direct Coombs’ test, rarely associated with hemolytic anemia.
- May cause ↑ BUN, serum creatinine, potassium, sodium, prolactin, uric acid, AST, ALT, alkaline phosphatase, and bilirubin.
- May cause prolonged prothrombin times.
- May interfere with serum creatinine and AST measurements.

Implementation ⬆ ⬇

PO: Fluid retention and expanded volume may cause tolerance to develop within 2–3 mo after initiation of therapy. Diuretics may be added to regimen at this time to maintain control.
- Dose increases should be made with the evening dose to minimize drowsiness.

Patient/Family Teaching ⬆ ⬇

Emphasize the importance of continuing to take this medication, even if feeling well. Instruct patient to take medication at the same time each day; last dose of the day should be taken at bedtime. Take missed doses as soon as remembered but not if almost time for next dose. Do not double doses.
Encourage patient to comply with additional interventions for hypertension (weight reduction, low-sodium diet, smoking cessation, moderation of alcohol consumption, regular exercise, and stress management). Methyldopa controls but does not cure hypertension.
Instruct patient and family on proper technique for monitoring BP. Advise them to check BP at least weekly and to report significant changes.
Instruct patient to notify health care professional if fever, muscle aches, or flu-like syndrome occurs.
Inform patient that urine may darken or turn red-black when left standing.
May cause drowsiness. Advise patient to avoid driving or other activities requiring alertness until response to medication is known. Drowsiness usually subsides after 7–10 days of continuous use.
Caution patient to avoid sudden changes in position to decrease orthostatic hypotension.
Advise patient that frequent mouth rinses, good oral hygiene, and sugarless gum or candy may minimize dry mouth. Notify health care professional if dry mouth continues for >2 wk.
Caution patient to avoid concurrent use of alcohol or other CNS depressants.
Advise patient to notify health care professional of all Rx or OTC medications, vitamins, or herbal products being taken and to consult with health care professional before taking other medications, especially cough, cold, or allergy remedies.
Advise patient to notify health care professional of medication regimen before treatment or surgery.

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Pronunciation ⬇

Classifications ⬆ ⬇

Indications ⬆ ⬇

Action ⬆ ⬇

Pharmacokinetics ⬆ ⬇