methyldopa [IV]

Adult Dosing

Hypertension

250-500 mg IV q6 hrs
MAX: 1 g q6 hrs

Pediatric Dosing

Hypertension

20-40 mg/kg/day IV divided q6 hrs
MAX: 65 mg/kg/day in divided doses or 3 g/day whichever is less

[Outline]

Adult Dosing
Pediatric Dosing

Indications ⬆ ⬇

Contraindications ⬆ ⬇

Hypersensitivity to any of the ingredients of the product
Active hepatic disease such as acute hepatitis and active cirrhosis
Liver disorders previously associated with methyldopa
Concomitant therapy with monoamine oxidase (MAO) inhibitors

Black Box Warnings ⬆ ⬇

Dosing Adjustment ⬆ ⬇

Renal Dose Adjustment

Renal impairment: Reduce dose/adjust frequency; dose adjustments not defined

Hepatic Dose Adjustment

Hepatic cirrhosis/Hepatitis: Contraindicated
Previous hepatic impairment with methyldopa: Contraindicated

Warnings/Precautions ⬆ ⬇

Positive Coombs test, hemolytic anemia, and liver disorders may occur; monitor patient closely because of potentially fatal complications
With prelonged therapy 10-20% patients develop a positive direct Coombs test which usually occurs between 6 and 12 months of therapy
If Coombs-positive hemolytic anemia occurs, discontinue the therapy
Monitor CBC at baseline; liver function tests during 1st 6-12 wks of treatment; if unexplained fever then periodically
Monitor hematocrit, Hb, cardiac function at baseline, then periodically
If need of transfusion arrises in patients receiving therapy, both a direct and indirect Coombs test should be performed
Jaundice, with or without fever may occur with onset within first 2-3 months of therapy
Rarely fatal hepatic necrosis has been reported with use of methyldopa
If fever, abnormalities in liver function tests or jaundice appear discontinue therapy
Patients taking methyldopa may have experience clinical edema, CHF or weight gain which may be controlled by a diuretic
Pardoxical pressor response has ben reported with IV administration
Rarely involuntary choreoathetotic movements have been observed during therapy with methyldopa in patients with severe cerebrovascular disease, if synptoms occur discontinue the therapy

Pregnancy/Breast Feeding ⬆ ⬇

Pregnancy Category:C

Breastfeeding: Probably safe; methyldopa is excreted in breastmilk in small amounts and thus would not be expected to cause any adeverse events in breastfed infants. This information is based upon LactMed database (available at http://toxnet.nlm.nih.gov/cgi-bin/sis/htmlgen?LACT last accessed 12 July 2013). According to the manufacturer caution should be exercised when administering methyldopate to a nursing women.

Adverse Reactions ⬆ ⬇

CNS: Sedation, headache, asthenia, depression, dizziness, light headedness
PSYCHIATRIC: Parkinsonism, Bell's palsy, decreased mental acuity, involuntary choreoathetotic movements, symptoms of cerebrovascular insufficiency, psychic disturbances, paresthesias
CV: Aggravation of angina pectoris, congestive heart failure, prolonged carotid sinus hypersensitivity, orthostatic hypotension, hypotension, bradycardia
GI: Pancreaitis, colitis, vomiting, diarrhea, sialadenitis, sore tongue, nausea, constipation, distension, flatus, dryness of mouth
METABOLIC: Hyperprolactinemia, Rise in BUN
HEMA: Bone marrow depression, leukopenia, granulocytopenia, thrombocytopenia, hemolytic anemia, LE cells, rheumatoid factor, positive Coombs test
HEPA: Liver disorders including hepatitis, jaundice, abnormal liver function tests
MUSC: Arthralgia, myalgia
RESP: Nasal stuffiness
DERM: Toxic epidermal necrolysis, rash
GU: Amenorrhea, breast enlargement, gynecomastia, lactation, impotence, decreased libido, disorder of ejaculation, impotence
Misc: Systemic lupus erythematosus, drug fever

Clinical Pharmacology ⬆ ⬇

Antihypertensive agent; undergoes metabolism to form alpha-methyl-norepinephrine, which then lowers arterial pressure by stimulation of central inhibitory alpha-adrenergic receptors, false neurotransmission, and/or reduction of plasma renin activity
Extensively metabolised in liver
Excretion: 49% excreted as methyldopa and its mono-O-sulfate
Half-life: 90-127 minutes

Brands and Availability ⬆ ⬇