Pregnancy Risk Category C
How supplied
Tablets: 10 mg, 25 mg, 50 mg, 100 mg
Injection: 20 mg/ml
Action
Unknown. A direct-acting vasodilator that primarily relaxes arteriolar smooth muscle.
Indications & dosage
Essential hypertension (orally, alone or with other antihypertensives), severe essential hypertension (parenterally, to lower blood pressure quickly)--
Adults: P.O.--initially, 10 mg P.O. q.i.d.; gradually increased to 50 mg q.i.d., p.r.n. Maximum recommended dose is 200 mg daily, but some patients may need 300 to 400 mg daily.
I.V.--10 to 20 mg given slowly and repeated as needed, switching to oral antihypertensives as soon as possible.
I.M.--10 to 50 mg, repeated as needed, switching to oral form as soon as possible.
Children: P.O.--initially, 0.75 mg/kg/day P.O. divided into four doses; gradually increased over 3 to 4 weeks to maximum of 7.5 mg/kg or 200 mg daily. Maximum initial P.O. dose is 25 mg.
I.V.--0.1 to 0.2 mg/kg I.V. q 4 to 6 hours, p.r.n. Maximum initial parenteral dose is 20 mg.
Adverse reactions
CNS: peripheral neuritis, headache, dizziness.
CV: orthostatic hypotension, tachycardia, edema, angina, palpitations.
EENT: nasal congestion.
GI: nausea, vomiting, diarrhea, anorexia, constipation.
Hematologic: neutropenia, leukopenia, agranulocytopenia, agranulocytosis, thrombocytopenia with or without purpura; decreased hemoglobin level and RBC count.
Skin: rash.
Other: lupus-like syndrome.
Interactions
Drug-drug. Diazoxide, MAO inhibitors: may cause severe hypotension. Use together cautiously.
Diuretics, other hypotensive drugs: increased risk of excessive hypotension. Dosage adjustment may be needed.
Indomethacin: may decrease effects of hydralazine. Monitor blood pressure.
Effects on diagnostic tests
Drug may cause positive antinuclear antibody titer and positive lupus erythematosus cell preparation.
Contraindications
Contraindicated in patients with hypersensitivity to drug, coronary artery disease, or mitral valvular rheumatic heart disease.
Nursing considerations
I.V. administration
Patient teaching
*Liquid contains alcohol. **May contain tartrazine. †Canada ‡Australia §U.K. OTCOver the counter
Reactions may be common, uncommon, life-threatening, or COMMON AND LIFE-THREATENING