HYDRALAZINE HYDROCHLORIDE (hye-dral'a-zeen) Alazine, Apresoline Classifications: cardiovascular agent; nonnitrate vasodilator; antihypertensive Pregnancy Category: C
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10 mg, 25 mg, 50 mg, 100 mg tablets; 20 mg/mL vial
Reduces BP mainly by direct effect on vascular smooth muscles of arterial-resistance vessels, resulting in vasodilation. Has
little effect on venous-capacitance vessels. Hypotensive effect may be limited by sympathetic reflexes, which increase heart
rate, stroke volume, and cardiac output.
Diastolic response is often greater than systolic response. Vasodilation reduces peripheral resistance and substantially improves
cardiac output, and renal and cerebral blood flow. Postural hypotensive effect is reportedly less than that produced by ganglionic
blocking agents.
Most commonly in stepped-care approach to treat moderate to severe hypertension. Also in early malignant hypertension and
resistant hypertension that persists after sympathectomy.
Conjunctively with cardiac glycosides and other vasodilators in short-term treatment of acute CHF; unexplained pulmonary hypertension.
Coronary artery disease, mitral valvular rheumatic heart disease, MI, tachycardia, SLE. Safe use during pregnancy (category
C) or lactation is established.
Cerebrovascular accident, advanced renal impairment, use with MAO INHIBITORS.
Hypertension Adult: PO 1050 mg q.i.d. IM 1050 mg q46h IV 1020 mg q46h Geriatric: PO Start with 10 mg 23 times/d Child: PO 37.5 mg/kg/d in 4 divided doses IV/IM 1.73.5 mg/kg/d in 4 divided doses
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Oral
- Give with food; bioavailability is increased by taking it with food.
- Discontinue gradually to avoid sudden rise in BP and acute heart failure.
- Inform patients of the dangers of abrupt withdrawal.
Intramuscular
- Give deep into a large muscle.
Intravenous PREPARE: Direct: Give undiluted. Use immediately after being drawn into syringe. Do not add to IV solutions.
ADMINISTER: Direct: Give each 10 mg or fraction thereof over 1 min.
INCOMPATIBILITIES Solution/additive:
Aminophylline,
ampicillin,
chlorothiazide,
edetate calcium disodium,
hydrocortisone,
mephentermine,
methohexital,
nitroglycerin,
phenobarbital,
verapamil.
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- Store at 15°30° C (59°86° F) in tight, light-resistant containers unless otherwise directed.
Avoid freezing.
Body as a Whole: Hypersensitivity (rash, urticaria, pruritus, fever, chills, arthralgia, eosinophilia, cholangitis, hepatitis, obstructive
jaundice). CNS:
Headache, dizziness, tremors. CV:
Palpitation, angina, tachycardia, flushing, paradoxical pressor response. Overdose: arrhythmia, shock. Special Senses: Lacrimation, conjunctivitis. GI: Anorexia, nausea, vomiting, diarrhea, constipation, abdominal pain, paralytic ileus. Urogenital: Difficulty in urination, glomerulonephritis. Hematologic: Decreased hematocrit and hemoglobin, anemia, agranulocytosis (rare). Other: Nasal congestion, muscle cramps, SLE-like syndrome, fixed drug eruption, edema.
Positive direct Coombs' tests in patients with hydralazine-induced SLE. Hydralazine interferes with urinary 17-OHCS determinations (modified Glenn-Nelson technique).
Drug:
beta blockers and other antihypertensive agents compound hypotensive effects.
Absorption: Readily absorbed from GI tract. Onset: 2030 min. Peak: 2 h. Duration: 26 h. Distribution: Crosses placenta; distributed into breast milk. Metabolism: Metabolized in intestinal wall and liver. Elimination: 90% rapidly excreted in urine; 10% excreted in feces. Half-Life: 28 h.
Assessment & Drug Effects
- Lab tests: Determine antinuclear antibody titer before initiation of therapy and periodically during prolonged therapy.
- Make baseline and periodic determinations of BUN, creatinine clearance, uric acid, serum potassium, blood glucose, and ECG.
- Monitor for S&S of SLE, especially with prolonged therapy.
- Monitor BP and HR closely. Check every 5 min until it is stabilized at desired level, then every 15 min thereafter throughout
hypertensive crisis.
- Monitor I&O when drug is given parenterally and in those with renal dysfunction.
Patient & Family Education
- Monitor weight, check for edema, and report weight gain to physician.
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Note: Some patients experience headache and palpitations within 24 h after first PO dose; symptoms usually subside spontaneously.
- Make position changes slowly and avoid standing still, hot baths/showers, strenuous exercise, and excessive alcohol intake.
- Do not drive or engage in other potentially hazardous activities until response to drug is known.
- Do not breast feed while taking this drug without consulting physician.