Brand and Other Names:
- Classes: Vasodilators
Dosing & Uses
Dosage Forms & Strengths
Severe Essential Hypertension
10 mg PO q6hr for 2-4 days; 25 mg q6hr daily for the first week; increase to 50 mg q6hr from second week on; adjust dose to lowest effective levels
20-40 mg IM/IV; repeat as necessary
- Change to oral therapy as soon as possible
Initial: 10 mg PO q6hr for 2-4 days; may increase gradually by 10-25 mg/dose every 2-5 days up to 50 mg PO q6hr (some patients require 300 mg/day)
See also combo with isosorbide dinitrate
20-40 mg IV/IM; repeat PRN
- 5-10 mg IV/IM initially, THEN 5-10 mg q20-30min PRN, OR
- 0.5-10 mg/hr IV infusion
Congestive Heart Failure
Initial dose: 10-25 mg q6-8hr PO
Maintenance dose: 225-300 mg/day divided q6-8hr PO
- Adjust dose per individual response
Dosage Forms & Strengths
3 months - 1 year: 0.1-0.5 mg/kd/dose IV q6-8hr; not to excced 2 mg/kg IV q6hr; titrate dose for blood pressure control
>1 year: 0.1-0.2 mg/kg IV/IM q4-6hr PRN initially; may increase to usual dose of 1.7-3.5 mg/kg/day divided q4-6hr; not to exceed 20 mg/dose IM or IV or 2 mg/kg q3-6hr with cumulative dose not to exceed 9 mg/kg
Serious - Use Alternative
Significant - Monitor Closely
Frequency Not Defined
Hypersensitivity to hydralazine
Coronary artery disease
Mitral valve rheumatic heart disease
May induce SLE-type syndrome (usually at >200 mg/day); instruct patients to report joint/chest pain or fever; consider discontinuation if occurs
Use caution in CVA, severe renal impairment, volume depletion, preexisting hypotension, concurrency with other hypotensive agents, CAD (potential contraindication)
Discontinue slowly to avoid rapid rise in blood pressure
Use with caution in patients with pulmonary hypertension; may cause hypotension
Increases fluid and sodium retention; may require treatment or increase in diutretic dose
Peripheral neuritis reported; treat symptoms with pyridoxine
Pregnancy & Lactation
Pregnancy category: C
Lactation: Excreted in breast milk; use caution
A:Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B:May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk.
C:Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done.
D:Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk.
X:Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist.
NA:Information not available.
Mechanism of Action
Direct vasodilator; dilates arterioles with little effect on vein; decreases systemic resistance, which subsequently decreases blood pressure.
Bioavailability: Slow acetylator: 30-50%; rapid acetylator: 22-30%
Onset: 5-20 min, maximum effect 10-80 min (IV); 20-30 min (PO)
Duration: 3-8 hr (PO); 1-4 hr (IV)
Protein bound: 85-90%
Vd: 0.3-8.2 L/kg
Significantly metabolized in liver by acetylation; slow and rapid acetylator
Metabolites: Phthalazine and pyruvic acid hydrazone metabolites (inactive metabolite)
Half-life: 2-8 hr (normal renal function); 7-16 hr (end-stage renal disease)
Excretion: Urine (14%; unchanged)
HLA-DRw4 appears in 73% of patients experiencing hydralazine-associated SLE
Solution: D5W, D10/LR, fructose 10%, fructose 10%/NS
Additive: Aminophylline, ampicillin, chlorothiazide, dobutamine, CaNa2EDTA, ethacrynate, hydrocortisone sodium succinate, mephentermine, methohexital, nitroglycerin, phenobarbital, verapamil
Y-site: Aminophylline, ampicillin, diazoxide, furosemide
Solution: Dextrose-Ringer combinations, D5/LR, dextrose 2.5%/½LR, dextrose-saline combinations, D10W, Ringer, LR, ½NS, NS, Na-lactate 1/6M
Y-site: Heparin, hydrocortisone sodium succinate, nitroglycerin (compatible for 3 hr; may form slight ppt), KCl, verapamil, vit B/C
Prepare immediately before use
Minimize contact with metal parts during preparation and administration
Administer IM or as rapid IV injection directly into vein
Avoid adding drug to infusion solution
Store at controlled room temp
Do not refrigerate
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|1||This drug is available at the lowest co-pay. Most commonly, these are generic drugs.|
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