hydralazine
Brand: Apresoline
Prototype Drug
Drug Class: direct vasodilator
Drug Family: antihypertensive
Subclass: arteriolar dilator
Organ Systems: cardiovascular
Mechanism of Action
Direct arteriolar vasodilator; mechanism involves opening K+ channels and inhibiting IP3-mediated calcium release; reduces afterload.
vascular smooth muscle (direct)
Indications
- hypertension (adjunct)
- hypertensive emergency (IV)
- heart failure (combined with isosorbide dinitrate in Black patients)
- hypertension in pregnancy (IV)
Contraindications
- coronary artery disease (reflex tachycardia may worsen angina)
- mitral valve rheumatic disease
- SLE
Adverse Effects
Common
- reflex tachycardia
- fluid retention
- headache
- flushing
- nasal congestion
Serious
- drug-induced lupus (slow acetylators, high doses >200 mg/day)
- angina exacerbation
Pharmacokinetics (ADME)
| Absorption | 30-50% oral bioavailability (first-pass; slow vs fast acetylators vary significantly) |
| Distribution | wide |
| Metabolism | hepatic N-acetyltransferase (NAT2) — slow acetylators higher exposure |
| Excretion | renal |
| Half-life | 3-7 hours |
| Onset | 20-30 min oral; 5-20 min IV |
| Peak | 1-2 hours |
| Duration | 6-12 hours |
| Protein Binding | 87% |
| Vd | large |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| MAOIs | severe hypotension | major |
| beta-blockers | useful combination — beta-blockers blunt reflex tachycardia | beneficial |
Nursing Considerations
- A-HeFT trial: hydralazine+isosorbide dinitrate reduced mortality in Black patients with HFrEF
- Monitor for drug-induced lupus: fever, joint pain, rash, ANA positive (slow acetylators at highest risk)
- Often combined with beta-blocker (prevents reflex tachycardia) and diuretic (prevents fluid retention)
- IV form used for hypertensive emergency in pregnancy
Clinical Pearls
- A-HeFT: isosorbide dinitrate + hydralazine reduces mortality in self-identified Black patients with HFrEF
- Drug-induced lupus: risk in slow NAT2 acetylators at doses >200 mg/day; positive ANA but usually resolves on stopping
- Arteriolar selectivity only — venous capacitance unaffected (unlike nitrates)
Safety Profile
Pregnancy safe
Lactation use-with-caution
Renal Adjustment Required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.