Hydralazine

Provider Level

RN/Paramedic

Class

Direct-acting peripheral vasodilator

Mechanism of Action

Directly relaxes arteriolar smooth muscle, resulting in decreased systemic vascular resistance and lowered blood pressure with minimal effect on venous capacitance.

Indications

Severe hypertension, hypertensive emergencies (particularly preeclampsia and eclampsia).

Contraindications

Hypersensitivity, coronary artery disease, mitral valvular rheumatic heart disease, dissecting aortic aneurysm.

Routes

IV, IM, PO

Onset / Duration

Onset: 5 to 20 minutes (IV) or 10 to 30 minutes (IM). Duration: 2 to 6 hours.

Adverse Effects

Reflex tachycardia, headache, flushing, profound hypotension, angina, arrhythmias, nausea, vomiting.

Precautions & Interactions

May cause reflex tachycardia and increase myocardial oxygen demand. Use caution in patients with suspected stroke, cardiovascular disease, or increased intracranial pressure.

Special Considerations

Continuous blood pressure and ECG monitoring are required. Often used in pregnancy for pregnancy-induced hypertension. Do not use as first-line therapy for undifferentiated hypertensive emergencies without specific protocol guidance.