Hydralazine hydrochloride

How it works

It relaxes arteriolar smooth muscle to reduce systemic vascular resistance and afterload; the resulting fall in blood pressure can trigger reflex tachycardia and fluid retention.

Prescribing in practice

• Long-term use, particularly at higher doses or in slow acetylators, can cause a drug-induced lupus-like syndrome, so persistent arthralgia, rash or systemic symptoms should prompt review.
• Reflex tachycardia and sodium and water retention often necessitate co-prescription of a beta-blocker and a diuretic.
• It can precipitate or worsen angina and should be used with caution in coronary artery disease.

Monitoring

Monitor blood pressure and heart rate, with review for lupus-like symptoms (and antinuclear antibodies if suspected) during prolonged therapy.

Counselling the patient

• Report persistent joint pain, unexplained fever or a facial rash.
• Palpitations and headache can occur as your body adjusts.
• Rise slowly from sitting or lying to reduce dizziness.

Evidence & guidelines

The combination of hydralazine with a nitrate is supported in heart failure, notably in the A-HeFT trial in self-identified Black patients.