Hydralazine + Isosorbide Dinitrate (HFrEF)

How it works

Hydralazine relaxes arterial smooth muscle to reduce afterload, while isosorbide dinitrate acts as a nitric oxide donor causing venodilation and reduced preload; together they improve cardiac output in heart failure.

Prescribing in practice

• Hydralazine can cause a drug-induced lupus-like syndrome, more likely at higher doses and in slow acetylators, so review patients for unexplained arthralgia, rash or fever.
• Reflex tachycardia and fluid retention may occur and can offset benefit, so monitor heart rate and fluid status.
• Headache and flushing from the nitrate component are common, particularly on initiation.

Monitoring

Monitor blood pressure, heart rate, fluid status and symptoms; remain alert for features of a lupus-like syndrome (arthralgia, rash, fever) during longer-term use.

Counselling the patient

• Report persistent joint or muscle pain, rash, fever or unexplained tiredness.
• Headache is common at first and usually settles; do not stop the medicines abruptly.
• Rise slowly from sitting or lying to reduce light-headedness.

Evidence & guidelines

Recommended as add-on or alternative therapy in heart failure with reduced ejection fraction, including in people of African or Caribbean origin (NICE NG106).