Hydralazine – a medicine for very high blood pressure

Hydralazine – a medicine for very high blood pressure

Hydralazine is a blood pressure tablet usually only prescribed by hospital based hypertension specialist doctors. It is often used when three other tablets are not achieving good blood pressure control.

What is hydralazine?

• A Direct Vasodilator: Unlike other blood pressure meds that work on hormones or heart rate, hydralazine acts directly on the walls of your blood vessels
• Established Therapy: It is an older, well-studied medication that has been used for decades

How it works

• Relaxes Blood Vessels: It sends a signal to the smooth muscles in the walls of your arteries to relax
• Widens the ‘Pipe’: By relaxing these muscles, the arteries widen (dilate), which allows blood to flow through more easily
• Lowers Resistance: This decreased resistance means your heart doesn’t have to pump as hard to move blood through your body, resulting in lower blood pressure

Who is hydralazine used for?

• Hypertension (High Blood Pressure)
• It is often a ‘Third (or fourth) Line’ Choice: It can be added when 2-3 other common blood pressure medications (like ACE inhibitors, beta-blockers or diuretics) aren’t enough on their own
• Heart Failure: In some cases, it is used in combination with other drugs (like isosorbide dinitrate) to help the heart pump more efficiently
• Hypertensive Emergency: In hospital settings, an injectable form can be used for rapid blood pressure reduction

Dose

• Dose Range: 12.5 mg twice a day to 100 mg three (or four) times a day
• Oral Tablets: Most patients take it as a pill. It should be taken at the same time every day to keep levels steady

Note. Never Stop Abruptly: Stopping hydralazine suddenly can cause a ‘rebound’ spike in blood pressure

Side-Effects

Common side-effects

• Headache (this often improves as your body gets used to the drug)
• Heart palpitations or a fast heartbeat (tachycardia)
• Flushing or feeling warm
• Nausea or loss of appetite

Less common (but more serious) side-effects

• Drug-Induced Lupus (SLE): Some patients develop a condition that mimics Lupus, causing joint pain, fever, and fatigue. This usually goes away once the drug is stopped
• Extreme Low Blood Pressure: Feeling dizzy or fainting, especially when standing up quickly
• Fluid Retention: Swelling (oedema) in the feet or ankles

Monitoring

Your doctor should monitor:

• Blood Pressure
• Heart Rate: Since the body sometimes tries to ‘compensate’ for wider blood vessels by beating faster, your doctor should monitor your pulse
• ANA Blood Test: If you develop joint pain or a rash, your doctor may run a blood test (Antinuclear Antibody) to check for the Lupus-like syndrome mentioned above