Hydralazine

Hydralazine is a vasodilator medicine used to treat high blood pressure and, together with isosorbide dinitrate, in selected patients with heart failure. This guide covers hydralazine uses, how it works, dosage, side effects, precautions, drug interactions, use in pregnancy and breastfeeding and brand names.

What is Hydralazine?

Hydralazine is a direct-acting vasodilator used to treat high blood pressure (hypertension). It is also used, together with isosorbide dinitrate, in selected patients with heart failure. It works by relaxing the blood vessel walls, allowing blood to flow more easily to vital organs and tissues and reducing the strain on the heart.

Hydralazine at a Glance

How Hydralazine Works

Hydralazine works by directly relaxing the smooth muscles in the blood vessels. This vasodilation (widening of the blood vessels) helps to lower blood pressure and decrease heart workload. The exact mechanism is not fully understood.

When Is Hydralazine Used?

• Hypertension: For controlling high blood pressure, alone or along with other blood pressure medicines, especially when other medicines are not enough.
• Heart failure (HFrEF): Hydralazine is used together with isosorbide dinitrate, not on its own. Guidelines recommend the combination for self-identified African American patients with HFrEF and NYHA class III-IV symptoms who are receiving optimal medical therapy. It may also be considered for patients who cannot take first-line medicines (ACE inhibitors, ARBs or ARNIs) because of intolerance or renal insufficiency. Your doctor decides whether these medicines are suitable for you.

Hydralazine Dosage

• Adult oral dose for hypertension: 25 mg 3-4 times daily, increased as needed according to blood pressure response and how well it is tolerated. The usual range is 100-200 mg/day. A maximum of 300 mg/day may be needed in a few resistant patients.
• Pediatric oral dose for hypertension: The usual starting dose is 0.75 mg/kg/day in four divided doses. A doctor may increase it gradually over the next 3-4 weeks, up to 7.5 mg/kg/day, with a total daily dose not exceeding 200 mg. Controlled clinical trial evidence in children is limited, although there is clinical experience with its use.

These doses apply to oral hypertension treatment. Heart failure, injectable (hospital) use and other situations may follow different regimens set by the treating doctor. Dosing is individualized. Take this medicine only as advised by your doctor or healthcare professional, and do not start, stop, or change the dose on your own.

How to Take Hydralazine

Take hydralazine regularly and continuously as directed. Take it consistently with regard to meals, according to your doctor’s instructions. Food can increase the amount of hydralazine absorbed, so keeping to the same routine helps.

Side Effects of Hydralazine

• Common: Headache, loss of appetite, nausea, vomiting, diarrhoea, palpitations, fast heart rate (tachycardia) and chest pain (angina).
• Less frequent: Dizziness, low blood pressure, fluid retention or swelling, breathlessness, flushing, nasal congestion, and numbness or tingling.
• Serious:
  • Lupus-like syndrome: Hydralazine can cause an illness resembling lupus. The risk is higher with larger doses and may increase with longer treatment. Symptoms include joint pain, fever, chest pain and unusual or persistent tiredness. Not everyone develops it.
  • Blood count abnormalities.
  • Rarely, liver inflammation (hepatitis).

Report new or persistent numbness or tingling to your doctor, as hydralazine can be associated with peripheral neuritis (nerve inflammation). Contact your doctor promptly if you notice joint pain, fever, chest pain, unusual tiredness, easy bruising or any worrying symptom.

Who Should Not Take Hydralazine? (Contraindications)

Hydralazine should not be used in people with:

• Known hypersensitivity (allergy) to hydralazine
• Coronary artery disease
• Mitral valvular rheumatic heart disease

Other conditions below call for caution and monitoring but are not listed as contraindications.

Hydralazine Precautions and Monitoring

• Hydralazine can provoke angina and ECG changes of myocardial ischaemia, so doctors use it with caution when coronary artery disease is suspected.
• Use caution in people with previous cerebrovascular disease (such as a stroke) and in advanced kidney disease.
• With prolonged treatment, doctors may check complete blood counts (CBC) and antinuclear antibody (ANA) levels, even if you feel well. Whether and how often depends on your treatment and your doctor’s judgement. Do not order these tests yourself.
• If a lupus-like illness develops, tell your doctor. Do not stop the medicine on your own.

Hydralazine Drug Interactions

• Other blood pressure medicines: Combining hydralazine with other antihypertensives can increase the blood-pressure-lowering effect and may call for monitoring.
• MAO inhibitors: Use with caution in patients taking hydralazine.
• Diazoxide injection: Combining it with hydralazine can cause a profound fall in blood pressure.
• Intentional combinations: Doctors may deliberately combine hydralazine with medicines such as thiazide diuretics or beta blockers, or with isosorbide dinitrate in heart failure. These are planned regimens, not prohibited combinations. Doses are adjusted individually.

This list is not complete. Tell your doctor or pharmacist about all prescription medicines, over-the-counter medicines, supplements, and herbal products you use.

Hydralazine in Pregnancy and Breastfeeding

• Pregnancy: Hydralazine may be used during pregnancy when clinically indicated. For example, injectable hydralazine is a recognised option for urgent treatment of acute, severe high blood pressure in pregnancy and after delivery. Your doctor will weigh the benefits of controlling blood pressure against potential risks. Adequate, well-controlled studies in pregnant women are lacking. Do not start, stop, or change treatment without medical advice.
• Breastfeeding: Hydralazine passes into breast milk, and available data are limited. LactMed, the NIH drugs-and-lactation database, considers it an acceptable antihypertensive for nursing mothers based on available evidence and long clinical experience. Discuss your individual situation with your doctor.

Hydralazine Brands and Strengths in India

Brands listed in India include:

• Hydralaze (Dahlia Pharmaceutical): 25 mg tablet
• Hydrastat-25 (Johnlee Pharmaceuticals): 25 mg tablet
• Aprezine (RMPL Pharma): 25 mg tablet
• Apresol (Ordain Health Care Global): 25 mg tablet

Brand availability may vary by location and over time. Hydralazine tablets are also made in other strengths (US labels list 10, 25, 50 and 100 mg), and your doctor will decide which suits you.

How HealthPil Can Help

Medicines should be started, adjusted, or stopped only under the guidance of a qualified healthcare professional. If you have questions about this medicine, its side effects, or your treatment plan, you can consult a doctor through HealthPil. For blood pressure and heart concerns, HealthPil can connect you with a cardiologist.