Hydralazine

High Blood Pressure

Hydralazine is primarily used to treat hypertension (high blood pressure). It may be prescribed alone or alongside other medications, such as diuretics, to help lower blood pressure. Managing high blood pressure is essential for reducing the risk of life-threatening complications, including:

• Strokes
• Heart attacks
• Kidney failure

By keeping blood pressure within a healthy range, the medication reduces the workload on the heart and prevents damage to the arteries.

Heart Failure

In certain situations, hydralazine is used as part of a combination therapy to treat heart failure. It is often paired with other medications, such as nitrates, to help the heart pump blood more effectively throughout the body. This use is typically reserved for patients who continue to have symptoms despite using standard heart failure treatments.

Mechanism of Action

Hydralazine belongs to a class of medications known as peripheral vasodilators. It works by acting directly on the smooth muscles in the walls of the blood vessels, causing them to relax and expand.

When these blood vessels widen, it creates more space for blood to circulate. This process has several effects on the cardiovascular system:

• Reduced Resistance: It lowers the resistance that blood faces as it travels through the arteries.
• Lower Blood Pressure: By reducing resistance, the overall pressure within the circulatory system decreases.
• Decreased Heart Workload: Because the blood vessels are wider, the heart does not have to pump as hard to move blood through the body.

Although the exact chemical process that causes the muscles to relax is not fully established, the medication primarily targets the arteries and arterioles rather than the veins.

Common Side Effects

The following side effects are more common and may go away as your body adjusts to the medicine:

• Headache
• Loss of appetite
• Nausea or vomiting
• Diarrhea
• Fast or pounding heartbeat
• Dizziness

Serious Side Effects

Contact your healthcare provider immediately if you experience any of the following:

• Fever, chills, or sore throat
• Joint or muscle pain
• Skin rash
• Swollen glands
• Chest pain
• Numbness or tingling in the hands or feet
• Painful or difficult urination
• Blood in the urine

Hydralazine can sometimes cause a condition similar to lupus, which may involve symptoms like fever, joint pain, and chest pain. These symptoms usually improve after the medication is discontinued.

Heart and Vascular Risks

Hydralazine can cause a significant increase in heart rate and may worsen symptoms of chest pain (angina). Because of these effects, it is typically not used in people with coronary artery disease or certain types of heart valve disease, such as mitral valvular rheumatic heart disease. In some cases, the drug has been associated with heart attacks.

Drug-Induced Lupus

Long-term use or high doses of hydralazine may cause a condition similar to systemic lupus erythematosus. Symptoms often include:

• Joint pain or swelling
• Fever
• Chest pain
• General feeling of being unwell

This condition is more common in people who process the medication slowly (slow acetylators). If these symptoms occur, a healthcare provider may perform blood tests, such as an antinuclear antibody (ANA) titer, and may recommend stopping the medication.

Nerve and Blood Concerns

Some individuals may experience peripheral neuritis, which involves numbness, tingling, or burning sensations in the hands or feet. This is sometimes managed by taking vitamin B6 (pyridoxine).

Rarely, hydralazine can cause changes in blood cell counts, such as a decrease in white blood cells or red blood cells. Periodic blood tests are often used to monitor for these changes during treatment.

Genetic Considerations

The way the body breaks down hydralazine depends on an enzyme process called acetylation. People who are slow acetylators may have higher levels of the drug in their system, which increases the risk of side effects and the development of the lupus-like syndrome.

Pregnancy

There are no adequate and well-controlled studies of hydralazine use in pregnant women. Research in animals has shown that high doses of the medication may cause birth defects, such as cleft palate, in certain species. Because of these findings, healthcare providers typically only prescribe hydralazine during pregnancy if the potential benefit justifies the potential risk to the developing baby.

Breastfeeding

Hydralazine has been shown to pass into breast milk in small amounts. While there are no specific reports of adverse effects on nursing infants, the safety of using this medication while breastfeeding is not fully established. It is important to discuss the risks and benefits with a healthcare provider if you are breastfeeding or planning to breastfeed while taking this medication.

Available Forms

Hydralazine is primarily available in the following forms:

• Oral Tablet: This form is taken by mouth and is the most common method for long-term management.
• Injectable Solution: This form is intended for intramuscular or intravenous administration. It is typically administered by a healthcare professional in a clinical or hospital setting.

Combination Products

Hydralazine is also available in combination with other medications in a single oral tablet. These combination products may include:

• Hydralazine and hydrochlorothiazide (a diuretic).
• Hydralazine and isosorbide dinitrate (a nitrate).

FDA Approval and Indications

Hydralazine is FDA-approved for the treatment of essential hypertension, also known as high blood pressure. It may be used alone or in combination with other medications to help lower blood pressure. Additionally, the FDA has approved fixed-dose combinations of hydralazine and isosorbide dinitrate for the treatment of heart failure in specific patient populations, particularly to improve survival and reduce hospitalizations in Black patients.

Safety Communications

The FDA monitors the safety of hydralazine through the FDA Adverse Event Reporting System (FAERS). In 2016, the agency identified a potential safety signal regarding drug-induced lupus erythematosus and vasculitis (inflammation of the blood vessels) associated with hydralazine use. These conditions occur when the immune system mistakenly attacks healthy tissues or blood vessels.

Pharmacogenomic Information

The FDA-approved labeling for hydralazine includes information about how genetic variations can affect how the body processes the medication. Specifically, the rate at which a person's liver metabolizes the drug, known as acetylation, can influence safety. Individuals who are slow acetylators may have higher levels of the drug in their system, which can increase the risk of developing drug-induced lupus.

Regulatory Requirements

Hydralazine is available as a generic prescription medication in oral tablet and injectable forms. It does not currently require a Risk Evaluation and Mitigation Strategy (REMS) program, and it does not carry a Boxed Warning, which is the FDA's most serious category of warning for approved drugs.

Generic Availability

Hydralazine is available as a generic drug. Generic medications are typically less expensive than brand-name versions because they do not require the same initial research and marketing costs.

Factors Influencing Cost

The amount you pay for hydralazine can be affected by several factors:

• Insurance Coverage: Most insurance plans, including Medicare Part D, cover generic hydralazine. Your specific out-of-pocket cost will depend on your plan's copayments, coinsurance, and deductible requirements.
• Pharmacy Selection: Prices for the same prescription can vary between different retail pharmacies, mail-order services, and local clinics.
• Prescription Details: The total cost may change based on the dosage strength and the number of tablets prescribed for each refill.

Because prices can fluctuate, patients are encouraged to check with their insurance provider or pharmacist to determine their specific costs. Some pharmacies may also offer discount programs for generic medications.