Hydralazine – StatPearls – NCBI Bookshelf

Continuing Education Activity

Hydralazine is a direct vasodilator used orally to treat essential hypertension, among other diseases, and intravenously to rapidly reduce blood pressure in hypertensive urgency or emergency. Per JNC 8 guidelines, it is not a first-line agent for the treatment of essential hypertension. This is due to hydralazine’s stimulation of the sympathetic nervous system, among several other adverse effects that make the current newer first-line agents more efficacious. This activity outlines the indications, mechanism of action, administration, contraindications, and adverse effects of hydralazine.

Objectives:

• Identify the indications for initiating hydralazine therapy.

• Summarize the theorized mechanism of action of hydralazine.

• Discuss the parameters of hydralazine administration.

• Outline how an interprofessional team can coordinate the use and monitoring of hydralazine to obtain the best patient outcomes.

Access free multiple choice questions on this topic.

Indications

Hydralazine is primarily used to treat hypertension and hypertensive urgency/emergency.[1] It has also been utilized in the treatment of eclampsia along with heart failure with reduced ejection fraction (HFrEF) when in combination with isosorbide dinitrate.[2] 

In current practice, oral hydralazine is used in essential hypertension refractory to other therapeutic agents.[2] Studies comparing its effects as an add-on medication to multidrug treatment for hypertension have proved effective but not as efficacious as other multi-modal first-line therapies (calcium channel blockers, angiotensin-converting enzyme inhibitors/angiotensin II receptor blockers, thiazides).[2] Per the JNC 8 guideline algorithm, hydralazine can be considered if initiation of first-line therapy titrated to its maximum dose and/or the addition of a second first-line agent does not meet blood pressure reduction goals. In these guidelines, hydralazine is categorized with other medications, including beta-blockers and aldosterone antagonists, that have more compelling additional indications when compared to hydralazine, such as their use in heart failure and pregnancy. [3]   

IV hydralazine has had increased off-label use in the setting of hypertensive emergencies. It is often given to hospitalized patients but has little evidence of improved outcomes. Reasons for this include highly variable blood pressure changes and adverse hypotensive episodes.[4]

IV hydralazine along with IV labetalol are considered first-line therapy for the treatment of acute-onset, severe hypertension in pregnancy and during the postpartum period. Either of these medications should be administered during the intrapartum or postpartum period if severe blood pressure persists for greater than 15 minutes.[5] 

For African-American patients with severe heart failure (New York Heart Association Class III and IV) with reduced ejection fraction (HFrEF), the American Heart Association recommends ACE inhibitors and beta-blockers as first-line therapy.[6] Within this population, the use of hydralazine in combination with isosorbide dinitrate has demonstrated a mortality benefit, although more recent studies have shown less robust efficacy. [7] Per the 2019 American College of Cardiology expert consensus guidelines, fixed-dose long-acting nitrates, and hydralazine can be added to African American people already receiving an ACE inhibitor, ARB, or ARNI plus a beta-blocker.[8]

Mechanism of Action

Hydralazine is a direct arteriole vasodilator. Although the mechanism is not completely understood, it is theorized to be associated with intracellular calcium homeostasis. Specifically, it acts to inhibit inositol trisphosphate (IP3)-induced release of calcium from the smooth muscle cells’ sarcoplasmic reticulum and inhibits myosin phosphorylation within the arterial smooth muscle.[2] This reduces peripheral vascular resistance and leads to a compensatory baroreceptor-mediated release of epinephrine and norepinephrine, which, as a result, increases venous return and cardiac output. Given hydralazine’s stimulation of the sympathetic nervous system, it consequently leads to tachyphylaxis and tachycardia. It is sometimes given with a beta-blocker or diuretic for better patient tolerance. [2]

Hydralazine is metabolized by the liver. It undergoes polymorphic acetylation. Slow acetylators require lower doses of the drug. Both the acetylated drug and unchanged drug are excreted in the urine and feces.[1]

For intravenous dosing, the blood-pressure-lowering effects occur within 5 to 30 minutes with a total duration of 2 to 6 hours. For oral dosing, the blood-pressure-lowering effects occur within 20 to 30 minutes with a total duration of 2 to 4 hours.[2]

Administration

For the treatment of hypertensive emergencies, hydralazine should be administered at a dosage of 10 mg via slow IV infusion with a maximum initial dose of 20 mg. This can be repeated every 4-6 hours as needed. Due to its unpredictable response and prolonged duration of action, hydralazine is not a desirable first-line agent for acute treatment.[9]

To treat essential hypertension, hydralazine should be initiated at a dosage of 10 mg orally four times daily for the first 2 to 4 days, then increased to 25 mg four times daily to complete 1 week of treatment. It can then be increased to 50 mg four times daily for maintenance therapy. The oral dosage maximum is 300 mg per day.[9] 

For the treatment of Stage C Heart Failure with Reduced Ejection Fraction (HFrEF), the recommended fixed initial dose combination of hydralazine and isosorbide dinitrate is 37.5 mg hydralazine/20 mg isosorbide dinitrate 3 times daily with a maximum dose of 75 mg hydralazine/40 mg isosorbide dinitrate 3 times daily.[10]

Adverse Effects

Hydralazine has been reported to cause headaches, nausea, flushing, hypotension, palpitations, tachycardia, dizziness, and angina.[11]

Immune phenomena such as drug-induced lupus erythematosus (DILE), serum sickness, hemolytic anemia, vasculitis, and glomerulonephritis have been reported using hydralazine.[12]

Hydralazine-related DILE, also known as hydralazine-induced lupus syndrome (HILS), usually occurs with greater than 6 months of exposure, and roughly 5-8% of hydralazine users are at risk of developing DILE. [12] The incidence of HILS is dose-dependent. The syndrome typically manifests with arthralgias, myalgias, serositis, and fevers; cardiac involvement is rare [13]. The risk factors for developing DILE include slow acetylator phenotype, family history of autoimmune disease, and decreased renal function. There have also been associations between DILE occurrence and certain human leukocyte antigens (HLA). Discontinuation of hydralazine usually resolves the lupus-like syndrome.[12]

Cases of drug-induced liver injury (DILI) have also been reported with the use of hydralazine. Symptoms of DILI are consistent with hepatitis and include nausea, vomiting, dark urine, jaundice, abdominal pain, and pruritus. Treatment entails discontinuation of hydralazine.[14]

There have been rare cases of toxic epidermal necrolysis (TEN) reported in association with hydralazine.[15][16]

There have also been rare cases reported of polyneuritis that are amenable to pyridoxine supplements.[17] 

Contraindications

Coronary artery disease: this is due to hydralazine’s stimulation of the sympathetic nervous system. This leads to increased cardiac output and oxygen demand, which can provoke myocardial ischemia.[18]

Lactation: use caution in breastfeeding women as it is unknown if hydralazine is excreted in human milk[19]

Aortic dissection:  it can increase aortic wall shear stress 

Monitoring

A complete blood count (CBC) and an antinuclear antibody (ANA) titer should be obtained prior to initiating therapy and periodically during therapy. In 95-100% of HILS, the serum ANA titer is positive. Abnormal hematologic findings to be aware of in HILS includes anemia, leukopenia, and/or agranulocytosis.[20] Risks versus benefits must be discussed with the patient with positive ANA titers before initiating therapy with hydralazine.[11]

If the patient develops arthralgias, fever, chest pain, continued malaise, hematologic findings mentioned above, or other unexplained signs or symptoms related to DILE, the drug should be discontinued immediately, and corticosteroids and/or immunosuppressive therapy should be considered in life-threatening cases. [13]

Toxicity

Published reports of toxicity with acute use of hydralazine are uncommon. Signs of toxicity include hypotension, tachycardia, headaches, and generalized flushing.[21] Chronic toxicity could lead to DILE.[22] There is no specific treatment for an overdose other than supportive therapy. Fluids should be given initially, followed by vasopressors should fluids fail to improve the hypotension. Tachycardia or ischemia can be treated with beta-blockers with attention to blood pressure prior to administration.[22]

Enhancing Healthcare Team Outcomes

Hydralazine should not be considered a first-line agent for essential hypertension but can be considered in hypertension refractory to other first-line medications. The newer hypertensive medications are more efficacious with fewer adverse effects. The recommended dosing of three to four times daily makes hydralazine patient compliance a challenge. Patients tend to tolerate this medication better when the hydralazine is given with a beta-blocker and/or diuretic. [2]

IV hydralazine has had increased off-label use for the treatment of hypertensive urgency or emergency.[4] However, it should not be considered for first-line therapy due to tachyphylaxis, highly variable blood pressure, and adverse hypotension.[2]

For African Americans with HFrEF, the combination of hydralazine and isosorbide dinitrate can be added to medication therapy if the patient is already receiving an ACE inhibitor, ARB, or ARNI and a beta-blocker.[6] In clinical practice, this combination has been used in heart failure patients as a preload and afterload reducer, especially in patients who cannot tolerate beta-blockers and ACE inhibitors or ARBs and would benefit from therapy reducing their systolic blood pressure.[8]

While hydralazine is relatively safe, it is important to be aware of some of its adverse effects, which, although rare, include triggering lupus-like syndrome.[11] This can usually be reversed upon discontinuation of the drug.[13] 

An interprofessional team approach involving clinicians, mid-level practitioners, and specialists, plus the nursing staff and pharmacists, can help monitor the patient’s therapeutic results, watch for potential adverse events, provide patient medication counseling regarding dosing and signs of toxicity, check for drug-drug interactions, and alert the prescriber. These types of interprofessional strategies will result in improved outcomes from hydralazine therapy. [Level 5]

Review Questions

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References

1.

Kirsten R, Nelson K, Kirsten D, Heintz B. Clinical pharmacokinetics of vasodilators. Part I. Clin Pharmacokinet. 1998 Jun;34(6):457-82. [PubMed: 9646008]

2.

McComb MN, Chao JY, Ng TM. Direct Vasodilators and Sympatholytic Agents. J Cardiovasc Pharmacol Ther. 2016 Jan;21(1):3-19. [PubMed: 26033778]

3.

James PA, Oparil S, Carter BL, Cushman WC, Dennison-Himmelfarb C, Handler J, Lackland DT, LeFevre ML, MacKenzie TD, Ogedegbe O, Smith SC, Svetkey LP, Taler SJ, Townsend RR, Wright JT, Narva AS, Ortiz E. 2014 evidence-based guideline for the management of high blood pressure in adults: report from the panel members appointed to the Eighth Joint National Committee (JNC 8). JAMA. 2014 Feb 05;311(5):507-20. [PubMed: 24352797]

4.

Campbell P, Baker WL, Bendel SD, White WB. Intravenous hydralazine for blood pressure management in the hospitalized patient: its use is often unjustified. J Am Soc Hypertens. 2011 Nov-Dec;5(6):473-7. [PMC free article: PMC3218202] [PubMed: 21890447]

5.

ACOG Committee Opinion No. 767: Emergent Therapy for Acute-Onset, Severe Hypertension During Pregnancy and the Postpartum Period. Obstet Gynecol. 2019 Feb;133(2):e174-e180. [PubMed: 30575639]

6.

Taylor AL, Ziesche S, Yancy C, Carson P, D’Agostino R, Ferdinand K, Taylor M, Adams K, Sabolinski M, Worcel M, Cohn JN., African-American Heart Failure Trial Investigators. Combination of isosorbide dinitrate and hydralazine in blacks with heart failure. N Engl J Med. 2004 Nov 11;351(20):2049-57. [PubMed: 15533851]

7.

Ziaeian B, Fonarow GC, Heidenreich PA. Clinical Effectiveness of Hydralazine-Isosorbide Dinitrate in African-American Patients With Heart Failure. JACC Heart Fail. 2017 Sep;5(9):632-639. [PMC free article: PMC5581201] [PubMed: 28711446]

8.

Hollenberg SM, Warner Stevenson L, Ahmad T, Amin VJ, Bozkurt B, Butler J, Davis LL, Drazner MH, Kirkpatrick JN, Peterson PN, Reed BN, Roy CL, Storrow AB. 2019 ACC Expert Consensus Decision Pathway on Risk Assessment, Management, and Clinical Trajectory of Patients Hospitalized With Heart Failure: A Report of the American College of Cardiology Solution Set Oversight Committee. J Am Coll Cardiol. 2019 Oct 15;74(15):1966-2011. [PubMed: 31526538]

9.

Whelton PK, Carey RM, Aronow WS, Casey DE, Collins KJ, Dennison Himmelfarb C, DePalma SM, Gidding S, Jamerson KA, Jones DW, MacLaughlin EJ, Muntner P, Ovbiagele B, Smith SC, Spencer CC, Stafford RS, Taler SJ, Thomas RJ, Williams KA, Williamson JD, Wright JT. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension. 2018 Jun;71(6):e13-e115. [PubMed: 29133356]

10.

WRITING COMMITTEE MEMBERS. Yancy CW, Jessup M, Bozkurt B, Butler J, Casey DE, Drazner MH, Fonarow GC, Geraci SA, Horwich T, Januzzi JL, Johnson MR, Kasper EK, Levy WC, Masoudi FA, McBride PE, McMurray JJ, Mitchell JE, Peterson PN, Riegel B, Sam F, Stevenson LW, Tang WH, Tsai EJ, Wilkoff BL., American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines. 2013 ACCF/AHA guideline for the management of heart failure: a report of the American College of Cardiology Foundation/American Heart Association Task Force on practice guidelines. Circulation. 2013 Oct 15;128(16):e240-327. [PubMed: 23741058]

11.

Riddiough MA. Preventing, detecting and managing adverse reactions of antihypertensive agents in the ambulant patient with essential hypertension. Am J Hosp Pharm. 1977 May;34(5):465-79. [PubMed: 326040]

12.

He Y, Sawalha AH. Drug-induced lupus erythematosus: an update on drugs and mechanisms. Curr Opin Rheumatol. 2018 Sep;30(5):490-497. [PMC free article: PMC7299070] [PubMed: 29870500]

13.

Chamsi-Pasha MA, Bassiouny M, Kim ES. Hydralazine-induced lupus syndrome presenting with large pericardial effusion. QJM. 2014 Apr;107(4):305-7. [PubMed: 24194564]

14.

Amjad W, John G, Gulru S. Hydralazine-Induced Autoimmune Hepatitis Precipitated by the Blood Transfusion. Am J Ther. 2018 Jul/Aug;25(4):e514-e516. [PubMed: 29045246]

15.

Chan JC, Yap DY, Yeung CK. Hydralazine-induced toxic epidermal necrolysis in a patient on continuous ambulatory peritoneal dialysis. J Clin Pharm Ther. 2014 Jun;39(3):322-4. [PubMed: 24588409]

16.

Mahfouz A, Mahmoud AN, Ashfaq PA, Siyabi KH. A case report of hydralazine-induced skin reaction: Probable toxic epidermal necrolysis (TEN). Am J Case Rep. 2014;15:135-8. [PMC free article: PMC3979803] [PubMed: 24719674]

17.

KIRKENDALL WM, PAGE EB. Polyneuritis occurring during hydralazine therapy; report of two cases and discussion of adverse reactions to hydralazine. J Am Med Assoc. 1958 May 24;167(4):427-32. [PubMed: 13538717]

18.

Rosendorff C, Lackland DT, Allison M, Aronow WS, Black HR, Blumenthal RS, Cannon CP, de Lemos JA, Elliott WJ, Findeiss L, Gersh BJ, Gore JM, Levy D, Long JB, O’Connor CM, O’Gara PT, Ogedegbe G, Oparil S, White WB., American Heart Association, American College of Cardiology, and American Society of Hypertension. Treatment of hypertension in patients with coronary artery disease: a scientific statement from the American Heart Association, American College of Cardiology, and American Society of Hypertension. Hypertension. 2015 Jun;65(6):1372-407. [PubMed: 25828847]

19.

Drugs and Lactation Database (LactMed®) [Internet]. National Institute of Child Health and Human Development; Bethesda (MD): Jan 18, 2021. Hydralazine. [PubMed: 30000013]

20.

Iyer P, Dirweesh A, Zijoo R. Hydralazine Induced Lupus Syndrome Presenting with Recurrent Pericardial Effusion and a Negative Antinuclear Antibody. Case Rep Rheumatol. 2017;2017:5245904. [PMC free article: PMC5282409] [PubMed: 28194293]

21.

Arce C, Segura-Pacheco B, Perez-Cardenas E, Taja-Chayeb L, Candelaria M, Dueñnas-Gonzalez A. Hydralazine target: from blood vessels to the epigenome. J Transl Med. 2006 Feb 28;4:10. [PMC free article: PMC1413557] [PubMed: 16507100]

22.

Smith BA, Ferguson DB. Acute hydralazine overdose: marked ECG abnormalities in a young adult. Ann Emerg Med. 1992 Mar;21(3):326-30. [PubMed: 1536497]

Disclosure: Linda Herman declares no relevant financial relationships with ineligible companies.

Disclosure: Zachary Bruss declares no relevant financial relationships with ineligible companies.

Disclosure: Vijai Tivakaran declares no relevant financial relationships with ineligible companies.

Hydralazine: MedlinePlus Drug Information

pronounced as (hye dral’ a zeen)

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Hydralazine is used to treat high blood pressure. Hydralazine is in a class of medications called vasodilators. It works by relaxing the blood vessels so that blood can flow more easily through the body.

High blood pressure is a common condition and when not treated, can cause damage to the brain, heart, blood vessels, kidneys and other parts of the body. Damage to these organs may cause heart disease, a heart attack, heart failure, stroke, kidney failure, loss of vision, and other problems. In addition to taking medication, making lifestyle changes will also help to control your blood pressure. These changes include eating a diet that is low in fat and salt, maintaining a healthy weight, exercising at least 30 minutes most days, not smoking, and using alcohol in moderation.

Hydralazine comes as a tablet to take by mouth. It usually is taken two to four a day. Take hydralazine at around the same times every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take hydralazine exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.

Hydralazine controls high blood pressure but does not cure it. Continue to take hydralazine even if you feel well. Do not stop taking hydralazine without talking to your doctor.

Hydralazine is also used after heart valve replacement and in the treatment of heart failure. Talk to your doctor about the possible risks of using this medication for your condition.

This medication is sometimes prescribed for other uses; ask your doctor or pharmacist for more information.

Before taking hydralazine,

• tell your doctor and pharmacist if you are allergic to hydralazine, aspirin, tartrazine (a yellow dye in some processed foods and medications), any other medications, or any of the ingredients in hydralazine tablets. Ask your pharmacist for a list of the ingredients.
• tell your doctor and pharmacist what other prescription and nonprescription medications, vitamins, and nutritional supplements you are taking or plan to take. Be sure to mention any of the following: indomethacin (Indocin, Tivorbex), metoprolol (Lopressor, Toprol-XL, in Dutoprol), and propranolol (Inderal LA, Innopran XL, in Inderide).
• tell your doctor if you have ever had a heart attack, or have coronary artery disease, rheumatic heart disease, or heart, kidney or liver disease.
• tell your doctor if you are pregnant, plan to become pregnant, or are breast-feeding. If you become pregnant while taking hydralazine, call your doctor.
• if you are having surgery, including dental surgery, tell the doctor or dentist that you are taking hydralazine.
• ask your doctor about the safe use of alcohol while you are taking hydralazine. Alcohol can make the side effects from hydralazine worse.

Take hydralazine with meals or a snack.

Your doctor may prescribe a low-salt or low-sodium diet. Follow these directions carefully.

Take the missed dose as soon as you remember it. However, if it is almost time for the next dose, skip the missed dose and continue your regular dosing schedule. Do not take a double dose to make up for a missed one.

Hydralazine may cause side effects. Tell your doctor if any of these symptoms are severe or do not go away:

• flushing
• headache
• upset stomach
• vomiting
• loss of appetite
• diarrhea
• constipation
• eye tearing
• stuffy nose
• rash

Some side effects can be serious.

If you experience any of the following symptoms, call your doctor immediately:

• fainting
• joint or muscle pain
• fever
• rapid heartbeat
• chest pain
• swollen ankles or feet
• numbing or tingling in hands or feet

If you experience a serious side effect, you or your doctor may send a report to the Food and Drug Administration’s (FDA) MedWatch Adverse Event Reporting program online (http://www.fda.gov/Safety/MedWatch) or by phone (1-800-332-1088).

Keep this medication in the container it came in, tightly closed, and out of reach of children. Store at room temperature and away from excess heat and moisture (not in the bathroom).

Unneeded medications should be disposed of in special ways to ensure that pets, children, and other people cannot consume them. However, you should not flush this medication down the toilet. Instead, the best way to dispose of your medication is through a medicine take-back program. Talk to your pharmacist or contact your local garbage/recycling department to learn about take-back programs in your community. See the FDA’s Safe Disposal of Medicines website (http://goo.gl/c4Rm4p) for more information if you do not have access to a take-back program.

It is important to keep all medication out of sight and reach of children as many containers (such as weekly pill minders and those for eye drops, creams, patches, and inhalers) are not child-resistant and young children can open them easily. To protect young children from poisoning, always lock safety caps and immediately place the medication in a safe location – one that is up and away and out of their sight and reach. http://www.upandaway.org

In case of overdose, call the poison control helpline at 1-800-222-1222. Information is also available online at https://www.poisonhelp.org/help. If the victim has collapsed, had a seizure, has trouble breathing, or can’t be awakened, immediately call emergency services at 911.

• Apresoline^®¶
• Dralzine^®¶

• Apresazide^® (containing Hydralazine, Hydrochlorothiazide)^¶
• Apresoline-Esidrix^® (containing Hydralazine, Hydrochlorothiazide)^¶
• BiDil^® (containing Hydralazine, Isosorbide Dinitrate)
• Dralserp^® (containing Hydralazine, Reserpine)^¶
• Hydra-Zide^® (containing Hydralazine, Hydrochlorothiazide)
• Hydrap-ES^® (containing Hydralazine, Hydrochlorothiazide, Reserpine)^¶
• Marpres^® (containing Hydralazine, Hydrochlorothiazide, Reserpine)^¶
• Ser-Ap-Es^® (containing Hydralazine, Hydrochlorothiazide, Reserpine)^¶
• Serathide^® (containing Hydralazine, Hydrochlorothiazide, Reserpine)^¶
• Serpazide^® (containing Hydralazine, Hydrochlorothiazide, Reserpine)^¶
• Serpex^® (containing Hydralazine, Hydrochlorothiazide, Reserpine)^¶
• Unipres^® (containing Hydralazine, Hydrochlorothiazide, Reserpine)^¶

^¶ This branded product is no longer on the market. Generic alternatives may be available.

Last Revised – 06/15/2017

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Hydralazine – description of the substance, pharmacology, use, contraindications, formula

Contents

• Structural formula

• Russian name

• English title

• Latin name

• chemical name

• Gross formula

• Pharmacological group of the substance Hydralazine

• Nosological classification

• CAS code

• pharmachologic effect

• Characteristic

• Pharmacology

• Application of the substance Hydralazine

• Contraindications

• Side effects of Hydralazine

• Dosage and administration

• Precautionary measures

• special instructions

Structural formula

Russian name

Hydralazine

English name

Hydralazine

Latin name

Hydralazinum (born ) Hydralazini)

Chemical name

1(2H)-Phthalazinonhydrazone (as base and monohydrochloride )

Gross formula

C ₈ H ₈ N ₄

Pharmacological group of the substance Hydralazine

Vasodilators

Nosological classification

ICD-10 code list

• I10 Essential (primary) hypertension

• I15 Secondary hypertension

• I50. 0 Congestive heart failure

• O15 Eclampsia

CAS code

86-54-4

Pharmacological action

Pharmacological action –

vasodilator , antihypertensive .

Characteristics

White crystalline powder. Let’s dissolve in water in the ratio 4,4:100, it is a little — in alcohol.

Pharmacology

Inhibits calcium transport into arteriole myofibril cells and/or releases intracellular ions. A decrease in blood pressure is accompanied by a reflex increase in the tone of the sympathetic nervous system, an increase in cardiac output; increases renal blood flow.

Use of the substance Hydralazine

Arterial hypertension, hypertensive crisis, congestive heart failure with high afterload, eclampsia.

Contraindications

Hypersensitivity, severe arterial atherosclerosis, systemic lupus erythematosus, peripheral neuropathies.

Side effects of the substance Hydralazine

Headache, dizziness, fever, hypotension, tachycardia, cardialgia, angina pectoris, hot flashes, sweating, lacrimation, nausea, vomiting, lupus-like syndrome.

Dosage and administration

Inside, after meals, starting with 10-25 mg 2-4 times a day, with a gradual increase to 100-200 mg/day (in 4 divided doses). Higher doses: single – 100 mg, daily – 300 mg. Course 2-4 weeks; repeated course – after 3-5 months.

Precautions

Use with caution in coronary insufficiency.

Special instructions

Forms colored complexes with iron, and therefore contact of the moistened preparation or its solutions with iron objects should be avoided.

Information for healthcare professionals only.
Are you a healthcare professional?

Hydralazine for cats and dogs

11/24/2022 Medicines323

Product Information

General Description

Hydralazine is a medicine that opens blood vessels, treats high blood pressure, and helps treat congestive heart failure.

Dosage

The veterinarian determines the dosage of the medicine for a particular living creature, based on a variety of data – the weight and age of the animal, previous diseases, medications taken, and much more.

Do not self-medicate unless you want to lose your pet! Contact your veterinarian!

How it works

Hydralazine relaxes the smooth muscles of the blood vessels. Nerve signals trigger the release of calcium, which contracts the muscles. Without calcium, muscles cannot contract and blood vessels cannot constrict. When hydralazine inhibits the movement of calcium, the blood vessels are forced to relax, reducing the pressure within them.

Storage Information

Read the product label for storage information.

Missed dose?

Give the dose as soon as possible. If it’s almost time for your next dose, skip the missed dose and continue as usual. Do not give your pet two doses at once.

Side effects and drug reactions

Hydralazine may cause the following side effects:

• Hypotension
• Vomiting
• Diarrhea
• Lethargy
• Conjunctivitis
• Increased water or urinary pressure
• Constipation

Hydralazine may react with these drugs:

• ta-blockers
• Sympathomimetic
• Digoxin
• Furosemide

USE THIS WITH CAUTION DRUG FOR ANIMALS WITH KIDNEY OR HEART DISEASE.