Hydralazine


Concise Prescribing Info
Indications/Uses
Listed in Dosage.
Dosage/Direction for Use
Adult : PO Hypertension Combined with β-blockers and diuretics: Initial: 25 mg bid, increase gradually according to response. Max: 200 mg/day. Congestive heart failure Combined with nitrate: Initial: 25 mg 3-4 times/day, may increase dose every 2 days if necessary. Maintenance: 50-75 mg 4 times/day. IV Hypertensive crisis Initial: 5-10 mg via slow inj, may repeat after 20-30 minutes if necessary. Alternatively, via infusion at a rate of 0.2-0.3 mg/min. Maintenance: 0.5-0.15 mg/min.
Dosage Details
Intravenous
Hypertensive crisis
Adult: Initially, 5-10 mg via slow inj, may repeat after 20-30 minutes if necessary. Alternatively, via infusion at a rate of 0.2-0.3 mg/min. Maintenance: 0.5-0.15 mg/min.

Oral
Congestive heart failure
Adult: In combination with nitrate: Initially, 25 mg 3-4 times daily, may increase dose every 2 days if necessary. Maintenance: 50-75 mg 4 times daily.

Oral
Hypertension
Adult: In combination with ß-blockers and diuretics: Initially, 25 mg bid, increase gradually according to response. Max: 200 mg daily.
Renal Impairment
CrCl (mL/min) Dosage
<30
Adjust dose or dosing interval according to clinical response.
Hepatic Impairment
Adjust dose or dosing interval according to clinical response.
Administration
Should be taken with food.
Reconstitution
IV inj: Reconstitute vial labelled as containing 20 mg with 1 mL sterile water for injection; further dilute with 10 mL NaCl 0.9%. IV infusion: Add reconstituted IV inj to 500 mL NaCl 0.9%, sorbitol 5% solution or Ringers solution.
Contraindications
Idiopathic systemic lupus erythematosus (SLE) and related diseases, severe tachycardia, heart failure associated with high cardiac output(e.g. thyrotoxicosis), myocardial insufficiency due to mechanical obstruction (e.g. aortic or mitral stenosis or constrictive pericarditis), cor pulmonale, dissecting aortic aneurysm, coronary artery disease (CAD), mitral valvular rheumatic heart disease, porphyria.
Special Precautions
Patient with cerebrovascular disease, suspected CAD, mitral valvular disease. Slow acetylators. Renal and hepatic impairment. Pregnancy and lactation. Avoid abrupt withdrawal.
Adverse Reactions
Significant: SLE-like syndrome, blood dyscrasias (e.g. reduction in Hb and RBC count, leucopenia, agranulocytosis, purpura), postural hypotension, peripheral neuritis, anginal attacks, ECG changes.
Cardiac disorders: Tachycardia, palpitation.
Gastrointestinal disorders: Diarrhoea, nausea, vomiting, paralytic ileus, constipation.
Metabolism and nutrition disorders: Anorexia, oedema.
Musculoskeletal and connective tissue disorders: Arthralgia, joint swelling, myalgia.
Nervous system disorders: Headache, dizziness.
Renal and urinary disorders: Reduced urinary volume.
Vascular disorders: Flushing, orthostatic hypotension.
IM/IV/Parenteral/PO: C
Patient Counseling Information
This drug may cause dizziness or hypotension, if affected, do not drive or operate machinery.
MonitoringParameters
Monitor blood pressure and heart rate; CBC and antinuclear antibody (ANA) titer prior to therapy and periodically thereafter; urine analysis at intervals of approx 6 months during long-term treatment.
Overdosage
Symptoms: Pronounced hypotension and tachycardia, headache, flushing, myocardial ischaemia, cardiac arrhythmias, shock, coma. Management: Symptomatic and supportive treatment. Perform gastric lavage or give emetic treatment in conscious patients as soon as possible. Administer IV fluids or plasma expander as needed. May administer angiotensin or norepinephrine IV to raise blood pressure with caution, avoiding precipitation or aggravation of cardiac arrhythmia or tachycardia.
Drug Interactions
Enhanced hypotensive effect with other antihypertensive agents (e.g. vasodilators, Ca channel blockers, ACE inhibitors, diuretics), anaesthetics, TCA (e.g. imipramine, clomipramine), major tranquilisers, nitrates or CNS depressants. May cause marked hypotension with diazoxide. May increase bioavailability of β-blockers (e.g. propranolol). Antagonised hypotensive effect with oestrogens and NSAIDs (e.g. ibuprofen, diclofenac).
Food Interaction
Enhanced hypotensive effect with alcohol.
Action
Description: Hydralazine is a direct-acting vasodilator which acts predominantly on the arterioles. The exact mechanism of action is unknown, but it is thought to exert its vasodilating effect through direct relaxation of vascular smooth muscle by inhibition of Ca release from the sarcoplasmic reticulum and inhibition of myosin phosphorylation in the arterial smooth muscle cells.
Onset: 10-80 minutes (IV).
Duration: Up to 12 hours (IV/IM).
Pharmacokinetics:
Absorption: Rapidly absorbed from the gastrointestinal tract. Bioavailability: Approx 22-69%, depending on acetylator status. Time to peak plasma concentration: 1-2 hours (oral).
Distribution: Crosses placenta, enters breastmilk (small amounts). Plasma protein binding: 87%.
Metabolism: Undergoes extensive first-pass metabolism in the liver via acetylation.
Excretion: Via urine as metabolites. Elimination half-life: 3-7 hours.
Chemical Structure

Click on icon to see table/diagram/image
Storage
Tab: Store between 15-30°C. IV inj: Store between 20-25°C. Protect from light.
ATC Classification
C02DB02 - hydralazine ; Belongs to the class of hydrazinophthalazine derivatives. Used in the treatment of hypertension.
Disclaimer: This information is independently developed by MIMS based on Hydralazine from various references and is provided for your reference only. Therapeutic uses, prescribing information and product availability may vary between countries. Please refer to MIMS Product Monographs for specific and locally approved prescribing information. Although great effort has been made to ensure content accuracy, MIMS shall not be held responsible or liable for any claims or damages arising from the use or misuse of the information contained herein, its contents or omissions, or otherwise. Copyright © 2020 MIMS. All rights reserved. Powered by MIMS.com
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