HYDRALAZINE injectable

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    Prescription under medical supervision


    Therapeutic action

    • Antihypertensive vasodilatator


    • Hypertension in pregnancy, in case of severe symptoms or when oral treatment is not possible

    Forms and strengths, route of administration

    • Powder for injection, in 20 mg vial, to be dissolved in 1 ml of water for injection, for IV infusion or slow diluted IV injection


    Dosage should be adjusted according to blood pressure (BP). The goal is to reduce the blood pressure to 140/90 mmHg. Diastolic BP must not fall below 90 mmHg.


    By IV infusion

    • Dilute 100 mg (5 vials of reconstituted hydralazine solution) in 500 ml of 0.9% sodium chloride or Ringer lactate, to obtain a solution containing 200 micrograms/ml.
    • Initial dose: 200 to 300 micrograms/minute
    • Maintenance dose: 50 to 150 micrograms/minute
    • Administer by increasing the rate up to 20 drops/minute (max. 30 drops/minute), check BP every 5 minutes.
    • As soon as hypertension is controlled, decrease progressively the rate (15 drops/minute, then 10, then 5) until stopping infusion. An abrupt discontinuation may provoke a hypertensive crisis.


    By slow diluted IV injection

    • Dilute 20 mg (1 vial of reconstituted hydralazine solution in 1 ml of water for injection) in 9 ml of 0.9% sodium chloride, to obtain 10 ml of solution containing 2 mg/ml.
    • Administer 5 mg (2.5 ml of the diluted solution) over 2 to 4 minutes. Check BP for 20 minutes. If BP remains uncontrolled, repeat injection. Continue repeating if necessary, waiting 20 minutes between each injection (max. 20 mg total dose).


    • According to clinical response.

    Change to oral treatment as soon possible with labetalol or methyldopa.

    Contra-indications, adverse effects, precautions

    • Administer with caution to patients with heart failure, coronary insufficiency, recent myocardial infarction, severe tachycardia, history of stroke.
    • May cause:
      • hypotension, tachycardia, headache, gastrointestinal disturbances;
      • abrupt fall in maternal blood pressure with placental hypoperfusion and foetal death when administered too rapidly by IV injection or in case of overdose.
    • Reduce doses in patients with renal or hepatic impairment.
    • Do not exceed recommended dosage and administration rate. During administration, monitor maternal BP and heart rate, as well as foetal heart rate.
    • In the event of hypotension, administer Ringer lactate to maintain diastolic BP ≥ 90 mmHg.
    • Breast-feeding: no contra-indication


    • For administration, only use sodium chloride 0.9% or Ringer lactate (incompatibility with glucose and other solutions).
    • Do not mix with other drugs in the same syringe or infusion bottle.


    –  Below 25 °C 
    Reconstituted solution must be used immediately.