- 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.
Reconstituted solution must be used immediately.