HYDRALAZINE injectable

Therapeutic action

• Antihypertensive vasodilatator

Indications

• 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

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).

Duration

• 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

Remarks

• 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.

Storage