Labetalol Injectable: Dosing and Precautions

Therapeutic action

Non cardioselective beta-blocker.

Indications

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

Forms and strengths, route of administration

This drug should only be used by well trained personnel in well-equipped hospitals.

• 100 mg ampoule (5 mg/ml, 20 ml) for IV injection.

Dose

• One dose of 20 mg (4 ml) over at least one minute.
• If hypertension remains uncontrolled 5 and 10 minutes after injection, administer another dose of 20 mg (4 ml).
• Administer additional doses of 40 mg (8 ml) then 80 mg (16 ml) at 10 minute intervals as long as hypertension is not controlled.
• Maximum total dose: 300 mg.
• Adjust dosage according to blood pressure. The goal is to reduce blood pressure to 140/90 mmHg and keep diastolic pressure at 90 mmHg or above.

Duration

According to clinical response. Change to oral treatment as soon as possible.

Contra-indications, adverse effects, precautions

• Do not administer to patients with asthma, chronic obstructive bronchopneumonia, heart failure, severe hypotension, bradycardia under 50/minute, atrio-ventricular heart blocks, Raynaud's syndrome, or hepatic impairment.
• May cause bradycardia, orthostatic hypotension, heart failure, bronchospasm, hypoglycaemia, gastrointestinal disturbances, dizziness, headache, weakness, and urinary retention.
• Abrupt fall in maternal blood pressure with placental hypoperfusion and foetal death may occur when administered too rapidly by IV injection or in overdose.
• Administer with caution to patients with diabetes.
• Reduce dosage in patients with renal impairment.
• Do not exceed the recommended dosage and administration rate.
• During administration, monitor maternal blood pressure and heart rate, as well as foetal heart rate.
• In the event of anaphylactic shock, there is a risk of resistance to epinephrine.
• Avoid or monitor combination with mefloquine, digoxin, amiodarone, diltiazem, verapamil, tricyclic antidepressants, neuroleptics, and other antihypertensive drugs.
• Monitor the newborn for hypoglycaemia, bradycardia, and respiratory distress occurring most often during the first 24 hours and until 72 hours after birth.
• In the event of hypotension, administer Ringer lactate to maintain diastolic blood pressure at 90 mmHg or above.
• Breast-feeding: no contra-indication.
• Labetalol IV is also used in hypertensive crises with serious end-organ damage.