labetalol hydrochloride: clinical use

Prescribing considerations

• Do not withdraw abruptly, particularly in ischaemic heart disease or heart failure.
• Use additional care in hepatic impairment. Investigate symptoms suggesting liver dysfunction and discontinue permanently if liver injury is confirmed.
• Labetalol can mask tachycardia from hypoglycaemia, thyrotoxicosis or acute blood loss.
• Tell ophthalmic surgeons about current or previous treatment before cataract surgery because alpha-blockade may be relevant to intraoperative floppy iris syndrome.
• Use in phaeochromocytoma only after adequate alpha-blockade.

Contraindications and cautions

• Hypersensitivity to labetalol or product excipients
• Asthma, previous bronchospasm or obstructive airway disease
• Second- or third-degree heart block without an appropriate pacemaker, sick sinus syndrome or significant sinus-node dysfunction
• Severe bradycardia or hypotension
• Cardiogenic shock or uncontrolled or uncompensated heart failure
• Untreated phaeochromocytoma
• Prinzmetal angina
• For the selected tablet product: severe peripheral circulatory disturbance, prolonged fasting and metabolic acidosis

Monitoring

• Blood pressure, including postural symptoms, and heart rate
• Signs of heart failure or bronchospasm
• Liver tests when symptoms or signs suggest hepatic dysfunction
• Glucose and recognition of hypoglycaemia where clinically relevant
• During intravenous use: continuous clinical observation of blood pressure and pulse, with respiratory monitoring where impairment is possible
• After late-pregnancy exposure: neonatal heart rate, blood pressure, breathing and blood glucose as clinically indicated

Clinical pharmacology

Labetalol combines selective alpha-1 antagonism with non-selective beta blockade. It undergoes substantial hepatic first-pass metabolism after oral administration, is about half protein-bound and is mainly converted to inactive glucuronide metabolites eliminated in urine and bile.

Formulation and product differences

• The selected film-coated tablet is for oral use, should be taken with food and contains sucrose.
• The selected solution is for intravenous injection or infusion in hospital and contains glucose monohydrate.
• The intravenous solution is incompatible with sodium bicarbonate injection; compatibility and dilution instructions are product-specific.

Tablet

Route: Oral

Strengths: 50 mg, 100 mg, 200 mg, 400 mg

Injection

Route: Parenteral

Strengths: 5 mg/mL