LABETOLOL

Indications & Dose:

Controlled hypotension in anaesthesia

• BY INTRAVENOUS INFUSION, OR BY INTRAVENOUS INJECTION

Adult: (consult product literature or local protocols

Hypertension of pregnancy

• BY INTRAVENOUS INFUSION

Adult: Initially 20 mg/hour, then increased if necessary to 40 mg/hour after 30 minutes, then increased ifnecessary to 80 mg/hour after 30 minutes, then increased if necessary to 160 mg/hour after 30 minutes, adjusted according to response; Usual maximum 160 mg/hour

• BY MOUTH

¶ Adult: Use dose for hypertension

Hypertension following myocardial infarction l

• BY INTRAVENOUS INFUSION

Adult: 15 mg/hour, then increased to up to 120 mg/hour, dose to be increased gradually

Hypertensive emergencies

• BY INTRAVENOUS INJECTION

Adult: 50 mg, to be given over at least 1 minute, then 50 mg every 5 minutes if required until a satisfactory response occurs; maximum 200 mg per course

• BY INTRAVENOUS INFUSION

Adult: Initially 2 mg/minute until a satisfactory response is achieved, then discontinue; usual dose 50–200 m

Hypertension l

• BY MOUTH

Adult: Initially 100 mg twice daily, dose to be increased at intervals of 14 days; usual dose 200 mg twice daily, increased if necessary up to 800 mg daily in 2 divided doses, to be taken with food, higher doses to be given in 3–4 divided doses; maximum 2.4 g per day

Elderly: Initially 50 mg twice daily, dose to be increased at intervals of 14 days; usual dose 200 mg twice daily, increased if necessary up to 800 mg daily in 2 divided doses, to be taken with food, higher doses to be given in 3–4 divided doses; maximum 2.4 g per day

• BY INTRAVENOUS INJECTION

Adult: 50 mg, dose to be given over at least 1 minute, then 50 mg after 5 minutes if required; maximum 200 mg per course

• BY INTRAVENOUS INFUSION

Adult: Initially 2 mg/minute until a satisfactory response is achieved, then discontinue; usual dose 50–200 mg

Contraindications:

Br onchial asthma, cardiogenic shock, overt cardiac failure, second and third degree AV block, severe sinus bradycardia

Side Effects:

CNS: Anxiety. catatonia. dizziness, drowsiness, fatigue, headache. lethargy, mental changes, nightmares. paresthesias (scalp tingling) CV: AV block, bradycardia, chest pain, CHF, orthostatic hypotension, ventricular dysrhythmias

EENT: Double vision, dry burning eyes, sore throat, tinnitus, visual changes

GI: Diarrhea, nausea, vomiting

GU: Dysuria. ejaculatory failure, impotence, Peyronie’s disease

HEME: Agranulocytosis, thrombocytopenic purpura (reported with other b-blockers only) (rare)

MS: Asthenia. muscle cramps, toxic myopathy

RESP: Bronchospasm, dyspnea, wheezing

SKIN: Alopecia, fever. pruritus, rash, urticaria

Cautions:

Precautions:

Anesthesia/surgery (myocardial depression), avoid abrupt withdrawal, bronchospastic airways, congestive heart failure, diabetes mellitus, hyperthyroidism/ thyrotoxicosis (labetolol unlike propranolol, does not decrease T3 levels), concurrent clonidine (discontinue labetolol several days prior to withdrawal of clonidine); peripheral vascular disease, renal disease 

Interaction:

Drugs 

• a1-blockers: Potential enhanced first dose response (marked initial drop in blood pressure, particularly on standing)


• Amiodarone: Symptomatic bradycardia and sinus arrest, especially patients with bradycardia, sick sinus syndrome, or partial AV node block


• Cimetidine: Increased plasma labetolol concentrations


• Clonidine: Withdrawal of clonidine abruptly may exaggerate the hypertension due to unopposed alpha stimulation; safer than other b-blockers, however


• Digoxin: Additive prolongation of AV conduction time


• Dihydropyridine calcium channel blockers: Severe hypotension or impaired cardiac performance; most prevalent with impaired left ventricular function,cardiac arrhythmias, or aortic stenos


• Diltiazem: Potentiates b-adrenergic effects; hypotension, left ventricular failure, and AV conduction disturbances problematic in elderly, patwith left ventricular dysfunction, aortic stenosis, or with large doses of either drug


• Epinephrine: Increased diastolic pressure and bradycardia during epinephrine infusions


• Hypoglycemic agents: Masked hypoglycemia, hyperglycemia


• NSAIDs: Reduced hypotensive effects of b-blockers


• Theophylline: Antagonistic pharmacodynamic effects


• Verapamil: Potentiates b-adrenergic effects: hypotension, left ventricular failure, and AV conduction disturbances problematic in elderly, patients with ventricular dysfunction, aortic stenosis, or with large doses of either drug

Warnings:

Adverse Effects:

Lactations:

Pregnancy category C: smiliar drug, atenolol, frequently used in the third trimester for treatment of hypertension (many studies of efficacy and safety of’ atenolol in pregnancy -induced hypertension); long-term use has been associated with intrauterine growth retardation: only a small amount of’ drug appears it) milk (0.004% of’ dose): unlikely to be therapeutically significant

Special Precautions:

Counselling:

Side Effects Or Adverse Reactions:

Patient And Carer Advice: