Labetalol hydrochloride

CLINICAL USE

Beta-adrenoceptor blocker:Hypertensive crisis, hypertension

DOSE IN NORMAL RENAL FUNCTION

Oral: 50–800 mg twice daily (in 3–4 divided doses in high doses); maximum 2.4 g daily

IV infusion

: 2 mg/minute until satisfactory response; usual total dose 50–200 mgIV bolus: 50 mg over 1 minute, repeated at 5 minute intervals to a total dose of 200 mgPregnancy: 20–160 mg/hour Hypertension after an MI: 15–120 mg/ hour

PHARMACOKINETICS

Molecular weight :364.9

%Protein binding :50

%Excreted unchanged in urine : 5

Volume of distribution (L/kg) :5.6

half-life – normal/ESRD (hrs) :4–8/Unchanged

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 : Dose as in normal renal function

10 to 20 : Dose as in normal renal function

<10 : Dose as in normal renal function

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD :Not dialysed. Dose as in normal renal function

HD :Not dialysed. Dose as in normal renal function

HDF/high flux :Unknown dialysability. Dose as in normal renal function

CAV/VVHD :Probably not dialysed. Dose as in normal renal function

IMPORTANT DRUG INTERACTIONS

Potentially hazardous interactions with other drugs

Anaesthetics: enhanced hypotensive effect

Analgesics: NSAIDs antagonise hypotensive effect

Anti-arrhythmics: increased risk of myocardial depression and bradycardia; increased risk of bradycardia, myocardial depression and AV block with amiodarone

Antidepressants: enhanced hypotensive effect with MAOIs; concentration of imipramine increasedAntihypertensives; enhanced hypotensive effect; increased risk of withdrawal hypertension with clonidine; increased risk of first dose hypotensive effect with post-synaptic alpha-blockers such as prazosin

Antimalarials: increased risk of bradycardia with mefloquineAntipsychotics enhanced hypotensive effect with phenothiazines

Calcium-channel blockers: increased risk of bradycardia and AV block with diltiazem; hypotension and heart failure possible with nifedipine and nisoldipine; asystole, severe hypotension and heart failure with verapamil

Diuretics: enhanced hypotensive effect

Moxisylyte: possible severe postural hypotension

Sympathomimetics: severe hypertension with adrenaline and noradrenaline and possibly with dobutamineTropisetron: increased risk of ventricular arrhythmias – use with caution

ADMINISTRATION

Reconstition

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Route

Oral, IV

Rate of Administration

2 mg/minute initially then titrate according to response or to indication

Comments

200 mg labetalol (40 mL) to 200 mL glucose 5%Can be used undiluted. (UK Critical Care Group, Minimum Infusion Volumes for fluid restricted critically ill patients, 3rd Edition, 2006)

OTHER INFORMATION

No adverse effects on renal function No accumulation in renal impairment Hypoglycaemia can occur in dialysis patientsTachyphylaxis can occur with prolonged us

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