metoprolol tartrate

CLINICAL USE

Beta-adrenoceptor blocker:Hypertension Angina Cardiac arrhythmias Migraine prophylaxis Hyperthyroidism

DOSE IN NORMAL RENAL FUNCTION

Oral:Hypertension: 100–400 mg daily in divided dosesAngina: 50–100 mg 2–3 times daily Arrhythmias: 100–300 mg in 2–3 divided dosesMigraine: 100–200 mg daily in divided dosesHyperthyroidism: 50 mg 4 times daily IV: 5 mg repeated after 5 minutes to a total dose of 15 mgIn surgery: 2–4 mg by slow IV injection then 2 mg as required to a maximum of 10 mg

PHARMACOKINETICS

Molecular weight &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :684.8

%Protein binding &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :10–12

%Excreted unchanged in urine &nbsp &nbsp : 5–10

Volume of distribution (L/kg) &nbsp &nbsp &nbsp :5.6

half-life – normal/ESRD (hrs)&nbsp &nbsp &nbsp :1–9 (av: 3.5)/Unchanged

DOSE IN RENAL IMPAIRMENT

GFR (mL/MIN)

20 to 50 &nbsp &nbsp : Dose as in normal renal function

10 to 20 &nbsp &nbsp : Start with small doses and titrate in accordance with response

<10 &nbsp &nbsp &nbsp &nbsp &nbsp : Start with small doses and titrate in accordance with response

DOSE IN PATIENTS UNDERGOING RENAL REPLACEMENT THERAPIES

CAPD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp:Not dialysed. Dose as in GFR <10 mL/min

HD &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp &nbsp :Not dialysed. Dose as in GFR <10 mL/min

HDF/high flux &nbsp :Dialysed. Dose as in GFR

<10 &nbsp &nbsp &nbsp &nbsp &nbsp : mL/min

CAV/VVHD &nbsp &nbsp &nbsp:Probably dialysed. Dose as in GFR 10 to 20 mL/min

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; concentration increased by propafenone

Antibacterials: concentration reduced by rifampicin

Antidepressants: enhanced hypotensive effect with MAOIs; concentration increased by citalopram and escitalopram and possibly by paroxetineAntihypertensives; 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 mefloquine; avoid with artemether/lumefantrineAntipsychotics 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 dobutamineMetoprolol tartrate.476 METoProLoL TArTrATETropisetron: increased risk of ventricular arrhythmias – use with caution

ADMINISTRATION

Reconstition

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Route

Oral, IV

Rate of Administration

For bolus injection, 1–2 mg/minute or by continuous infusion via CRIP

Comments

A total dose of 10–15 mg IV is usually sufficient

OTHER INFORMATION

Can cause hypoglycaemia in dialysis patientsAlmost all the drug is excreted as inactive metabolites. Accumulation of the metabolites will occur in renal failure, but does not seem to cause any side effects.

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