OzEMedicine - Wiki for Australian Emergency Medicine Doctors

esmolol

Beta1 blocker with T1/2=10min due to rapid hydrolysis of an ester linkage by RBC esterases thus useful as antiarrhythmic & in critically ill pt.
Peak IV effect 6-10min, rapid attenuation over 20min. after stop inf.
May have striking hypotensive effects in normal subjects!!
Little if any intrinsic activity, no memb-stab. activity;
250mg/ml to dilute or as 10mg/ml, infusion concentrations > 10mg/ml irritate vein and should be given via CVC
incompatible with bicarbonate but compatible with dopamine, morphine, nitroprusside, nitroglycerin, lignocaine

calcium channel blockers ⇒ AV block, myocardial depression, risk of cardiac arrest
vasocontrictor inotropes (dopamine, adrenaline) ⇒ danger of blocking contractility when systemic vascular resistance is high
catecholamine depleting agents ⇒ marked hypotension, bradycardia
digoxin ⇒ digoxin levels 10-20% higher
morphine ⇒ esmolol levels 46% higher
suxamethonium ⇒ longer duration of action of suxamethonium to 5-8min.

see SVT, AF
0.5mg/kg IV esmolol diluted over 1 minute, then 50ug/kg/min infusion (eg. 5g in 500ml 5%D ⇒ 10mg/ml) for 4 min
if heart rate controlled maintain infusion at rate that controls heart rate
if heart rate not controlled, give increase in titrated steps with each step consisting of:
- further load dose 0.5mg/kg over 1min
- increase infusion rate by 50ug/kg/min (to max. rate of 200ug/kg/min) for 4-10min
once rate stabilised can change to longer acting agent:
- propranolol 10-30mg 6-8h o, or digoxin 0.125-0.5mg 6h o/iv
- halve esmolol infusion rate 30min after 1st dose of longer acting agent
- if satisfactory rate control maintained for 1st hour after 2nd dose of longer acting agent, cease esmolol.
(max. 300µg/kg/min?) Can use for up to 48hrs;