see also beta blockers

• 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;