 Primary FRCA Syllabus
Systematic Pharmacology
 Drugs acting on the autonomic nervous system: cholinergic and adrenergic agonists and antagonists ....drugs acting on the heart..antihypertensives …. 
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 Final FRCA Syllabus
Applied Clinical Pharmacology
Pharmacological control of myocardial function, vascular resistance, heart rate and blood pressure.
Esmolol (Brevibloc)
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Chemical:
An aryloxypropanolamine
Uses:
Esmolol is recommended for the acute treatment of supraventricular tachyarrhythmia (SVT), including paroxysmal supraventricular tachycardia (PSVT), rate control in non pre-excited AF or atrial flutter, ectopic atrial tachycardia, inappropriate sinus tachycardia, and polymorphic VT due to torsades de pointes or myocardial ischaemia.
Presentation:
As a clear solution for injection containing 10/250mg/ml of Esmolol hydrochloride.
Mode of action:
Competitive blockade of beta-adrenoceptors; the drug is relatively selective for beta-1 receptors and has little intrinsic sympathomimetic activity.
Route:
Administered by iv infusion diluted in any crystalloid (not sodium bicarbonate) at a rate of 50-150ucg/kg/min according to response. The major advantage of Esmolol is that its peak effects are observed within 6-10 minutes of administration, and wear off within 20 minutes of cessation of infusion.
Esmolol is administered as an IV loading dose of 0.5 mg/kg over one minute, followed by a  maintenance infusion of 50 mcg/kg per minute for 4 minutes. If the response is inadequate, a second bolus of 0.5 mg/kg is infused over one minute, with an increase of the maintenance infusion to 100 mcg/kg/minute. The bolus dose and the titration of the infusion dose (addition of 50 mcg/kg/minute) can be repeated every 4 minutes to a maximum infusion rate of 300 mcg/kg/minute. Infusions can be maintained up to 48 hours if needed. Esmolol requires no dosage adjustments with renal or hepatic impairment. Esmolol is a very short acting agent with an average half-life of 9 minutes in adults.
Effects
Cardiovascular:
Fall in blood pressure and a dose dependent fall in heart rate.
Cardiac output falls by 20%. Esmolol obtunds the cardiovascular responses to intubation and sternotomy, and protects against infarction in animal models of myocardial ischaemia.
Respiratory:
Little effect on airways resistance.
Toxicity:
Hypotension, bradycardia, bronchospasm, nausea and vomiting, alteration of taste and CNS disturbances may occur.
Distribution:
56% protein-bound in plasma. Volume of distribution 3.4 l/kg.
Metabolism:
Hydrolysis by esterases in red blood cells to methanol and a primary acid metabolite which has weak beta-adrenergic antagonist activity. Elimination half-life is approximately 3.5 hours.
Excretion:
80% appears in the urine as the major acid metabolite. <1% is excreted unchanged.
Use of Esmolol in resuscitation
Click here to view the latest guidelines for management of Narrow Complex Tachycardia (use of Esmolol recommended).
References
[i] Use of beta-blockade to prevent death after noncardiac surgery. Wallace A, Mangano DT. West J Med 1997 Mar;166(3):203-4.
[ii] Reduction of Myocardial Reperfusion Injury by High-Dose beta-Blockade with Esmolol. Geissler HJ. Thorac Cardiovasc Surg 2002 Dec;50(6):367-72.
[iii] Esmolol in acute ischemic syndromes. Mitchell RG et al. Am Heart J 2002 Nov;144(5):E9
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