ESMOLOL

1) Therapeutic drug action & mechanism(pharmacology)

• Ultra-short-acting b1-receptor selective adrenoceptor antagonist [actually only modestly selective)

• Occupies b-receptors and competitively reduces receptor occupancy by catecholamines and other b-agonists

• Lowers BP in patients with hypertension

• Action as antiarrhythmic [class II] and antihypertensive

2) Indications

• Safer to use than longer acting antagonists in critically ill patients that require b-blockade

• Useful in controlling supraventricular arrhythmias [by increasing AV nodal refractory period thereby slowing ventricular response to atrial flutter & atrial fibrillation], perioperative hypertension & MI in acutely ill patients

• Can also reduce VEB’s especially if irritability of heart due to catecholamines

• Increase stroke volume in obstructive cardiomyopathy [reduced ventricular ejection & decreased ventricular outflow resistance]

• Reduce systolic BP in dissecting aortic aneurysm

• May be effective in facilitating defibrillation

3) Effects on organs—side effects

• Negative inotrope & chronotrope; reduces MVO2

• Although selective b1-receptor blocker, may still blockade bronchial smooth muscle b2-receptor resulting in possible increased airway resistance

4) Toxic effects/ precautions with administration

• Give with caution to patients with abnormal myocardial function [eg MI or CCF] as cardiac output may be dependent on sympathetic drive resulting in cardiac decompensation

5) Contraindications

• Should be avoided in asthmatics

• Right ventricular failure secondary to pulmonary hypertension

• Significant right ventricular hypertrophy

• Heart blocks and bradycardias

6) Reversal, antagonism or antidote

• Stop infusion [short half life]

7) Loading dose, maintenance dose, frequency & method of administration

• Continuous infusions to quickly achieve steady state concentration

• Therapeutic actions are rapidly terminated when infusion is ceased

• Bolus 25 mg followed by a continuous infusion of 50 - 250 mg/Kg/min

8) Drug’s metabolism—Drug’s excretion—Half life (pharmacokinetics)

• Half life: 10 min

• Contains an ester linkage which is rapidly metabolised by esterases in red blood cells

9) Important drug interactions

• Use with caution with other agents that cause myocardial depression [eg antiarrhythmics and anaesthetic gases]