In two multicenter, randomized, double-blind, controlled comparisons of esmolol hydrochloride with placebo and propranolol, maintenance doses of 50 to 300 mcg/kg/min (0.05 to 0.3 mg/kg/min) of esmolol hydrochloride were found to be more effective than placebo and about as effective as propranolol, 3-6 mg given by bolus injections, in the treatment of supraventricular tachycardia, principally atrial fibrillation and atrial flutter. The majority of these patients developed their arrhythmias postoperatively. About 60-70% of the patients treated with esmolol hydrochloride had a desired therapeutic effect (either a 20% reduction in heart rate, a decrease in heart rate to less than 100 bpm, or, rarely, conversion to NSR) and about 95% of those who responded did so at a dosage of 200 mcg/kg/min (0.2 mg/kg/min) or less. The average effective dosage of esmolol hydrochloride was approximately 100-115 mcg/kg/min (0.1-0.115 mg/kg/min) in the two studies. Other multicenter baseline-controlled studies gave essentially similar results. In the comparison with propranolol, about 50% of patients in both the esmolol hydrochloride and propranolol groups were on concomitant digoxin. Response rates were slightly higher with both beta blockers in the digoxin-treated patients.
In all studies significant decreases of blood pressure occurred in 20-50% of patients, identified either as adverse reaction reports by investigators, or by observation of systolic pressure less than 90 mmHg or diastolic pressure less than 50 mmHg. The hypotension was symptomatic (mainly diaphoresis or dizziness) in about 12% of patients, and therapy was discontinued in about 11% of patients, about half of whom were symptomatic. In comparison to propranolol, hypotension was about three times as frequent with esmolol hydrochloride, 53% vs. 17%. The hypotension was rapidly reversible with decreased infusion rate or after discontinuation of therapy with esmolol hydrochloride. For both esmolol hydrochloride and propranolol, hypotension was reported less frequently in patients receiving concomitant digoxin.
Esmolol hydrochloride is indicated for the rapid control of ventricular rate in patients with atrial fibrillation or atrial flutter in perioperative, postoperative, or other emergent circumstances where short term control of ventricular rate with a short-acting agent is desirable. Esmolol hydrochloride is also indicated in noncompensatory sinus tachycardia where, in the physician’s judgment, the rapid heart rate requires specific intervention. Esmolol hydrochloride is not intended for use in chronic settings where transfer to another agent is anticipated.
Dosage needs to be titrated, using ventricular rate as the guide.
An initial loading dose of 0.5 milligrams/kg (500 micrograms/kg) infused over a minute duration followed by a maintenance infusion of 0.05 milligrams/kg/min (50 micrograms/kg/min) for the next 4 minutes is recommended. This should give a rough guide with respect to the responsiveness of ventricular rate.
After the 4 minutes of initial maintenance infusion (total treatment duration being 5 minutes), depending upon the desired ventricular response, the maintenance infusion may be continued at 0.05 mg/kg/min or increased step-wise (e.g. 0.1 mg/kg/min, 0.15 mg/kg/min to a maximum of 0.2 mg/kg/min) with each step being maintained for 4 or more minutes.
If more rapid slowing of ventricular response is imperative, the 0.5 mg/kg loading dose infused over a 1 minute period may be repeated, followed by a maintenance infusion of 0.1 mg/kg/min for 4 minutes. Then, depending upon ventricular rate, another (and final) loading dose of 0.5 mg/kg/min infused over a 1 minute period may be administered followed by a maintenance infusion of 0.15 mg/kg/min. If needed, after 4 minutes of the 0.15 mg/kg/min maintenance infusion, the maintenance infusion may be increased to a maximum of 0.2 mg/kg/min.
In the absence of loading doses, constant infusion of a single concentration of esmolol reaches pharmacokinetic and pharmacodynamic steady-state in about 30 minutes. Maintenance infusions (with or without loading doses) may be continued for as long as 24 hours.
The following table summarizes the above and assumes that 3 loading doses (the maximum recommended) are infused over 1 minute and incremental maintenance doses are required after each loading dose. There should be no 4th loading dose, but the maintenance dose may be incremented one more time.
| Elapsed Time | Loading Dose (over 1 minute) | Maintenance Dose (over 4 minutes) |
| (minutes) | micrograms/kg/min | milligrams/kg/min | micrograms/kg/min | milligrams/kg/min |
| 0 – 1 | 500 | 0.5 | | |
| 1 – 5 | | | 50 | 0.05 |
| 5 – 6 | 500 | 0.5 | | |
| 6 – 10 | | | 100 | 0.1 |
| 10 – 11 | 500 | 0.5 | | |
| 11 – 15 | | | 150 | 0.15 |
| 15 – 16 | · | · | | |
| 16 - 20 | | | As the desired heart rate or endpoint is approached, the loading infusion may be omitted and the maintenance infusion titrated to 300 mcg/kg/min (0.3 mg/kg/min) or downward as appropriate. Maintenance dosages above 200 mcg/kg/min (0.2 mg/kg/min) have not been shown to have significantly increased benefits. The interval between titration steps may be increased. 200 | 0.2 |
| > 20 | | | Maintenance dose titrated to heart rate or other clinical endpoint. |
In the treatment of supraventricular tachycardia, responses to esmolol hydrochloride usually (over 95%) occur within the range of 50 to 200 micrograms/kg/min (0.05 to 0.2 milligrams/kg/min). The average effective dosage is approximately 100 micrograms/kg/min (0.1 milligrams/kg/min) although dosages as low as 25 micrograms/kg/min (0.025 milligrams/kg/min) have been adequate in some patients. Dosages as high as 300 micrograms/kg/min (0.3 milligrams/kg/min) have been used, but these provide little added effect and increase the rate of adverse effects, so doses greater than 200 micrograms/kg/min are not recommended. Dosage of esmolol hydrochloride in supraventricular tachycardia must be individualized by titration in which each step consists of a loading dosage followed by a maintenance dosage.
This specific dosage regimen has not been studied intraoperatively and, because of the time required for titration, may not be optimal for intraoperative use.
The safety of dosages above 300 mcg/kg/min (0.3 mg/kg/min) has not been studied.
In the event of an adverse reaction, the dosage of esmolol hydrochloride may be reduced or discontinued. If a local infusion site reaction develops, an alternate infusion site should be used and caution should be taken to prevent extravasation. The use of butterfly needles should be avoided.
Abrupt cessation of esmolol hydrochloride in patients has not been reported to produce the withdrawal effects which may occur with abrupt withdrawal of beta blockers following chronic use in coronary artery disease (CAD) patients. However, caution should still be used in abruptly discontinuing infusions of esmolol hydrochloride in CAD patients.
After achieving an adequate control of the heart rate and a stable clinical status in patients with supraventricular tachycardia, transition to alternative antiarrhythmic agents such as propranolol, digoxin, or verapamil, may be accomplished.
A recommended guideline for such a transition is given below but the physician should carefully consider the labeling instructions for the alternative agent selected.
| Alternative Agent | Dosage |
| Propranolol hydrochloride | 10-20 mg q 4-6 hrs |
| Digoxin | 0.125-0.5 mg q 6 hrs (p.o. or i.v.) |
| Verapamil | 80 mg q 6 hrs |
The dosage of esmolol hydrochloride should be reduced as follows:
- Thirty minutes following the first dose of the alternative agent, reduce the infusion rate of esmolol hydrochloride by one-half (50%).
- Following the second dose of the alternative agent, monitor the patient’s response and if satisfactory control is maintained for the first hour, discontinue esmolol hydrochloride.
The use of infusions of esmolol hydrochloride up to 24 hours has been well documented; in addition, limited data from 24-48 hrs (N=48) indicate that esmolol hydrochloride is well tolerated up to 48 hours.