NCT02466542.

Methods	RCT, parallel design
Participants	Estimated number of randomized participants: 60 Inclusion criteria: women; 18‐75 years of age; scheduled for elective mastectomy; ASA I or II Exclusion criteria: unstable angina; poorly controlled asthma; substance abuse; sinus bradycardia; heart failure > 1st degree atrioventricular block; pregnant; allergy to dipyrone, morphine; chronic pain; severe hepatic disease; severe kidney disease; neurological disease; in other clinical studies; refusal to participate in the study; any other condition that, in the opinion of the investigator, may pose a risk to the participants or interfere with the study objectives
Interventions	Esmolol vs placebo
Outcomes	Intended outcome measures: pain scores; analgesic requirement; adverse events (incidence of tachycardia, hypertension, hypotension; bradycardia, use of vasopressors, recovery times, PONV, pruritis, urinary retention, drowsiness)
Notes	Study is completed. Awaiting publication of study results in order to assess eligibility for the review