Malmstrom 2006.

Study characteristics
Methods	Type: clinical Design: parallel Objective: to assess analgesic effect of intravenous lidocaine on pain following the removal of impacted third molars. Treatment duration: 1 hour Follow‐up duration (including treatment duration): 6 hours Washout between cross‐over periods: NA
Data	Country: USA Condition: pain after removal of third molars Number of people randomised: 10 to each placebo (40 in total to all study arms) Number of people analysed: 10 for active placebo and 9 for standard placebo
Comparisons	Active placebo: diphenhydramine (bolus of 10 mg, continuous infusion of 40 mg) Standard placebo: saline infusion Experimental intervention: likely matched intervention: lidocaine (1.25 mg/kg bolus and 2.75 mg/kg infusion). The fourth intervention arm was oral oxycodone/acetaminophen (10 mg/650 mg; matched by placebo tablets in the other arms) Administration: IV
Outcomes	Participant‐reported outcome: TOPAR1 and TOPAR6 (weighted total of pain relief scores over the first hour and the first 6 hours). Trial's own primary time point was TOPAR2, which was not the earliest post‐treatment time point. Observer‐reported outcome: none Harm outcome: number of participants with 1 or more adverse experiences. Paper also reports number of each particular side effect. Co‐intervention outcome: number of people requesting rescue medication, and median time to rescue medication (acetaminophen/hydrocodone 500/5 mg)
Terminology for active placebo	"Active placebo" a priori
Scores and unpleasantness of the active placebo	Adequacy: 2 Risk of therapeutic effect: 2 Unpleasant/neutral/pleasant: unpleasant
Funding and conflicts of interest	Industry funded. All 7 trial authors appear to be employed by Merck.
Notes	CIs were truncated at 0 for the lower bound; we recalculated and used the untruncated interval.
Risk of bias
Item	Authors' judgement	Support for judgement
Free from risk of bias arising from the randomisation process	Unclear	Computer‐generated schedule. No information on allocation concealment. Baseline differences do not suggest a problem.
Free from risk of bias in selection of the reported result All outcomes	Unclear	No information.