Background: Transdermal scopolamine (TDS) is a potential long-acting prophylactic antiemetic initially developed to prevent motion sickness. TDS is a centrally acting anticholinergic agent that was approved in 2001 by the US Food and Drug Administration for the prevention of postoperative nausea and vomiting (PONV). Although TDS has been reported to be clinically efficacious in the prevention of PONV, several adverse events (AEs), such as sedation, dry mouth, blurred vision, central cholinergic syndrome, and confusion (particularly in elderly patients with mild cognitive impairment), are potential concerns.
Objective: The aim of this study was to explore the efficacy and tolerability of TDS in the prevention of PONV in adults.
Methods: A systematic search of PubMed, EMBASE, and the Cochrane Library for randomized controlled trials in adults that compared the effects of TDS and placebo on postoperative nausea, vomiting, and PONV was conducted in March 2009, and an update was conducted in July 2010. Without any language restrictions, a search with the following terms was performed: postoperative, postoperative, postanesthe*, postanaesthe*, post-anesthe*, post-anaesthe*, anesthesia, anaesthesia, surgery, surgeries, surgical, nausea, vomiting, emesis, retching, scopolamine, and hyoscine. Identified studies were then hand-searched for further relevant literature.
Results: Data from 25 randomized controlled trials were analyzed (N = 3298). In the postanesthesia care unit, TDS was associated with a significantly reduced risk for postoperative nausea compared with placebo (relative risk [RR] = 0.77; 95% CI, 0.61-0.98; P = 0.03). TDS was also associated with a significantly reduced risk for postoperative nausea (RR = 0.59; 95% CI, 0.48-0.73; P < 0.001), postoperative vomiting (RR = 0.68; 95% CI, 0.61-0.76; P < 0.001), and PONV (RR = 0.73; 95% CI, 0.60-0.88; P = 0.001) during the first 24 hours after the start of anesthesia. TDS appeared to be effective compared with placebo in the prevention of postoperative nausea when treatment was initiated the night before (early application) (RR = 0.56; 95% CI, 0.41-0.75; P < 0.001) or on the day of surgery (late application) (RR = 0.61; 95% CI, 0.47-0.79; P < 0.001). TDS was associated with a higher prevalence of visual disturbances at 24 to 48 hours compared with placebo (RR = 3.35; 95% CI, 1.78-6.32). Analyses of confusion and other AEs did not show a significant association with TDS.
Conclusions: In this systematic review and metaanalysis, TDS was associated with significant reductions in PONV with both early and late patch application during the first 24 hours after the start of anesthesia. TDS was associated with a higher prevalence of visual disturbances at 24 to 48 hours after surgery, but no other AEs, compared with placebo.