PurposeTopical anesthesia analgesic therapy has diverse applicability in solving the barrier properties of skin and unfavorable physicochemical properties of drugs. Lidocaine (LID) combined with prilocaine (PRI) has been used as a topical preparation for dermal anesthesia for treatment of conditions such as paresthesia.Materials and methodsIn this study, for combination anesthesia and overcoming the drawbacks of LID and PRI, respectively, LID- and PRI-loaded solid lipid nanoparticles (SLNs) and nanostructured lipid carriers (NLCs) were prepared and characterized by determination of their particle size, drug loading capacity, stability, in vitro drug release behavior and in vitro cellular viability. Ex vivo skin permeation and in vivo anesthesia analgesic efficiency of these two systems were also evaluated and compared.ResultsResults revealed that combination delivery of the dual drugs exhibited more remarkable efficiency than signal drug-loaded systems. SLN systems have better ex vivo skin permeation ability than NLCs. NLC systems revealed a stronger in vivo anesthesia analgesic effect than SLN systems.ConclusionIt can be concluded that SLNs and NLCs have different advantages, and that both carriers are promising dual drug delivery systems for topical anesthetic analgesic therapy.

Background Acetaminophen is a widely clinically used analgesic. However, the clinical effect of the route of administration on postoperative analgesia as well as on postoperative nausea and vomiting in patients undergoing general anesthesia remains unclear. This study aimed to explore whether the route of administration of acetaminophen affects postoperative analgesia, nausea, and vomiting in patients undergoing general anesthesia. Methods We included all randomized controlled trials investigating the effects of the route of administration of acetaminophen on postoperative pain, nausea, and vomiting in patients undergoing general anesthesia. Independent examiners reviewed the literature and extracted data, with disagreements resolved through negotiation or the involvement of a third party. The Cochrane risk assessment tool was used to evaluate the quality of the included randomized controlled trials. A narrative synthesis was conducted to summarize the qualitative information from the included studies. A meta‐integration of quantitative data was performed using RevMan 5.4. Results Ten studies met the inclusion criteria. Eight studies assessed postoperative pain, whereas two assessed postoperative nausea and vomiting. Data from the eight studies assessing postoperative pain confirmed that there was no difference between intravenously and orally administered acetaminophen in adults (OR = −0.13; 95% CI, −0.36 to 0.11; p = 0.3). Data from the two studies assessing postoperative nausea and vomiting revealed no difference between intravenously and orally administered acetaminophen in adults (OR = 0.89; 95% CI, 0.64–1.25; p = 0.51). The included studies were of poor quality, with a heterogeneity of 68%. Conclusions No differences in postoperative analgesia or postoperative nausea and vomiting were observed between the routes of administration (intravenous vs. oral) of acetaminophen in adult patients undergoing general anesthesia. There is a need for future large sample studies to increase the reliability of the results.