Should the wheel be reinvented in a human study?

Recently, Zimmer and colleagues reported a lack of analgesic efficacy from intraperitoneal nebulization of bupivacaine using the Insuflow® device for patients undergoing laparoscopic cholecystectomy. This is not surprising. An in vitro study in 2008 showed that hot evaporation-based devices, similar to Insuflow®, are unable to transport drug molecules dissolved in a water solvent. These results are in keeping with the physical principle that hot evaporation enables only evaporation of the solvent (e.g., water) and not of the solute (e.g., bupivacaine). Although this well-conducted human study has a defendable medical justification and a high theoretical interest, it is not acceptable to choose a human model for an experimental study that attempts to explore a question whose answer has already been published years before in a bench setting.