Data Metamizole Acceptance Rat

Data concerning the following project/manuscript:No option for analgesia refinement: Sprague-Dawley rats reject voluntary ingestion of metamizole via drinking water or palatable carrier media

Background: The non-opioid analgesic metamizole (MET) is widely used for pain management in humans and animals. In laboratory rodents, voluntary oral self-intake of MET might represent a non-invasive refinement measure. Therefore, this study evaluated the acceptance of MET in drinking water and in palatable carrier substrates in RjHan:SD rats (male, female).
Results: Initially, a MET target dosage of 1000 mg/kg/24 h in the drinking water drastically decreased fluid consumption within 24 hours (-87.95%). Subsequent acceptance trials, including lower dosages, and different formulations, without and with sweetening of water, did not lead to improved acceptance. Regarding the palatable carrier substrates offered as an alternative delivery method, rats did neither show much interest in hazelnut spread nor peanut butter. Lactose-free cream induced gastrointestinal side effects and acceptance decreased after 2 days. Baby food, however, was readily consumed by 100% during a 5-day training. Nevertheless, the attractiveness was not sufficient to mask the aversive taste of 100 mg/kg MET per portion, resulting in limited intake and prolonged consumption time.
Conclusions: In conclusion, voluntary oral intake of MET for analgesic therapy in RjHan:SD rats must be considered infeasible. Our results should be taken as a warning regarding the application in other rat strains or other animal species.