Stability and compatibility of the mixture of tramadol, ketorolac, metoclopramide and ranitidine in a solution for intravenous perfusion.

Objective: To determine whether a mixture for intravenous perfusion containing tramadol (5 mg/ml), ranitidine (1.5 mg/ml), ketorolac (1.5 mg/ml) and metoclopramide (0.5 mg/ml) in a 0.9% sodium chlorides solution is compatible and stable at room temperature during a 48-hour period.

Methods: We tested the mixture for stability using the HPLC technique (high performance liquid chromatography), with parallel visual assessments of any changes in colour, appearance of precipitate or phase separation indicating incompatibilities between the components.

Results: At the end of the trial, chromatography data showed a mean metoclopramide concentration between 100% and 105% of the initial level, while concentrations of tramadol, ketorolac and ranitidine were between 99% and 102% of initial levels. There was no evidence of incompatibility between the drugs at any time during the study period.

Conclusions: The combination is stable as a solution and its components are physically and chemically compatible in the concentrations used in the study, during at least 48 hours at room temperature.