Background Simultaneous administration of drugs is a common gesture in different care units. This gesture may be causing some major complications for patients. In 1996, serious accidents in premature or newborns concomitantly treated with ceftriaxone and intravenous calcium gluconate were reported in France. In 2002, a death was reported in a newborn after administration of calcium gluconate plus ceftriaxone despite the difference in routes of drugs administration and the difference in time of injection.

Purpose We tried to study the different physicochemical interactions that some antibiotics might have with cationic ions used in injectable form in hospital.

Material and methods We have selected the most consumed antibiotics in our university hospital and we tested them with bivalent cations commonly consumed in care services. The evaluation of the nature of the mixture was made using the solubility product of the melange of antibiotic and cation. We mix 0.5 mL of each cation solution concentrated to 5% and 0.5 mL of each antibiotic solution.

Results The solubility product expressed in (mol/l)2 of the melange of each antibiotic with each cation are summarised in the table below:

Conclusion Knowledge of drug interactions is essential for a better use of these drugs in hospital. Interactions of certain antibiotics commonly used with bivalent cations can lead to some precipitates undetected by nurses who administer the injectable treatments, which could cause serious accidents during the simultaneous use in patients. The summary of product characteristics of these antibiotics should incorporate these interactions to avoid those unforeseen accidents.

References and/or Acknowledgements Acknowledgements to analytical chemistry team.

No conflict of interest