Background and importance The sensitivity of drugs to dietary influences largely depends on their physicochemical properties. Interactions between drugs and foods may induce a change in the physicochemical and pharmacological properties of the active ingredient, such as its bioavailability and toxicity.

Aim and objectives To determine the physicochemical incompatibility of the active ingredient (AI) of some antibiotics in the presence of divalent cations found frequently in our daily diet or in patients using parenteral nutrition at the hospital.

Material and methods We selected nine active ingredients of the most commonly used antibiotics at the hospital, mixed separately with four divalent cations. The mixtures were made by introducing the components in an equivalent amount into test tubes. The tests were carried out under two conditions: (1) ambient temperature and (2) after heating and acidification of the mixtures with HCl. 90 AI/cation mixtures were made and analysed after 1 hour. The physicochemical properties previously established for both the active ingredients and the cations were compared with the new data using UV visible spectroscopy.

Results Results are represented in table 1.

Conclusion and relevance Compatibility data with oral or parenteral nutrition is often missing for most of the frequently used drugs requiring a case-by-case assessment. The clinical pharmacist’s understanding of physicochemical and pharmacological phenomena related to drug and food incompatibilities is a useful resource in the management and prevention of this problem.

References and/or acknowledgements 1. We want to thank the team of analytical chemistry and bromatology laboratory.

Conflict of interest No conflict of interest