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Summary Background & aims Wernicke's encephalopathy is associated mainly with malnourishment in alcohol-dependent patients but can be caused also by cancer, Crohn's disease, gastrointestinal surgery or prolonged parenteral nutrition (PN) without adequate supplementation of vitamins. The disorder, with a significant mortality rate of up to 20%, is often associated with the underlying disease and intensifies after administration of non-supplemented PN. Thus, it seems justified to add thiamine to PN admixtures prepared for parenterally fed patients. Due to the lack of data on the stability of thiamine in PN admixtures at concentrations exceeding 60 mg/L, we decided to determine the possibility of adding a high dose of thiamine (800 mg per bag, 320 mg/L) to PN admixtures in order to treat Wernicke's encephalopathy in malnourished patients. Methods The study aimed to assess the stability of the physical properties of PN admixtures (pH, zeta potential, particle size) and to determine thiamine content using an HPLC method. Results Thiamine was found to degrade regardless of the PN admixture composition and storage conditions. The highest decrease in thiamine content was observed at room temperature without light protection whereas the lowest at a temperature of 4 ± 1 °C with light protection. Conclusions The treatment of Wernicke's encephalopathy in parenterally fed patients is possible with the use of high thiamine doses (800 mg) added to PN admixtures without a decrease in the drug content above 10% within the first 24 h. It should be emphasized that thiamine as a photosensitive drug must be stored and administered under conditions ensuring light protection.

Objectives Supplementation of parenteral nutrition (PN) admixtures with other parenteral drugs may be desired especially in the case of polypharmacy and limited vascular access. Metronidazole (MTZ) is administered in surgical and critically ill patients often requiring concomitant nutritional therapy in the form of parenteral nutrition. The aim of the study was to evaluate the possibility of the concomitant administration of MTZ with PN admixtures from one container. Methods MTZ (1500 mg) was combined with six different PN admixtures and stored for 7 days before the simulation of administration. The mean droplet size (MDS) of the lipid emulsion, zeta potential, color, and pH of the tested samples were determined every 24 h. The content of MTZ was determined by the high-performance liquid chromatography method within the same time frames. Results PN admixtures supplemented with MTZ were characterized by a pH range from 6.19 to 6.38 and zeta potential range from –21.6 mV to –8.8 mV. For all samples the pharmacopeial criteria for intravenously administered emulsions were met: The visual inspection showed no sign of emulsion destabilization or precipitation, and the MDS was 90% of the initial value throughout the whole study period. Conclusions Results showed the physicochemical compatibility and stability of PN admixtures supplemented with MTZ at the dose of 1500 mg. Such formulations can be stored at a temperature of 5°C for up to 7 d before administration to the patient.