[Infusion mixtures--study of clinical practice in Austria]

Options in parenteral therapy increasingly require administration of several medications simultaneously. Very little is known about the compatibility and pharmacological stability of such mixtures. We investigated how widespread this practice is, which carrier solutions are most commonly used, and whether specific medication mixtures ('cocktails') or constant formulations for TPN are applied. Upon our request, physicians and nursing staff of 54 general hospital wards (19 surgical, 18 internal medicine, 17 intensive care) in 17 Austrian hospitals recorded the parenteral admixtures for one week under the supervision of a hospital pharmacist. We found that: 1. Admixing is commonly practiced in all wards. In all but one of the wards two or even more medications are added into one single infusion. 2. Carrier solutions were: Dextrose/fructose (87% of the wards), electrolytes (90%), amino acids (40%), fat emulsions (26%), colloids (14.8%), albumin (5.5%) and Solcoseryl (5.5%). 3. Fixed combinations for i.v. therapy are practiced in 70% of the wards (mostly analgetics with corticosteroids or vitamins) 4. In almost half of the units constant formulations for TPN exist (46%). Only few of the combinations named have been investigated or tested for stability. The compatibility of most of the admixtures is unknown, while a few are clearly incompatible. Admixtures to one of the carrier solutions (Solcoseryl) are known to have caused serious complications before. For several admixtures, conflicting data about compatibility were found in the literature. The theoretical basis for incompatibilities is discussed together with some typical examples. Also some rules for admixtures are given. Questions concerning the compatibility of simultaneous parenteral drug applications are too specific to be answered for most physicians. Advice and counseling on this subject should become a new task for clinical pharmacists.