[Drug interactions in practice]

As potential modulators of drug safety and effectiveness the compatibility and stability of drugs are important elements in drug prescription and drug administration to patients. According to various characteristics, important differences between areas of stationary hospital care and ambulatory care are evident. While the challenges in the ambulatory care setting have been focussed on dermatological topical medication, incompatibility assessment is a challenge for the physician and the pharmacist in a hospital setting. Particularly in intensive care patients often up to 20 different drugs are administered in only few infusion devices or through a limited number of parenteral infusion lines. Among the compounds most often incriminated to cause incompatibilities are furosemide, phenytoin, midazolam and diazepam when used as i.v. admixtures. In recent years new challenges arose in ambulatory care in the area of oncologic treatment. Cytotoxic drug therapy and supportive care therefore requires increasing attention in terms of incompatibility of ready to use combined drug admixtures. To prevent incompatibilities never more than one drug should be added, nutrition solutions should never be used as carrier solutions for drug administration, mixtures should not be stored and should be administered immediately after preparation. During the administration of unavoidable mixtures visible changes of the solutions should be carefully sought.