Background Starting in 2007, the Pharmacy Institute at Bajcsy-Zsilinszky Hospital in Budapest was the first healthcare institution in Hungary to use centralised medicines Daily Dose System (DDS).

The number of medicines administered to a patient may increase the probability of drug interactions. If physicians prescribe treatment without due foresight this may cause subsequent problems for the patient.

Purpose Pharmacists are the last cheque-point in the medicines system. The study sought to justify the importance of this by monitoring interactions.

Materials and Methods The incidence of theoretical and clinically relevant interactions was followed on the cardiology department at Bajcsy-Zsilinszky Hospital in a four-week period cross-sectional study. During this period, the drug treatment and the potential interactions were examined by using NovoHosp.win software.

Results A total of 218 patients were registered in the study, gender distribution of the sample: 100 women (46%) and 118 men (54%). A total of 1,893 drugs were prescribed, an average of 9 drugs per patient. The NovoHosp.win software found 603 interactions, which was an average of 3 interactions per patient. 174 patients had at least one possible interaction, but clinically relevant problems (increased APTT and INR values, potassium level differences and uric acid changes) had only arisen in 25 patients, 8 women (32%) and 17 men (68%). The software indicated 4 theoretical and 1 clinically relevant interactions in this patient group. The relevant interactions were classified as follows: potassium level differences 19%, uric acid changes 22%, APTT abnormalities 37%, changes in INR 22%.

Conclusions In the present study, 25 patients had 30 relevant interactions, as a result of which medicines were changed on 22 occasions. Changes in the dose, dose adjustments or drug substitution abolished the interactions. The study also demonstrates the importance of cooperation between hospital/clinical pharmacists and physicians.

No conflict of interest.