Drug interactions in geriatic patients treated with venlafaxine

Motivation: The proportion of those over the age of 65 is increasing. Elders are more likely than younger people to be affected by many diseases and to be prescribed the related therapy (polypharmacy). Polypharmacy frequently causes wrong drug concentration in blood due to multiple drug interactions and other factors both genetic and external (i. e. smoke). Problem statement: Computer software which give information regarding drug-drug interactions and dosage management can be a powerful tool to prevent drug interactions but they are often not reliable. In this study the aim is to demonstrate the importance of integrating theoretical data contained in these programs with the real clinical and physiological condition of each patient. Results: In a population of 878 psychiatric patients treated with venlafaxine, only 50,11% had the blood concentration of the drug within the dose related reference range while 32,23% were under it and 17,54% were above it. The dose related reference range gives information on drug-drug interactions and in this case patients with a blood concentration of venlafaxine under it were mostly prescribed mirtazapin, morphine and pantoprazol. Afterwards these data were assessed according to sex, alcohol consumption, smoke and coffee. Conclusion: This is a clear evidence of the importance of individualised therapy. More efforts are needed to develop programs that meet the needs of the individual patient. Further analysis are being carried out.