Background The main recurrent problem after liver transplantation is the rejection of the transplanted organ, which is why immunosuppressants are widely used as post-transplant drug therapy. This drug class has a large number of theoretical potential drug interactions (TPDIs) with other drugs often needed by those patients.

Purpose This work aims to outline the profile of the main TPDIs to which patients undergoing liver transplant surgery are exposed.

Materials and methods This is a cross-sectional, retrospective and observational study. In January of 2011, were collected medical prescriptions of patients admitted to the intensive care unit (ICU) of Hospital de Clinicas – UNICAMP between January and December of 2010. The study included only patients who were hospitalised for more than 24 h, underwent liver transplant surgery, were more than 18 years old, and had their drug prescriptions in the ICU in the medical records available for inspection.

Results The study included 25 patients, an average age of 51.64±11.96, 173 prescriptions were evaluated, an average of 6.92±2.72 prescriptions per patient. The number of TPDIs varied between 1 and 36, an average of 12.48±9.15 per patient. The 312 TPDIs observed in the medical prescriptions were classified according to the Micromedex database as contraindicated (12), major (101), moderate (183) and minor (16). Tacrolimus stood out as the main drug and it was present in 57% of the prescriptions and also in 10 different types of TPDIs.

Conclusions This study helped to design the drug therapy profile used in liver transplant patients in ICU of a Brazilian public hospital, showing that there is a high incidence of theoretical potential drug interactions in prescriptions. The clinical relevance of this work is in its contribution to the prevention of preventable adverse events associated with drug therapy, between them the rejection of the transplanted organ to failure of the immunosuppressive regimen adopted.