Background Drug-drug interactions are a frequent problem in liver transplant (LT) patients, further hindering pharmacotherapeutic management, which is a very important risk to the patient’s life.

Purpose To detect drug-drug interaction of clinical relevance in LT patients in a tertiary hospital.

Materials and Methods Descriptive transversal study of the LT patients in our hospital during 2011 who were admitted to the Digestive Surgery Unit (DSU). Variables analysed were: sex, number of drugs prescribed at admission and number of days of hospitalisation in the DSU. Data were collected from clinical and pharmacotherapeutic histories and the unit dose dispensing log. Drug-drug interactions were detected and analysed by the Micromedex Healthcare series^® database. The results were analysed with the SPSS v.19 statistics software.

Results Of a total of 51 transplant patients, we included 44 (5 patients died and in 2 patients the medicines were not recorded at admission to the DSU).

75% of patients were male and 25% female, mean age of patients was 53 ± 12 years. The median number of days in hospital was 11 [9.18] days. The mean number of drugs prescribed on admission was 11 ± 2.5 drugs/patient.

The total number of drug interactions detected was 210 of which 153 (72.9%) were clinically relevant, representing a prevalence of 84.1% of liver transplant patients.

Of the main variables studied, only the number of drugs prescribed was found to be directly proportional (p < 0.05) to the number of clinically relevant interactions detected, thus no relationship was obtained between age or the number of days hospitalised.

Conclusions Liver transplant patients are critically ill patients with highly complex treatment. A high prevalence of clinically relevant interactions was detected related to polypharmacy and the use of high-risk medicines.

The presence of a pharmacist in this Unit would be beneficial to comprehensively review these patients’ treatment.

No conflict of interest.