Background: Standardised substitution of those drugs not included in the hospitaĺs formulary constitutes one of several methods used to improve therapeutic efficiency, due to reduction of variability in pharmaceutical practice and prevention of potential medication errors.
Objectives: To evaluate quality of drug substitution procedures in those drugs not included in the hospital's formulary.
Methods: Assessment study in a surgical hospital with 314 beds, using structural, process and outcome criteria from 1998 to 2002.
Results: Compliance degree for structure, process and outcome criteria were 100, 89 and 35%, respectively, while the established standards were 100%. Prevalence values for patients with substituted medication, increased from 2.9 (95%CI, 2.4-3.6) in 1998 to 11.1% (95%CI, 10.2-12.1) in 2002. Non-substituted drugs annual cost decreased from 20,199 in 1998 to 12,356 Euro in 2002. Drug substitution made by the pharmacist had an acceptance degree of 82.5%. No interchange errors were found in 126 replaced drugs.
Conclusions: The development of quality programs to improve drug prescription adherence to the hospitaĺs formulary, specially those that promote therapeutic interchange under the Pharmacy Committee guidance, are helpful strategies to make a proficient management of patients pharmacotherapy.