Trends in oral drug bioavailability following bariatric surgery: examining the variable extent of impact on exposure of different drug classes.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Changes to oral drug bioavailability have been observed post bariatric surgery. However, the magnitude and the direction of changes have not been assessed systematically to provide insights into the parameters governing the observed trends. Understanding these can help with dose adjustments. WHAT THIS STUDY ADDS: Analysis of drug characteristics based on a biopharmaceutical classification system is not adequate to explain observed trends in altered oral drug bioavailability following bariatric surgery, although the findings suggest solubility to play an important role. AIMS: To identify the most commonly prescribed drugs in a bariatric surgery population and to assess existing evidence regarding trends in oral drug bioavailability post bariatric surgery. METHODS: A retrospective audit was undertaken to document commonly prescribed drugs amongst patients undergoing bariatric surgery in an NHS hospital in the UK and to assess practice for drug administration following bariatric surgery. The available literature was examined for trends relating to drug permeability and solubility with regards to the Biopharmaceutics Classification System (BCS) and main route of elimination. RESULTS: No significant difference in the 'post/pre surgery oral drug exposure ratio' (ppR) was apparent between BCS class I to IV drugs, with regards to dose number (Do) or main route of elimination. Drugs classified as 'solubility limited' displayed an overall reduction as compared with 'freely soluble' compounds, as well as an unaltered and increased ppR. CONCLUSION: Clinical studies establishing guidelines for commonly prescribed drugs, and the monitoring of drugs exhibiting a narrow therapeutic window or without a readily assessed clinical endpoint, are warranted. Using mechanistically based pharmacokinetic modelling for simulating the multivariate nature of changes in drug exposure may serve as a useful tool in the further understanding of postoperative trends in oral drug exposure and in developing practical clinical guidance.

Learning to work with electronic patient records and prescription charts: experiences and perceptions of hospital pharmacists.

BACKGROUND: The use of electronic patient records (EPR) and electronic prescribing systems (such as electronic patient medication and administration records (EPMAR)) have many benefits. Changes and problems can result, however. Anecdotally, how pharmacists respond to system introduction varies greatly; there is very little information regarding pharmacists' experience in the literature. OBJECTIVES: This study aimed to establish the changes that electronic systems afforded to hospital pharmacists' working practices and to investigate how and why they had responded to EPR and EPMAR. METHODS: Four semi-structured focus groups were conducted with pharmacists with different levels of seniority, with 4-6 participants in each. The focus groups were held 8 months after implementation of EPR and EPMAR were complete, and each focus group met once. Transcripts were analyzed manually using thematic analysis and data interpreted through the application of Actor Network Theory (ANT) and human activity systems as described in Engestrom's Expansive Learning Theory (ELT). RESULTS: The three main overarching themes identified involved reduced patient contact, professional representation in the clinical environment and documentation in the EPR. Pharmacists felt less visible to, and had poorer relationships with, patients as they no longer saw them when they checked prescriptions. Interprofessional relationships changed as pharmacists provided informal EPMAR training for doctors and spoke more often with nurses to relay important information. Changes in whether, what and how pharmacists recorded information also were seen, particularly between pharmacists of different generations and years of working at the hospital. Analysis of the changes afforded by electronic systems using ANT and ELT suggest that pharmacists develop individual working practices in response to changes that electronic systems provide. CONCLUSION: For implementation success of EPR and EPMAR systems, pharmacists need to be taught not just the practicalities of system use, but also how to ensure that patients remain the focus of care, in response to the professional changes that may well occur following computerization.