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.
Materials and Methods: The intraprocedureal images of 100 consecutive patients who underwent IVC filter retrieval over a 35 month period at a single institution were evaluated. The cohort consisted of 45 males and 55 females with an average age of 49.4 years (range, 20-79 y). All patients underwent a rotational venogram using an injection rate of 15ml/sec for 6 sec with a 2 sec x-ray delay prior to filter removal. In this study the AP view of the rotational venogram was examined separately from the full rotational venogram by a board certified radiologist blinded to alternative imaging findings and operative findings. The venograms were evaluated for embedment of the filter tip, filter fracture, leg protrusion, and IVC thrombus. Results: Using operative findings as the reference standard, tip embedding was found in 59 of the 100 filters. AP venography correctly identified 31 tip embedded filters (52.5% sensitivity) with 2 false positives (95.1% specificity) for an overall accuracy of 70%. Rotational venography correctly identified 58 tip embedded filters (98.3% sensitivity) with 1 false positive (97.6% specificity) for an overall accuracy of 98%. McNemar's test found a significant difference in the sensitivities of the two diagnostic approaches (po.05). Other findings of thrombus, filter fracture, and filter leg protrusion were not significantly different between the two groups. Conclusion: Rotational venograms more accurately detect tip embedded IVC filters compared to AP views alone. This has the potential to alter the approach taken and tools used for IVC filter retrieval. Were possible, rotational venograms should be obtained prior to filter removal in all cases.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.