Polypharmacy, Dosing Trends, and Drug-Drug Interaction Patterns After High-Level Limb Amputation Surgery

Abstract

Objective: The aim of this study was to examine perioperative medication patterns surrounding major amputation surgeries.

Design: A retrospective chart review of 216 cases of major amputations (transfemoral, hip disarticulation, hemipelvectomy, forequarter) at an academic hospital was conducted, examining medications, dosing changes, and drug-drug interaction warnings preoperatively and postoperatively.

Results: Medications increased in 76.9% (166/216), remained the same in 10.6% (23/216), and decreased in 12.5% (27/216) of cases. Average number of medications was 7 preoperatively and 10 postoperatively. In 189 cases with preoperative medications present, postoperative dosing remained the same for 74.3%, increased for 9.2%, decreased for 7.6%, and was unknown for 8.9% of medications. Increases in each of type C ("monitor therapy"), D ("consider therapy modification), and X ("avoid combination") drug-drug interaction warnings were seen respectively in 59.7%, 62.0%, and 5.1% of cases.

Conclusion: Polypharmacy is involved preoperatively and increased postoperatively in most cases of major limb amputation, with agent dosing remaining the same or increased in most cases. Drug-drug interaction warnings also increase. These occur at a time of abrupt changes to the body's size, compartments, and physiologic responses. More research and clinical attention are warranted given anticipated changes in pharmacokinetics and pharmacodynamics.