Preventable Pulmonary Embolism Post-TKR: A Case Study Highlighting the Need for Pharmacist-Led Discharge Counseling on NSAID-Anticoagulant Interactions

Background and Aim: VTE is a serious risk after knee replacement surgery. Poor pain management and unsupervised NSAID use may lead patients to skip anticoagulants, increasing clot risk. This case study explores the consequences of unsupervised consumption of over-the-counter (OTC) medications in a patient following total knee replacement (TKR). It specifically focuses on how interruption of prescribed thromboprophylaxis contributed to the development of venous thromboembolism (VTE). Presentation of Case: A 67-year-old woman with a history of type 2 diabetes mellitus and hypertension underwent an elective right total knee replacement procedure. After discharge, she was prescribed oral apixaban (2.5 mg twice daily) as part of her thromboprophylaxis regimen. To manage postoperative pain, the patient independently consumed multiple doses of diclofenac obtained over the counter. She experienced epigastric discomfort, dizziness, and mild bleeding from the surgical site. Concerned about these symptoms, she missed scheduled doses of apixaban and significantly reduced her level of physical activity. Within three days, she was presented with calf swelling, tachycardia, and decreased oxygen saturation, with diagnostics confirming right popliteal deep vein thrombosis (DVT) and segmental pulmonary embolism (PE). Discussion: This case highlights the risks associated with unsupervised OTC medication use. Diclofenac, when taken together with anticoagulant therapy, can increase the possibility of bleeding complications. The patient’s fear of bleeding led to non-adherence to anticoagulant therapy, while reduced mobility further increased the likelihood of thrombus formation. Together, these factors created a clinical situation that facilitated the development of VTE. Conclusion: This case emphasizes that uncontrolled use of OTC analgesics may lead to significant drug interactions. Effective patient education at discharge, proper medication review, and the involvement of clinical pharmacists are important measures to reduce the risk of such complications.