Thrombosis Secondary to Intravenous Dicyclomine Administration: A Case Report and Literature Review

<b>Introduction:</b> Dicyclomine is an antimuscarinic agent approved for treatment of irritable bowel syndrome-associated abdominal pain. Intravenous (IV) administration should be avoided due to potential for thrombosis, but real-world evidence is generally lacking. This case report presents a thrombotic complication associated with inadvertent IV administration of dicyclomine. <b>Case:</b> A 43-year-old man with chronic colitis and recurrent <i>Clostridioides difficile</i> infections presented to a community hospital complaining of moderate-severe suprapubic abdominal pain and nausea/vomiting/diarrhea for 5 days. Computed tomography showed descending colonic wall thickening and proctitis, without perforation or abscess. Initial orders consisted of ketorolac 15 mg IV and dicyclomine 20 mg intramuscularly. The nurse inadvertently mixed ketorolac and dicyclomine in the same syringe and administered them simultaneously. Ultrasound subsequently confirmed a non-occlusive right axillary vein thrombosis and an occlusive superficial right basilic vein thrombosis. The patient was started on therapeutic enoxaparin subcutaneously. He was enrolled in a patient assistance program and was discharged on rivaroxaban dispensed from the hospital's outpatient pharmacy. <b>Discussion:</b> Dicyclomine is more selective for the M₁ and M₃ receptors, and the M₃ receptor causes nitric oxide activation. As dicyclomine was unintentionally administered IV, the inhibition of nitric oxide could potentially lead to clotting. The simultaneous administration of ketorolac promoted a pro-thrombotic state, via cyclo-oxygenase-2-mediation vasoconstriction. Naranjo algorithm assessment indicated "possible" potential for a drug-induced adverse event. The pharmacist submitted an adverse drug event report and revisions to barcode medication administration were implemented. <b>Conclusion:</b> Thrombotic complications are possible following IV dicyclomine administration and pharmacy personnel must implement safeguards to prevent inadvertent administration.