Abstracts

Rationale: Treatment adherence is associated with positive treatment outcomes. Non-adherence is often associated with adverse drug effects. Thus, it is important for prescribers to be cognizant of all potential adverse drug effects to maximize medication adherence and treatment outcomes. Delusional parasitosis (DP) is characterized by the persistent belief that parasites are infesting the body, despite evidence to the contrary [Trenton A, Pansare N, Tobia A, Bisen V, Kaufman KR. Delusional parasitosis on the psychiatric consultation service – a longitudinal perspective: Case study. BJPsych Open. 2017;3(3):154-158]. It can occur in a wide variety of medical and psychiatric conditions or on its own, but it is rare to occur as a side-effect of medication use. To our knowledge this is the second instance of topiramate(TPM)-induced DP.

Methods: Case report.

Results: A 51-year-old woman with a history of chronic migraine headaches, fibromyalgia, and morbid obesity treated with a Rouen Y gastric bypass with complications resulting in 3 revision surgeries (the last of which was in 2002) was started on TPM for migraine prophylaxis. The patient had no prior history or family history of psychiatric conditions or DP. When first seen in consultation in 2019, the patient was on a daily regimen of propranolol 20 mg, nortriptyline 25 mg, and duloxetine 60 mg for ongoing migraine prophylaxis but continued to experience more than 10 headache days per month. The patient was started on TPM 25 mg daily with the ultimate goal dose being 50 mg twice daily. Approximately three months later, prior to any further TPM titration, the patient presented for follow-up and reported a significant reduction in migraine days per month. However, she developed new onset DP, trichotillomania, pruritus, and anxiety disorder not otherwise specified. TPM was the only recent medication change in the patient’s regimen without any dosing changes in her other medications; TPM was immediately discontinued. Hydroxyzine 50 mg four times daily as needed was started for both anxiety and pruritus. The patient returned 6 weeks later and reported that her DP was completely resolved. Her trichotillomania and anxiety disorder not otherwise specified resolved in 12 weeks and she was weaned off hydroxyzine without return of any symptoms. For both clinical and ethical reasons, the patient was not rechallenged with TPM to confirm the probable (by Naranjo scale) diagnosis of TPM-induced DP.

Conclusions: We report the second case of TPM-induced DP. Though this adverse effect is rare, TPM-induced DP is relevant to all prescribers of TPM, especially as TPM is prescribed off label for multiple conditions.

Funding: None.