Ciprofloxacin's Structure Causing Fluoride-Related Toxicity: A Case Report.

Background: Ciprofloxacin is a fluoroquinolone antibiotic widely used in clinical practice with a fluorine atom in its chemical structure. Like other antibiotics, it can induce several adverse effects, such as tendinopathy, musculoskeletal toxicity, peripheral neuropathy, and cardiotoxicity, thereby causing relevant and irreversible health injuries. Ciprofloxacin fluoride's adverse toxicological effect associated with a urinary fluoride concentration above the reference value has not yet been reported.

Objective: This case report aimed to provide evidence of ciprofloxacin treatment intoxication, an antibiotic containing a fluorine atom in its chemical structure, associated with a fluoride urine concentration above the reference value.

Case presentation: A 32-year-old man developed tendinopathy and peripheral neuropathy on the third day's night after initiating the ciprofloxacin doses, exhibiting symptoms comparable to a low-power electrical discharge and very intense motor agitation. After following habitual laboratory exams, a urinary fluoride measurement was performed by an ion-selective electrode. The urinary fluoride concentration was above the reference values in mg/g of creatinine.

Conclusion: This is the first study that has described an association among ciprofloxacinfluoride, tendinopathies, and peripheral neuropathy. The patient's symptomatology has suggested a toxic effect related to fluoride. We consider the documented finding of a fluorine atom at the ciprofloxacin structure and its toxic potential neuropathies and tendinopathies as an issue of alert.