Moderate
ciprofloxacin × metformin
Fluoroquinolone antibacterials×Biguanides. Oral antihyperglycemic agents
Mechanism
Fluoroquinolones disrupt glucose homeostasis – they can cause both hypoglycemia (especially in older patients on glucose-lowering therapy) and hyperglycemia. The mechanism is unclear; suggested mechanism is blockade of ATP-sensitive K+ channels in β-cells. FDA black-box warning from 2018 regarding severe hypoglycemia with fluoroquinolones.
Management
During ciprofloxacin in a metformin-treated patient, self-monitor glucose twice daily. For tachycardia, sweating, tremor, or confusion, immediately check glucose and treat hypoglycemia if needed. Where possible, choose a non-fluoroquinolone antibiotic in T2D patients.
Sources
- FDA: FDA Drug Safety Communication: FDA reinforces safety information about serious low blood sugar levels and mental health side effects with fluoroquinolone antibiotics (2018)— FDA Drug Safety Communication, July 10, 2018
- Lexicomp: Lexicomp Drug Interactions (2024)— Wolters Kluwer Clinical Drug Information, Inc. Lexi-Interact Online, 2024