ModerateCalcium channel blockers (dihydropyridines)×Fluoroquinolone antibacterials
Updated · Methodology
Mechanism
Amlodipine is broken down in the liver by the CYP3A4 enzyme. The US Food and Drug Administration (FDA) classifies ciprofloxacin as a moderate CYP3A4 inhibitor (FDA table of CYP inhibitors). Moderate and strong inhibitors of this enzyme raise amlodipine blood levels and with them the risk of low blood pressure, more so in older patients (amlodipine SmPC; amlodipine FDA label). The labels give no specific data for this pair.
Symptoms
Dizziness and weakness, especially on standing, from low blood pressure; swelling of the ankles and feet (amlodipine labels). These effects are more marked in older patients (amlodipine SmPC).
Management
During the ciprofloxacin course, watch for signs of low blood pressure and for swelling to decide whether the amlodipine dose needs adjusting (amlodipine label of the US Food and Drug Administration, FDA). The Spanish amlodipine SmPC also states that moderate CYP3A4 inhibitors may require clinical monitoring and a dose adjustment, especially in older patients (amlodipine SmPC). Raise the amlodipine dose with caution in older patients (amlodipine SmPC).
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Sources
- FDA: For Healthcare Professionals: FDA's Examples of Drugs that Interact with CYP Enzymes and Transporter Systems (2026)– FDA, content current as of 05/29/2026, Table 1: ciprofloxacin – CYP1A2 and CYP3A moderate inhibitor
- AEMPS: Ficha técnica: Amlodipino (Norvas 10 mg) (nº registro 59160), secciones 4.4 y 4.5 (2024)– AEMPS, CIMA, nº registro 59160, revisión 01/2024, secciones 4.4 y 4.5
- FDA: Norvasc (amlodipine besylate) tablets prescribing information (Viatris) (2023)– FDA label, DailyMed setid 7367289c-b0b0-466a-83e2-558e2985c29f, revised 02/2023, sections 7.1 and 12.3