Moxifloxacin

How it works

It inhibits the bacterial enzymes DNA gyrase and topoisomerase IV, blocking DNA replication and leading to bacterial cell death.

Prescribing in practice

• The MHRA advises that systemic fluoroquinolones may cause disabling and potentially long-lasting tendon, muscle, joint and nervous-system effects, and aortic aneurysm/dissection, so they should be reserved for when other antibiotics are unsuitable.
• Moxifloxacin prolongs the QT interval and should be avoided with other QT-prolonging drugs and in patients with relevant cardiac risk factors.
• It should be used with caution in epilepsy and conditions predisposing to seizures, and tendon rupture risk is increased with corticosteroids and in older patients.

Monitoring

Monitor for tendon, neurological and cardiac symptoms, and consider ECG assessment where QT-prolongation risk factors are present.

Counselling the patient

• Stop the medicine and seek advice if you develop tendon pain or swelling, new pins-and-needles, or mood changes.
• Avoid taking it at the same time as indigestion remedies or iron and calcium supplements, which reduce absorption.

Evidence & guidelines

Restrictions on fluoroquinolone use follow MHRA Drug Safety Updates, and efficacy in respiratory infection is established in clinical trials and the SPC.