💊 Fluoroquinolones

Fluoroquinolones are a class of broad-spectrum bactericidal antibiotics. They are effective against a wide range of Gram-positive and Gram-negative bacteria, including atypical pathogens.

Fluoroquinolones inhibit bacterial DNA replication and transcription by interfering with DNA gyrase (topoisomerase II) and topoisomerase IV. This leads to DNA strand breaks and ultimately bacterial cell death.

They are typically reserved for serious infections where other antibiotics are unsuitable, such as complicated urinary tract infections, severe respiratory tract infections (e.g., hospital-acquired pneumonia), and some sexually transmitted infections. They are also used for bone and joint infections.

Known hypersensitivity is an absolute contraindication. They are generally avoided in children and adolescents due to concerns about cartilage damage. Caution is advised in patients with a history of epilepsy or conditions predisposing to seizures, as well as those with a history of QT prolongation or tendon disorders.

Common side effects include gastrointestinal disturbances, headache, and dizziness. Serious but rare effects include tendonitis and tendon rupture (especially Achilles tendon), QT prolongation and arrhythmias, peripheral neuropathy, and CNS effects (seizures, psychosis). C. difficile infection is also a risk.

No routine blood monitoring is typically required for short courses. Renal function should be monitored in patients with pre-existing impairment. Patients should be advised to report any tendon pain, numbness, tingling, or visual disturbances. ECG monitoring may be considered in patients at risk of QT prolongation.

Always check for a history of tendon disorders, epilepsy, or QT prolongation. Counsel patients on the importance of reporting any tendon pain or swelling immediately and to stop the medication. Advise on avoiding antacids, iron, or dairy products close to dosing. Warn about potential CNS effects and photosensitivity.

Ciprofloxacin, levofloxacin, and moxifloxacin are common fluoroquinolones. Key adverse effects include tendon rupture, QT prolongation, and peripheral neuropathy – these are significant and have led to restrictions on their use. Avoid in children. Interactions with antacids/iron/dairy are important. Can exacerbate myasthenia gravis.

SBA questions frequently highlight the serious adverse effects, particularly tendon rupture and QT prolongation, and the patient populations at risk. The restriction of their use due to these risks is a common theme. Drug interactions with antacids and warfarin are also often tested.