Achilles tendon rupture in a man on ciprofloxacin and prednisolone

A 62-year-old man presented to the emergency department with sudden left heel pain and difficulty walking. He had been well until that morning, when he felt a snapping sensation in his left heel while getting out of bed. He was unable to bear weight on the affected leg. He reported no previous injury or similar symptoms.

His medical history included chronic obstructive pulmonary disease (COPD). Ten days earlier he had been admitted to a respiratory ward with an exacerbation of COPD. On that day, he was started on oral prednisolone 40 mg once daily, which he had continued taking. Five days into the admission, he developed a urinary tract infection, and ciprofloxacin 500 mg twice daily was commenced. His other regular medications included salbutamol and tiotropium inhalers.

Examination showed marked swelling and bruising over the left heel, with a visible gap in the Achilles tendon. The Thompson's test was positive. An ultrasound and subsequent magnetic resonance imaging confirmed a complete rupture of the left Achilles tendon.

Ciprofloxacin was stopped immediately on suspicion of an adverse drug reaction. The patient was referred to the orthopaedic team. He underwent surgical repair of the tendon, followed by immobilisation in a below-knee cast. His prednisolone was continued at a reduced dose, with stress-dose cover during the perioperative period. There was no immediate change in his symptoms after stopping ciprofloxacin, as the rupture had already occurred. No rechallenge was performed.

The treating team considered possible causes. The patient's age and the concurrent use of prednisolone are recognised risk factors for Achilles tendon rupture. However, the temporal relationship with ciprofloxacin, a drug well known to cause tendinopathy and tendon rupture, was also a key consideration. He had no prior exposure to fluoroquinolones. The event was reported to the pharmacovigilance database for further analysis.