Bristol-Myers Squibb is to slap a stronger warning on its antibiotic Tequin after continued reports of both hypoglycaemia (low blood sugar) and hyperglycemia (high blood sugar) in patients given the drug. The antibiotic will also now be contraindicated in diabetics, but the warning did little to impact the firm’s share price – dropping less than 1% on the New York Stock Exchange on the news.

Tequin (gatifloxacin) is indicated for the treatment of patients with pneumonia, bronchitis, uncomplicated gonorrhea and various infections including infections of urinary tract, kidneys and skin. However, since the drug’s approval in 1999, the US Food and Drug Administration says there have been rare cases of life-threatening events reported globally in patients treated with the drug – most of which were reversible but a few of which had fatal outcomes.

The new label will include information highlighting other risk factors for developing low and high blood sugar while taking Tequin, including old age, poor kidney function and the concomitant use of glucose-modifying medicines.

"The FDA will continue monitoring Tequin's safety to ensure that its benefits outweigh the risks to patients," the agency said in a statement. The labeling was first updated in 2002 to include the risk of blood sugar changes.