Drug Interactions between lomefloxacin and repaglinide

MONITOR CLOSELY: Quinolone antibiotics may interfere with the therapeutic effects of insulin and other antidiabetic agents. The use of quinolones has been associated with disturbances in blood glucose homeostasis possibly stemming from effects on pancreatic beta cell ATP-sensitive potassium channels that regulate insulin secretion. Both hyperglycemia and hypoglycemia have been reported, usually in diabetic patients receiving concomitant treatment with an oral hypoglycemic agent or insulin. Although hyperglycemia is significantly more common and infection itself may be an underlying risk factor, hypoglycemia may cause greater morbidity and mortality. An internal safety review conducted by the U.S. Food and Drug Administration (FDA) identified at least 67 reports of severe hypoglycemia associated with quinolone use resulting in coma, death, or permanent and disabling injuries, primarily in elderly and diabetic patients with renal impairment and/or complicated infections. This is in addition to the numerous cases that have been reported for gatifloxacin, which led to its withdrawal from the U.S. market in 2008. Of the five quinolones that the FDA reviewed, levofloxacin had the most cases (44), followed by ciprofloxacin (12), moxifloxacin (9), ofloxacin (2), and gemifloxacin (0). Other quinolones such as nalidixic acid and norfloxacin, as well as some others that have never been marketed or are no longer marketed such as clinafloxacin and temafloxacin, have also been associated with dysglycemia, thus it is generally believed to be a class effect, albeit with varying risks amongst the individual agents. Available data also seem to indicate different time frames for the development of hypo- and hyperglycemia, with the former generally occurring within 1 to 3 days following quinolone initiation and the latter within 4 to 10 days later. Pharmacokinetically, ciprofloxacin is also a known inhibitor of CYP450 1A2 and 3A4 and may inhibit the hepatic metabolism of glyburide. Hypoglycemia in association with elevated serum glyburide level occurred in a patient after one week of ciprofloxacin therapy.

MANAGEMENT: Blood glucose should be closely monitored whenever quinolones are prescribed to diabetic patients, especially if they are elderly, have renal impairment, or are severely ill. Due to the risk of profound and potentially life-threatening hypoglycemia, particular caution is advised during concomitant use of insulin and insulin secretagogues (e.g., sulfonylureas, meglitinides). Patients should also be apprised of the increased risk of hypoglycemia and be alert to potential signs and symptoms such as headache, dizziness, drowsiness, nervousness, confusion, tremor, hunger, weakness, perspiration, palpitation, and tachycardia. If hypoglycemia occurs, patients should initiate appropriate remedial therapy immediately, discontinue the quinolone, and contact their physician. Alternative antibiotics may need to be considered.