Metabolic Acidosis and Rhabdomyolysis with Metformin overdosage

ABSTRACT

Metformin is a biguanide oral hypoglycemic agent used as first-line or as a part of multi-drug therapy in the treatment of Type 2 Diabetes Mellitus [DM]. Lactic acidosis is a well-known but relatively uncommon adverse effect of Metformin, especially in patients with co-existing renal failure. There are several case reports of inadvertent or intentional Metformin overdosage resulting in severe metabolic acidosis with hyperlactatemia and often fatal outcome. Continuous hemodiafiltration with other supportive therapies have resulted in successful management of the metabolic derangements and is presently the accepted standard therapy of Metformin intoxication. A twenty-two-year-old female presented with Metformin over-dosage of 50g and developed severe metabolic acidosis and rhabdomyolysis. Metabolic acidosis was prolonged; the pH level was 6.72, bicarbonate level <4 mmol/L and lactate level was more than 25 mmol/L. The patient was managed with crystalloids, bicarbonate infusions and continuous venovenous hemodiafiltration. The blood gas parameters normalized 48 hours after initiation of the treatment. Hemodiafiltration was continued for longer than usual due to the prolonged metabolic acidosis and until the elevated Creatine Kinase [CK] levels returned to normal. She made an uneventful recovery, without residual sequelae