Hemodialysis metformin

Lactic acidosis is a medical emergency that must be treated in a hospital setting. In a patient with lactic acidosis who is taking metformin, immediately discontinue the drug and promptly institute general supportive measures. Because metformin is dialyzable (with a clearance of up to 170 mL/min under good hemodynamic conditions), prompt hemodialysis is recommended to correct the acidosis and remove the accumulated metformin. Such management often results in prompt reversal of symptoms and recovery. 

All survived, but all needed hemodialysis. In all cases there were contraindications to metformin. 

A 42-year-old man developed nausea and vomiting and felt suicidal. He had type 2 diabetes and was taking metformin (56). His blood lactate concentration was 8.9 mmol/1, bicarbonate 16 mmol/1, and pH 7.2. Severe hypotension required intensive care. The lactate concentration rose to 22 mmol/1 and the bicarbonate fell to 6.7 mmol/1 and the pH to 6.89. The metformin concentration was high at 191 mg/1. He survived, having been treated with intermittent hemodialysis. 

A 61-year-old woman developed a bradydysrhythmia after a cardiac arrest (57). Her lactate concentration was 18 mmol/1, pH 6.60, blood glucose 19 mmol/1, and creatinine 1136 pmol/1. She had a 5-year history of type 2 diabetes treated with glimepiride 3 mg/day and metformin 850 mg tds, and 4 months before admission had had a serum creatinine concentration of 1.1 mg/dl. In the few days before admission she had had abdominal pain, nausea, and a speech disorder. She was treated with hemodialysis, and 6 weeks later the creatinine was 0.54 mg/dl. Further information about events leading to the acute renal insufficiency was not given, but a diagnosis of metformin-associated lactic acidosis was made. 

Five patients with metformin-associated severe lactic acidosis, seen between 1 September 1998 and 31 May 2001, have been reported (58). Two had attempted suicide. All had severe metabolic acidosis with a high anion gap and raised blood lactate concentrations. Four developed profound hypotension and three had acute respiratory failure. Three had normal preceding renal function. Three required conventional hemodialysis and two continuous renal replacement therapy. 

The results of hemodialysis in biguanide-induced lactic acidosis are variable. Metformin and buformin are dialy-sable, but phenformin is poorly eliminated. Successful continuous venovenous hemofiltration has been reported (81). 

A 70-year-old man survived a suicidal attempt with metformin 63 g (132). His serum lactate concentration was 24 mmol/1 and creatinine 216 pmol/1. He received bicarbonate hemodialysis, blood pressure support, and active warming for hypothermia. After 6 hours lactate and creatinine normalized. 

Metformin is removed by hemodialysis, which can also help correct severe lactic acidosis. Continuous venovenous hemodiafiltration has also been recommended. 

A 46-year-old woman with a 6-year history of diabetes mellitus and previously normal renal function developed anuria, hearing loss, myoclonus, and confusion with hallucinations. She was taking lisinopril, hydrochlorothiazide, furose-mide, atorvastatin, omeprazole, salmeterol/fluti-casone and salbutamol by inhalation, metformin, insulin, oxycodone, alprazolam, ven-lafaxine, and gabapentin 300 mg tds. The gabapentin blood concentration was 17.6 mg/1. All her symptoms improved after one session of hemodialysis and had resolved at the time of discharge 4 days later. 

In a similar retrospective study over 5 years, 30 patients with metformin-associated lactic acidosis were admitted to intensive care three had taken an overdose 21 survived [36 ]. Prothrombin time was also related to survival, which may imply that liver function is particularly important. Not all patients received hemodialysis, but there was no difference in survival between those who did and did not. 

---