Do risk factors for lactic acidosis influence dosing of metformin?
BACKGROUND
Metformin is commonly prescribed to treat type 2 diabetes mellitus, however it is associated with the potentially lethal condition of lactic acidosis. Prescribing guidelines have been developed to minimize the risk of lactic acidosis development, although some suggest they are inappropriate and have created confusion amongst prescribers. The aim of this study was to investigate whether metformin dose was influenced by the presence of risk factors for lactic acidosis.


METHODS
The study was prospective, and retrieved information from patients admitted to hospital who were prescribed metformin at their time of admission.


RESULTS
Eighty-three patients were included in the study, 60 of whom had a least one risk factor for lactic acidosis. Of those 60 patients, 78.3% had a dose adjustment, with renal impairment, hepatic impairment, surgery and use of radiological contrast media--the risk factors most likely to result in a dose adjustment. When dose adjustments did occur, metformin was withheld on 88.7% of occasions.


CONCLUSIONS
Metformin dose was influenced by the presence of risk factors for lactic acidosis, although it was dependent upon the number and particular risk factor/s present.
School of Pharmacy, University of Queensland, St Lucia, Brisbane, Australia.
S
S
Millican
N
N
Cottrell
B
B
Green
D000140:Acidosis, Lactic / Q000139:chemically induced* / Q000517:prevention & control; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003924:Diabetes Mellitus, Type 2 / Q000188:drug therapy*; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D005260:Female; D006801:Humans; D007004:Hypoglycemic Agents / Q000008:administration & dosage* / Q000009:adverse effects* / Q000627:therapeutic use; D008297:Male; D008687:Metformin / Q000008:administration & dosage* / Q000009:adverse effects* / Q000627:therapeutic use; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors
D007004:Hypoglycemic Agents; D008687:Metformin