<prompt> Which of the following characteristics make metformin a preferred biguanide than phenformin?It is more potentIt is less liable to cause lactic acidosisIt does not interfere with vitamin B12 absorptionIt is not contraindicated in patients with kidney disease  <response>: Ref: KDT 6e p269 Incidence of lactic acidosis is more with phenformin and that of megaloblastc anemia due to interference with vitamin B12 absorption is more with metformin. 