This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Pharmacology
Lactic acidosis is common with: 
Select and explain. 
A. Metformin, B. Phenformin, C. Repaglinide, D. Rosiglitazone
B: Phenformin
Answer: B: Phenformin 
Explanation: Small increase in blood lactate occurs with metformin but lactic acidosis is rare because it is poorly concentrated in hepatic cells. phenformin has been withdrawn from the market due to risk of lactic acidosis (REF.Essential of medical pharmacology K D TRIPATHI 6 Edition, Page No - 269)