A 53-year-old man presents to your primary care office because over the past few weeks, he has noticed that he has been thirstier and has been urinating more frequently. His current medications include ibuprofen for headaches, isoniazid for tuberculosis and aspirin for back pains. His family history is significant for heart disease in father and type 2 diabetes in mother. On examination, his weight was 132 kg (BMI 39.5) and blood pressure 145/71, and signs of mild peripheral neuropathy were present. Laboratory tests noted an HbA1c value of 8.1% and fasting glucose level is 158 mg/dL. All other laboratory studies are normal. You tell the patient that he has type 2 diabetes and you decide to begin him on metformin. Patient asks you about the most significant adverse effects of this medication. Which of the following medications can cause lactic acidosis?
