WBR0673

Author	[[PageAuthor::Yazan Daaboul, M.D. (Reviewed by Serge Korjian)]]
Exam Type	ExamType::USMLE Step 1
Main Category	MainCategory::Pharmacology
Sub Category	SubCategory::Endocrine
Prompt	[[Prompt::A 52-year-old obese man, with a past medical history significant for hypertension, dyslipidemia, diverticulosis, and chronic kidney disease presents to the physician's office for his annual check-up. Routine work-up shows an HbA1c of 7.5%. The physician decides he wants to start the patient on oral antidiabetic therapy given this finding. Which of the following medications must be avoided in the patient?]]
Answer A	AnswerA::Pioglitazone
Answer A Explanation	[[AnswerAExp::Pioglitazone is a thiazolidinedione (TZD). It is not contraindicated in chronic kidney disease. It is contraindicated in patients with heart failure due to the exacerbation of CHF symptoms.]]
Answer B	AnswerB::Pramlintide
Answer B Explanation	[[AnswerBExp::Pramlintide is an amylin analog that decreases glucagon. It is not contraindicated in renal failure.]]
Answer C	AnswerC::Metformin
Answer C Explanation	AnswerCExp::Metformin is a biguanide that is commonly used as a first line therapy for type 2 diabetes mellitus. It is contraindicated in renal failure and in patients among the age of 80 years. It has been associated, in rare cases, with lactic acidosis.
Answer D	AnswerD::Exenatide
Answer D Explanation	[[AnswerDExp::Exenatide is a GLP-1 analog that increases insulin and decreases the release of glucagon. It is associated with GI distress and pancreatitis.]]
Answer E	AnswerE::Glimepiride
Answer E Explanation	[[AnswerEExp::Glimepiride is a second generation sulfonylurea (SU). It is not contraindicated in renal failure but requires caution due to the increased risk of hypoglycemia.]]
Right Answer	RightAnswer::C
Explanation	[[Explanation::The patient is newly diagnosed with type 2 diabetes mellitus, with an elevated HbA1c > 6.4 % and requires oral anti-diabetic pharmacological therapy. Generally, metformin, a biguanide that acts as a sensitizer, is considered a first line therapy for patients with type 2 diabetes mellitus. However, it is contraindicated in renal failure and should not be initiated in patients above 80 years of age. This is due to the relatively increased risk of lactic acidosis in these patients. Another important contraindication for metformin is recent administration of contrast material (within 48 hours) also due to the increased risk of lactic acidosis. Since the patient is known to have chronic kidney disease, metformin is thus contraindicated and must be avoided. Educational Objective: Metformin is contraindicated in renal failure due to the increased risk of lactic acidosis. References: Jones GC, Macklin JP, Alexander WD. Contraindications to the use of metformin. BMJ. 2003;326(7379):4-5.]]
Approved	Approved::Yes
Keyword	WBRKeyword::Metformin, WBRKeyword::Diabetes mellitus, WBRKeyword::Contraindication, WBRKeyword::Renal failure, WBRKeyword::Chronic kidney disease, WBRKeyword::Oral antidiabetic, WBRKeyword::Oral antidiabetic therapy
Linked Question	Linked::
Order in Linked Questions	LinkedOrder::