View source for WBR0673

 {{WBRQuestion
|QuestionAuthor= {{YD}} (Reviewed by Serge Korjian)
|ExamType=USMLE Step 1
|MainCategory=Pharmacology
|SubCategory=Endocrine
|MainCategory=Pharmacology
|SubCategory=Endocrine
|MainCategory=Pharmacology
|SubCategory=Endocrine
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|SubCategory=Endocrine
|MainCategory=Pharmacology
|SubCategory=Endocrine
|MainCategory=Pharmacology
|SubCategory=Endocrine
|MainCategory=Pharmacology
|SubCategory=Endocrine
|MainCategory=Pharmacology
|MainCategory=Pharmacology
|SubCategory=Endocrine
|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?
|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.

|AnswerA=Pioglitazone
|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.
|AnswerB=Pramlintide
|AnswerBExp=[[Pramlintide]] is an amylin analog that decreases glucagon. It is not contraindicated in renal failure.
|AnswerC=Metformin
|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.
|AnswerD=Exenatide
|AnswerDExp=[[Exenatide]] is a GLP-1 analog that increases insulin and decreases the release of [[glucagon]]. It is associated with GI distress and [[pancreatitis]].
|AnswerE=Glimepiride
|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]].
|EducationalObjectives=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.
|RightAnswer=C
|WBRKeyword=Metformin, Diabetes mellitus, Contraindication, Renal failure, Chronic kidney disease, Oral antidiabetic,  Oral antidiabetic therapy
|Approved=Yes
}}