A nurse is assessing a client who is receiving gemfibrozil. The nurse should identify which of the following findings as an adverse effect of this medication?

The correct answer is B: Muscle tenderness. Gemfibrozil is known to cause myopathy, which presents as muscle tenderness, weakness, or pain. This adverse effect is important to monitor because it can progress to rhabdomyolysis, a severe condition characterized by muscle breakdown. Dependent edema (choice A) is not a common adverse effect of gemfibrozil. Tremors (choice C) are not typically associated with this medication. Hyperkalemia (choice D) is also not a common side effect of gemfibrozil. It is important for the nurse to monitor for muscle tenderness and weakness in clients taking gemfibrozil to prevent serious complications.