A nurse is assessing a client who has started taking theophylline. Which of the following client findings should indicate to the nurse that the medication is effective?

A. “You should take this medication once each day at bedtime.” This statement is incorrect because rifampin is typically taken on an empty stomach, either 1 hour before or 2 hours after a meal, to ensure optimal absorption. Taking it at bedtime is not a standard recommendation.
B. “You can continue to wear soft contact lenses while taking this medication.” This statement is incorrect because rifampin can cause discoloration of bodily fluids, including tears, which can stain soft contact lenses. Patients are usually advised to avoid wearing soft contact lenses during treatment.
C. “This medication will not interfere with the effectiveness of oral contraceptives.” This statement is incorrect because rifampin is known to reduce the effectiveness of oral contraceptives. Patients should be advised to use an alternative or additional form of contraception while taking rifampin.
D. “Your urine will turn orange while you are taking this medication.” This statement is correct. Rifampin commonly causes a harmless discoloration of urine, sweat, saliva, and tears to an orange or reddish color. Patients should be informed about this side effect to avoid unnecessary concern.

A. Gemfibrozil is a lipid-lowering agent and does not have a significant interaction with nitroglycerin. It is not contraindicated for use with nitroglycerin.
B. Lansoprazole is a proton pump inhibitor used to treat acid-related stomach issues. It does not interact with nitroglycerin and is safe to use concurrently.
C. Diazepam is a benzodiazepine used for anxiety and muscle spasms. While it can cause hypotension, it is not specifically contraindicated with nitroglycerin.
D. Sildenafil is a phosphodiesterase inhibitor used to treat erectile dysfunction. It is contraindicated with nitroglycerin because both medications cause vasodilation, which can lead to severe hypotension and cardiovascular collapse. Patients should not use these medications together.