Pharmacology TB Drugs #7

Question

The nurse will provide teaching on side effects of rifampin, isoniazid, and ethambutol to a patient with tuberculosis. These medications will have which adverse reactions? Select all that apply.

Answers

  1. Isoniazid may cause dark urine and yellowing of the skin.
    • Rationale:

      This answer is correct because isoniazid may cause yellowing of the skin or darkened urine since 10-20% of persons taking the drug will develop elevated liver function values. Liver function should be monitored through assessment and periodic monitoring of liver function blood tests.

  2. Ethambutol causes contact lenses to be stained orange.
    • Rationale:

      This answer is not correct because rifampin, not ethambutol, can cause orangey-red body fluids, including tears. The patient should be educated about this side effect of rifampin.

  3. Rifampin causes contact lenses to become stained orange.
    • Rationale:

      This answer is correct because rifampin can cause orangey-red body fluids, including tears. The patient should be educated about this side effect of rifampin and encouraged to wear glasses during treatment to keep contact lenses from being discolored.

  4. Ethambutol may cause visual disturbances.
    • Rationale:

      This answer is correct because ethambutol has the risk of ocular toxicity and the patient should be educated about the risk of this. Ethambutol may also cause optic neuritis including symptoms of blurred vision, spots in the field of vision, or red/green color blindness. Therefore, any visual disturbance or changes should be reported immediately.

  5. Potential for birth defects or miscarriage of fetus.
    • Rationale:

      This answer is correct because these drugs are a pregnancy category risk C. Studies have shown miscarriages and birth defects in animal reproduction that prove harmful to the fetus.

Overview

Isoniazid, rifampin, and ethambutol are medications used to treat tuberculosis. Each medication has specific, common adverse side effects which the patient should be informed about before taking.

Explanation

Drugs used to treat tuberculosis include isoniazid, rifampin, and ethambutol. Each has specific adverse effects that should be shared with all clients. Isoniazid may cause yellowing of the skin or darkened urine since 10-20% of persons taking the drug will develop elevated liver function values. Ethambutol may cause optic neuritis including symptoms of blurred vision, spots in field of vision, or red/green color blindness. Rifampin may cause excretion of orange color in body fluids including tears, which may cause contact lenses to be orange-stained. Ethambutol does not cause contact lenses to stain orange (selection B is therefore incorrect).

Learning Outcomes

Drugs used to treat tuberculosis include isoniazid, rifampin, and ethambutol. Each has specific adverse effects that should be shared with all patients. Isoniazid may cause yellowing of the skin or darkened urine since 10-20% of persons taking the drug will develop elevated liver function values. Ethambutol has the risk of ocular toxicity and the patient should be educated about the risk of this. Ethambutol may cause optic neuritis including symptoms of blurred vision, spots in the field of vision, or red/green color blindness. Rifampin may cause excretion of orange color in body fluids including tears, which may cause contact lenses to be orange-stained.

Test Taking Tip

The medications used to treat serious conditions generally have serious side effects, such as ototoxicity, nephrotoxicity, hepatotoxicity, etc. The patient should be carefully assessed and appropriate blood tests monitored.

Video Rationale