A 50 year old female with end stage renal disease (ESRD), develops pulmonary tuberculosis. Which one of the following drugs should be used in a reduced dose?
**Core Concept:** In patients with end-stage renal disease (ESRD), drug dosing must be adjusted due to altered pharmacokinetics. Renal failure affects the elimination of medications through urine, leading to higher drug concentrations and potential toxicity.
**Why the Correct Answer is Right:** The correct answer, option D (Rifampicin), is used in the treatment of pulmonary tuberculosis. In patients with ESRD, rifampicin is highly protein-bound resulting in increased toxic effects and reduced clearance. Additionally, rifampicin induces renal function, leading to further decreased drug clearance and increased toxicity risk.
**Why Each Wrong Option is Incorrect:**
A. Ethambutol (Option A) is not dosed based on renal function in patients with ESRD, as it is primarily eliminated through the liver and not the kidneys.
B. Isoniazid (Option B) is dosed based on weight rather than renal function in patients with ESRD. While isoniazid can cause hepatotoxicity, the question specifically asks for a drug to be used in a reduced dose based on renal function.
C. Pyrazinamide (Option C) is not dosed based on renal function in patients with ESRD, as it is primarily eliminated through the liver and not the kidneys.
**Clinical Pearl:** When treating tuberculosis in patients with ESRD, consider alternative regimens such as the modified MDR-TB regimen, which does not include rifampicin, to minimize the risk of toxicity.
**Correct Answer:** D. Rifampicin should be used in a reduced dose in patients with ESRD due to altered pharmacokinetics and increased toxicity risk.