From the Guidelines
Rifampicin (RIF) does not require dose adjustment in patients with impaired renal function.
Reasons for this decision
- RIF is metabolized by the liver, so conventional dosing may be used in the setting of renal insufficiency 1.
- RIF is not cleared by hemodialysis because of its high molecular weight, wide distribution into tissues, high degree of protein binding, and rapid hepatic metabolism 1.
- Other drugs such as INH, PZA, and EMB may require dose adjustment or have their metabolites accumulate in patients with renal insufficiency 1.
- Ethionamide is also not cleared by the kidneys, nor is the drug removed with hemodialysis, so no dose adjustment is necessary 1, but RIF is more commonly used and has more established guidelines.
Key points to consider
- Patients with renal insufficiency may require altered dosing of certain antituberculosis medications to avoid toxicity and ensure efficacy 1.
- The dosing interval should be increased instead of decreasing the dose to avoid low peak serum concentrations 1.
- Serum concentrations should be monitored in patients with renal insufficiency to avoid toxicity, especially when using drugs that are cleared by the kidneys 1.
From the Research
Anti-Tuberculosis Drugs and Renal Function
The relationship between anti-tuberculosis (TB) drugs and renal function is crucial, especially in patients with impaired renal function.
- Studies have shown that some anti-TB drugs require dose adjustment in patients with impaired renal function 2.
- However, one study suggests that levofloxacin does not require dose adjustment, as its pharmacokinetics are not significantly affected by weight or renal function 3.
- Another study found that moxifloxacin also does not appear to be affected by weight, but higher doses may be needed to optimize its pharmacokinetic/pharmacodynamic target attainment 3.
Specific Anti-TB Drugs and Dose Adjustment
- Isoniazid, rifampin, pyrazinamide, and ethambutol are commonly used anti-TB drugs that may require dose adjustment in patients with impaired renal function 4, 2.
- However, levofloxacin and moxifloxacin may not require dose adjustment, making them potential options for patients with impaired renal function 3.
- It is essential to note that the dosage adjustment of anti-TB drugs should be based on individual patient factors, including renal function, weight, and other comorbidities 2.
Clinical Implications
- Patients with chronic kidney disease (CKD) are at increased risk of TB and may require dose adjustment of anti-TB drugs 5, 2.
- The use of therapeutic drug monitoring (TDM) can help optimize anti-TB drug dosing and minimize adverse events in patients with CKD 4, 5.
- Clinicians should be aware of the potential interactions between anti-TB drugs and other medications, as well as the need for dose adjustment in patients with impaired renal function 4, 2.