A few drug classes have a narrow therapeutic range, making it necessary for clinicians to monitor drug ranges due to the risk of drug toxicity. Antibiotics are a commonly used drug class, and we will review a few drug classes and how their metabolism is affected in patients with CKD. Frequently, dialysis patients have poor vascular access options; therefore, dialysis nurses are asked to draw multiple labs to check for specific drug levels. It is crucial to understand when these drug levels may be drawn. Often, the clinicians requesting the labs are not nephrologists, and in such cases, dialysis nurses should be able to educate and properly communicate with non-dialysis specialized personnel. This section will focus on two common examples.
Aminoglycosides, e.g., Gentamicin (peak of 5-8 mg/L and a trough of 0.5-2 mg/L). The peak is usually drawn 30 min after a 30 -45 min infusion. The trough is generally drawn immediately prior to the dose. Both are drawn around the third dose.
Digoxin has a therapeutic dose range of 0.8-2.0 ng/mL, and the lab is usually checked 5-7 days after the first dose in patients with normal renal function and 15-20 days in anephric patients. The lab sample should be drawn 12 hours after the maintenance dose is administered in all patients.
Most drug dosing must be adjusted in patients with ESRD, and some drugs may be avoided altogether. In today’s healthcare climate laden with polypharmacy and over-prescription, nurses must understand which drugs place their patients at increased risk for experiencing toxic side effects. We will examine a few common drugs and review how the doses change depending on the GFR.
Acetaminophen can be administered at standard doses as often as every 4 hours in patients with a GFR > 50 mL/min. In patients with a GFR between 10-50 mL/min, the standard 4-hour doses should be administered at 6-hour intervals. And in patients with a GFR < 10mL/min, the standard dose should be administered at 8-hour intervals. Patients on hemodialysis and peritoneal dialysis should also receive their dose reduced to 8-hour intervals.
Acetazolamide is a carbonic anhydrase inhibitor commonly used as a diuretic or for the treatment of glaucoma. In patients with a GFR > 50 mL/min, the standard dose should be administered every 6 hours. If the GFR is between 10-50 mL/min, the dose should be prolonged to q12h, and if the GFR is less than 10 mL/min, the dose should be prolonged to q24h. In patients receiving hemodialysis and peritoneal dialysis, the dose should be administered q24h.
Acetylsalicylic acid (Aspirin) can be administered q4h in patients with a GFR > 50 mL/min. The dose should be prolonged to q4-6h in patients with a GFR between 10 - 50 mL/min. It should be avoided entirely in patients with a GFR < 10 mL/min. Patients on hemodialysis and peritoneal dialysis may receive standard doses as patients with a normal GFR because it is appropriately cleared during dialysis.
When administering Atenolol in patients with CKD, the dose must be decreased by 50% in patients with a GFR between 10 - 50 mL/min. In patients with a GFR < 10 mL/min, the dose should be decreased to 33% of the daily dose administered every 24 hours.
Cefazolin is typically administered q8h in patients with GFR > 50 mL/min. In patients with a GFR between 10 -50 mL/min, the dose should be prolonged to q12h. If the GFR is < 10mL/min, the dose should be halved and administered q24-48h. In hemodialysis patients, the dose should be weight-based at 15-20 mg/kg.
Digoxin dose should be decreased by 10 – 25% of the standard dose administered to patients with a normal GFR. And in patients with a GFR < 10 mL/min, the dose is decreased to 10-25%, and the timing is prolonged to q24-48h.
Rivaroxaban (Xarelto) and Triamterene should be avoided in patients with a GFR < 50 mL/min, including dialysis patients.