From the Guidelines
Amoxicillin does not typically increase blood urea nitrogen (BUN) and serum creatinine levels in most patients with normal kidney function, but it can cause acute interstitial nephritis in rare cases, particularly in those with pre-existing kidney disease or older adults. According to the study published in the International Journal of Oral Science 1, patients on hemodialysis are prone to several types of infection due to their immunocompromised status, and amoxicillin is often used as an antibiotic prophylaxis. However, the study also notes that nephrotoxic drugs should be avoided entirely, and the choice of antibiotics and dose adjustments should be made based on comments from the patient’s nephrologist before the implant surgery to decrease the side effects from chronic kidney disease (CKD).
The mechanism behind amoxicillin-induced nephritis involves an immune-mediated hypersensitivity reaction that causes inflammation in the kidney's interstitial tissue, temporarily impairing kidney function. Symptoms of this reaction may include fever, rash, decreased urine output, and general malaise. If you notice these symptoms while taking amoxicillin, you should contact your healthcare provider immediately. For patients with known kidney impairment, amoxicillin dosing may need to be adjusted, as the medication is primarily eliminated through the kidneys. Regular monitoring of kidney function may be recommended for high-risk patients on prolonged amoxicillin therapy.
In contrast, other studies have shown that certain medications, such as amphotericin B, cidofovir, and foscarnet, have known nephrotoxic potential and should be administered under close supervision 1. The dosing of these medications should be adjusted based on the patient's creatinine clearance and kidney function. However, amoxicillin is not typically considered a nephrotoxic medication, and its use is generally safe in patients with normal kidney function.
Key points to consider:
- Amoxicillin can cause acute interstitial nephritis in rare cases, particularly in those with pre-existing kidney disease or older adults
- Nephrotoxic drugs should be avoided entirely in patients with CKD
- The choice of antibiotics and dose adjustments should be made based on comments from the patient’s nephrologist before the implant surgery
- Regular monitoring of kidney function may be recommended for high-risk patients on prolonged amoxicillin therapy
- Amoxicillin is primarily eliminated through the kidneys, and dosing may need to be adjusted in patients with known kidney impairment.
From the FDA Drug Label
High blood levels may occur more readily in patients with impaired renal function because of decreased renal clearance of amoxicillin The FDA drug label does not answer the question.
From the Research
Amoxicillin and Kidney Function
- Amoxicillin is an antibiotic that can potentially affect kidney function, particularly in patients with preexisting renal insufficiency 2.
- Prolonged use of certain antibiotics, including amoxicillin, may require periodic checks of electrolytes, creatinine, and blood urea nitrogen levels 2.
Blood Urea Nitrogen and Serum Creatinine
- Blood urea nitrogen and serum creatinine are commonly used markers of kidney function, but they can be influenced by many renal and nonrenal factors independent of kidney function 3, 4, 5.
- Elevations in blood urea nitrogen and/or serum creatinine do not necessarily indicate structural renal disease, and normal values do not rule out significant reduction in glomerular filtration rate 4.
- The blood urea nitrogen to serum creatinine ratio can be a valuable tool in determining renal functional and structural integrity 4.
Monitoring Kidney Function
- Monitoring kidney function is essential, especially in patients at high risk for kidney toxicity, such as the elderly and those with preexisting renal insufficiency 2, 5.
- Newer biomarkers, such as urine albumin and urine protein, may permit earlier and more accurate identification of acute kidney injury 3, 6.
- A combined use of functional and damage markers may advance the field of biomarkers of drug-induced kidney toxicity 3.
Amoxicillin-Specific Effects
- There is no direct evidence in the provided studies that amoxicillin increases blood urea nitrogen and serum creatinine levels.
- However, it is recommended to monitor kidney function periodically in patients taking amoxicillin, especially those with preexisting renal insufficiency 2.