Cephalosporins & Penicillins Renal Dosing by Creatinine Clearance

This chart covers renal dose adjustment for the 12 cephalosporins & penicillins in this registry: Amoxicillin, Amoxicillin-Clavulanate, Ampicillin, Aztreonam, Cefazolin, Cefepime, Ceftazidime, Ceftriaxone, Cefuroxime, Cephalexin, Penicillin G and Piperacillin-Tazobactam. Of these, 11 are dosed by creatinine clearance from Cockcroft-Gault; and 1 has no CrCl dose band (Ceftriaxone). Each drug links to its own page with the full threshold, cautions, and an FDA-label reference.

Reviewed and approved by Dr. Rishi Kumar Kafle, MBBS, MD, FASN. Always confirm against the label.

Cephalosporins & Penicillins: renal dosing chart

Cutoffs That Change Cephalosporins & Penicillins Doses

The rules above name 5 creatinine clearance cutoffs, from 60 down to 10 mL/min. Each line lists the drugs whose rule changes at that value:

• 60 mL/min: Cefepime
• 50 mL/min: Cefazolin and Ceftazidime
• 40 mL/min: Piperacillin-Tazobactam
• 30 mL/min: Amoxicillin-Clavulanate and Aztreonam
• 10 mL/min: Amoxicillin, Amoxicillin-Clavulanate, Ampicillin, Aztreonam, Cefazolin, Cefuroxime, Cephalexin and Penicillin G

Rules without a numeric renal-function cutoff: Ceftriaxone. Read their full rule in the chart and on each drug page. A cutoff that sits between two bands still needs the label wording, because some labels use "less than" and others "at or below" the value.

Worked Example: Cephalosporins & Penicillins at a CrCl of About 49 mL/min

A 70-year-old man weighing 70 kg with a serum creatinine of 1.4 mg/dL has a Cockcroft-Gault creatinine clearance of about 49 mL/min. The rules to check first are those with a numbered step above that value: Cefazolin (50 mL/min), Cefepime (60 mL/min) and Ceftazidime (50 mL/min). The numbered steps of Amoxicillin (10 mL/min), Amoxicillin-Clavulanate (30 mL/min), Ampicillin (10 mL/min), Aztreonam (30 mL/min), Cefuroxime (10 mL/min), Cephalexin (10 mL/min), Penicillin G (10 mL/min) and Piperacillin-Tazobactam (40 mL/min) sit lower, so they matter as clearance falls further.

How the Cephalosporins & Penicillins Cutoffs Compare With the Standard Bands

Many renally cleared drugs follow four broad creatinine clearance bands: above 50, 30-50, 15-30, and below 15 mL/min. Of the 5 CrCl cutoffs named in this class, 2 sit on a standard band edge (50 and 30 mL/min) and 3 do not (60, 40 and 10 mL/min), so the generic bands are only a rough guide for cephalosporins & penicillins. Where a drug's own cutoff and the generic band disagree, the drug's cutoff takes precedence.

Avoidance, Dialysis and Monitoring Notes

• Avoid or contraindicated: Amoxicillin-Clavulanate (<30 -> avoid 875/XR; avoid <30 (875 mg)).
• Dialysis: no cephalosporins & penicillins rule here mentions dialysis, so take dialysis dosing from each label.
• Levels and monitoring: none of these rules is level-guided; monitor renal function and clinical response.

Which Renal Estimate the Labels Use for Cephalosporins & Penicillins

Apply these thresholds to Cockcroft-Gault creatinine clearance in mL/min from the creatinine clearance calculator, because the labels were written against that estimate. eGFR in mL/min/1.73m² is a different quantity; see CrCl vs eGFR.

Where These Thresholds Come From

The 12 rules for cephalosporins & penicillins were compiled from FPnotebook (6 drugs), standard clinical pharmacology references (2 drugs), the FDA label (2 drugs), the UNMC renal dosing guide (2 drugs) and the Pharmacy Times renal dosing reference (1 drug). Each threshold should still be confirmed against the current label before prescribing. Every value has been reviewed by a clinician, and each drug page links its label through DailyMed.

How Reduced Kidney Function Affects Cephalosporins & Penicillins

Renal impairment slows the elimination of cephalosporins & penicillins and of any active metabolites the kidney clears. It also shifts the balance of benefit and harm, so dose-related adverse effects become more likely at the same nominal dose. The chart above gives the key caution for each agent. When one agent must be avoided below a cutoff, another in the class may be safer, so weigh the indication, the patient's trajectory, and monitoring availability. Record the estimate, the equation, the weight, and the date behind each dose, and re-estimate once a changing creatinine settles.

Calculate the Patient's CrCl First

Estimate creatinine clearance with the Cockcroft-Gault equation and the right dosing weight. Use actual body weight when it is below ideal body weight, ideal body weight up to 130% of ideal, and adjusted body weight above 130% of ideal, as in obesity. Re-estimate whenever kidney function may have changed, since acute illness and dehydration can lower clearance within days.

Related classes: Carbapenems renal dosing (the other beta-lactam class on this site); Fluoroquinolones renal dosing (other renally dosed antibiotics).