Aminoglycosides Renal Dosing by Creatinine Clearance

This chart covers renal dose adjustment for the 4 aminoglycosides in this registry: Amikacin, Gentamicin, Plazomicin and Tobramycin. Of these, all 4 are dosed by creatinine clearance from the Cockcroft-Gault equation, in mL/min. 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.

Aminoglycosides: renal dosing chart

Cutoffs That Change Aminoglycosides Doses

The rules above name 2 creatinine clearance cutoffs, from 90 down to 15 mL/min. Each line lists the drugs whose rule changes at that value:

• 90 mL/min: Plazomicin
• 15 mL/min: Plazomicin

Rules without a numeric renal-function cutoff: Amikacin, Gentamicin and Tobramycin. 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: Aminoglycosides 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: Plazomicin (90 mL/min). Amikacin, Gentamicin and Tobramycin name a reduction that is not tied to a single CrCl cutoff, so read the full rule at any clearance.

How the Aminoglycosides 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 2 CrCl cutoffs named in this class, 1 sits on a standard band edge (15 mL/min) and 1 does not (90 mL/min), so the generic bands are only a rough guide for aminoglycosides. 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: no aminoglycosides rule in this registry names an avoidance limit.
• Dialysis: no aminoglycosides rule here mentions dialysis, so take dialysis dosing from each label.
• Levels and monitoring: Amikacin (level-guided); Gentamicin (trough-guided); Plazomicin (TDM); Tobramycin (level-guided).
• Shared cautions: nephro/ototoxicity (Amikacin, Gentamicin and Tobramycin).

Which Renal Estimate the Labels Use for Aminoglycosides

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 4 rules for aminoglycosides were compiled from the UNMC renal dosing guide (3 drugs) and the FDA label (1 drug). Thresholds cross-checked against the FDA label or a guideline source: Gentamicin. Every value has been reviewed by a clinician, and each drug page links its label through DailyMed.

How Reduced Kidney Function Affects Aminoglycosides

Renal impairment slows the elimination of aminoglycosides 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: Other Antimicrobials renal dosing (includes vancomycin, also dosed with drug-level monitoring); Carbapenems renal dosing (other renally dosed antibiotics).