Once-daily or less frequent aminoglycoside dosing for empirical and directed therapy in adults

The aminoglycoside dosage in adults depends on the patient’s kidney function and the drug’s volume of distribution, which are related to body weight.

Aminoglycosides are hydrophilic drugs that are preferentially distributed into lean tissue, so lean body weight (LBW) is the most accurate weight descriptor for calculating aminoglycoside doses. A large study¹ recommended the use of LBW for dosing because it performed better than total body weight and ideal body weight in estimating gentamicin volume of distribution across all patients, including underweight patients and those with obesityPai 2011.

Calculated starting doses using other weight metrics can differ substantially, particularly at the higher end of the weight range; therefore, a conservative approach to dosing and prompt therapeutic drug monitoring may be preferred to avoid toxicity in these patients.

Expert advice is required for aminoglycoside dosing in adults with obesity with a body mass index (BMI) of 35 kg/m² or more.

Modified aminoglycoside dosages may be required for patients with altered pharmacokinetics.

Although the aminoglycoside dosage depends on the patient’s kidney function, if the patient is critically ill it is appropriate to administer one empirical dose without ascertaining kidney function. A single dose of aminoglycoside is generally safe, even in patients with impaired kidney function, and can be lifesaving; however, subsequent dosing requires careful consideration. In patients with a creatinine clearance of less than 20 mL/min who are not critically ill, consider an alternative antimicrobial. See Aminoglycoside use in patients with kidney impairment for more information.

If plasma concentration monitoring is indicated, see Once-daily or less frequent aminoglycoside dosing: plasma concentration monitoring for monitoring advice.