Dosing Weights

Different weights should be used for drugs dosed on a mg/kg basis depending on the physicochemical properties of the drug, as noted in the table below. For patients with extreme obesity or who are significantly underweight, or if toxicity is suspected, consult ID Pharmacy for dosing assistance.

Ideal and adjusted body weight calculator.

Drug Name Adjustment in Obesity
Acyclovir IV
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
AmBisome (liposomal amphotericin B)
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
Amikacin
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
Cidofovir
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
Colistin IV
Ideal Body Weight when patient weight >120% of ideal body weight
Daptomycin
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
Flucytosine
Ideal Body Weight when patient weight >120% of ideal body weight
Foscarnet
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
Ganciclovir
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
Gentamicin
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
Pentamidine IV
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
Plazomicin
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
Polymyxin B
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
TMP/SMX (trimethoprim/sulfamethoxazole)
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
Tobramycin
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight
Voriconazole
Use total body weight, except if total body weight is >120% of ideal body weight, then use adjusted body weight