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Dosing weight — IBW / ABW / LBW
Pick the right dosing weight per drug. IBW (Devine) for non-depolarizing NMBs. LBW (Janmahasatian) for propofol induction + lipophilic drugs in obese patients. ABW for aminoglycosides + initial heparin. Total body weight (TBW) for sux + vanc + propofol maintenance.
IBW
65.9 kg
Devine — non-depolarizing NMBs
ABW
71.6 kg
Aminoglycosides, initial heparin
LBW
58.6 kg
Propofol induction, lipophilic drugs
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- IBW (M) = 50 + 2.3 × (66.9 in − 60) = 65.9 kg
- ABW = IBW + 0.4 × (TBW − IBW) = 65.9 + 0.4 × (80 − 65.9) = 71.6 kg
- BMI = 27.7 kg/m²
- LBW (Janmahasatian, M) = (9270 × 80) / (6680 + 216 × 27.7) = 58.6 kg
Quick dosing-weight reference
| Drug | Use which weight |
|---|---|
| Succinylcholine | TBW |
| Rocuronium / vecuronium / cisatracurium | IBW |
| Propofol — induction | LBW |
| Propofol — maintenance infusion | TBW |
| Fentanyl / opioids (obese) | LBW |
| Aminoglycosides (gent, tobra) | ABW |
| Vancomycin | TBW |
| Heparin (initial bolus) | ABW |
| Acetaminophen | TBW (cap 75 mg/kg/day or 4 g) |
Clinical note: Devine IBW formula (1974) anchors most clinical practice. Janmahasatian LBW is more accurate than older Hume / James formulas in obesity and is now preferred for propofol + lipophilic dosing per modern pharmacokinetic modeling. ABW = IBW + 0.4 × (TBW − IBW). Education only.