WEBFor example, for a newly developed drug molecule, the NOAEL value in rat weighing approximately 150 g is 18 mg/kg. To calculate the starting dose for human studies, use Equation 1. HED (mg / kg = 18 × (0.15 / 60) (0.33) = 2.5 mg / kg. Thus, for a 60 kg human, the dose is 150 mg.