No Observed Adverse Effect Level [NOAEL]

The no observed adverse effect level (NOAEL) is the highest tested dose of a medicine at which there is no increase in the frequency of any adverse effects (biological or statistically significant) when compared to its control.

Although the NOAEL approach involves some consideration of pharmacokinetics and pharmacodynamics properties, its focus is on the estimation of the highest ‘safe’ dose, looking for a safety window based on toxicological threshold.