Bioequivalence and Bioavailability Forum

Hi Sridhar.e,

❝ can any one explain difference between Linear and Non-linear pharmacokinetics.

In practice: If Cmax or AUC or Clearance scales linear with the ingested dose, then kinetics is linear. For example, if the Cmax is 50 ng/mL at a dose of 100 mg, and it is 100 ng/mL at a dose of 200 mg, then it would seem linear at least in that interval.
This mainly has bearings on the dose you might need to apply in your BE trial if you wish to apply for waivers of some strengths. The design used for a linear drug is not necessarily different from the design used for a non-linear drug.

If the drug displays a more-than-proportional trace of Cmax (or AUC or CL) versus dose, then a dose at the upper end may be more discriminative. And vice versa.

Don't get bogged down by the discussion of terminology; linearity vs proportionality. I believe it is not particularly difficult to find people who happily spend hours on it. Just let them.

Finding out if a drug is linear is sometimes tricky. Often such ADME behaviour can be looked up on SPC's or prescr. info but if you need to study the phenomenon yourself then this is a pretty troublesome affair.