According to the present regulations, acetaminophen
is a BCS class III API, although possessing
properties borderline to BCS Class I. Other
workers also classified acetaminophen as BCS
Class III.89 The classification of Kasim et al.21 as
BCS Class IV is probably due to use of incorrect
solubility data.
Both of the current BCS Guidances allow the
possibility for a biowaiver exclusively for BCS
class I drugs.86,87 The permeability of acetaminophen,
just below the critical value of 90% absorbed,
formally excludes it from the present biowaiver
criteria. However, extensions of the present
requirements to BCS Class III APIs have received
increasing attention