Absorption Window

Absorption Window refers to the specific region of the gastrointestinal tract where a drug is most efficiently absorbed into systemic circulation, determined by physicochemical properties, transporter expression, pH conditions, and transit time along the gut. Drugs must be released and dissolved within this window to achieve adequate oral bioavailability.

The pharmaceutical industry uses absorption window characterisation to guide controlled-release formulation design, ensuring drug release aligns temporally and spatially with the absorptive region. Drugs with narrow absorption windows confined to the upper intestine require rapid dissolution to prevent bypass. Gamma scintigraphy and pharmacokinetic modelling map absorption windows in clinical studies. As oral delivery of complex molecules advances, absorption window identification remains essential for optimising bioavailability and designing delivery systems that reliably achieve therapeutic exposure.