1. DRUG
ABSORPTION
Prepared By:
Abhishek Mishra
Chemical Technology(III-year)
Pharmaceutical Technology

2. Outline
 Pharmacokinetics.
 Determinants of Drug activity.
 What is Drug Absorption ??
& its Mechanism..!!!
 Factor affecting Drug Absorption.
 Fick’s Law of Diffusion

3. Pharmacokinetics
Absorption
Distribution
Metabolism(Bio-transformation)
Excretion

4. Determinants of Drug Activity

6. Drug Absorption
 The translocation(transfer) of drug
from the site of administration into
the blood-stream
 Must be described BOTH in terms
of rate and extent

7. Mechanisms of Drug Absorption
 All drug absorption requires crossing of bio
membranes
 Passive non-ionic diffusion
 Facilitated diffusion or carrier-mediated
transport
 Active transport
 Pinocytosis, endocytosis, phagocytosis

9. Factors Determining the Rate and
Extent of Drug Absorption
 Physicochemical properties of the drug
– Stereo chemical properties
– Solubility
 Molecular size
 Dosage form and delivery system
 Vehicles
 Dose

10. Cont’d
 Route and site of administration
 Contact time with absorptive surface
 pH at site of absorption
 Integrity of the membrane
 Vascularization and blood flow at
absorptive site

11. Fick’s Law of Diffusion
Rate
of
Penetration
Partition
Coefficient
Membrane
Thickness
Diffusion
Coefficient[ [] ]x
[ ]
= x Surface
Area[ ] Concen-
tration
Gradient
[ ]x
Solutions> Emulsions> Suspensions> Capsules>
Tablets> Coated Tablets> Enteric Coated Tablet>
Sustain Release Tablet
Order of Drug Absorption