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PharmD clinical pharmacy program Level 3, Semester 2 Biopharmaceutics & Pharmacokinetics (PT608(

CHAPTER SUMMARY

I- Sites of drug administration
Intravascular routes- Extravascular routes
II- Membranes and mechanism of drug transport
i)- Mechanisms of drug absorption
1. Passive diffusion
2. Carrier-Mediated Transport
3. Vesicular Transport
4. Pore (Convective) Transport
5. Ion-Pair Formation
ii). Gastrointestinal physiological factors affecting drug absorption
pH , hepatic metabolism, gastric emptying, intestinal motility and transit time, drug stability in

GIT, effect of Food on Drug Absorption from GIT
III. Physicochemical and dosage form factors affecting drug absorptions
i). Physicochemical Factors of Drug Affecting Absorption
1. Factors affecting the dissolution rate
(A). Solubility and dissolution
(B). Physiological factors affecting dissolution rate
(C). Drug factors affecting dissolution rate

 Surface area and particle size
 Crystal form (polymorphism, solvates, amorphous solids)
 Solubility in the diffusion layer,
 Salt formation

(D) Poorly Soluble Drugs
2. Factors affecting the concentration of drug in solution in the DI fluids
(A) Complexation
(B) Adsorption
(C) Micellar Solubilization
(D) Chemical stability of the drug in the GI fluids
3. Factors affecting the passage of drug through GI membranes
(A) Drug dissociation and lipid solubility
(B) Influence of the type of dosage form

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