This presentation comes under subject Biopharmaceutics and Pharmacokinetic under B. Pharm Program

1. BIOPHARMACEUTICS &
PHARMACOKINETICS

2. Biopharmaceutical Consideration in
Dosage form Design

3. FACTORS AFFECTING GI ABSORPTION OF
DRUG FROM ITS DOSAGE FORM
Dept. of Pharamceutics, KCP, CBE - 32

4. DRUG SOLUBILITY & DISSOLUTION RATE
Dept. of Pharamceutics, KCP, CBE - 32 Physicochemical Properties of Drug Substances

5. DRUG SOLUBILITY & DISSOLUTION RATE
Dept. of Pharamceutics, KCP, CBE - 32 Physicochemical Properties of Drug Substances

6. THEORIES OF DRUG DISSOLUTION

7. 1. Solution of the solid to form a thin film or layer at the solid / liquid
interface called Stagnant film or diffusion layer which is saturated with
the drug; this step is usually rapid
2. Diffusion of the soluble solute from the stagnant layer to the bulk of the
solution; this step is slower and is therefore the rate determining step in
drug dissolution
Diffusion layer model / Film Theory
THEORIES OF DRUG DISSOLUTION
This is the simplest and most common theory of dissolution.
Here the process of dissolution of solid particles in a liquid, in t
he absence of reactive or chemical forces, consecutive two steps

8. Diffusion layer model / Film Theory
THEORIES OF DRUG DISSOLUTION

10. Non sink conditions :-
Modified noyes-whitney’s equation represents the first order dissolution process,
the driving force which the concentration gradient (Cs- Cb), and this condition is
said as non sink condition , done only for in-vitro
Sink conditions :-
The in-vivo dissolution is always rapid than in-vitro dissolution because the
moment the drugs dissolves , it is absorbed in the systemic circulation , as a
jresult Cb= 0 and the dissolution is at maximum.

11. HIXON-CROWELL CUBE ROOT RELATIONSHIP
Dept. of Pharamceutics, KCP, CBE - 32

12. DANCKWERT’S MODEL/PENETRATION OR
SURFACE RENEWAL THEORY
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13. DANCKWERT’S MODEL/PENETRATION OR
SURFACE RENEWAL THEORY
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14. INTERFACIAL BARRIER MODEL
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15. PARTICLE SIZE & SURFACE AREA
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16. PARTICLE SIZE & SURFACE AREA
Dept. of Pharamceutics, KCP, CBE - 32

17. Three Reasons has been suggested for such an outcome
The hydrophobic surface of the drugs adsorbs air on to th
eir
surface which inhibits their wettability
PARTICLE SIZE & SURFACE AREA
The particles reaggregates to form large particles
due to their high
surface free energy, which either float on the sur
face or settle on the
bottom of the dissolution medium.
Electrically induced agglomeration owing to surf
ace charges prevents intimate contact of the dru
g with the dissolution medium
Dept. of Pharamceutics, KCP, CBE - 32

18. 01 02
Use of surfactant as a wetting age
nt which
- decrease the interfacial tentio
n.
- displace the absorbed air with
the solvent.
Ex… Tween 80 on Phenacetin
PARTICLE SIZE & SURFACE AREA
 The absolute surface area of the hydrophobic drugs can be converted to their effectiv
e surface area by
Add hydrophilic diluents like P
EG, PVP,
dextrose etc. which coat the sur
face of
hydrophobic drug particles.
01 02
Molecular dispersion /Solid sol
ution where
the sparingly soluble drug is m
olecularly
trapped in the lattice of a hydro
philic agent such as Cyclodextri
ns
 In addition to increasing the dissolution rate, the second mechanism by which a redu
ction in particle
size improves drug dissolution is through an increase in its solubility
Solid dispersion where such a d
rug is
dispersed in a soluble carrier s
uch as PVP,
PEG, Urea etc.,
Dept. of Pharamceutics, KCP, CBE - 32

19. POLYMORPHISM & AMORPHISM
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20. POLYMORPHISM & AMORPHISM
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21. POLYMORPHISM & AMORPHISM
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22. PSEUDOPLOYMORPHISM
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23. SALT FORM OF DRUG
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24. SALT FORM OF DRUG
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Dissolution and absorption of an acidic drug administered in a salt form

25. SALT FORM OF DRUG
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26. pH-PARTION HYPOTHESIS
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27. pH-PARTION HYPOTHESIS - Drug pKa and GI pH
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28. pH-PARTION HYPOTHESIS - Drug pKa and GI pH
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29. LIMITATIONS OF pH-PARTION HYPOTHESIS
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30. DRUG STABILITY
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31. Thank you