1. PRESENTED BY:- GUIDED BY:-
TARUN POKHARIYAL Mr. AJAY KUMAR TIWARI
M.PHARM.(1st SEM.) LECTURER
DEPT. OF pharmaceutics
JAIPUR NATIONAL UNIVERSITY
JAIPUR
DATE:-15 NOV.2011

2. (A). PHARMACEUTICAL FACTORS:-
I. PHSICOCHEMICAL PROPERTIES OF DRUG:-
1. DRUG SOLUBILITY AND DISSOLUTION RATE
Solid disintegration dissolution Drug in permeation Drug
Solid
dosag solution at across mem. in
drug
e form absorption the
particles
site body
Maximum absorbable dose (MAD) is
used to correlate drug absorption
MAD= Ka Sgi Vgi tr
Ka= intrinsic absorption rate constant
Sgi=solubility of drug in GI fluid
Vgi=volume of GI fluid present.
tr= residence of drug in GI

3. BIOPHARMACEUTICS CLASSIFICATION SYSTEM:-
CLASS I DRUG:- high solubility and high
permeability
eg. diltiazem
CLASS II DRUG:-low solubility and high permeability
eg.nifedipine.
CLASS III DRUG:-high solubility and low permeability
eg. Insulin.
CLASS IV DRUG:-low solubility and low permeability
eg. taxol

4. THEORIES OF DRUG DISSOLUTION:-
DISSOLUTION IS THE MASS TRANSFER FROM SOLID
SURFACE TO THE LIQUID PHASE.
Theories:-
1.Diffusion layer model/film theory
2.danckwerts’s model/penetration theory
3.Interfacial barrier model/limited solvation theory

5.  DIFFUSION LAYER MODEL/ FILM THEORY:-

6.  The rate of dissolution is given by Noyes
and Whitney:
dc
= k (Cs- Cb)
Where, dt
dc/dt= dissolution rate of the drug
K= dissolution rate constant
Cs= concentration of drug in stagnant layer
Cb= concentration of drug in the bulk of the
solution at time t

7. dC DAKw/o (Cs – Cb )
dt Vh
Where,
D= diffusion coefficient of drug.
A= surface area of dissolving solid.
Kw/o= water/oil partition coefficient of drug.
V= volume of dissolution medium.
h= thickness of stagnant layer.
(Cs – Cb )= conc. gradient for diffusion of drug.

8.  This is first order dissolution rate process,
for which the driving force is concentration
gradient.
 This is true for in-vitro dissolution which is
characterized by non-sink conditions.
 The in-vivo dissolution is rapid as sink
conditions are maintained by absorption of
drug in systemic circulation i.e. Cb=0 and
rate of dissolution is maximum.

9.  Under sink conditions, if the volume and
surface area of the solid are kept constant,
then
dC K
dt
This represents that the dissolution rate is
constant under sink conditions and follows zero
zero order dissolution
order kinetics. under sink condition
first order dissolution under
non-sink condition
Conc. of drug
Time

10. Danckwert’s model/Penetration or surface renewal
Theory :-
Dankwert takes into account the eddies or
packets that are present in the agitated fluid
which reach the solid
liquid interface, absorb the solute by diffusion
and carry it into the bulk of solution.
These packets get continuously replaced by new
ones and expose to new solid surface each time,
thus the theory is called as surface renewal
theory.

11. III. Interfacial barrier model/Double barrier or
Limited solvation theory :-
 The concept of this theory is explained by
following equation-
G = Ki (Cs - Cb)
Where,
G = dissolution rate per unit area,
Ki = effective interfacial transport constant.

12. 2. PARTICLE SIZE & EFFECTIVE SURFACE AREA OF
DRUG:-
TWO TYPES OF SURFACE AREA CAN BE DEFINED:-
1.ABSOLUTE SURFACE AREA
2.EFFECTIVE SURFACE AREA
3. POLYMORPHISM:-
enantiotropic polymorph:-which can be reversibly
change into another form by altering the temp.or
pressure.
Monotropic polymorph:-is the one which is unstable
at all temp. and pressure.

13.  Internal structure of a compound

Crystalline noncrystalline
Polymorph( Molecular
single adduct
molecule)
Stocheometric
enantiotropic Nonstochiometric
complexes
complexes
Organic
monotropic Hydrates
solvates

14.  5. drug pka and lipophilicity and gi Ph
(PH PARTITION HYPOTHESIS):-
This theory states for those drug compound of
molecular weight greater than 100 which primariliy
transported across the biomembrane by passive
diffusion.
Most drugs are weak electrolyte(weak acid or base)
If the pH of either side of membrane is different than
the compartment whose pH favours greater
ionisation of drug will contain greater amount of
drug and only unionised fraction of drug if
sufficiently lipid soluble can permeate the
membrane passively until the conc. Ofunionised
drug on either side of membrane become equal.

15.  6. DRUG STABILITY:-
 Degredation of drug into inactive form.
 Interaction with one or more different components
7. STERIOCHEMICAL NATURE OF THE DRUG:-
DOSAGE FORM(PHARMACOTECHNICAL)
FACTORS:-
1) DISINEGRATION TIME:-
2) DISSOLUTION TIME:-
3) MANUFACTURING VARIABLES:-
*excipients and manufacturing process*
EXCIPIENTS:-vehicle,
diluents(filler),
binder and granulating agents,
disintegrants,
lubricants,
surfactants,
viscosity imparters
,buffers,
complexing agents,
Colorants
Crystal growth inhibitors.

16. MANUFACTURING VARIABLES:-
*Method of granulation-wet granulation method is
most conventional technique but limited.
Most recent method is APOC(agglomerative phase of
communition)
*Compression force:-
*Intensity of packing of capsule contents-
4.NATURE AND TYPE OF DOSAGE FORM
5.PRODUCT AGE AND STORAGE CONDITION

17.  PATIENT RELATED FACTORS:-
1. AGE-
2. GASTRIC EMPTYING:-the passage from stomach
to small intastine.
Gastric emptying is first order process
 Gastric emptying rate:-is the speed at which the
stomach content empty into intestine.
 Gastric emptying time:-is the time required for
gastric content to empty into small intestine.
 Gastric emptying t1/2 is the time taken for half the
stomach content to empty.
FACTORS EFFECTING GASTRIC EMPTYING:-
 VOLUME OF MEAL
 COMPOSITION OF MEAL
 PHYSICAL STATE AND VISCOSITY OF MEAL
 TEMP. OF MEAL

18.  GI pH
 Electrolyte and osmotic pressure
 Body posture
 Emotional state
 Exercise
 Disease state
 Drug
3.INTESTINAL TRANSIT:-the passage of drug
through intestine called as intestinal transit.
4.GIT Ph:- it influence absorption in various
ways;-

19. a. Disintegration
b. Dissolution
c. Absorption
d. Stability
5.Disease state :-
a. GIT disease
b. Cardiovascular disease
c. Hepatic disease
6.BLOOD FLOW TO GIT:-

20. 7.GASTROINTESTINAL CONTENT:-
1. Food- drug interaction
2. Fluid volume
3. Interaction of drug with normal gi contents
4. Drug –drug interaction
8. PRESYSTEMIC METABOLISM:-
The loss of drug through biotransformation by such
eliminating organs during its passage to systemic
circulation is called first pass metabolism.
Three types of systems:-
1. Luminal enzyme (digestive and bacterial enzyme)
2. Gut wall enzyme
3. Hepatic enzyme