pharmacutcal factors of drug absorbtion

1. RMACUTICAL FACTORS OF DRUG ABSORBTION.
Presented by y.d.n.satish
Reg no 121825101004
Mpharm 2 semester pharmacutics

2. .INTRODUCTION OF ABSORBTION
.TRANSPORT PROCESS
.FACTORS AFFECTING DRUG ABSORBTION
1.Physiological factors
2. physiochemical factors
3.pharmaceutical factors

3. ABSORBTION
.Defnition;the process of movement of unchanged drug from the
site of adminstration to systemic circulation.

4. CELL MEMBRANE
1.lipid layer
- phospholipid
- cholestrol
- glycolipids

5. 2.proteins
. Integral membrane protein
.lipid ancored proteins
.peripheral proteins

6. TRANSPORT PROCESS
.passive diffusion
.pore transport
.facilitated diffusion
.active transport
.pinocytosis

7. 1.PHYSIOLOGICAL FACTORS.
.age
.gastric emptying
.intestinal transist
.gastro intestinal pH
.diseased state
.gastro intestinal contents ..pre systamic metabolism

8. AGE; in childrens and infants gastric ph is high and intensional surface and
flow is low.
When in adults altered in gastric emptying,decrease intestinal surface
area;decrease gastric blood flow.in drug absorbtion

9. Gastric emptying.
.gastric emptying is the passage of drug from stomach to smaall intestine.
.gastric emptying is dealyed when co-adminstred with food.
.factors that influence g.e are valume of meal,composition of meal,temperature of
meal,body posture,exercise ,diseases state etc

10. Intestinal transist time.
Since intestine is the major site of absorbtion of most of drugs long intestinal
transit time is desirable for the complete absorbtion of drugs.
.dealyed intestinal transit is desirable for
-drugs that dissolve only in intestine (entric coated)
-drugs absorbed from specefic sites in the intestine.

11. Gastro intestinal pH;
A difference in ph is observed between gastric and colon fluids.the gi ph increases
gradually from the stomach to the colon and rectum.
The ph of gi fluids influence the drug absorbtion in sevral ways.
-dissolution
-stabity

12. DISEASE STATE
.gi disease;infection such as achlorhydria,malaabsorbtion and sugeries such as
gastrectonomy effect the absorbtion of drugs to grater extent.
.disorders such as hepatic cirrhosis influence the bioavalibility mainly of drugs that
undergoes considerable first pass hepatic metabolism e.g propranolol

13. PRESYSTAMIC METABOLISM;
The main reason for disease in bioavalibility of the drug are decresed absorbtion
or first pass metabolism
.various enzyme that effect presystamic metabolism of drugs’
-Gutwall enzyme’
-hepatic enzyme
-bacterial enzyme

14. 2.physiochemical factors;
Drug solubity and dissolution rate
Particle size
Polymorphism and amorphism
Psudopolymorphism
Salt form of drug
Pka of drug

15. Particle size
.the absorbtion of the drug can be increased by increasing the particle surface
area by micronization...
Smaller
the drug
particle
Greater the
surface area

16. Polymorphism and amorphism;
.when substance exists in defferent crystaliine
forms it is polymorphism..

17. AMORPHISIM.
.they have greater aques solubility than the crytaline forms
because the energy required to transfer a molecule from
crystaline lattice is greater than required for the non crystalline
soild.
E.g novabacin
.the order of dissolution hence absorbtion for different soild
dosage forms is
amorphous>meta-stable>stable..

18. PH PARTION HYPOTHESIS;
UNIONIZED DRUG
HIGH ABSORBTION
IONISED DRUG
LOW ABSORBTION

19. SALTS FORMATION OF A DRUG.
.salt of weak acid and weak bases have much higher aqueos
solubility than free acid or base.
.therefore if a drug can be given as a salt ,the solubity can be
increased the dissolution can be improved.

20. 3.pharmacutical factors.
Manufacturing variables
-method of granulation
-compression force
Nature and type of dosage form
Pharmacutical ingriedent and exipients
Storage conditions...

21. Manufacturing variables;
1.method of granulation; the method of dry granulation can
be used to produce tablets that dissolve at faster rate .
2.compression force;influence the hardness
density,porosity,disintegration dissolution of tablet.

22. Nature and type of dosage forms;
.bioavalibility of a drug from various dosage forms in the
following order
.solution >emulsion >suspension >capsules>tablets>coated
tablets>entric coated tablets>sustained release tablets

24. Pharmacutical excipients.
.product storage conditions.

25. Refrences.
TESTBOOK OF BIOPHARMACEUTICS AND
PHARMACOKINETICS ,BY D.M.BRAHMANKAR PG NO5-97