1. Patient Related
Factors
Affecting drug absorption
Presented by,Presented by,
Hinglajia HetalHinglajia Hetal
RatilalRatilal

2. Patient Related Factors

3. Age

4. Age
Infants
• Gastric pH high
• Intestinal surface low
• Blood flow to GIT low
Elderly persons
 Altered gastric emptying
 Decreased intestinal surface area
& GI blood flow
 Higher incidents of achlorhydria
 Bacterial overgrowth
Altered Absorption
pattern

5. GastricGastric
emptyingemptying

6. Gastric emptying
Apart from dissolution of a drug & its permeation through the
bio membrane, the passage from stomach to the small
intestine, called as gastric emptying.
Rate limiting step, because the major site of drug absorption is
intestine.
It increases bioavailability of a drug.
It is first order process.

7. Rapid gastric emptyingRapid gastric emptying
advisable where,advisable where,

8. Delay gastric emptying
advisable where,

9. Gastric acid
quantifying parameters
• Gastric emptying rate is the speed at which the
stomach contents empty into the intestine.
• Gastric emptying time is the time required for the
gastric content to empty into the small intestine.
• Longer the gastric emptying time , lesser the gastric emptying
rate.
• Gastric emptying t1/2 is the time taken for half the
stomach contents to empty.

10. Factors affecting on
gastric emptying

12. Intestinal transiIntestinal transit

13. Intestinal transitIntestinal transit
Small intestine- major site for drug absorption,
long intestinal transit is desirable for complete
drug absorption
The residence time depends on the intestine that
occurs due to peristaltic contractions..
It promotes drug absorption by,
Increasing drug intestinal membrane contact,
Enhancing dissolution especially poorly soluble
drugs, through induced agitation.

14.  Delayed intestinal
transit is desirable for,

15. Intestinal transitIntestinal transit
 Promotes..
 Diarrhea
 Laxatives
 Drugs like metoclopramide
 Demotes..
 Food
 Pregnancy
 Anticholinergics

16. GastrointestinalGastrointestinal
pHpH

17.  107
fold difference in the H+
ion
concentration is observed
between the gastric & colon fluids.

18. Blood Flow To
The GIT

19. The GIT is extensively supplied by blood capillary network & the
lymphatic system.
The blood flow rate to the GIT is 500 to 1000 times (28% of
cardiac output) more than the lymph flow.
GI perfusion rate could be a rate limiting step in the absorption of
lipid soluble drugs.
The perfusion rate increases after meals but absorption is not
influenced significantly.

20. Disease States

21. Classes of diseases
states, can affect on
Bioavailability of drug
Gastrointestinal diseases
Cardiovascular diseases
Hepatic diseases

22. Gastrointestinal
diseases
Altered GI motility
GI diseases & infections
Achlorhydria – decreased gastric acid secretion &
increased stomach pH
Malabsorption syndrome
Celiac disease
Crohn’s disease
Infections like gastroenteritis, cholera, colitis,
amoeviasis & constipation
GI surgery

23. Cardiovascular diseases:
CHF influence bioavailability of drug viz.
oedema of intestine,
Decreased blood flow to the GIT & gastric
emptying rate,
Altered GI pH, secretion & microbial flora
Hepatic diseases:
Such as hepatic cirrhosis.

24. Presynaptic
metabolism
(First-pass effects)

25.  Before a drug reaches blood circulation, it has to pass for
the first time through organs of elimination namely the GIT
& liver.
 The loss of drug through biotransformation by such
eliminating organs during its passage to systemic
circulation is called as FIRST-PASS METABOLISM
 Following system affect on FIRST-PASS METABOLISM
 Luminal enzymes
 Digestive enzymes
 Bacterial enzymes
 Mucosal / Gut wall enzymes
 Hepatic enzymes

27. What is gastric emptying? Describe its
role in drug absorption
 Write a note on factors affecting drug
absorption.
QUESTIONSQUESTIONS
ASKEDASKED

28. For further reading regarding this topic,
please refer the books like Brahmankar,
Remington, Alton and another related
books…..!