The document discusses the processes the body undergoes to metabolize drugs, including absorption, distribution, metabolism, and elimination. It describes various routes of drug administration like oral, intravenous, intramuscular, and subcutaneous. Oral administration is the most common but can be affected by food intake. Intravenous administration enters distribution directly without first pass metabolism. Different mechanisms underlie drug absorption, including passive diffusion, facilitated diffusion, active transport, and exocytosis/endocytosis.

1. What body does to
drug..

2. Definition:
What the body does to drug.
1.Route of drug administration
2.Absorption
3.Distribution
4.Metabolism
5.Elimination

3. IV administration
Lacks absortion

5. Enteral:
Oral:
 Safest & most common
route of administration
Food may affect the
absorption
Patient’s complaince is
required
Available in enteric coatted
and extended release forms
Sublingual/Buccal:
 Placed under the tongue
or between the gums &
cheeks
 Directly enters into the
systemic circulation
 Limited to certain drugs
 dose may be lost if
swallowed

6. Parenteral:
Intravenous:
Does not enter into absorption as
well as the first pass metabolism
 Straightly enters into the
Distribution
 Can cause immediate effect
 Can cause local irritation & fear
 used for administration of large
volume drugs

7. Intramuscular:
 Aqueous solution prompt
 Can be used moderate drugs
 Can be more painful
 suitable for oily substances
 Can cause intramuscular hemorrhage
Subcutaneous:
 suitable for slow release
drugs
 Can cause pain & necrosis if
irritated

8.  Some other routes of drugs include the transdermal patch, rectal,
as well inhalation
Transdermal is one of the safest mode of administration
Rectal is used if the patient is already vomiting or if the drug
causes vomitting
Inhalation is used for avoidance of systemic side effects while it is
straightly focusing on respiratory system

9. Definition
Transfer of drug from the site of administration into the
plasma
Mechanism of absorption of drugs:
The important mechanisms which are involved in the drugs
are
Passive diffusion
Facilitated diffusion
Active transport
Exocytosis/endocytosis

10. Passive diffusion:
Movement towards the concernteration gradient
Its unsaturable does not require ATP, carrier protein
Lipophilic drugs can readily pass through the lipid bilayer
Hydrophilic drugs dissolve in water & transfer through the aqueous
pores present in the membrane
Facilitated diffusion:
Movement towards the concernteration gradient
It is saturable, requires carrier protein but does not require ATP
Drugs bind to carrier proteins & carrier protein undergoes
cnformational changes& allows the passage of drugs inside the
membrane

11. Active transport:
 Movement against the concernteration gradient
Saturable, requires carrier proteins ,require ATP
 Transport occurs through the carrier proteinsWith the
hydrolysis of ATP
Exocytosis/Endocytosis:
 Useful for drugs with high molecular weight
 Engulfment of drug by the membrane
 Engulfed drug is incorporated into the vesicle &
transported into the cell interior