The document discusses drug biotransformation, the chemical conversion of drugs and xenobiotics within an organism, focusing on its role in altering drug activity and excretion. It outlines the processes of Phase I and Phase II reactions that facilitate drug metabolism and factors impacting these metabolic pathways. Additionally, it emphasizes the significance of biotransformation in pharmacokinetics and toxicity studies.

1. DRUG BIO-TRASFORMATION
BY:
MD. MYNUL HASAN
SOUTHEAST UNIVERSITY

2. Biotransformation
The conversion of molecules from one form to another
within an organism, often associated with change
(increase, decrease, or little change) in pharmacologic
activity; refers especially to drugs and other xenobiotics.
The metabolism of a drug or toxin in a body is an
example of a biotransformation. The body typically
deals with a foreign compound by making it more water-
soluble, to increase the rate of its excretion through the
urine.

3. History
 Welsh biochemist
 Metabolism of sulfonamides,
benzene, aniline, acetanilide,
phenacetin, thalidomide and
stilbesterol
 Metabolism of TNT (Trinitrotoluene)
with regard to toxicity in munitions
(1942)
1909 - 1979
Richard Tecwyn Williams

4. The role of biotransformation
Alteration or termination of drug activity
Converts pro-drug to active compound
Coverts less active drug to more active drug
Produces toxic compound
Terminates drug actions

5. WHERE DO DRUG
BIOTRANSFORMATIONS OCCUR

6. The pathways of drug metabolism
phase І
phase II
Phase 1 reaction include oxidation ,reduction and
hydrolysis.
Phase 1 reactions usually convert the parent drug to a
more polar metabolite by introducing or unmasking a
functional group (-OH, NH2 , -SH). If phase 1
metabolites are sufficiently polar, they may be readily
excreted.

9. Phase 2 reactions:- An endogenous An
endogenous substrate such as glucuronic acid,
sulfuric substrate such as glucuronic acid,
sulfuric acid, acetic acid, or an amino acid
combines acid, acetic acid, or an amino acid
combines with the functional group to form a
highly with the functional group to form a
highly polar conjugate.

12. Plasma level time curve of
mephenytion

13. Factors affecting Drug Metabolism
Genetic factors
Diet & environmental factors
Age & sex
Drug-drug interactions during
metabolism
Interactions between drugs &
endogenous compounds
Disease affecting drug metabolism

14. drug metabolism plays a major role and determines the
fate of the prospective drugs.
Drug metabolism must take place only after the drugs
reach their specific target site and produce the desired
effects.
Drug metabolism has an important role in the
determination of the pharmacokinetic (PK) parameters
like- Oral Biioavailability
Clearane and Half life.
 Drug metabolism is very essential in the toxicity studies
too.
 The persistence of the compounds in the systemic
circulation for long period causes toxicity.
Importance of Biotransformation

15. THANK YOU