Pharmacogenomics

Pharmacogenomics is the study of the role of the genome in drug response.

-Pharmacogenomics is the study how an individual genetic inheritance affected the body response to the drug.

-Pharmacogenomics aims to develop rational drug with respect to patients genotype to ensure maximum efficiency with minimal adverse effect.

-Taking into account the variability in the drug response from person to person, pharma-cogenesis ends at one drug for each individual [one drug for a group of persons with similar properties i.e. identical agent]

-Therefore, a better effect of the drug will be achieve preventing the adverse drug reaction.

Traditional drug designing ends at one for all approaches and the does depend on majority an age factor i.e low dose for young once and high dose for adults.

-But such problem can be illuminated by one person is equal to one drug approaches.

Four Steps in Pharmacokinetics [ADME]

1.    Absorption.

2.    Distribution.

3.    Metabolism.

4.    Excretion.

SNP: - Single Nucleotide Polymorphism.

            Enzyme present in liver [at the side of metabolism]

            e.g. Cytochrome, P450, TPMT, VKORC

In case of active drug: -

1.    Enzyme activity high, drug dose is high.

2.    Enzyme activity high, drug dose is low.

In case of inactive drug.

3.    Enzyme activity high, drug dose is low.

4.    Enzyme activity low, drug dose is high.

- All the drugs we inject are metabolism by our body.

- some drugs get activated after metabolism and some remain active                    before   metabolism.

- This metabolism is carried out by special enzyme, which are generally present in liver cells.

e.g. Cytochrome P450

- This enzyme are expressed whenever they are required for the expression are not identical in every individual.

-Each gene sequence varies approximately nucleotide 100-300 bases. This is called as single, nucleotide polymorphism [SNP]

- Because the genes are different in their sequence the enzyme produced by expression of this gene also very in their activity from person to person.

- Therefore, the role of metabolism of a drug in each individual may differ

e.g. In case of drug which get inactivated after metabolism may show different response in different individual having different enzyme different individual having different enzyme activities.

1.    In person having highly active enzyme the drug will be metabolised very fast and excreted from the body may not rich which is required to excretes its therapeutic effect.

2.    In case of person having less enzyme activity the drug will be metabolise slowly, therefore it may remain in active from for a long period in the body.

3.    The person with very slow metabolic rate may show toxic effect of that drug [e.g. in case of cytotoxic drug used in cancer therapy]

Benefit of Pharmacogenomics: -

1.    Production of powerful medicine; -

2.    Accuracy of therapy will be increased.

3.    The undesirable side effect will be minimized and the patient will be prescribed drug based on their genotypes.

Disadvantages: -

1.    It is not possible to study genotype of each individual.

2.    One drug one-person approach is very costly.

3.    It is not yet in use.

REFERENCE: -

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