Monday, July 19, 2010

What is drug receptors How drug resistance occurs explanation on drug receptor theory

What is drug receptors? How drug resistance occurs, explaination on the basis of drug receptor theory:
Drug receptors are the sites on the tissues or proteins or enzymes or on cell wall or cell organelles of microorganisms where a drug gets attached to a particular site. These receptor sites are specific to a particular drug, drugs bind to this receptor through covalent or hydrogen bonding or ionic bonding and this binding is responsible for further physicochemical events which impart a desired effect of a drug.
Physicochemical events as discussed in earlier are due to inhibition or activation or agonistic action , or just by physical properties of a drug molecule , on the particular receptor site.

Reasons why these receptor sites are specific:
The drugs are designed with the intention of mimicking the chemical structures of biochemicals in our body that may be an amino acid sequence of an enzyme which takes part in any biochemical reaction, or a modification of a atomic group of an naturally occurring metabolite , (Anti metabolite drugs).

1. Drug molecules may mimic naturally occurring enzyme or biochemical’s so that the drug is taken up by the biochemical path way reaction systems.

2. Drug molecule may mimic as agonist to which brig about activation of the path way.

3. Drug molecule may mimic as antagonist which bring about Inhibitory actions.
The receptors are just the complementary points on the systems where a drug is suppose to impart its desired action, these points may be multiple for a drug, as a Azo nitrogen, or carboxylic acid group on a drug taking part in the reaction, or a drug molecule hindering the naturally occurring enzyme or a biochemical molecule from taking part in its normal reaction path way ,owning to its stearic hindrance or spatial arrangement around the receptor site .

Hence the drug receptors are unique for particular drugs.

Drug resistance and Receptors
In case of an resistance the receptor sites changes its orientation , than the earlier one , or it changes the affinity towards a particular bio molecule so that the drug molecule do not bind to the receptor site , may drugs act competitively so the naturally occurring biochemical’s concentrations (Enzyme Induction ) increases .
We have written other phenomenon’s of drug resistance in details over here

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