The Drug and it’s properties

The Drug

The Drug is refer to any substance that brings about a change in biological function through it’s chemical actions.

The substance that act on living system at chemical(mollecular) level.

Drug may be:

. Synthesized in the body i.e harmones.

- Or they may be chemicals not synthesized in the body i.e Xenobiotics (both naturally and artificially prepared).

- Toxins are drugs as well.

Properties of Drugs

1. Physical properties of drug

2. Drug mollecular size

3. Drug reactivity and drug receptor bonding

4. Shape of the drug

5. Activation of prodrug

6. Drug nomenclature

1.Physical Nature of drug

> The drugs may be solid, liquid or gas at room temperature.

> Drug can be carbohydrates, proteins and lipids.

> Drug can be weak acids or bases.

2.Drug Size

>The mollecular size of drug may be varies from very small (lithium ions, MW 7) to very large (Alteplase, MW 59000).

> Vast majority of drugs have mollecular weight between 100-1000.

3.Drug Shape

> Shape of drug should match the receptor, the site to which drug is attached. The drug and receptor just act like a key and it’s lock.

> Drugs may be exhibit the phenomenon of CHIRALITY (sterioisomerism) i.e the drug may exhibit as enanchiomeric pairs. Example: Labetolol has four enantiomers, but one of these will ne more potent than its minor images, reflecting a better fit to its receptor.

4. Drug Reactivity and Drug-Receptor Bonding

-Drug interact with receptor by means of chemical bonds or forces. Three major types:

(i) COVALENT BONDING : it is strong amd in most cases irreversible.

(ii) IONIC or ELECTRONIC BONDING : It is much more common but weaker than covalent bonding.

(iii) HYDROPHOBIC BONDS : They are usually quite weak & probably most important in interaction of highly lipid soluble drugs with cell membrane lipids.

— Drug which binds through weak bonds to it’s receptor is generally more selective than drug which binds through very strong bonds.

5. PRODRUG

> These are some drugs which must undergo chemical conversion (BIOACTIVATION) within the body to become an active pharmacological agent.

6. Nomenclature Of Drugs

••• any drug has three names

(i) CHEMICAL NAME which is based upon chemical structure.

(ii) GENERIC NAME / APPROVED NAME is the official name of drug given in Pharmacopoeia.

(iii) PATENT / PROPRIERTY / MARKET NAME given by pharmaceutical companies.

For Example= Chemical name —> dihydro-dibenz-azepin-yl, Generic name—>Imipramine, Market name—>Tofranil.

Comments

Cholinergic neuron & Cholinergic Receptors

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AGONIST & ANTAGONIST with types

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Cholinergic Drugs (Direct acting) Part-1

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Mechanism of absorption of Drugs

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Cholinergic Drugs (direct acting) Part-2

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Distribution of Drug in simplest way Pharmacology

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Drug clearance & Half Life & Dose

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Review of Routes of Drug Administration

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