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By:-Upendra Agrawal

General Pharmacology

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1. Introduction 2. Pharmacokinetic 3. Pharmacodynamic 4. Drug5. Various physiochemical properties the of

drugs6. Drug receptor interaction 7. Routes of administration8. Conclusion9. References

Contents

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Pharmacology: It is the science of drugs as it deals with the interaction of exogenously administered chemical molecule (Drug) with living system.

Father of pharmacology: Oswald Schmiedeberg. Two main division of pharmacology are: 1. Pharmacokinetic : what the body does to

drug 2. Pharmacodynamic: what the drug does to

body

1. Inroduction

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It is the quantitative study of drug movement in, through and out of the body.

Schematically process of pharmacokinetic: Transportation Absorption

Distribution-

storage

receptor metabolism free drug binding : (Effect) excretion.

2.Pharmacokinetic

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Biological membrane

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2. specialized transport or carrier mediated:

b. Active transport .

Transportation

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Absorption is movement of the drug from its site of administration in to the circulation.

factor affecting absorption: a. aqueous solubility b. concentration c. area of absorbing surface d. vuscularity of the absorbing

surface e. Ph influence f. Route of administration

Absorption

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It is the fraction of the drug that reaches to systemic circulation from a given dose in unchanged from in an unchanged form.

Intravenous route gives 100% bioavailability as it directly enters the circulation.

The term bioavailability is generally used for drugs given through oral route.

Bioequivalent: Two formulation of the same drug having equal bioavailability.

Bioinequivalent: if formulation differ in there bioavailability.

Bioavailability

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Once a drug has gained access to the blood stream, it gets distributed to other tissue that initially had no drug , concentration gradient being in the direction of plasma to tissue.

Factor affecting drug distribution: a. lipid solubility (various barrier) b. ionization at physiological Ph c. extent of binding to plasma and tissue protein d. presence of tissue specific transporter e. difference in the regional blood flow f. First pass metabolism. Movement of the drug proceed until an equilibrium is

established between unbound drug in plasma and tissue fluids.

Distribution

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It means chemical alteration of the drug in the body.

Primary sites of drug metabolism is liver , others are –kidney, intestine lungs and plasma.

Biotransformation of drug may lead may lead to the following:

a. Inactivation b. Active metabolite from an active

drug c. activation of inactive drug

(prodrug).

Metabolism (Biotransformation)

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Excretion is the removal of the drug and its metabolite from the body.

Drugs and their metabolites are excreted in: 1. Urine 2. faeces 3. exhaled air 4. saliva and sweat 5. milk

Excretion

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Pharmacodynamic is the study of drug effects. It attempts to elucidate the complete action-effect sequence and dose-effect relationship.

Principles of drug action: drugs do not impart new function to any system , organ

or cell they only alter the pace of ongoing activity. Types of drug action: 1. Stimulation 2. Depression 3. Irritation 4. Replacement 5. Cytotoxic action

3. Pharmacodynamic

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Majority of the drugs produce their effect by interacting with a discrete target biomolecule.

There are four major target of drug: 1. Enzymes 2. ion-channel 3. Transporters 4. receptors.

Mechanism of drug action

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It is a single chemical entity present in a

medicine that is used for diagnosis,

prevention, treatment/cure of a disease.

According to the WHO : Drug is any

substance or product that is used or is

intended to be used to modify or explore

physiological system or pathological states

for the benefits of the recipient.

4. Drug

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1. Lipid water solubility2. Molecular size3. Particle size4. Degree of ionization5. Physical forms 6. Chemical nature7. Dosage forms8. Formulation 9. Concentration 10. Shape

5.Various physiochemical properties of drugs.

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Receptor are (specific) protein and have

specificity and selectivity . No drug is truly

specific but many have a relatively

selective action on one type of receptor. Drug+ receptor Drug –receptor

complex

Response

6.Drug receptor interaction

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Affinity: the ability of the drug to get bound to the receptor is known as affinity.

Intrinsic activity: The ability of the drug to produce a pharmacological action after combining with the receptor.

Agonist: A drug that is capable of producing pharmacological action after binding to the receptor.

Antagonist: drugs that bind to receptor but are not capable of producing pharmacological action. These produce receptor blockade.

Various terms releted to drug receptor interaction

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7.Routes of drug administration

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Pharmacology is both a basic an applied science. It forms the backbone of rational therapeutics.

Conclusion

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KD TRIPATHI , Edition 6th year 2010 , published by JYPEE BROTHER MEDICAL PUBLISHER.

TARA V SHANBHAG, edition 1st year 2011 ELSEVIER.

WWW.themednote.com Wiki.ubc.ca/biological_membrenes

References

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