GENERAL PHARMACOLOGY BIOAVAILABILITY SOURCES OF DRUG METABOLISM ADMINISTRATION

2.  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.

3.  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: Adrug 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.

4.  Pharmacotherapeutics : Use of drugs in prevention & treatment of disease.
 Chemotherapy: Effect of drugs upon microorganisms,
parasites and neoplastic cells living & multiplying in living organism.
 Pharmacogenomics: Relationship of individual’s genetic makeup to his/her
response to specific drugs.
 Toxicology: It is the study of poisonous effect of drugs and other chemicals
(household, environmental pollutant, industrial, agricultural, homicidal) with
emphasis on detection, prevention and treatment of poisonings.
 Pharmacovigilence: It is the science and activities relating to detection, assessment,
understanding and prevention of adverse effect or any other possible drug related
problem.

5. 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.

7. • Existence of many names for each drug causes confusing situation.
• A DRUG HAS AT LEAST THREE TYPES OF NAMES:
 Chemical name (IUPAC) or scientific name:
 Based on molecular structure of the drug
 Very long, too complex to use in common practice
 International Nonproprietary/generic name:
 - Given by FDA/WHO while approved, the short hand version of chemical
name
 - Recommended in RX
 Proprietary/trademark/Brand name:
 Given by the pharmaceutical company
 Costly

8. PrimarySource:
 Information ispresented by authors without anyevaluation by asecondparty. Providesmust current information
aboutdrugs.
 Examples;articles published in journals(eg British Medical Journal), thesisetc.
Secondarysource:
 Theoriginal sourcehasbeenevaluated by secondparty other than thepublisher.
(Modifiedandrearranged form)
 Examples; review articles like lexis-nexis,Medlineetc
Tertiarysource:
 Information obtained from primary and secondarysourceand arrangedina manner to represent acomposite of
theavailable information.
 Examples;RepresentativeformPharmacopeias- BP,USP,IPetc., Encyclopedia DictionariesGuides,text books

9. It is the quantitative study of drug movement in, through and out of the body.
It attempts to analyze chemical metabolism and to discover the fate of a chemical
from the moment that it is administered up to the point at which it is
completely eliminated from the body.
Transportation Absorption Distribution
Storage
Metabolism Free drugReceptor
Binding :
(Effect)
Excretion
Schematic Process of Pharmacokinetic:

10. Absorption is movement of the drug from its site of
administration in to the circulation.
FACTOR AFFECTINGABSORPTION:
a. Aqueous solubility
b. Concentration
c. Area of absorbing surface
d. Vascularity of the absorbing surface
e. Ph Influence
f. Route of Drug Administration
Drug
Ionised form
Water soluble
Cant cross
biological
membrane
Un-ionised
form
Lipid soluble
Cross
biological
membrane

11. It is the fraction of the drug that reaches to systemic circulation
from a given dose in an unchanged form.
The term bioavailability is generally used for drugs given through
oralroute.
Intravenous route gives 100% bioavailability as it directly enters the
circulation.
Bioequivalent: Two formulation of the same drug having equal
bioavailability.
Bioinequivalent: If formulation differ in there bioavailability.

12. 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:
 Lipid Solubility (various barrier)
 Ionization at physiological Ph
 Extent of binding to plasma and tissue protein
 Presence of tissuespecific transporter
 Difference in the regional blood flow
 First pass metabolism.
Movement of the drug proceed until an equilibrium is established
between unbound drug in plasma and tissue fluids.

13. 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:
 Inactivation
 Active metabolite from an active drug
 Activation of inactive drug (Prodrug)

14. Enzyme
Inducer
Increase
metabolism
Decrease
effect
Doseshould
beincreased
Tolerance
Enzyme
Inhibitors
Decrease
Metabolism
Predisposes
toxicity

15. Excretion is the removal of the drug and its metabolite
from the body.
DRUGS AND THEIR METABOLITES ARE EXCRETED IN:
 Urine- Most of drugs(Paracetamol)
 Feces- Rifampicin
 Exhaled air- General anaesthetics
 Saliva and sweat- Lithium
 Milk- Atropine

16. 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:
Stimulation- Adrenaline
Depression- Barbituates and general anaesthetics
Irritation- Methyl salicylate
Replacement- Insulin for DM
Cytotoxic action- Anticancer drugs( Methotrxate)

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