Pharmacology

Pharmacology:

Pharmacology is the science of drugs, which deals with the detailed study of sources, chemical nature, route of administration, absorption, distribution, metabolism, excretion, mechanism, therapeutic & other use, and side effects of drugs.

Types of pharmacology:

Pharmacodynamics and
pharmacokinetics.

Pharmacodynamics:

Pharmacodynamics deals with the biochemical and physiological effects of drugs and their mechanism of action. In short, what the drug does to the body is pharmacodynamics.

Pharmacokinetics:

Pharmacokinetics deals with the study of the absorption, distribution, biotransformation (metabolism), and excretion (ADME) of drugs and their metabolites in the intact organism. In short, what the body does to the drug is pharmacokinetics.

Drug:

Drugs are any substance other than food that acts on the living organism to alter the physiological process and pathological state that are used for the prevention, diagnosis & treatment of diseases.

Source:

Plants: such as Atropine, Morphine, and Digoxin.
Human and animals: such as epinephrine, insulin, and adrenocorticotropic hormone.
Minerals: such as iron, iodine, and zinc.
Synthetic and chemical substances: such as sodium bicarbonate.

Medicine:

Medicine is a formulated form of drug having a definite dose, dosage form, labeling, and packaging.

Dose:

The amount of drugs or medicinal preparation to be administered at one time is called a dose. Example:- 5mg at night.

Dosage:

Determination of the amount, frequency and the number of doses of drugs for a patient is called dosage. Example:- 5 mg 3 times daily.

Over-the-counter drug (O.T.C drug):

These drugs can be used without a prescription. Example:- Aspirin, Paracetamol, Antacid.

Half-life (t1/2):

This is the period of time required for the amount of drug in the body to be reduced by one-half.

Prodrug:

The drug does not produce any pharmacological effect until they are chemically altered within the body are called prodrug. Example:- Enalapril (Enalaprilat-active form). Prodrugs are used

To avoid toxicity
To increase the bioavailability

Prescription:

The written direction for the preparation and administration of the drug.

Bioavailability:

The rate and extent of a drug that goes into the systemic circulation after the administration.

Mechanism of action:

Refers to the specific biochemical interaction through which a drug substance produces its pharmacological effect.

Therapeutic class;

Is a set of medications that have similar chemical structures, mechanisms of action, and a related mode of action and are used to treat the same types of diseases.

The median lethal dose (LD50):

It is the amount of the substance required (usually per body weight) to kill 50% of the test population.

Potency:

The potency of a drug means the amount of drug which is required to produce a particular effect. Potencies are compared based on doses that produce the same effect.

Receptors:

Receptors are macromolecular structure lipoproteins in nature, present in the cell membrane or inside the cell which interact with specific drugs in a specific way and give specific effects. Example- H1 & H2 Receptors.

Agonist:

The drug which has both affinities for receptors and efficacy is called an agonist.

Antagonist:

An antagonist is a drug that has an affinity for a receptor but lacks efficacy. Example- Antihistamine for Histamine.

Placebo:

Placebo means "I will please". A harmless inert substance that is given as a medicine to satisfy the patient's desire for drug therapy is called a placebo.

Route of administration:

The way by which, the drug is introduced into the body.

Oral: Drug swallowing directly by mouth.
Sublingual: Drug placed under the tongue, where it dissolved.
Buccal: Placing a drug between the gums and cheek.
Rectal: Uses the rectum as a route of administration.
Translingual: On the tongue.
Subcutaneous (SC): Hypodermic into the subcutaneous tissue, just below the skin.
Intramuscular (IM): Into the muscle.
Intravenous (IV): Allow injection of drugs and other substances directly into the bloodstream through the vein.
Inhalation: As applying drugs directly onto the lungs.
Topical Route: Skin, Eye, Nose, Ear, etc.
Transdermal: Absorption of the drug through the skin. Example:- Transdermal patches.

First pass metabolism:

The intestinal and hepatic degradation or alteration of a drug or substance taken by mouth, after absorption, removes some of the active substance from the blood before it enters the general circulation.

Adverse effects:

Any response to a drug that is noxious and unintended and that occurs at the dose used in man for prophylaxis, diagnosis, or treatment.

Side effects:

Unwanted, usually unavoidable drug effect within the therapeutic dose range.

Toxic effect:

An unwanted effect due to a toxic dose is called a toxic effect.

pH:

A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid, and higher values are more alkaline.

Drug misuse:

Taking or using medicine in a way that is not intended.

Example,

Using the drug longer than advised by the doctor
Using a drug not prescribed for you
Taking more of the drug than the doctor prescribed

Drug abuse:

Drug abuse is an inappropriate intake of substances either continually or periodically.

Drug Interaction:

Drug interaction is a situation in which a substance affects the activity of a drug when two drugs are administered together. The interaction of the two drugs may also increase the risk that side effects.

Digestion:

Digestion is the breakdown of food constituents into smaller ones in preparation for absorption.

Drug allergy:

Drug allergy is an immunological reaction to a drug.

Therapeutic dose:

The therapeutic dose of a drug is the amount needed to treat a disease.

Biological drug:

A substance that is made from a living organism and is used in the prevention, diagnosis, or treatment of cancer and other diseases. Biological drugs include antibodies, interleukins, and vaccines.

Non-Biological:

These are medical compounds that cannot be defined as small molecular, fully identifiable drugs with active pharmaceutical ingredients.

The generic name:

The generic name is given for the drug to being the official name.

The chemical name:

The chemical name is the name by which the chemist knows it.

The trademark or brand name (proprietary name):

The trademark or brand name is the name given by the drug manufacturer.

Example:

Esomeprazole: (generic name).
Exium: (brand name).

Antibiotic:

Antibiotic is a substance that is used to kill or inhibit the growth of microorganisms.

Classification of Antibiotics:

Antibiotics can be classified in several ways as given below:

On the basis of Mechanism of action
On the basis of Structural similarities
On the basis of Mode of action

1. On the basis of Mechanism of action:

Protein synthesis inhibitor

Example: Azithromycin, Erythromycin

Cell wall synthesis inhibitor

Example: Amoxicillin, Cephradine

DNA synthesis inhibitor

Example: Ciprofloxacin, Gemifloxacin

RNA synthesis inhibitor

Example: Rifampicin

Folic acid inhibitor

Example: Silver Sulphadiazine, Sulfadoxine.

2. On the basis of structural similarities:

i . Beta Lactum:

a. Penicillin:

* Narrow Spectrum- Oxacillin, Dicloxacillin

* Broad Spectrum- Ampicillin, Amoxicillin, Flucloxacillin

b. Cephalosporin:

i. 1st generation- Cephradine, Cephalexin

ii. 2nd generation- Cefaclor, Cefuroxime

iii. 3rd generation- Cefixime, Ceftriaxone, Ceftibuten

iv. 4th generation- Cefepime, Cefpirome

v 5th generation- Ceftaroline, Ceftabiprole

ii. Macrolides:

a. Azithromycin

b. Erythromycin

c. Roxithromycin

iii. Fluoroquinolones:

a. Ciprofloxacin

b. Levofloxacin

c. Gemifloxacin

iv. Tetracyclines:

a. Oxytetracycline

b. Demeclocycline

c. Doxycycline

v. Aminoglycosides:

a. Gentamycin

b. Neomycin

c. Tobramycin

vi. Others:

a. Mupirocin

3. On the basis of Mode of action:

a) Bacteriostatic: is a biological or chemical agent that is used to inhibit the growth of microorganisms.

Example: Tetracycline, Chloramphenicol, Erythromycin, Lincomycin etc.

b) Bactericidal: is a biological or chemical agent that is used to kill the microorganism.

Example: Cephalosporin, Penicillin, Aminoglycosides, cotrimoxazole, Metronidazole etc.

Pregnancy category:

Category A: Well-controlled studies in humans show no fetal risk.

Category B: Animal studies show no risk, but there are no controlled studies on pregnant women.

Category C: Animal studies show risk but there are no controlled studies on women or in women and animals are not available.

Category D: Definite fetal abnormalities in human studies but potential benefits may outweigh the risk.

Common Terminology:

BP: British Pharmacopoeia
USP: United States of Pharmacopoeia
NF: National Formulary
BNF: British National Formulary
INN: International Nonproprietary Names
MRP: Maximum Retail Price
IP: Indicative Price
GMP: Good Manufacturing Practice
cGMP: Current Good Manufacturing Practice
FDA: Food and Drug Administration
ISO: International Organization for Standardization
Batch No: Manufacturing Batch Number
DAR No: Drug Administration Registration Number
MA No: Marketing Authorization Number
GP: General Practitioner/Prescriber
SACMO: Sub-Assistant Community Medical Officer
LMAF: Local Medical Assistant and Family Planning
RMP: Rural Medical Practitioner
MBBS: Bachelor of Medicine, Bachelor of Surgery
FCPS: Fellow of College of Physicians and Surgeons
MD: Doctor of Medicine
BDS: Bachelor of Dental Surgery
DMF: Diploma of Medicine Faculty
BID: Twice a day
TID: Thrice in a day
PO: By mouth

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