The document provides an overview of pharmacology, covering its definition, branches, and the various routes of drug administration, including their advantages and disadvantages. It discusses drug absorption, bioavailability, distribution, biotransformation, and excretion, highlighting mechanisms of absorption like passive diffusion and active transport. Additionally, it details factors affecting absorption, such as physical and physiological properties, and elaborates on the different sources and natures of drugs.

1. Mr. Mayur A. Haral
Department of
Pharmacology
Ishwar Deshmukh Institute
of Pharmacy, Digras 445203

2. Topic in This chapter
• General Pharmacology
• Introduction and scope of Pharmacology
• Various routes of drug administration - advantages and disadvantages
• Drug absorption - definition, types, factors affecting drug absorption
• Bioavailability and the factors affecting bioavailability
• Drug distribution - definition, factors affecting drug distribution
• Biotransformation of drugs - Definition, types of biotransformation
reactions, factors influencing drug metabolisms
• Excretion of drugs - Definition, routes of drug excretion

3. Introduction and scope of Pharmacology
• "Pharmacology” can be defined as the study of interactions between drug and
biological system. It can be defined as the science of drugs or study of drug. The
word “pharmacology " derived from Greek word.
• Pharmacon – Drug, Logos – studied Which means pharmacology is the study of
drug and their action of living body. It includes the knowledge of history source,
biochemistry and physiological effects, mechanism of action and therapeutic uses
of drug.
“Branch of pharmacology”
1. Pharmacokinetics 2. Pharmacodynamics
3. Therapeutics 4. Toxicology
5. Chemotherapy

4. Definition
1. Pharmacokinetics:– What body does to the drug. In this the study of the action
of drugs on target organ. It deals with the study of absorption, distribution,
metabolism, excretion of drugs. (what body does with the drug)
2. Pharmacodynamics: – What drugs dose the body. It deals with the mechanism
of action and pharmacological effect of drug. (what drug does with the body)
3. Therapeutic:- Is branch, which deals with the cure of disease and is defined as
“to take care of”
4. Toxicology :- Toxicology is traditionally defined as "the science of poisons." It
deals with effect of poisons methods for their detection, diagnosis and treatment.
5. Chemotherapy:- It is the branch of pharmacology that deals with drugs, capable
of destroying the causative organism without destroying host cells. The mechanism
undertaken in chemotherapy.

5. • Sources of Drug
1.Minerals- Liquid Paraffin, Magnesium Sulphate, Magnesium Trisillicate.
2.Animals – Insulin, Heparin, Thyroid extract.
3.Plants- Morphine, Quinine.
4.Synthetic- Aspirin, Sulphonamide.
5.Micro-Organism- Penicillin, Streptomycin
• Nature of Drug
1.Alkaloids- Morphine, Atropine.
2.Glycosides- Digitalis.
3.Fixes oil- Peanut oil, Coconut oil.
4.Volatile oils- Oil of Eucalyptus, Ginger oil, Peppermint oil.
5.Gums- Agar.
6.Tannins- Tincture cayachu.

6. Various Routes of Drug Administration

7. Various Routes of Drug Administration
Oral
In this route of administration the drug either
liquid or solid preparation is placed in mouth
cavity is swallowed along with drinks such as
water, milk etc.
• Advantage:-
1.Most of medicinal preparations are consumed
orally.
2.Economical chance of acute drug reaction.
Very convenient for children and aged people.
• Disadvantage:-
1.Onset of action is very slow.
2.Irritation to gastric mucosa.
3.It is not useful in emergency cases.
Topical / Local Route
1. It is the simplest route
2. Drugs used for local application are dusting
powder, lotions, pastes, ointments& plasters
3. The site where drugs are commonly applied
are skin, eye, nose, throat, ear, rectum &
vagina
4. In this techniques drug absorption through
intact skin depends upon lipid solubility of
drugs

8. Various Routes of Drug Administration
Sublingual
This dosage form is placed under the tongue and
allow to dissolve in the mouth cavity. The drug
is absorbed by sublingual mucosa.
• Advantage:-
1. Onset of action very quick.
2. 100% absorption is possible as degradation
of drug by digestive enzymes is prevented.
• Application:-
1. Tri-nitroglycerine in angina pectoris.
2. Isoprenaline in bronchial asthma.
Buccal route
In buccal route drug kept within the mouth
around the cheeks or buccal cavity, where it
disintegrates and get absorbed.
• Advantage:-
1. Rapid absorption of the drug.
2. Drugs do not undergo first- pass
metabolism.
3. Portal circulation is by passed.
• Disadvantages:-
1. Only small dose can take.
2. Sometime complete drug is not absorbed.
3. Not effective in emergencies.

9. Various Routes of Drug Administration
Parenteral Administration
Intramuscular (IM) Route
In this route the drug is administration into the
muscles.
Advantage
1. Rapid onset of action.
2. No G.I.T. related factors.
3. Mild irritants can be metabolism.
4. The absorption is reasonably uniform.
Disadvantage
1. Only 10ml of drug is given.
2. Local pain cause, Abscess and infection.
3. Can cause nervous damage.
Intravenous (IV) Route
IV is the route of drug administration in which
the drugs are administered into the veins.
Injection are preferred for orally unabsorbed
Drugs like Atracurium (neuromuscular
blocker).IV route shows rapid effect the
maintains level of drug in circulation.
Advantage:-
1. 100% bioavailability.
2. It this route shows rapid effect.
3. This route is the best in the case of diarrhea
and vomiting.
Disadvantage:-
1. This route is less safe than oral route.
2. Technical and trained person required.
3. Inconvenient and painful causing irritation,
cellulitis and thrombophlebitis.

10. Parenteral Administration
Subcutaneous Route (SC)
This route of administration the drug gives under
the skin.
Example:- Hormonal drug (Insulin injection)
Advantage
1. Can be easily self-administering by the
patient.
2. Complete but slow adsorption.
3. Low risk of systematic infection.
Disadvantage:-
1. Maximum 2ml of drug may be injected.
2. Less painful then the IV /IM route.
3. Irritatant drugs cause tissue damage.
Intra-arterial
This route of drug administration the drugs are
given into the arteries. Vasodilator, anticancer
drugs are given by skin route.
Advantage:-
1. Rapid onset of action.
2. No G.I.T. related factors.
3. Mild irritants can be metabolism.
4. The absorption is reasonably uniform.
Disadvantage:-
1. Only 10ml of drug is given.
2. Local pain cause, Abscess and infection.
3. Can cause nervous damage.

11. Various Routes of Drug Administration
Parenteral Administration
ID – Intradermal
SC – Subcutaneous
IV – Intravenous
IM – Intramuscular

12. Drug Absorption
Absorption is movement of the drug from its site of administration into the circulation. Not only the fraction of the
administered dose that gets absorbed but also the rate of absorption is important.
Disintegration- Breaking up of solid dosage form into granules.
Dissolution- Entry of granules the aqueous phase.
Absorption- Entry of dissolved drug molecules into the blood flow.
Physiology
• Plasma membrane mediates entrance and exit of material
• This ability of plasma membrane to permit certain substances to enter & exit, but to restrict passage of others, is
referred to as “ Selective permeability”
• Plasma membrane is a tri-laminar structure containing phospholipid & protein layer.
• Absorption of drug from gut obeys the laws of transfer of molecules across the biological membranes.
Transport Mechanism
Most of the drugs are absorbed by “Passive Diffusion”.
Few of the active agents are absorbed by “Active transport” or “Carrier mediated transport” mechanism.

13. Passive Diffusion
• This is the most commonest mechanism by which most
of the drugs are transport across cell membrane.
• Passive transport process is referred to as “Diffusion”
and occurs when there is greater movement of
molecules or ions from a region of their higher
concentration to a region of their lower concentration.
• Thus “passive diffusion” is dependent on “
concentration gradient”
• Drugs, which are lipid soluble (unionized) are
transferred across the cell membrane by passive
diffusion.
• In this process, bi-directional movement of the
concerned molecules depends on the concentration
gradient without involvement of energy.
• This process in not depend on pH of medium, provided
the drug dissolve in intestinal fluid and reaches the
absorption surface.

14. Active transport
• This is a well defined and specialized process in which drug is transported
against a concentration gradient with the involvement of energy.
• The drug attached to a special carrier in the membrane which facilities diffusion
across membrane and release the drug
• Inorganic ions like sodium, potassium, chloride & calcium are absorbed by
active transport.
• Drugs like synthetic drugs, steroids and hormones are absorbed by this
transport.
Significance
Knowledge regarding the rate of absorption is necessary
• To determine the frequency of absorption
• To define duration of effective action.
• For anticipation of desired and undesired effect of drug.

16. Factor affecting Absorption of Drugs
1. Physical Properties: (a) Particle Size (b) Lipid and water solubility
2. Dosage form: (a) Particle size (b) Formulation
3. Physiological factors: (a) pH (b) Ionization (c) Presence of other agents (d) Presence of disease
(e) Area of absorption (f) Gastro- Intestinal time.