This presentation includes the detail information of pharmacokinetics. How body react with drug. Route of drug administration. In this presentation there is a given all the relevant data related to the general pharmacology which is used full for the D. pharm, B. Pharm, Pharm D students . Pharmacodynamics : - What drug does to body.
Pharmacokinetics : - What body does to the drug.
Pharmacotherapeutics : - Use of drugs in prevention & treatment of disease.
Clinical pharmacology : - Scientific study of drugs in man.
Toxicology : - Aspect of pharmacology deals with adverse effects of Drugs.
Pharmacodynamic agents : - Designed to have pharmacodynamic effects in the
recipient.
Chemotherapeutic agents : - Designed to inhibit/kill parasites/malignant cells & does not have or
with minimal pharmacodynamic effects in recipient.
Orphan drugs : - Drugs or Biological Products for diagnosis/treatment/ Prevention of a
rare disease.
E.g.:- Liothyronine (T3), Desmopressin, Baclofen, Digoxin Antibody.PHARMACOKINETICS
Absorption of Drugs:-
A) Simple diffusion: - Bidirectional process rate of transfer across the membrane is proportional to
concn gradient. E.g.:- H20 soluble drugs with low mol-wt, lipid soluble drugs.
B) Active transport: - requires energy – independent of physical properties of membrane. E.g.:- H20
soluble drugs with high mol-wt.
Carrier mediated transport: - E.g.:- Intestinal absorption of Ca2+
.
C) Pinocytosis: - Important in unicellular organisms like Amoeba.
Bioavailability: - Amount of drug reaches systemic circulation following a non-vascular drug
administration.
Auc oral
F = Auc iv
Barriers:-
B.B.B:- made up of choroid cells (strong Barrier).
Testis Barrier: - made up of seroid cells.
Placental Barrier: - made up of sertoli cells (weak Barrier).
Endothelial Barrier: - in all blood cells (very weak).
For absorption of vitB12, IF factor is required which is synthesized by parietal cells?2 types of metabolism: - a. Non synthetic reaction (phase I reaction)
i. Oxidation
ii. Reduction
iii. Hydrolysis
iv. Cyclilization
v. Decyclilization
b. Synthetic reaction (Phase II reaction) conjugation reactions
i. Glucoronide conjugation
ii. Acetylation
iii. Methylation
iv. Sulfate conjugation
v. Glycine conjugation
vi. Glutathion conjugation Remember:- Many drugs are eliminated by the kidney without being.
3. Introduction
• What body does to the drug ?
• DEF- -- Study of movement of drug through body (change in
concentration of drug from entry to its exit out of body).
Pharmacon – Drug Kinetics – Movement
• Also called ADME study .
A D M E
ABSORPTION
DISTRIBUTION METABOLISM
EXCRETION
D
O
L
O
How body reacts with drug?
4. Absorption
1) ABSORPTION –Movement of drug from route of administration into
systemic circulation (all the process before drug enters to systemic
circulation).
2) Drug transport across the membrane takes place either by passive or
active transport.
GETTING INTO
BODY
Weakly acidic drug
Unionised form
Better absorbed
from the stomach
in
Weakly basic drug
Unionised in
Better absorbed from the
intestine
in
5. Factors Affecting Absorption
Physical state
of drug
1. Liquids are better absorbed than solid.
2. Crystalloids are more readily absorbed than colloids.
3. Aqueous are more quickly absorbed than oily solutions
Particle size
1. Smaller particle size se surface area for absorption due to that
absorption rate is se.
Concentration 1. Higher concentration of drugs aids in better absorption of those
drugs.
Absorbing
surface
1. Absorption rate of gastrointestinal mucosa is more than pulmonary
endothelium of skin.
2. Absorption of drugs from highly vascular membrane will be rapid.
3. Larger the surface more is the absorption. Absorption from intestine is
more than stomach
6. Functional
integrity of GIT
pH of Drug
Formulation
1. Absorption of drug from the GIT may be effectively sed by se
in peristaltic activity.
1. Acidic drugs absorbed from the stomach. E.g., Salicylates and
barbiturates.
2. Basic drugs absorbed from the intestine. E.g., Pethidine and
ephedrine.
1. Calcium and magnesium ions reduced the absorption of
tetracycline.
2. Low degree of ionisation, high lipid/water partition coefficient
of non-ionised form and smaller molecular size of water soluble
substance , all favours rapid absorption.
7. Bioavailability
It is the fraction of a drug that reaches systemic circulation
100
mg
50
mg
50%
Bioavailability
8. Factors affecting bioavailability
Bioavailability
Concentration
Particle size
Physical state of
drugs
Dissolution rate
Absorbing surface
Functional integrity
of GIT
pH of drug
Gastric emptying
time
Degree of
ionization
Molecular
weight
Lipid solubility
First pass
metabolism
Disease state of
the gut
Formulation
9. Distribution
After the drug reaches into the blood circulation it may be distributed
to various tissue and organs.
Vd= Volume of distribution
Vd =
𝐓𝐨𝐭𝐚𝐥 𝐚𝐦𝐨𝐮𝐧𝐭 𝐨𝐟 𝐝𝐫𝐮𝐠 𝐢𝐧 𝐛𝐨𝐝𝐲
𝐂𝐨𝐧𝐜𝐞𝐧𝐭𝐫𝐚𝐭𝐢𝐨𝐧 𝐨𝐟 𝐝𝐫𝐮𝐠 𝐢𝐧 𝐩𝐥𝐚𝐬𝐦𝐚
10. Factors affecting distribution
Physiological
Factors
Physiochemical
Properties of Drug
1. Cardiac output
2. Regional blood flow
3. Capillary permeability
4. Tissue volume
5. Special tissue characteristics
such as blood brain barrier
1. Binding to plasma proteins
2. Binding to other tissues like fat,
liver, bone etc
3. Affinity for tissue constituents
4. Tissue redistribution
11. Metabolism
• Also called biotransformation
• 2 types of metabolism: - a. Non synthetic reaction (phase I reaction)
i. Oxidation
ii. Reduction
iii. Hydrolysis
iv. Cyclilization
v. Decyclilization
b. Synthetic reaction (Phase II reaction) conjugation reactions
i. Glucoronide conjugation
ii. Acetylation
iii. Methylation
iv. Sulfate conjugation
v. Glycine conjugation
vi. Glutathion conjugation
13. Genetic
factors
1. Acetylation of drugs show genetic polymorphism.
2. The individual fall clearly under fast and slow acetylation.
Nutritional
status of
individual
Environmental
factors
Diseases
state of
individual
1. Drugs or environmental toxins can induce hepatic microsomal enzyme oxidising
system or cyp450 resulting into rapid metabolism and elimination of drug.
2. The environmental pollutants like pesticides can induce metabolism.
1. Malnutrition in children and in malnourished elderly, the drug oxidation rate is
severely decreased.
2. Whereas high protein diet act as metabolising enzyme inducers.
3. Alcohol consumption have both enzyme induction effect at low dose and at high
dose metabolic inhibition effect.
1. Liver being major site of drug metabolism, in patients with liver diseases (cirrhosis)
metabolism of drug is severely reduced, resulting in drug toxicity.
2. Similarly in patients with kidney disease; se elimination of drug metabolites is
observed.
14. Drug – drug
interaction
Drug food
interaction
Simultaneous administration of two drugs causing interaction may
show:- Inhibitory effect or stimulatory effect
Tyramine present in cheese, bananas may not metabolized by MAO if
MAO- inhibitors is given and a severe hypertension crisis may result.
15. Excretion
• Elimination from body
Organs
involved in
drug
excretion
Kidneys Lungs
Intestines
Bile
Skin
Saliva & Milk
Remember:- Many
drugs are eliminated
by the kidney
without being. Renal
disease can therefore
slow excretion of
some drugs
16. REFERENCE
• Dr. Yadav A. V. , Mrs. Dubal A. S. , Pharmacology, Nirali
Prakashan,first edition, June 2022, Page no. :-1.1-1.20
• Tripathi K. D., Essentials of medical pharmacology, Jaypee brothers
medical,8th Edition, 2018 Page no. 01-22.
