An introduction to pharmacology for medical students

1. Introduction, Drug Development
and Routes of Drug
administration
Dr. Jagan

2. Learning objectives
• What is Pharmacology and its divisions
• What are the sources of drugs
• Drug Development
• List and discuss the common routes of drug administration.
• Advantages and Disadvantages of different route of drug
administration.

3. Introduction
• Pharmacology – Science of Drugs.
Source, chemistry, formulation, dosage, mechanism,
use, adverse effects.
“Study as to how drugs can alter the
Physiological or biochemical functions
of a living organism”

4. What is a Drug?
A pure chemical substance used for the treatment,
prevention or diagnosis of a disease in human
beings/animals.
WHO: Any substance or product that is used or intended to
be used to modify or explore physiological systems or
pathological states for the benefit of the recipient.

5. Drug Nomenclature
Chemical name Generic name Proprietary/Brand name
Acetyl salicylic acid Aspirin Dispirin
Ecospirin
Acetaminophen Paracetamol Crocin
Calpol
Aminobenzyl Penicillin Ampicillin Biocillin
Roscillin

6. Subdivisions of Pharmacology
Pharmacokinetics:
What the body does to the drug?
Absorption, Distribution, Metabolism & Excretion of drugs
Pharmacodynamics:
What the drug does to the body?
The biological effects produced by the drug and its mechanism of action
Where and how the drug acts?

7. Preclinical Pharmacology
New drug development using animal models
Clinical Pharmacology
Clinical evaluation of a new drug in healthy volunteers and patients
Toxicology
Adverse effects of drugs/chemicals & treatment of poisoning

8. Source of Drugs
•Natural and Synthetic Plants
•Animals, Micro organisms and Minerals
•Genetic engineering – Recombinant DNA
•Synthetic – Paracetamol, Diazepam, Ranitidine,
Metronidazole,
•Minerals: FeSO4, Al(OH) 3, MgSO4, I131 and P32

9. Vinca rosea Papaver somniferum Atropa belladonna Datura metel
Vincristine Morphine Atropine Atropine
Vinblastine Codeine
Papaverine

10. Digitalis purpurea
Glycosides – Digoxin
Digitoxin
Cassia occidentalis
Anthroquinone -
Sennosides

11. Insulin Thyroxine Pituitary extract
Animal source of Drugs

12. MICRO ORGANISMS
Penicillium notatum – Penicillin
Streptomyces griseus – Streptomycin
Recombinant DNA Technology - Yeast, E.coli -
Human insulin
Growth hormone
Hepatitis B vaccine
Interferon's
Monoclonal antibodies

13. Drug Trails

14. Drug Trails – Contd..

15. Drug Formulations
Tablets
Capsule
Syrup Injection
Inhalation

16. Routes of drug administration
Selection of Route:
Condition of the patient.
Routine treatment or emergency
Physical and chemical properties of drug
Site of desired action

17. Different routes of drug administration
Enteral route
Oral
Sublingual
Rectal
Parenteral route
Intravenous Intramuscular
Intradermal Subcutaneous
Intra-arterial Intra thecal
Intraperitoneal Intramedullary
Intra-articular Intra cardiac
Inhalational

18. Oral route:
•Most common
•Safe
•Convenient
•No assistance needed
•Painless
•Cheap
•Both solid and liquid dosage forms

19. Demerits:
Slow onset,
Not useful in emergency,
Unpalatable drug, unabsorbed drug
Vomiting
Unconscious, uncooperative patients
Drug destroyed in GI juice.

20. Correct Incorrect

21. Sublingual route:
lipid soluble, non-irritating drugs.
Rapid action, liver, intestine bypassed.
No first pass metabolism
Nitroglycerine, Isoprenaline, Clonidine.
Rectal route:
Suppository, enema.
Fast absorption
Recurrent vomiting, 50% bypasses liver.
Irritant drugs should not give.
Diazepam

22. Parenteral routes:
Drugs enter into tissue fluid or blood
* Faster action in emergency,
* No gastric irritation or vomiting
* Unconscious, uncooperative or vomiting patients
* No interference by GI juice
* Liver is bypassed

23. Disadvantages of Parenteral route:
Sterilization and cost
* Painful and invasive
* Assistance needed

24. Subcutaneous route:
• Self injection is possible
• Repository preparations for prolonged action.
• Dermojet – mass inoculation
• Pellet implantation – hormones contraceptives.

25. Intramuscular route:
• Deltoid, triceps, gluteus, rectus femoris
• Rich vascular and sensory nerve
• Faster absorption. Less painful
• Depot preparations
Intradermal route:
• Injected into the skin. BCG vaccine
• Sensitivity testing.

26. Intravenous route:
• Slow infusion of large volume or bolus injection
• Irritant drugs
• Immediate distribution and action
• 100 % bioavailability, emergency titration of response
possible
• Only aqueous solution injected
• Vital organs exposed to high drug concentration
• Very risky route.
• Thrombophlebitis.

27. Cutaneous route.
Slow, prolonged absorption of highly lipid soluble
drugs. Liver bypassed.
Transdermal patch
• Drug in solution or polymer
• For slow & Continuous release.
• Nitroglycerine, Nicotine, Estradiol, Hyoscine and
Clonidine.
• Chest, Lower back, Mastoid

28. Transdermal patch

29. Inhalation:
• Volatile liquids and gases.
• General anesthesia.
• Large alveolar surface- fast action
• Powders – Salbutamol
Nasal
• Powder or nebulised solution
• Desmopressin, Insulin, GnRH agonist

30. Drug administration for local effects
Skin: ointment, cream and paste
Mouth & pharynx: paints, mouth wash, gargle and lozenges.
Eyes, ears & nose: drops and ointments.
Intra cardiac – Adrenaline
Intramedullary:
Ocuserts – Pilocarpine

31. Special routes of drug administration
Intra-articular injection
Intrathecal injection
Retrobulbar injection
Intra-arterial injection.

32. 1
Which of the following routes have the highest bioavailability?
a. Oral
b. Intramuscular
c. Intravenous
d. Subcutaneous

33. 2
Which of the following is an advantage of sublingual administration?
a. Slow absorption
b. Slow action
c. Less bio - availability
d. Avoid first pass-metabolism

34. 3
Transdermal drug delivery systems offer the following advantages except:
a. They produce high peak plasma concentration of the drug
b. They produce smooth and nonfluctuating plasma concentration of the
drug
c. They minimize interindividual variations in the achieved plasma drug
concentration
d. They avoid hepatic first-pass metabolism of the drug

35. 4
When medications are applied to the skin to produce a long period of
systemic effect, the delivery type is best referred to as:
a. Transdermal.
b. Topical.
c. Intradermal.
d. Subcutaneous.

36. 5
What is an advantage of sublingual drug administration compared
with other routes of administration?
a. Sublingual drug administration can be used for the administration
of drugs with low potency.
b. Sublingual drug administration allows for less frequent drug
administration because the drug slowly enters the blood.
c. Sublingual drug administration has a high first-pass metabolism,
making it ideal for administration of pro-drugs.
d. Sublingual drug administration is faster due to the rich supply of
blood vessels under the tongue.

37. REFERENCES:
KATZUNG BASIC & CLINICAL PHARMACOLOGY: by Bertram Katzung, Anthony Trevor -Published by McGraw-Hill – 13th
Edition - ISBN 978-0-07-182505-4.
KATZUNG AND TREVOR’S PHARMACOLOGY: EXAMINATION & BOARD REVIEW by Anthony J. Trevor/ Bertram G.
Katzung/ Susan B. Masters – Published by McGraw-Hill - Edition 11 – ISBN-13: 978-0071826358.
ESSENTIALS OF MEDICAL PHARMACOLOGY: by K. D. Tripathi – Publisher: Jyapee Brothers; Edition 7- ISBN-978-
9350259375.
GOODMAN AND GILMAN'S THE PHARMACOLOGICAL BASIS OF THERAPEUTICS: by Laurence Brunton, Bruce Chabner,
BjornKnollman - Publisher: McGraw Hill Education; Edition 12 - ISBN-13: 978-0071624428.

38. Thank you