Introduction to pharmacology important concepts

1. Introduction to pharmacology
Handout for Lecture 1
Updated 2016
123 123

2. Topics
• What is pharmacology ?
• Why we study It ?
• What is a drug ?
• Rational use of drugs.
• Drug characteristics ?
– sources, classification, names etc
SDL
• You should be familiar with dosage forms , routes of administration
commonly used in clinical practice
• http://www.aapd.org/media/policies_guidelines/rs_common
meds.pdf.

3. √√√Drugs :
ideally : chemical agents that can be used to diagnose,
prevent and treat illness
2nd
goal : prevent progression or ameliorate symptoms
√√√ Clinical Pharmacology:
clinical use of drugs in humans (patients and volunteers)
Drug profile
Its History, chemical structure, source
Its pharmacodynamics (PD ).
Its pharmacokinetics (PK) .
Its clinical indications & contraindications , precautions
Its adverse drug effects (ADE) & management of toxicity.
Other : Available preparations , dose , cost .
Pregnancy category , perception restriction
* drugs may be also used To promote healing; To control or slow progress
of disease; To decrease risk or complications; As replacement therapy

4. Major Uses for Drugs in clinical practice
• Essential drug list about 400 drugs
Classified according to therapeutic indications
1. ANAESTHETI CS
1.1 General anesthetics
1.2 Local anesthetics
1.3 Preoperative medication and sedation for short-term
procedures
2. ANALGESICS, ANTIPYRETICS, NON-STEROIDAL ANTI-
INFLAMMATORY MEDICINES (NSAIMs)
2.1 Non-opioids and non-steroidal anti-inflammatory medicines
(NSAIMs)
2.2 Opioids Analgesics
See http://apps.who.int/medicinedocs/documents/s23527en/s23527en.pdf

5. General Principles of Rational Drug Prescribing
• All members of health care team must be responsible for
medication safety and prevention of medication errors

6. • 6 steps:
• 1: Determining the patient’s problem
• 2: Determining the object of the treatment
• 3: Verification of the suitability of the P-treatment
for the specific patient
• 4: Onset of treatment
• 5: Information, instructions and precautions
• 6: Monitoring (and termination) of treatment
•
•General Principles of Rational Drug Prescribing
.

7. Concept no 2
Almost ALL DRUGS ARE
POISONS
The only thing that determines if a
drug provides a benefit or kills a
patient is how we administer it ( dose,
route, age ,etc )
Examples : sodium nitoprosside IV ( drug ) , orally very toxic
1 tablet of acetaminophen ( panadol ) treatment of headache , 10-12
tablets ( liver failure if not treated )

8. Examples of adverse drug effects
(ADE )

9. Concept 3 : Our Therapeutic
Goal
Optimal pharmacotherapy : ie
maximum efficacy & minimal
toxicity ?
i.e To achieve drug concentrations at the site of
action (target tissue)…that are sufficiently
high enough…to produce the intended effect
without producing adverse drug reactions.

10. Therapeutic Classification
Is based on therapeutic use of certain group of drugs.
• For example:
– Anticoagulants.
– Antidepressants.
– Antineoplastics.
Pharmacologic Classification
• More specific than therapeutic classification
• Requires understanding of biochemistry and physiology
• Based on how the drug produces its effect at molecular, tissue,
or body-system level
Ex : Cholinergic agonists { act on the receptors that are activated by
Aceylcholine (Ach )
o direct acting
o indirect acting
− reversible
− irreversible
Classification of Drugs
Don’t wary they are just example
, you are not requested to
memorize

11. Further Classification of drugs
Therapeutic action e.g: Antibiotics
sub class. in view of
Mechanism
Cell - wall inhibitors
Chemistry B-lactam antibiotics
o Pencillins
o Cephalosporins
spectrum Cephalosporin's are classified as
1st ,
2nd
, 3rd
generation

12. Some drug characteristics
• Physicochemical charctestics
– Solid ; Liquid & Gaseous drugs
– Hydrophilic , lipophilic
– water solubility ,
– Many drugs are weak acids or bases.
• Drug Size & Mol. Wt
some are small simple molecules, others complex structures
Most drugs have molecular weights between 100 and 1,000
• Some drugs are chairal ( optically active )

13. Nomenclature
• Chemical name
– Acetylsalicylic acid
• √√√Generic or nonproprietary name ( use it in
prescription )
– Aspirin
• Trade name (Name brand)
many

14. Specific Forms of Adverse Effects
• Hypersensitivity
• Extension of pharmacological effect .
• Idiosyncratic reactions
• Iatrogenic reactions
• Teratogenic
• Interactions with other drugs
– Synergism ( 1+1 = 5 )
– Antagonism ( 1+1 = zero )
– Potentiation (1+1 = 1.5 )

15. Classification with regard to prescription
I
Drugs with high abuse potential and no accepted medical use
II
Drugs with high abuse potential and accepted medical use
III
Drugs with moderate abuse potential and accepted medical use
IV
Drugs with low abuse potential and accepted medical use
V
Drugs with limited abuse potential and accepted medical use
1-OTC ( out of the counter ,)
2-Prescription drugs
3-Controlled substances (1-V)

16. Pregnancy Classifications
• A—No risk demonstrated to the fetus in any
trimester.
• B—No adverse effects in animals—no human studies
• C— animal studies show adverse reactions
Only given after risks to the fetus is considered
D—Definite fetal risks. Only given in life threatening
situations
• X—Absolute fetal abnormalities

17. Key Points
• The objective of drug therapy is to provide maximum
benefit within minimum harm.
• This requires knowledge the drug Pk & PD and variables
affecting these properties.
• Patients are unique, drug therapy must be provided in
individual basis.
• Rational use of drugs is responsibility of all staff involved
in health care