1. L. Scheffler IB Chemistry 3-4 Lincoln High School
Drugs and Medicines
L. Scheffler
IB Chemistry 3-4
Lincoln High School
Version 1.05 1

2. Health and the Human Body
The human body maintains an intricate balance of thousands of chemical reactions.
These systems must respond to constantly changing demands from the individual’s activities.
These systems are subject to challenges from defects and malfunctions resulting from
genetic abnormalities.
environmental challenges.
changes accumulated through age.
attacks from microorganisms. 2

3. Lines of Defense Barriers to prevent entry Skin Mucous membranes
Closures and secretions of natural openings: lips, eyelids etc.
Defense against attack invaders
White blood cells (Phagocytes)]
Blood clotting to prevent blood loss
Inflammatory response.
Immune system
Antibodies.
Memory cells to enable the body to fight repeat invasions. 3

4. Origins of Pharmacology
From earliest times people have used natural substances such as medicinal herbs to
-- relieve pain
-- heal injuries
-- cure diseases
Some folk remedies contained certain active ingredients that were of medicinal value. 4

5. Examples of Folk Remedies
Morphine
extracted from poppy used to treat pain in the 19th century.
Salicylic acid
extracted from willow bark an a precursor to aspirin.
Quinine
Used in South America to treat malaria. 5

6. Definition of a Medicine
Any chemical substance that
Alters a physiological state
Alters mood or emotions
Alters incoming sensory sensations
Sometimes it is difficult to determine whether a drug has any medicinal value.
The legitimate purpose of a drug is usually to improve health.
Use of drugs in some cases is controversial. 6

7. The Placebo Effect
Healing is a complex interaction between mind and body that is not entirely understood.
The Placebo Effect
Merely taking any medicine may trigger responses in the body that result in changes in the mental/emotional or physiological states of the person without having any medicinal action. 7

8. Drugs and Medicines
Access to drugs and medicines is controlled in most countries but the definition of what constitutes a drug may vary.
Examples:
Melatonin
Codeine 8

9. Methods of Administering Drugs
Drugs must reach blood stream to be transported to critical tissues.
The method of administration determines rate at which the drug is absorbed in the blood.
Five common points of entry:
Oral
Inhalation
Topical
Injection
Anal 9

10. Methods of Administering Drugs
Injection methods
Intradermal
Between layers of skin
Subcutaneous
Under the skin
Intramuscular
In the muscle
Intravenous
Directly in the vein 10

11. Research, Development and Drug Testing
Development of new drugs is long and expensive process
Several stages in development include:
Isolation or chemical synthesis
Laboratory studies
Animal testing to determine LD50
Clinical testing to determine effectiveness
Approval by the FDA for market 11

12. Research, Development and Drug Testing
The development of a new drug is a time consuming process
Determination of the Lethal Dose or LD50. This is the concentration that will kill 50% of the animals in a test sample
The Effective Dose or ED50. is the concentration necessary to bring about a noticeable effect in 50% of the test sample
The Therapeutic Index is the ratio of
LD50.
ED50. 12

13. Clinical Trials
All drugs that are approved for market must be clinically tested multiple times
Most clinical tests are done on volunteers using a double blind study
Some of the volunteers receive a placebo while others receive the therapeutic medicine
Neither the researcher nor the participants know in advance who receives which 13

14. Drug Development
All medicines have some side effects and the appropriate dosage must be determined.
To determine the following must be considered:
Lethal Dose or LD50
Effective Dose or ED50
Therapeutic Index
Toxic Range
Therapeutic Level
Sub-therapeutic level 14

15. Contraindications or Side Effects
Contraindications are additional and often undesirable effects that result from the use of a particular drug to treat a particular condition.
Side effects are somewhat relative depending on the reason the drug is prescribed 15

16. Risk to Benefit Ratio
The prescribing physician must weigh the benefits from the use of a drug against the undesirable side effects when determining a suitable level of risk
The level of risk that is acceptable is related to the severity and the degree to which the condition is life threatening
Examples: Chemotherapy, Pain Killers etc 16

17. Tolerance Over time the body adapts the presence of a drug
The person receiving the drug needs ever larger doses to achieve the original effect.
Tolerance results in increased risks of dependency/addiction
Increased risks of toxic levels
Possibility of immunity in anti-bacterials. 17

18. Thalidomide --An Example of Improper Drug Approval
Developed in Germany in the 1953.
Used as a tranquilizer ( ).
Prescribed to combat morning sickness in the early months of pregnancy.
Marketed widely in Europe but never approved by the FDA in the USA.
Caused major birth defects in ABOUT 10,000 children whose mothers had taken thalidomide. 18

19. Thalidomide
Thalidomide has two optical isomers, one of which is a powerful teratogen.
Chiral
Carbon 19

20. Thalidomide Thalidomide is both a tranquilizer and a teratogen
It is sometimes used to treat some symptoms of Hansen’s disease. (Leprosy) 20

21. Drug Classification Drug Categories Depressants Stimulants Antacids
Analgesics
Antibacterial
Antiviral
Mind Altering Drugs 21

22. Review
When defining drugs what are three ways in which drugs affect the body?
Explain the following: Therapeutic index, tolerance, the placebo effect, effective dose, lethal dose.
Outline the steps in bringing a drug to market.
What happened with the drug, thalidomide, that resulted in a major drug catastrophe? 22