THE PHARMACOLOGY AND

PHYSIOLOGY OF DRUGSGoldberg Chapter 5

SOC 204 Drugs & Society

Pharmacology

• Different drugs produce different effects within the psyche andsoma

• The interaction between drugs and living organisms is called pharmacology

• Drug pharmacology relates to the way it is administered, absorbed, distributed, metabolized, and excreted

• Drugs that act quickly and produce intense effects are more likely to be abused than are drugs that act slowly

Drug Actions

• Drugs affect various organs, including the nervous system.

• The nervous system consists of the central nervous system (CNS), the autonomic nervous system (ANS), and the peripheral nervous system (PNS)

• The CNS consists of the brain and spinal cord, and is composed of nerve cells (neurons)

• Information is transmitted electrically within the neuron, and chemically between neurons

Nervous System

• Homeostasis

• Neurons

• Glial Cells

You have approximately 100

billion neurons and 100

trillion synapses in your

brain. How long would it take

to count to a trillion?

A. All day

B. A month

C. A trillion seconds

D. 32,000 years All day

A month

A trilli

on seco

nds

32,000 years

0%

35%

43%

22%

Nervous System

• Somatic Nervous System• Sensory Information

• Autonomic Nervous

System

• Sympathetic Branch –Fight/Flight/Freeze

• Parasympathetic Branch –regulate body functions

• Central Nervous System• Brain & Spinal Cord

The Brain

Action Potential

https://www.youtu

be.com/watch?v=H

nKMB11ih2o

Synaptic Gap

https://www.y

outube.com/w

atch?v=XGIN

Q7xhPkM

Your neurotransmitter

• What it does

• What happens if you have too much?

• What happens if you have too little?

Chemical Pathways

1. Dopamine (excitatory)

• Found in basal ganglia and other regions – behavior & emotions, including pleasure

• Nigrostriatal dopamine pathway

• Related to muscle rigidity

• Mesolimbic dopamine pathway

• Related to psychotic behavior

• Possible component of the “reward” properties of drugs

Chemical Pathways

2. Acetylcholine (excitatory)

• Found in the cerebral cortex & basal ganglia

• Involved in Alzheimer’s disease, learning, memory

storage, movement

3. Norepinephrine (excitatory & inhibitory)

• Regulates level of arousal and attentiveness, memory

• May play a role in initiation of food intake (appetite)

Chemical Pathways

4. Serotonin (inhibitory or excitatory)

• Found in the brain stem raphe nuclei

• May have a role in impulsivity, aggression, depression, control of food, and alcohol intake

• Hallucinogenic drugs influence serotonin pathways

5. GABA (Gamma-amino butyric acid) (inhibitory)

• Found in most regions of the brain

• Inhibitory neurotransmitter, sleep, anxiety

Were you here

yesterday?

A. Yes

B. No

Yes No

25%

75%

Chemical Pathways

6. Glutamate (excitatory)

• Found in most regions of the brain

• Excitatory neurotransmitter, involved in long-term

memory

7. Endorphins (inhibitory)

• Opioid-like chemical occurring naturally in the brain

• Play a role in pain relief

People who engage in

strenuous exercise

actually emit a

neurotransmitter that

contributes to a “high”

feeling.

A. True

B. False

True

False

4%

96%

The neurotransmitter responsible

for control of alertness and the

fight-or-flight response is:

A. GABA

B. Dopamine

C. Serotonin

D. Norepinephrine

GABA

Dopamin

e

Seroto

nin

Norepin

ephrine

4%

86%

7%4%

This neurotransmitter is

the brain’s major

inhibitory

neurotransmitter

A. Serotonin

B. GABA

C. Endorphins

D. AcetylcholineSero

tonin

GABA

Endorphin

s

Acety

lcholin

e

14%

4%

39%43%

This neurotransmitter

has a huge influence

on mood

A. Endorphins

B. Glutamate

C. Serotonin

D. Acetylcholine

Endorphin

s

Gluta

mate

Seroto

nin

Acety

lcholin

e

4% 4%

89%

4%

This

neurotransmitter is

responsible for

feelings of

pleasure/reward.A. Glutamate

B. Serotonin

C. Dopamine

D. GABAGlu

tam

ate

Seroto

nin

Dopamin

e

GABA

0% 0%

100%

0%

Lifecycle of a

Neurotransmitter

1. Neurotransmitter precursors are found circulating in the blood supply

2. Uptake: Selected precursors are taken up by cells, a process requiring energy

3. Synthesis: Precursors are changed (synthesized) into neurotransmitters through the action of enzymes

4. Storage: Neurotransmitters are stored in small vesicles

Lifecycle of a

Neurotransmitter

5. When the action potential arrives, neurotransmitters are released into the synapse

6. Released neurotransmitters bind with receptors on the membrane of the next neuron

7. Neurotransmitters may have excitatory or inhibitory effects

8. Once a signal has been sent, neurotransmitters are removed from the synapse; may return or be metabolized

Drug Actions

• Alter neurotransmitter availability

• Agonists - Mimic neurotransmitters

• Antagonists = Occupy neurotransmitter and prevent its activation

• Interference with reuptake

• Video: https://www.youtube.com/watch?v=uXREQnFGHGA

Names of Drugs

• Chemical name: Complete chemical description of the molecule

• Example: N'-[2-[[5-(dimethylaminomethyl)-2-furyl] methylsulfanyl]ethyl]-N-methyl-2-nitro-ethene-1,1-diamine

• Generic name: Official (legal) name, listed in the United States Pharmacopoeia (USP)

• Example: ranitidine

• Brand name: Specific drug or formulation trademarked by manufacturer; can be patented for 20 years

• Example: Zantac®

Classifications

One’s mood while

taking a psychoactive

drug will affect the

experience derived

from the drug.

A. True

B. False

True

False

4%

96%

Drug Effects

• Nonspecific effects

• Specific effects

• Placebo effects

Double-blind procedure

Dose-Response

• Dose-response relationship = correlation

between the response and the quantity of

drug administered

• Threshold = the dose at which an effect is

first observed

Older men are more

affected by a drug’s

effects than are

older women.

A. True

B. False

True

False

73%

27%

Dose

• Effective dose = the dose of a drug that produces a meaningful effect in some percentage of test subjects

• ED50 refers to the effective dose for half the animal subjects in a drug test

• Lethal dose = the dose of a drug that has a lethal effect in some percentage of test subjects

• LD50 refers to the lethal dose for half the animal subjects in a drug test

• Therapeutic index = LD50/ED50

• Always greater than one

If a drug has a lethal dose that is close to its

effective dose, that drug is more dangerous

than if the LD is far from the ED.

A. True

B. False

True

False

12%

88%

Mixing medications

with wine causes more

potential health

problems than mixing

medications with beer.

A. True

B. False

True

False

29%

71%

Dose

• Potency = measured by the amount of a drug required to produce a given effect

• Toxicity = capacity of a drug to do damage or cause adverse side effects

• Safety margin = difference between: • Dose that produces the desired therapeutic effect in

most patients

• Lowest dose that produces an unacceptable toxic reaction

• Most drugs have an LD1 well above the ED95

Women are less likely

today than they were

30 years ago to use

medicines while

pregnant.

A. True

B. False

True

False

54%

46%

Routes of Administration

Forms and

methods

of

taking drugs

oral ingestion

inhalation

injection

topical application

Distribution

Mechanisms

• Transport in the blood

• Blood-brain barrier

• Effects on all neurons

• Effects on neurotransmitters

• Enzyme induction

• Deactivation

Tolerance

• Pharmacological

• Behavioral

• Cross-tolerance

• Reverse tolerance

Video: https://www.youtube.com/watch?v=8-Qtd6RhfVA