Lesson B5 - Pharmacology

Question 1

Psychoactive drugs are agents that can act

Answer 1

on the central nervous system and alter sensation,

perception, mood, behaviour or consciousness.

Question 2

Psychoactive drugs-Chemical structure: Classification based on chemical structure does not work since some
drugs with similar chemical structures have different

Answer 2

pharmacological activities, while

other drugs with dissimilar structures have closely similar pharmacological activities.

Question 3

Psychoactive drugs do not create new behavioural or physiological responses, but

Answer 3

act by modifying ongoing physiological and biochemical responses

Question 4

Psychoactive drugs can either stimulate

Answer 4

or depress the central nervous system

Question 5

Cocaine: Acts by blocking

Answer 5

dopamine reuptake into presynaptic nerve terminals.

Question 6

Amphetamine and derivatives: Act by releasing

Answer 6

dopamine from presynaptic nerve

terminals.

Question 7

Caffeine: Caffeine is a blocker (competitive antagonist) of

Answer 7

adenosine at its receptors
located on cell membranes in the central and peripheral nervous system. Its action as a
psychostimulant results from antagonism of adenosine-induced neuronal inhibition.

Question 8

Nicotine: Stimulates a selective subgroup of acetylcholine receptors in

Answer 8

the central nervous system known as nicotinic receptors.

Question 9

The following are examples of general CNS depressants. There are at least six categories,
namely

Answer 9

barbiturates, non-barbiturate hypnotics, general anesthetics, ethyl alcohol,
benzodiazepines, and inhalants of abuse.

Question 10

The effects of CNS depressants are dependent on

Answer 10

dose

Question 11

. A small dose of barbiturate will cause relief of anxiety. As the dose increases, depression
of inhibitory neuronal pathways will result in

Answer 11

disinhibition

Question 12

barbiturates, commonly prescribed as

Answer 12

hypnotics (sleeping tablets) before the advent of the benzodiazepines, were commonly used in suicide attempts

Question 13

CNS depressants are marketed by

the pharmaceutical industry as

Answer 13

sedatives, anti-anxiety (Anxiolytic) agents, hypnotics, minor
tranquillizers, and major tranquillizers. It should be appreciated that the medical use of a CNS
depressant drug is usually a function of dose and that the above terms are convenient means for
marketing of drugs.

Question 14

. One of the
reasons that the barbiturates, once widely used as sedative-hypnotics, have been replaced in large
part by the benzodiazepines is

Answer 14

s that barbiturates have a lower therapeutic index than the

benzodiazepines.

Question 15

Four Principles of CNS Depressant Use

Answer 15

The effect of CNS depressants are additive, Use of a behavioural stimulant such as caffeine in a patient severely depressed by a CNS
depressant drug may, through non-specific antagonism, cause a temporary arousal of the
depressed individual. An individual consuming large doses of a CNS depressant for a prolonged period will
usually become physiologically dependent (addiction) upon the drug-Cross tolerance may be observed.

Question 16

Classification of Drugs that Alter Mood or Behaviour or that are Used to Treat CNS Disorders

Answer 16

1. CNS depressants (e.g. barbiturates, ethyl alcohol).
2. CNS stimulants (e.g. cocaine and amphetamine).
3. Antidepressants (e.g. tricyclic antidepressants) and mood stabilizers (e.g. lithium).
4. Antipsychotic drugs (e.g. phenothiazines, atypical antipsychotics.)
5. Narcotic analgesics (e.g. morphine).
6. Psychedelics and hallucinogens (e.g. lysergic acid diethylamide, LSD).
7. Cannabis.
8. Neurological drugs (e.g. antiepileptic drugs such as phenytoin).