B5: Classification of major psychoactive drugs
What are the four principles of cns depressant use?
1. The effect of cns depressants are additive 2. The 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...but whe the stimulant effect wears off the individual may be left in an even more depressed state 3. An individiual taking large doses for a long time will becom physiologically dependent. Exhibit rebound excitability as a withdrawal symptom 4. The use of any cns depressant drug is associated with the risk of inducing psychological dependence and tolerance
What are the 8 classifications of drugs that alter mood or behaviour or that are used to treat cns disorders?
1. cns depressants (barbs, ethyl alcohol) 2. cns stimulants (cocaine, amphetamine) 3. antidepressants (tricyclic antidepressants) and mood stabilizers (lithium) 4. antipsychotic drugs (phenothiazine, atypical antipsychotics) 5. Narcotic analgesics 6. Psychedelics and hallucinogens (lysergic acid diethylamide, (lsd)) 7. cannabis 8. neurological drugs (antiepileptic ones)
possible classification of psychoactive drugs
1. mechanism of action 2. chemical structure 3. major behavioural effect or major clinical or non medical use
How does caffeine work?
a blocker/competitive antagonist of adenosine at its receptors located on cell membranes in the central and peripheral nervous system antagonism of adenosine induced neuronal inhibition
What is a psychoactive drug?
agents that act on the central nervous system and alter sensation, perception, mood, behaviour or consciousness
What are the six categories of cns depressants
barbiturates non-barbiturate hypnotics general anesthetics ehtyl alcohol benzodiazepines inhalants of abuse
How does cocaine work?
by blocking dopamine reuptake into presynaptic nerve terminals
What are some examples of psychomotor stimulant drugs
cocaine amphetamine and derivatives caffeine nicotine
how do psychoactive drugs work?
modifying ongoing physiological and biochemical responses - don't create new behavioural or physiologica responses Can either stimulate or depress the central nervous system
how does nicotine work?
stimulates a selective subgroup of acetylcholine receptors in the cns known as nicotinic receptors
How do the amphetamines and their derivatives work?
they release dopamine from presynaptic nerve terminals
