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Chapter 8

chapter 8

15 Pages
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Department
Psychology
Course Code
PSYC62H3
Professor
Suzanne Erb

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CHAPTER 8 pg 169-181
SEDATIVEHYPNOTICS AND ANXIOLYTICS
Drugs with sedative—hypnotic properties are perhaps the most commonly used and
abused drugs in U.S. society, with alcohol topping the list.
Despite the fact that they posses all the qualities that society deems unacceptable
with respect to drugs (namely, toxicity, lethality, social disruptiveness, and
psychological and physical dependence), and despite the fact that they are more
destructive to individuals and society than all other drugs combined, they are readily
accepted in both recreational and medicinal contexts.
~20% patients seen in psychiatric facilities are alcoholics.
The term sedativehypnotic is used because, in most individuals, the lower doses
of these drugs have psychological calming effect, and somewhat higher does have a
hypnotic or sleep-inducing effect.
These drugs are also commonly called CNS depressants, because their
predominant tendency is to inhibit the excitability of neurons.
Not all neurons decrease their rate of firing, particularly at the lower doses.
In fact, while many neurons decrease their rate of firing with these drugs, others
may increase their rate of firing because of the removal of the inhibitory influence of
other neurons—an inhibition of inhibition or disinhibition.
Alcohol (ethanol) is the most used and abused recreational sedative-hypnotic drugs
in U.S. society, and barbiturates and benzodiazepines are among the most frequently
abused prescription sedative-hypnotics.
All of these drugs differ primarily in their quantitative aspects—that is, the latency
of onset, the intensity of effect, and the duration of actionwithout having any
distinct qualitative differences.
Their qualitative effects are directly dose related.
Lower doses induce sedation; moderate doses induce sleep somewhat similar to
natural sleep, in which the person is still responsive to pain; high doses induce sleep
to the point of anaesthesia; and successively higher dose can cause coma, respiratory
arrest and death.
www.notesolution.com
In the lower dose range, excitement, increase activity, pregariousness, and
aggression may occur in some individuals.
This phenomenon has commonly been attributed to the disruption of neural
pathways of higher cortical origin that play an inhibitory function of subcortical
centers of the brain= disinhibition.
BARBITURATES AND OTHER SEDATIVEHYPNOTICS
Barbiturates and other drugs in the sedativehypnotic class have effects so similar
to alcohols effects, except to note that long-term alcohol exposure probably has more
toxic physiological consequences.
Sedative-hypnotic compounds without the barbiturate structure, such as
methaqualone and glutethimide, have been synthesized, but their actions are
essentially indistinguishable from those of the barbiturates.
Barbiturates differ from each other primarily in terms of pharmacokinetics, which
determines how quickly the drugs act, their intensity of action, and their duration of
action. (all three properties are tied together)
These differences in these properties are a major factor in determining what these
drugs are used for. For example the ultrashort-duration ~15min is used as an
anaesthetic, they can be used as sedative, sleep inducers and an anticonvulsant.
Over the past 3 years the medical use of these drugs has declined considerably,
primarily because of the development of newer compounds with less toxicity of
dependence liability.
They are no longer under patent, and thus they are very inexpensive.
The general tendency of these drugs is to decrease the excitability of neurons
throughout the nervous system.
Although barbiturates depolarize some neurons, their predominant action
throughout the nervous system is to hyperpolarize neurons.
The inhibitory influence of barbiturates has been postulated to be due to their
ability to enhance GABAs activity at the GABAA type receptor, which results in the
opening of Cl- channels, allowing Cl- to slow into neurons and hyperpolarizing them.
The primary action of barbiturates appears to be one of prolonging the duration that
these channels remain open.
www.notesolution.com
The inhibitory effects of barbiturates may also be due to increase in potassium (K+)
conductance; the flow of K+ inside neurons to the outside.
Accompanying these activities is an increase in the levels of most neurotransmitters,
in all likelihood because of their decreased utilization.
The rate of oxygen consumption and cerebral glucose metabolism in all areas of the
brain is reduced with these drugs.
A wide variety of behaviours, perceptual processes, and mental activities are affected
by even the low doses of these drugs that are used for their calming and sedating
effects.
A consistent feature of barbiturates and the nonbarbiturate alternative in humans is
to increase EEG slow wave activity (theta and delta waves) and reduce alpha wave
and fast beta wave activity. (Alpha activity predominates when a person is in relaxed
awake state with his or her eyes closed; beta activity is more frequent when a person
concentrate on a task with his or her eyes open, and is associated with alertness;
theta activity often occurs when a person has the eyes closed under resting
condition, and is linked to sleepiness; and delta waves, when they predominate,
correspond to sleep.)
All stages have been presumed to have some functional significance, but there is no
consensus as to what specific function they have.
Most nonbenzodiazepine sedative-hypnotics tend to prolong the deeper stages of the
sleep and reduce the stage known as REM (rapid eye movement).
REM is the stage; in which vivid dreams are most common, but the ability to
suppress REM sleep is not restricted to the sedative-hypnotics, this can happen with
other drugs.
The mechanisms for inducing tolerance to alcohol apply to the barbiturates,
although the latter appear to have a greater effect than alcohol on the drug-
metabolizing enzymes of the liver increasing their levels up to five times their
normal level.
Cross-tolerance occurs with all of these substances, and the psychological and
physical dependence associated with them is quite similar.
The faster-acting compounds, which also have more intense effects and shorter
durations, are more likely to be abused, and the abstinence syndrome associated
www.notesolution.com

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Description
CHAPTER 8 pg 169-181 SEDATIVEHYPNOTICS AND ANXIOLYTICS Drugs with sedativehypnotic properties are perhaps the most commonly used and abused drugs in U.S. society, with alcohol topping the list. Despite the fact that they posses all the qualities that society deems unacceptable with respect to drugs (namely, toxicity, lethality, social disruptiveness, and psychological and physical dependence), and despite the fact that they are more destructive to individuals and society than all other drugs combined, they are readily accepted in both recreational and medicinal contexts. ~20% patients seen in psychiatric facilities are alcoholics. The term sedativehypnotic is used because, in most individuals, the lower doses of these drugs have psychological calming effect, and somewhat higher does have a hypnotic or sleep-inducing effect. These drugs are also commonly called CNS depressants, because their predominant tendency is to inhibit the excitability of neurons. Not all neurons decrease their rate of firing, particularly at the lower doses. In fact, while many neurons decrease their rate of firing with these drugs, others may increase their rate of firing because of the removal of the inhibitory influence of other neuronsan inhibition of inhibition or disinhibition. Alcohol (ethanol) is the most used and abused recreational sedative-hypnotic drugs in U.S. society, and barbiturates and benzodiazepines are among the most frequently abused prescription sedative-hypnotics. All of these drugs differ primarily in their quantitative aspectsthat is, the latency of onset, the intensity of effect, and the duration of actionwithout having any distinct qualitative differences. Their qualitative effects are directly dose related. Lower doses induce sedation; moderate doses induce sleep somewhat similar to natural sleep, in which the person is still responsive to pain; high doses induce sleep to the point of anaesthesia; and successively higher dose can cause coma, respiratory arrest and death. www.notesolution.com In the lower dose range, excitement, increase activity, pregariousness, and aggression may occur in some individuals. This phenomenon has commonly been attributed to the disruption of neural pathways of higher cortical origin that play an inhibitory function of subcortical centers of the brain= disinhibition. BARBITURATES AND OTHER SEDATIVEHYPNOTICS Barbiturates and other drugs in the sedativehypnotic class have effects so similar to alcohols effects, except to note that long-term alcohol exposure probably has more toxic physiological consequences. Sedative-hypnotic compounds without the barbiturate structure, such as methaqualone and glutethimide, have been synthesized, but their actions are essentially indistinguishable from those of the barbiturates. Barbiturates differ from each other primarily in terms of pharmacokinetics, which determines how quickly the drugs act, their intensity of action, and their duration of action. (all three properties are tied together) These differences in these properties are a major factor in determining what these drugs are used for. For example the ultrashort-duration ~15min is used as an anaesthetic, they can be used as sedative, sleep inducers and an anticonvulsant. Over the past 3 years the medical use of these drugs has declined considerably, primarily because of the development of newer compounds with less toxicity of dependence liability. They are no longer under patent, and thus they are very inexpensive. The general tendency of these drugs is to decrease the excitability of neurons throughout the nervous system. Although barbiturates depolarize some neurons, their predominant action throughout the nervous system is to hyperpolarize neurons. The inhibitory influence of barbiturates has been postulated to be due to their ability to enhance GABAs activity at the GABA A type receptor, which results in the opening of Cl- channels, allowing Cl- to slow into neurons and hyperpolarizing them. The primary action of barbiturates appears to be one of prolonging the duration that these channels remain open. www.notesolution.com
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