drugs all have a widespread effect in the brain that can be summed up as
decreased neural activity. The behavioral effects are very similar to the
effects of alcohol. At low doses these drugs might be prescribed for daytime
use to reduce anxiety (as a sedative). At higher doses many of these same
drugs are prescribed as sleeping pills (hypnotics). This grouip of prescription
drugs is often referred to as sedative-hypnotics, part of a larger
group of substances considered to be CNS depressants.
* the most widely
used depressant is alcohol
* the most widely
used prescribed types of sedative-hypnotics fall into the chemical grouping
called the benzodiapezines, which in
the past 30 years have replaced the barbiturates.
have a longer history than barbiturates but are less frequently used today
The names of barbiturates
always end with the letters "al"
grouped on the basis of the duration of their activity: short-acting, intermediate-acting,
or long-acting (refer to Table 8.1 on page 167 of your textbook).
In general, the
drugs that are the most lipid-soluble are the ones that have both the shortest
time of onset (i.e., they are absorbed and enter the brain rapidly) and
the shortest duration of action (i.e., they leave the brain quickly and
tend to be more rapidly metabolized).
Sedatives are usually
low dose of a long-acting barbiturate (like phenobarbital); and sleeping
pills are usually of higher dose of a short-acting drug (such as amobarbital
and physical dependence, and fatal overdose are possible drawbacks to barbiturates.
one of the classes of drugs that stimulate the activity of microsomal enzymes
of the liver. Some of the tolerance that develops is the result of an INCREASED
rate of deactivation caused by this stimulation.
They depress respiration
and, in large doses or in combination with alcohol, can completely stop
Mechanism of Action:
GABA (gamma amino butyric acid) receptor complex, which includes a barbiturate
binding site and a benzodiazepine receptor. When these chemicals bind to
their receptor respective receptor site, they enhance the normally
inhibitory effects of of GABA on its receptors.
Because of concerns
of addiction liability and the danger of overdose, new sedative or hypnotic
agents were accepted and utilized.
released in 1955, was the first modern antianxiety agent, was a revolutionary
replaced meprobamate and were considered a safer substitute than barbiturates.
Chlordiazepoxide (Librium) and Diazapam (Valium).
In looking at the
differences between barbiturates and so-called safer drugs (like benzodiazapines),
we have learned that it is the dose and the time course of
individual drugs that make the difference. A drug that has a rapid onset
of action will be more likely to produce psychological dependence than
a slow-acting drug. Physical dependence occurs when the drug leaves the
system more rapidly than the body can adapt. - one way to reduce the severity
of withdrawal symptoms is to reduce the dose of a drug slowly over time.
Drugs with a shorter duration of action leave the system quickly and are
much more likely to produce withdrawal symptoms than longer-acting drugs.
There might be a greater difference among the bartiturates and among the
benzodiazepines than there are between the two classes.
a benzodiazepine sold as a hypnotic in many countries but NOT the U.S.
appeared in the late 1950ís and early 1960ís and was incorrectly viewed
as safe, nonbarbiturate sleeping pill. Methaqqualone causes the same kind
of motor incoordination as alcohol and the barbiturates.
USES FOR SEDATIVE-HYPNOTIC
not curing neurotic behavior, is the one primary purpose of these drugs.
Most psychiatrists refer to the benzodiazepines as antiantiety agents (anxiolytics).
For a typical general practitioner, about half of the patients have NO
treatable physical ailment.
Because of the possibility
of tolerance, dependency, rebound insomnia, and hangover effects, the use
of hypnotic drugs has decreased - they are usually taken for only a few
nights at a time.
benzodiazepines are often used for the control of epileptic seizures
OF SEDATIVE-HYPNOTIC DRUGS
are more likely to lead to dependency than benzodiazepines are
can occur with any of the sedative-hypnotic drugs
Withdrawal can be
These drugs impair
judgement and coordination
by barbiturates has been reported (especially when used with alcohol)
is affected (respiration is depressed), sometimes to the point of respiratory
Abuse usually occurs
by an older person using these drugs for a long time for sedation or sleeping;
or by a young person using these drugs to get high (using sleeping pills
from home, etc.)
to these fumes makes users intoxicated, often slurring their speech and
causing them to have trouble walking
Because so many
different sovents are involved, it is impossible to characterize the potential
harm produced by abuse, except to say that several solvents have been linked
to kidney damage, brain damage and peripheral nerve damage and many produce
irritation to the respiratory tract and result in severe headaches. However,
several users of various inhalants have suffocated as a result of this
e.g., nitrous oxide, chloroform, ether, etc.
isoamyl nitrite, butyl nitrite, etc.
e.g., petroleum distillates, acetone, toluene, etc.
nitrous oxide, butane, propane, etc.
Use of inhalants