Benzodiazepines produce many therapeutic effects, including:
sedation before anesthesia
relief of anxiety and tension
skeletal muscle relaxation
Benzodiazepines are used in various clinical
situations and exert either a primary or a secondary sedative or hypnotic
effect. Ben-zodiazepines used primarily for their sedative or hypnotic effects
Benzodiazepines used primarily for the treatment of
Benzodiazepines are absorbed rapidly and completely
from the GI tract and are distributed widely in the body. Penetration into the
brain also occurs rapidly. Some benzodiazepines, such as diaze-pam and
lorazepam, may also be given parenterally.
The duration of effect is determined by the extent
of distribution. Triazolam binds quickly to fat and is widely distributed;
therefore, it has a short duration of action.
All benzodiazepines are metabolized in the liver
and excreted pri-marily in urine. Some benzodiazepines have active metabolites,
which may give these drugs a longer period of action.
Researchers believe that benzodiazepines work by
stimulating gamma-aminobutyric acid (GABA) receptors in the ascending reticular
activating system (RAS) of the brain. The RAS is associ-ated with wakefulness
and attention and includes the cerebral cortex and limbic, thalamic, and
hypothalamic levels of the cen-tral nervous system (CNS). (See How benzodiazepines work)
At low dosages, benzodiazepines decrease anxiety by
acting on the limbic system and other areas of the brain that help regulate
emotional activity. The drugs can usually calm or sedate the pa-tient without
At higher dosages, benzodiazepines induce sleep,
probably be-cause they depress the RAS of the brain.
Benzodiazepines increase total sleep time and
reduce the number of awakenings. In most cases, benzodiazepines don’t decrease
the time spent in rapid-eye-movement (REM) sleep, the state of sleep in which
brain activity resembles the activity it shows when awake; the body’s muscles
relax, and the eyes move rapidly. Be-cause benzodiazepines don’t decrease the
duration of REM sleep, they have a significant advantage over barbiturates.
During each sleep cycle the sleeping person
progresses from stage 1, which is drowsiness, to stages 3 and 4, which are
deep-sleep stages. Benzodiazepines reduce the amount of time spent in stages 3
and 4. The decrease in stage 4 sleep is accompanied by a reduction in
Clinical indications for benzodiazepines include:
relaxing the patient during the day of or before surgery
producing I.V. anesthesia
treating alcohol withdrawal symptoms
treating anxiety and seizure disorders
producing skeletal muscle relaxation.
Except for other CNS depressants such as alcohol,
few drugs in-teract with benzodiazepines.
When benzodiazepines are taken with other CNS
depressants (in-cluding alcohol and anticonvulsants), the result is enhanced
seda-tive and CNS depressant effects, including reduced level of
con-sciousness, reduced muscle coordination, respiratory depression, and death.
Hormonal contraceptives may reduce the metabolism
of fluraze pam hydrochloride, increasing the risk of toxicity.
Triazolam may be affected by inhibitors of the
CYP3A system (such as erythromycin and ketoconazole). (See Adverse reactionsto benzodiazepines.)