C H A P T E R 2 0
Anxiolytic and hypnotic agents
313
indications and special considerations. Such medications
include the following:
• Antihistamines (promethazine [
Phenergan
] and
trimeprazine [
Vallergan
] can be very sedating in some
people. They are used as preoperative medications and
postoperatively to decrease the need for narcotics.
• Buspirone (
Buspar
) (not available in Australia)
a newer antianxiety agent, has no sedative,
anticonvulsant or muscle relaxant properties, and
its mechanism of action is unknown. However, it
reduces the signs and symptoms of anxiety without
many of the CNS effects and severe adverse effects
associated with other anxiolytic drugs. It is rapidly
absorbed from the GI tract, metabolised in the liver
and excreted in urine.
• Chloral hydrate (generic) is frequently used to
produce nocturnal sedation or preoperative sedation.
Its mechanism of action is unknown. It is rapidly
absorbed from the GI tract and metabolised in the
liver and kidney for excretion in the bile and urine.
• Dexmedetomidine (
Precedex
) is given intravenously at
a starting dose of 1 mcg/kg over 10 minutes and then
a controlled infusion for up to 24 hours. It is used
for the sedation of newly intubated and mechanically
ventilated people in an intensive care unit.
• Zopiclone (
Imovane
) is a new agent used to treat
insomnia. It is thought to react with GABA sites near
benzodiazepine receptors. It is rapidly absorbed,
metabolised in the liver and excreted in the urine.
• Zolpidem (
Stilnox
) (not available in New Zealand) is
used for the short-term treatment of insomnia. It is
thought to work by affecting serotonin levels in the
sleep centre near the RAS. It is metabolised in the
liver and excreted in the urine.
CHAPTER SUMMARY
■■
Anxiolytics, or minor tranquillisers, are drugs used
to treat anxiety by depressing the CNS. When given
at higher doses, these drugs may be sedatives or
hypnotics.
■■
Sedatives block the awareness of and reaction to
environmental stimuli, resulting in associated CNS
depression that may cause drowsiness, lethargy and
other effects. This action can be beneficial when a
person is very excited or afraid.
■■
Hypnotics further depress the CNS, particularly
the RAS, to inhibit neuronal arousal and induce
sleep.
■■
Benzodiazepines are a group of drugs used as
anxiolytics. They react with GABA-inhibitory sites
to depress the CNS. They can cause drowsiness,
lethargy and other CNS effects.
TABLE 20.3
DRUGS IN FOCUS Other anxiolytic/hypnotic drugs
Drug name
Usual indications
buspirone (Buspar)
Oral drug for anxiety disorders; off-label use; signs and symptoms of premenstrual syndrome
Special considerations:
may cause dry mouth, headache; use with caution in people with
hepatic or renal impairment and in elderly people
chloral hydrate (generic)
Administered PO or PR for nocturnal sedation, preoperative sedation
Special considerations:
withdraw gradually over 2 weeks in people maintained for weeks or
months
dexmedetomidine
(Precedex)
IV drug used for newly intubated and mechanically ventilated people in the intensive care unit
Special considerations:
do not use longer than 24 hours; monitor person continually
promethazine (Phenergan)
PO, IM, or IV use to decrease the need for postoperative pain relief and for preoperative
sedation
Special considerations:
an antihistamine; monitor injection sites carefully; monitor people for
thickened respiratory secretions and breathing difficulties, a problem that can cause concern
after anaesthesia
trimeprazine (Vallergan)
Oral drug for sedation in children
Special considerations:
major component of dosage should be given at bedtime, or if daytime
doses are ordered, give directly after meals
zolpidem (Ambien,
Stilnox)
Oral drug for short-term treatment of insomnia
Special considerations:
dispense the least amount possible to depressed and/or suicidal
people; withdraw gradually if used for prolonged period; person should take before bed and
devote 4–8 hours to sleep; use with caution in people with hepatic or renal impairment; elderly
people are especially sensitive to these drugs—administer a lower dose and monitor these
people carefully
zopiclone (Imovane)
Oral drug for the treatment of insomnia
Special considerations:
tablet must be swallowed whole; instruct the person to take this drug
just before bed and allow 8 hours for sleep
