Pharmacology for Dentistry

Sedative & Hypnotics 73

It is rapidly absorbed following intra-
muscular administration with more than 90
percent bioavailability.

Adverse effects include local effects like
redness and phlebitis, apnoea (usually seen
on IV administration). Rarely nausea, vom-
iting, headache, drowsiness, hiccups and
retrograde amnesia may occur.

It is indicated for preoperative sedation,
conscious sedation prior to short diagnostic
or endoscopic procedures, induction of gen-
eral anaesthesia prior to administration of
other anaesthetic agents.

ALPRAZOLAM

CNS agents of the 1,4 benzodiazepine
class presumably exert their effects by
binding at stereo specific receptors at
several sites within the central nervous
system (CNS). Alprazolam like other
benzodiazepines exerts its anxiolytic
action by potentiating GABA activity.
GABA is a neurotransmitter which inhib-
its the CNS activity. Alprazolam acts
preferentially in midbrain, ascending
reticular formation (which maintains
wakefulness) and on limbic system
(thought and mental functions).

The pharmacological effects of
alprazolam do not differ appreciably
from those of diazepam. However,
alprazolam is about 10 times more potent
than diazepam.

Following oral administration, alprazolam
is readily absorbed. Peak concentration in the
plasma occur in one to two hours following
administration. Alprazolam and its metabo-
lites are excreted primarily in the urine.
Alprazolam is 80% bound to plasma proteins.

Alprazolam has caused a lower inci-

dence of drowsiness, light-headedness and

depression than diazepam. Alprazolam, like

other benzodiazepines, has the potential for

the development of tolerance and with-

drawal symptoms, although the incidence

is lower than that seen with other benzodi-

azepines. Alprazolam’s potential for drug

dependence is less in comparison to other

benzodiazepines.

It is used in the management of

generalised anxiety disorder or the short

term relief of symptoms of anxiety. It is also

indicated for the treatment of panic disor-

ders with or without agoraphobia.

CHLORDIAZEPOXIDE

It is the first benzodiazepine used clini-

cally. Adverse effects include nausea, ver-

tigo, headache and skin rash.

It is indicated in fear, anxiety, tension,

pre and postoperative apprehension

behavioural disorders, insomnia and emo-

tional disturbances.

CLONAZEPAM

It acts by enhancing GABA induced in-

crease in conductance of chloride in neurons.

After oral administration, over 80 per-

cent of clonazepam is absorbed. It is exten-

sively bound to plasma proteins and is

widely distributed. It is metabolised and the

metabolites are excreted in urine.

Adverse effects include impaired alert-

ness, amnesia, drowsiness, lethargy, respi-

ratory depression, salivary and bronchial

hypersecretion in infants, behavioural prob-

lems, muscle weakness, vertigo, ataxia and

dizziness.