Psychotropic Agents 101- MAO inhibitors along with barbitu-
rates, alcohol, narcotic analgesic can en-
hance and prolong the action of these
drugs. - Potentiate the toxic effects of tricyclic
antidepressants. - It’s use with anticholinergic antiparkin-
sonian drugs can lead symptoms simi-
lar to atropine poisoning.
Because of their toxic effects and seri-
ous interactions, they are not commonly
used. However, a new selective inhibitor is
used clinically.
MOCLOBEMIDE
It is a reversible and selective MAO-A
inhibitor used in the major depression. It is
devoid of anticholinergic, sedative and car-
diovascular effects of TCAs.
Side effects include sleep disturbances,
dizziness, nausea, headache, restlessness,
agitation, confusion state and nausea.
TRICYCLIC ANTIDEPRESSANTSTricyclic antidepressants are the most
commonly used drugs. They produce an-
tidepressant effect by blocking the neu-
ronal uptake of noradrenaline and exert
anti-cholinergic activity. They also inhibit
neuronal uptake of 5HT and dopamine.
The exact mechanism of action is not
known. The antidepressant effect is no-
ticed after three to four weeks of drug ad-
ministration.
TCAs lower seizure threshold and
overdose leads to convulsions. The side
effects are due to anticholinergic effect
leading to dry mouth, blurring of vision,
constipation, urinary hesitancy and tachy-
cardia. They also lead to postural hypoten-
sion due to a 1 blockade and inhibition of
cardiovascular reflexes. They also produce
T wave suppression or inversion. Oral
absorption is good and they are highly
bound to plasma proteins. They are exten-
sively metabolized in liver and metabo-
lites are excreted in urine.IMIPRAMINE
It is an efficacious drug in alleviating
depression. When the drug is given to de-
pressed patients, elevation of mood occurs
in about three weeks. Tolerance to anticho-
linergic effects occurs with continued use of
imipramine.
It is highly protein bound and is metabo-
lized to pharmacologically active metabo-
lite. It crosses placental barrier.
Adverse effects include dry mouth, ta-
chycardia, palpitation, impotence, constipa-
tion, difficulty in accommodation, rarely hy-
perpyrexia and paralytic ileus; lethargy,
headache, drowsiness, tremors, ataxia, sweat-
ing, convulsion, urticaria, skin rash, pruritus,
cholestatic jaundice, cardiac arrhythmias,
orthostatic hypotension, agranulocytosis,
gynaecomastia, galactorrhoea and depen-
dence; loss of weight or gain.
It is indicated in all types of depression,
nocturnal enuresis, intractable chronic pain,
narcolepsy, chorea, cachexia, mood distur-
bances and sleep apnoea syndrome.AMITRIPTYLINE
It causes sedation and after oral admin-
istration it is metabolised to nortriptyline
which is active form.
Adverse effects include epigastric dis-
tress, sedation, drowsiness, orthostatic hy-