Pharmacology for Dentistry

(Ben Green) #1
Psychotropic Agents 101


  1. MAO inhibitors along with barbitu-
    rates, alcohol, narcotic analgesic can en-
    hance and prolong the action of these
    drugs.

  2. Potentiate the toxic effects of tricyclic
    antidepressants.

  3. 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 ANTIDEPRESSANTS

Tricyclic 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-
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