104 Section 2/ Drugs Acting on CNSFLUOXETINE
A potent antidepressant drug, it does not
cause sedation. In CNS it inhibits the neu-
ronal uptake of 5-HT. It shows negligible
binding to histaminergic, muscarinic, α 1 adr-
energic receptors, so it is devoid of anticho-
linergic and hypotensive side effects.
After oral administration the drug is con-
verted to norfluoxetine which has a very
long lasting biological activity.
Adverse effects include drowsiness,
skin rash, insomnia, anxiety, weakness, fa-
tigue, nausea, anorexia, epigastric distress,
diarrhoea, tremor and sweating.
It is used in the treatment of depression
where sedation is not required and for pro-
phylaxis of recurrent depression.
MOOD STABILIZERS (ANTIMANIC DRUGS)LITHIUM CARBONATE
It has narrow therapeutic index and treat-
ment requires facility for therapeutic moni-
toring of serum lithium levels.
Exact mechanism of action is unknown.
It brings the patient of mania towards nor-
mal. Lithium decreases the neuronal uptake
of dopamine and noradrenaline and their
synthesis. It increases the rate of 5-HT syn-
thesis in brain. On continuous therapy cy-
clic mood changes are prevented.
It also inhibits ADH action on distal tu-
bules (diabetes insipidus like state), also has
insulin like action on glucose metabolism
and decreases thyroxine synthesis by inter-
fering with iodination of thyroxine.
After oral administration it is well ab-
sorbed and is not protein bound. It not
metabolised and is excreted mainly in urine
and it inhibits the reabsorption of sodium
in renal tubules. It has narrow margin of
safety.
Adverse effects include nausea, vomit-
ing, epigastric distress, polydipsia, polyuria,
diarrhoea, dizziness, ataxia, nystagums,
hyper-reflexia, arrhythmias, skin rash, gly-
cosuria and blurred vision.
It is indicated in acute hypomania, ma-
nia, recurrent mania, depression – cyclic
and recurring, unipolar depression, bipo-
lar depression, schizoaffective psychosis,
mental depression, cluster headache, che-
motherapy induced leukopenia and
agranulocytosis.