Depression, Causes, Anti-depression, Mechanism of Action, Lithium carbonate.

1. ANTI-DEPRESSANTS
PRESENTED BY:
GRACE SHAJI CHITTILAPPILLY
ASSISTANT PROFESSOR
DEPT. OF PHARMACEUTICAL CHEMISTRY
KARPAGAM COLLEGE OF PHARMACY, COIMBATORE - 32

2. CONTENTS
• INTRODUCTION
• MECHANISM OF ACTION
• LITHIUM CARBONATE

3. INTRODUCTION
• Depression is a severe psychiatric or mental illness characterized by
excessive sadness.
• It is a serious condition that can affect a person’s normal social life,
eating and sleeping habits.
• It is associated with delusions, hallucinations (psychotic depression)
and suicidal tendencies.
• It may range from mild conditions to severe depression.
• It has a strong genetic predisposition.

4. • Antidepressants are the drugs which elevate the mood in depressed patients and
hence they are also known as mood elevators.
• They act by increasing the neuronal transmission (synaptic availability) of
monoamines in CNS and periphery.
• Common side-effects of antidepressants include dry mouth, weight gain,
dizziness, headaches, sexual dysfunction and emotional blunting.
• There is slight increased risk of suicidal thinking and behavior when taken by
children, adolescents and young adults.
• Withdrawal syndrome can occur after stopping any antidepressant which
resembles recurrent depression.

5. MECHANISM OF ACTION
• Antidepressants commonly act by inhibiting monoamine reuptake or by
inhibiting monoamine oxidase (MAO).
• Lithium carbonate is an Monoamine oxidase inhibitor (MAOIs).
• MAO is a mitochondrial enzyme found in nerve and other tissues.
• Mechanism of Action:
Nor-epinephrine, serotonin and dopamine.
No break down of nor-epinephrine, serotonin and dopamine.
Monoamine oxidase inhibitor

6. Increasing the concentration of all three neurotransmitters in the brain.
Inactivate the enzymes by making stable complexes with the enzymes.
Permitting neurotransmitter molecules to escape degradation and accumulate within
synaptic cleft.
Cause activation of nor-epinephrine and serotonin receptors responsible for
antidepressant action.

8. LITHIUM CARBONATE
Molecular formula: Li2CO3
Molecular weight: 73.9 g/mole
Method of Preparation
LiOH CO2
Li2CO3
H2O
Lithium
hydroxide
Lithium
carbonate
+ +
2LiCl Na2CO3
Li2CO3 2NaCl
Lithium
chloride
Sodium
carbonate
Lithium
carbonate
+ +

9. Physical Properties
 Colour: White
 Odour: Odourless
 Taste: Slightly alkaline
 State: Crystalline or granular powder
 Solubility: Sparingly soluble in water, less soluble in boiling water and insoluble
in ethanol (95%).
Li2SO4 (NH4)2CO3
Li2CO3 (NH4)2SO4
Lithium
sulphate
Ammonium
carbonate
Lithium
carbonate
Ammonium
sulphate
+ +

10. Identification Test
1. Lithium carbonate + HCl introduced on a platinum wire red colour
to non-luminous flame.
2. 0.2g Li2CO3 + 1ml HCl
The residue obtained dissolves in 3ml of 95% ethanol
3. Carbonates
Sample + Magnesium sulphate solution, heat
White precipitate
Evaporate to dryness on a water bath

11. Test for Purity
 Appearance of solution
Arsenic
Calcium and magnesium
 Heavy metals
 Iron
 Potassium
 Sodium
 Chlorides
 Sulphates

12. Assay
• Method: Acid-base titration
0.5g Li2CO3 + 25ml 1M HCl
Titrate solution against 1M NaOH, using methyl orange as indicator
End point: Colour change from orange – red to yellow.
Li2CO3 2HCl 2LiCl H2O CO2
HCl NaOH NaCl H2O
+
+
+ +
+

13. Standards: not less than 98.5% and not more than 100.5% of Li2CO3.
Storage: Stored in a well closed container protected from moisture.
Uses
o First line drug in bipolar depressive disorder.
o Treatment of schizophrenia.

14. “Difficult roads lead to beautiful destination”