Reserpine

It is a plant alkaloid derived from the roots of plant Rauwolfia Serpentina.

Mechanism of action:
Reserpine works to prevent neuronal and chromaffin granule transporters by Mg2+/ATP dependent transport mechanism.
As a consequence accumulation of catecholamine transmitters by adrenergic transmitter vesicles is prevented resulting in great depletion of transmitters in both central and peripheral neurons that can remain for days to weeks. Monoamine oxidase has the ability of degrading norepinephrine in the cytoplasm.

It also exerts a direct vasodilating effect on vascular smooth muscles when administered intra-arterially.

Actions:
1. It causes sedation due to depletion of biogenic amines centrally.
2. It decreases cardiac rate, cardiac output and blood pressure.
3. It may also decrease peripheral vascular resistance.
4. It partially prevents cardiovascular reflexes.

Its effects appear to be irreversible.

Pharmacokinetics:
The drug is absorbed poorly from the G.I. Tract. It has slow onset of action and long duration of action.

Therapeutic uses:
1. In combination with thiazide diuretics it is used to treat mild to moderate hypertension and is mostly used in condition when no other anti-hypertensive agent showing affect.
2. Insomnia
3. It was used to treat snakebites
4. Insanity

Adverse effects:
Drowsiness, Sedation, lassitude, depression, bradycardia, diarrhea, Gastric acid secretion, Nasal congestion, Nausea, vomiting

Contraindications:
• Peptic ulcer
• Parkinsonism
• Pheochromocytoma

Precautions:
It must be used with caution in patients of depression as it may aggravate this condition.