• Nervous system: It is used in insomnia and irritative conditions of the central nervous system. It causes depletion of catecholamines at the central and peripheral level and depletion of Serotonin at the central level.

• Digestive system: root is a valuable remedy for dysentery and painful affections of bowel.

• Reproductive system: decoction of root is applied to increase uterine contractions and promote expulsion of fetus.

• Eyes: juice of leaves is instilled in eyes as a remedy for the opacities of cornea.

Role of reserpine compound present in Sarpgandha on central nervous system:
Reserpine works both in the central and the peripheral nervous systems to deplete stores of neurotransmitters: dopamine and norepinephrine at central and peripheral synapses, epinephrine in the adrenal glands, and serotonin (5-HT) in the CNS. 

A high dose of the drug might cause an initial effect stemming from the release of neurotransmitters, though this isn't usually clinically significant. Reserpine irreversibly damages the intracellular vesicles in which neurotransmitters are stored. The existing neurotransmitters leak out of the vesicles inside the neuron and are destroyed by MAO. Newly formed neurotransmitters can't be stored for later release. The drug has a long duration of action because new vesicles must be synthesized to start storing neurotransmitters once again--the old ones which have encountered the drug are permanently broken.

With vastly lowered catecholamines stores in adrenergic nerves and in the heart, heart rate is slowed and peripheral vascular tone is reduced (capillaries and arterioles open up). This causes a reduction in blood pressure. In the central nervous system, the depletion of dopamine tends to cause sedation and ameliorate some of the symptoms of schizophrenia (more modern antipsychotic drugs block one or more types of dopamine receptors--clearly you can get a similar effect either by blocking a receptor for a neurotransmitter or by removing the neurotransmitter.)

Use of Sarpgandha in hypertension
In a controlled intervention trial, 389 subjects, ages 21-55 years, with diastolic blood pressures 90-115 mm Hg were examined for 7-10 years. Subjects were randomly assigned to either a combination of a diuretic and Rauwolfia Serpentina, or an identical placebo. Diastolic blood pressure was reduced an average of 10 mm Hg and systolic by16 mm Hg in the active treatment group, with no change in the placebo group.

The Rauwolfia constituent ajmaline not only lowers blood pressure, but also has a potent anti arrhythmic effect. Studies have shown that ajmaline specifically depresses intraventricular conduction, suggesting this would be particularly effective in the treatment of re-entrant ventricular arrhythmias. In one study of 100 patients with essential hypertension, it was determined that serum cadmium levels were 43-percent higher and serum zinc levels 28-percent lower in hypertensives when compared with normotensive controls. When the patients were put on ajmaline, a preparation from Rauwolfia Serpentina, blood pressure was lowered significantly. It also appeared to decrease the elevated serum cadmium levels in these individuals

Dose: 1-2 Gms

Capsule Sarpgandha contains pure powder of Sarpgandha
Dosage: one capsule once a day.
Package 30 capsules

References

1. Dr.KM Nadkarni, The Indian Materia Medica, Vol.I, pg 1050 
2. Prof.P.V Sharma, Dravya Guna Vigyana, Vol II, pg36