Strychnine (C21H22N2O2 = 331.73) is an alkaloid derived from the dried ripe seed of Strychnos Nux Vomica, a tree indigenous to southeastern Asia.

Pharmacodynamics.

Central Nervous System. - Strychnine remarkably heightens synaptic conductivity in the anterior columns of the spinal cord, extending motor response and disrupting normal co-ordinating influences. It also greatly intensifies sensory irritability. It increases cerebral reflexes, especially those of the special senses.

Muscular System. - Strychnine has no direct action on voluntary muscle, but indirectly stimulates involuntary muscle.

Respiration. - Strychnine slightly quickens and deepens respiration, when administered in small doses. Poisonous doses produce asphyxia by spasm of the respiratory muscles.

Heart is not affected directly.

Blood-pressure. - Strychnine stimulates the vasomotor centers, raising slightly the blood-pressure through constrictor action in the splanchnic area, which is not offset by the peripheral dilatation.

Alimentary Tract. - Strychnine stimulates the flow of saliva.

Metabolism. - Oxidation is augmented by strychnine.

Temperature is slightly increased from the advanced oxidation.

Absorption takes place rapidly from the alimentary tract and from the subcutaneous tissues.

Excretion is mainly via kidneys, and is much prolonged (2 to 8 clays), though the greater part is eliminated in a few hours.

Tolerance is not acquirable; in fact, susceptibility to strychnine action seems to increase with its use.

Symptoms.

Therapeutic Doses. Improved appetite. Cheerfulness. Accentuated color-sense. Extended field of vision. Sharpened sense of hearing. More delicate tactility.

Poisonous Doses. Tense muscles of face and neck. Heightened reflex irritability. Restlessness. Involuntary tremors. Convulsive movements.

Risus sardonicus.

Facial cyanosis.

Opisthotonus.

Asphyxia and exhaustion.

Therapeutics.

The principal indication for Strychnine is as a stimulant for the central nervous system.

Dosage.

Strychnina, 0.0006 to 0.002 Gm. Strychninae Sulphas, 0.0006 to 0.002 Gm. Tinctura Nucis Vomicae, 0.3 to 1.2 mil.