Strychnine: properties, toxicity, history and uses

Chemical and physical characteristics

Purified strychnine is a complex organic molecule classified as an alkaloid. In its pure form it appears as colorless to white crystals with a very bitter taste. Chemically and pharmacologically it behaves like other indole alkaloids but has a distinctive rigid polycyclic structure that presented a major challenge to early structural chemists. The appearance and crystalline nature are often noted in chemical descriptions (crystalline form) and it is commonly referred to broadly as an alkaloid.

Strychnine is readily soluble in many organic solvents and only sparingly soluble in water. Typical solvent behavior includes good solubility in ethanol and chloroform but low water solubility, which affects both its historic use and methods of detection: soluble in alcohol, soluble in chloroform, and poorly soluble in water. Toxicity metrics are extreme: animal studies report lethal-dose measures in the low milligram-per-kilogram range and human fatalities can occur after small milligram exposures; see general discussions of LD50 and lethal dose.

Mechanism of action and clinical effects

Strychnine acts on the central nervous system, primarily by interfering with inhibitory neurotransmission in the spinal cord and brainstem. It antagonizes glycine-mediated inhibition, which leads to increased reflex excitability and severe, painful muscle spasms. Clinically this produces heightened sensitivity to stimuli, violent convulsions, a characteristic opisthotonic posture, and risk of respiratory failure from sustained muscle contraction. Although historically it was sometimes used in very small doses as a nervous system stimulant, that use is now obsolete and dangerous: see comparisons with mild stimulants such as caffeine and historical stimulant references at stimulant uses.

History, synthesis and scientific significance

Isolations of strychnine and brucine were reported during the 1800s as part of the rising field of natural product chemistry. Determining the molecule's exact arrangement of atoms required advances in analytical methods and synthetic chemistry; the structure was elucidated by mid-century researchers and became a landmark problem in organic chemistry. Subsequent total syntheses and studies of its three-dimensional shape helped shape tactics in synthetic organic chemistry and inspired numerous mechanistic investigations. For context on its chemical and forensic study see resources on analytical detection and synthetic history at chemical literature.

Uses, regulation and forensic importance

Historically strychnine was used as a pesticide and rodenticide and to control other small animals. It was applied to control populations of small vertebrates and birds, though its nonselective lethality and environmental persistence led to heavy regulation and the decline of such uses in many countries. Examples of these applications are summarized in regulatory and pest-control texts: small vertebrate control, use against birds, and use against rodents. Modern laws restrict its sale and use in many jurisdictions and require careful handling where permitted.

Treatment of poisoning and forensic detection

Because strychnine poisoning causes life-threatening convulsions, emergency care focuses on airway protection, control of seizures, and supportive measures. Benzodiazepines and other anticonvulsants are commonly used to suppress spasms; severe cases may require mechanical ventilation and intensive care. Decontamination and toxin removal (activated charcoal early after ingestion) and specialized testing of blood, urine, or tissue samples are used in diagnosis and forensic investigations. Analytical laboratories use solvent extraction and sensitive chromatographic methods to identify strychnine in biological specimens; for protocols and detection strategies consult general forensic toxicology guides at plant and toxin references and analytical resources at toxicology methods.

• Related compounds: brucine (less acutely toxic) and other Strychnos alkaloids.
• Risks: small quantities can be fatal; accidental or intentional poisonings require urgent treatment.
• Modern status: largely removed from routine medicinal use and tightly regulated as a pesticide or research chemical.

For further introductory material and primary references, including agricultural, clinical and chemical perspectives, consult specialist texts and databases that cover natural toxicants, forensic toxicology and pesticide regulation: see basic references at ecology, chemical data, pharmacology, and regulatory summaries at pesticide law and sports testing lists.