Nux Vomica Seed Powder (Strychnos nux-vomica)

Definition

Nux vomica is the dried ripe seed of Strychnos nux-vomica Linn., family Loganiaceae. It contains strychnine and brucine alkaloids and is highly toxic. The powder is greyish-white and intensely bitter — identification by microscopy is essential due to its dangerous alkaloid content.

General / Essential Features

Trichomes (seed hairs): unicellular, elongated, highly lignified with very thick walls and narrow lumen — the most diagnostic element; walls appear laminated (beaded) in optical section
Endosperm cells: polygonal cells with thick walls containing aleurone grains (protein bodies) and fixed oil — NOTE: no starch (important differential)
Stone cells (sclereids): thick-walled, isodiametric with distinct pits — present in groups
Parenchyma cells: thin-walled, elongated with intercellular spaces
Absence of starch: distinguishes from many other seeds
Intensely bitter taste: due to strychnine and brucine

Sites

Strychnos nux-vomica: native to India, Sri Lanka, Myanmar, northern Australia
Major alkaloids: strychnine (2.5–3%) and brucine (1–1.5%) in endosperm
Official in IP as source of strychnine and brucine alkaloids
Ayurvedic use: Kupilu — after detoxification (shodhana) for paralysis and arthritis

Pathophysiology

Strychnine is a selective competitive antagonist at glycine receptors (inhibitory neurotransmitter) in the spinal cord and brainstem. Blockade leads to uninhibited motor neuron firing — generalised muscle spasms, opisthotonos, and convulsions. Death occurs from respiratory muscle spasm and hypoxia. The minimum lethal dose is approximately 1–2 mg/kg in adults. Brucine has weaker strychnine-like activity.

Etiology

Strychnine poisoning: intentional, accidental, or as a rodenticide
Homeopathic use: Nux vomica 30C for digestive complaints, irritability
Ayurvedic Shuddha Kupilu: used for neuromuscular disorders after detoxification
Adulteration of herbal products with nux vomica: reported public health concern

Clinical Features

Onset: 15–30 minutes after ingestion
Heightened sensory perception: sound, touch, light trigger muscle spasms
Generalised tonic-clonic convulsions: opisthotonos, risus sardonicus (sardonic grin)
Clear sensorium during convulsions — distinguishes from epilepsy
Death from respiratory paralysis or hyperthermia

Diagnosis

Microscopy: lignified thick-walled trichomes with laminated walls, aleurone-containing endosperm cells (no starch)
Mandelin test: strychnine + conc. H2SO4 + KMnO2 → violet colour
Fluorescence test: brucine fluoresces under UV light
HPLC: quantification; IP limit: strychnine ≥2.5%
Ash value: acid-insoluble ash ≤0.5% (IP specification)

Treatment

Diazepam IV: first-line for seizure control
Barbiturates (phenobarbitone IV) for refractory convulsions
Neuromuscular blockade + mechanical ventilation in severe cases
Activated charcoal 50 g if no convulsions and airway protected
No specific antidote — ICU supportive management
Avoid stimulation (noise, light, touch) — triggers further convulsions

References

Trease, G.E. & Evans, W.C. (2009). Pharmacognosy (16th ed.). Elsevier Saunders.
Kokate, C.K., Purohit, A.P., & Gokhale, S.B. (2020). Pharmacognosy (56th ed.). Nirali Prakashan.
Indian Pharmacopoeia Commission. (2018). Indian Pharmacopoeia 2018 (8th ed.). Government of India.