52 yrs male presented with muscular stiffness and painful cramps. The face was drawn into a forced grimace ("sardonic grin," or risus sardonicus). Strychnine Poisoning was suspected; Strychnine is supposed to antagonize competitively

STRYCHNINE POISONINGMechanism of toxicity: Strychnine competitively antagonizes glycine, an inhibitory neurotransmitter released by post-synaptic inhibitory neurons in the spinal cord. Clinical presentation: Muscular stiffness and painful cramps precede generalized muscle contractions and opisthotonos.The face may be drawn into a forced grimace ("sardonic grin," or risus sardonicus).Repeated and prolonged muscle contractions often result in hypehermia, rhabdomyolysis, myoglobinuria, and renal failure.Hyperacusis, hyperalgesia, and increased visual stimulation.Death is usually caused by respiratory arrest owing to the intense contraction of the respiratory muscles.