This section is from the book "A Text-Book Of Pharmacology, Therapeutics And Materia Medica", by T. Lauder Brunton. Also available from Amazon: A text-book of pharmacology, therapeutics and materia medica.
The following drugs belong to this class :Depress without marked previous excitement.
Excite first and afterwards paralyse.
Such substances as morphine, chloral, etc, which diminish the conducting power of the grey matter of the cord for painful impressions, are useful as anodynes, though their action in lessening pain is probably often due to their effect on the brain as well as on the spinal cord. Spinal depressants which lessen reflex action are employed in diseases where there seems to be increased excitability of various parts of the cord, as evidenced by spasm, either tonic or clonic. They are therefore employed in tetanus, trismus neonatorum, chorea, writer's cramp, and paralysis agitans. The pathology of many nervous diseases is imperfectly known, and as the action of spinal depressants is frequently a complex one of combined stimulation and depression, some of the drugs included in this class are used in paraplegia due to myelitis, locomotor ataxy, and general paralysis.