<prompt> Respiratory centre depression can be caused by all except:OpiumStrychnineBarbituratesGelsemium  <response>: Ref:Parikhs Textbook of Medical Jurisprudence 6e p10,57 Strychnine stimulates the respiratory centre whereas other drugs given the option like opioids, barbiturates and gelsemium cause respiratory depression. Gelsemium has been traditionally been used to treat pain and respiratory ailments. Toxic symptoms include giddiness, weakness, ptosis, dilated pupils and respiratory depression. 