<prompt> Respiratory depression is caused by NEOpiumBarbiturateStrychnineGelsemine  <response>: C i.e. Strychnine Strychnine is a CNS and respiratory stimulantQ. Alcohol, barbiturates, opioidsQ, benzodiazepines, chloral hydrate, paraldehyde, mandrax melsedine, heroin brown sugar, general anesthetics, sedative hypnotics are CNS depressants. However few may initially stimulate CNS. Hallucinogens LSD peyote mescaline phencyclidine, ecstasy, khat catha edulis, cocaine and amphetamine are CNS stimulants psychotropics. 