All of the following statements concerning barbiturates are true EXCEPT one. Which one is the exception?

• Correct answer

  Barbiturates may increase the half-lives of drugs metabolized by the liver

• Barbiturates depress neuronal activily by increasing membrane ion conductance (primarily chloride), reducing glutamate-induced depolarizations and potentiating the inhibitory effects of GABA

• Compared with benzodiazepines, the barbiturates exhibit a steeper dose-response relationship

• Barbiturates may precipitate acute porphyria in susceptible patients