Effect of ascorbate on the toxicity of morphine in mice

The effects of ascorbic acid on the toxicity of morphine in mice were investigated. An intraperitoneal dose of sodium ascorbate (1 G/kg) injected 10 min prior to morphine (500 mg/kg, i.p.) was found to provide significant protection against mortality due to respiratory depression, while having no effect on the lethality of the pentobarbital. Pretreatment with ascorbate had no effect on the distribution of morphine in brain tissue, nor did it alter the pH of the plasma. Administration of ascorbate in vivo also produced no inactivation of binding to opioid receptors. It is postulated that ascorbate antagonizes the lethality of morphine by selectively affecting neuronal activity.