Distribution experimentsin vitroandin vivowith bromisoval and carbromal have shown carbromal to be more lipophilic and cumulative in brain and fat tissue. The half‐life of bromisoval in the rat is approximately 2·5 h, that of carbromal is longer and variable. Stimulation and inhibition experiments revealed that both drugs are metabolized and follow different patterns. Carbromal toxicity is enhanced by bromide treatment, whereas bromisoval toxicity is not. The results show that carbromal is more toxic than bromisoval for the r