Final answer:
When drugs like barbiturates or tranquilizers are mixed with alcohol, their effects are multiplied due to a synergistic effect.
Step-by-step explanation:
When drugs like barbiturates or tranquilizers are mixed with alcohol, their effects are multiplied due to a synergistic effect. This means that the combined effects of these drugs are greater than the sum of their individual effects. The interaction between barbiturates, tranquilizers, and alcohol can lead to dangerous levels of central nervous system depression and respiratory suppression.