Final answer:
Barbiturates and Methaqualone are depressants that suppress central nervous system activity. They act as agonists of the GABA neurotransmitter system and are prescribed to treat anxiety and insomnia.
Step-by-step explanation:
Barbiturates and Methaqualone are depressants. Depressants are drugs that tend to suppress central nervous system activity, leading to a lowering of neurotransmission levels in various areas of the brain. These drugs have a quieting effect on the brain by serving as agonists of the gamma-Aminobutyric acid (GABA) neurotransmitter system. They are often prescribed to treat anxiety and insomnia