Methaqualone is a depressant that modulates the activity of the GABA receptors in the brain and nervous system. It promotes relaxation, sleepiness and sometimes a feeling of euphoria. It causes a drop in blood pressure and slows the pulse rate. These properties are the reason why it was initially thought to be a useful sedative and anxiolytic. Common side effects of Methaqualone include dizziness, nausea, vomiting, diarrhea, abdominal cramps, fatigue, itching, rashes, sweating, dry mouth, tingling sensation in arms and legs, seizures and its depressant effects include reduced heart rate and respiration. The drug became banned in many countries and was withdrawn from many markets in the early 1980s.

VINBARBITAL, a barbiturate derivative, is a hypnotic drug. Also, it was used for analgesia and anesthesia in obstetrics.

Hexobarbital or hexobarbitone, (sold both in acid and sodium salt, brand name Evipan, and Tobinal), is a barbiturate derivative having hypnotic and sedative effects. It was used in the 1940s and 1950s as an agent for inducing anesthesia for surgery, as well as a rapid-acting, short-lasting hypnotic for general use, and has a relatively fast onset of effects and short duration of action. It was also used to murder women prisoners at Ravensbruck Concentration Camp. Modern barbiturates (such as Thiopental) has largely supplanted the use of hexobarbital as an anesthetic, as they allow for better control of the depth of anesthesia. Hexobarbital is still used in some scientific research. Hexobarbital binds at a distinct binding site associated with a Cl- ionophore at the GABA-A receptor, increasing the duration of time for which the Cl- ionophore is open. The post-synaptic inhibitory effect of GABA in the thalamus is, therefore, prolonged.

Secobarbital sodium, a barbiturate, is FDA approved for the treatment of insomnia and for pre-anesthetic use. This drug binds at a distinct site associated with a Cl- ionopore at the GABAA receptor, increasing the duration of time for which the Cl- ionopore is open. The post-synaptic inhibitory effect of GABA in the thalamus is, therefore, prolonged. Adverse reactions are drowsiness, lethargy, hangover, paradoxical excitement in elderly patients, somnolence. Rifampin may decrease secobarbital levels by increasing metabolism.

Proxibarbal is a non-sedative barbiturate with a specific anti-serotonin and anti-histamine effect, due to enzyme induction of serotoninase and histaminase. Its lack of unpleasant side-effects. Proxibarbal exists in ring-chain tautomeric equilibrium with the two diastereomers of valofan. Proxibarbal is metabolized to a five-membered lactone. Its only barbituric property is its ability to induce enzymes that destroy a surplus of neurohormones and rid people of their neurovegetative sufferings, including migraine and other types of vascular headache. Side effects are: dizziness, drowsiness, dyspepsia, allergic reactions. Proxibarbal enhances the effects of other depriving agents, including alcohol.

CHLORAL HYDRATE ANTIPYRINE is a 1:1 mixture of antipyrine with chloral hydrate. It was used as a hypnotic drug known as HYPNAL in the late 19th century.