Methyprylon (brand name Noludar) is a sedative agent, which used to treat insomnia. But then the drug was replaced in the market by another drugs with less side effects. The precise mechanism of action is not known, but was made suggestion, that methyprylon increases the effects of gamma-aminobutyric acid (GABA), an inhibitory neurotransmitter in the brain.

HEPTABARBITAL is an intermediate or short term barbiturate. It binds to the GABAA receptor at either the alpha or the beta subunit. This GABAA receptor binding decreases input resistance, depresses burst and tonic firing, especially in ventrobasal and intralaminar neurons, while at the same time increasing burst duration and mean conductance at individual chloride channels; this increases both the amplitude and decay time of inhibitory postsynaptic currents. HEPTABARBITAL was formerly used as a sedative and hypnotic drug.

Talbutal is a short to intermediate-acting barbiturate, which had been used under brand name Latusate as a sedative and hypnotic, but then this usage was discontinued. It was found, that talbutal binds at a distinct binding site at the GABAA receptor, increasing the duration of time for which the Cl- ionopore is open. Thus, the post-synaptic inhibitory effect of GABA in the thalamus is, therefore, prolonged.

Meparfynol is a tertiary hexanol and potent tranquilizer with hypnotic/sedative and anticonvulsant effects and exceptionally low therapeutic index. It was discovered by Bayer in 1913 and was used shortly thereafter for the treatment of insomnia, but its use was quickly phased out in response to newer drugs with far more favorable safety profiles. Meparfynol depresses monosynaptic and polysynaptic reflexes and exerted weak ganglion and neuromuscular blocking actions. Meparfynol also produces transitory hypotension, an increase of aortic blood flow. Perfusion of the coronary arteries with Meparfynol led to a slowing of the heart, diminished systolic amplitude, dysrhythmias, and increased coronary flow. Respiration was stimulated with small and depressed with larger doses of Meparfynol.

Pyrithyldione is a sedative and hypnotic drug. It was demonstrated that drug has certain advantages over the barbiturates. It was indicated in mild cases of insomnia and in small doses as a sedative agent during the day. Pyrithyldione was withdrawn from the marked due to several cases of agranulocytosis.

Sodium thiopental (also known as Sodium Pentothal, thiopental) was discovered in 1930s by investigators working for Abbott Laboratories. Thiopental sodium was used for the induction of general anesthesia and is used as an adjunct to provide hypnosis during balanced anesthesia with other anesthetic agents, including analgesics and muscle relaxants. Thiopental sodium was also used as an adjunct for control of convulsive disorders of various etiology, including those caused by local anesthetics. Finally, thiopental sodium had been used to reduce the intracranial pressure in patients with increased intracranial pressure, if controlled ventilation is provided. Nevertheless, these prescriptions of drug were discontinued. In addition, this drug was banned for use in US executions. Thiopental sodium acts through the CNS with particular activity in the mesencephalic reticular activating system. It was shown, that mechanism of action of sodium thiopental via GABAA receptor. Thiopental binds at a distinct binding 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.

AMOBARBITAL is a barbiturate derivative with hypnotic and sedative properties. In an in vitro study in rat thalamic slices amobarbital worked by activating GABAA receptors, which decreased input resistance, depressed burst and tonic firing, especially in ventrobasal and intralaminar neurons, while at the same time increasing burst duration and mean conductance at individual chloride channels; this increased both the amplitude and decay time of inhibitory postsynaptic currents. Adverse effects are mainly a consequence of dose-related CNS depression and the risk of dependence with continued use is high.

Butethal is a sedative and a hypnotic drug indicated for the treatment of severe intractable insomnia. It acts on receptors in the brain (GABA A receptors) causing the release of the chemical GABA. This chemical inhibits certain areas of the brain resulting in sleepiness. Common side effects are: drowsiness, sedation, unsteadiness, vertigo and inco- ordination. Also, hangover effect, paradoxical excitement, confusion, memory defects and skin rashes. Interactions may occur with the following: adrenocorticoids (cortisone-like medicine), anticoagulants (blood thinners), carbamazepine, corticotropin (barbiturates may decrease the effects of these medicines), central nervous system (CNS) depressants (using these medicines with barbiturates may result in increased CNS depressant effects), divalproex sodium, valproic acid (using these medicines with barbiturates may change the amount of either medicine that you need to take), and oral contraceptives containing estrogens (barbiturates may decrease the effectiveness of these oral contraceptives, and you may need to change to a different type of birth control).

Carbromal is containing bromide mild hypnotic that has been used to mild insomnia treatment. Carbromal is one of a number of hypnotics containing bromide, which releases the bromide ion on hydrolysis in the body. It has no advantages over other hypnotics. Chronic administration can cause accumulation of bromide ions which have the same distribution as chloride ions but are not actively transported out of cells and are excreted in the urine with a half-life of 10-12 days. Bromism may result from chronic carbromal ingestion and with a plasma bromine concentration of 10-15 mM, the signs are acne, cerebral retardation, cerebellar dysfunction, hyperreflexia, extensor plantar responses, and gastro¬intestinal symptoms. The risk of bromism developing makes carbromal a more dangerous drug than most other hypnotics.

Paraldehyde is the cyclic trimer of acetaldehyde molecules. It was introduced into clinical practice in the UK by the Italian physician Vincenzo Cervello in 1882. It is a central nervous system depressant and was soon found to be an effective anticonvulsant, hypnotic and sedative. It was included in some cough medicines as an expectorant (though there is no known mechanism for this function beyond the placebo effect). Paraldehyde also has been used in the treatment of alcoholism and in the treatment of nervous and mental conditions to calm or relax patients who are nervous or tense and to produce sleep. However, this medicine has generally been replaced by safer and more effective medicines for the treatment of alcoholism and in the treatment of nervous and mental conditions.