Methohexital is an ultrashort-acting barbiturate widely used in dentistry because of its rapid onset, predictable effects, and short duration of action. It was marked under the name brevital sodium for the intravenous anaesthesia. It has also been commonly used to induce deep sedation. Like other barbiturates, methohexital exerts its effects through the gamma-aminobutyric acid (GABA) receptor complex. By binding to its own receptor on the complex, methohexital augments the inhibitory effect of GABA on neurons and additionally can exert a similar effect independent of GABA.

Nitrous oxide (N2O, laughing gas) was first discovered by the English scientist Joseph Priestly and has been used for more than 150 years. It has remained one of the most widely used anesthetics in both dental and medical applications. This small and simple inorganic chemical molecule has indisputable effects of analgesia, anxiolysis, and anesthesia that are of great clinical interest. As a general anesthetic, it is very weak and is generally not used as a single agent. It may be used as a carrier gas with oxygen in combination with more potent general inhalational gases for surgical anesthesia. In dentistry, it is commonly used as a single agent (with oxygen) for partial sedation, most commonly in pediatric dental populations. Findings to date indicate that the analgesic effect of N2O is opioid in nature, and, like morphine, may involve a myriad of neuromodulators in the spinal cord. The anxiolytic effect of N2O, on the other hand, resembles that of benzodiazepines and may be initiated at selected subunits of the gamma-aminobutyric acid type A (GABA(A)) receptor. Similarly, the anesthetic effect of N2O may involve actions at GABA(A) receptors and possibly at N-methyl-D-aspartate receptors as well.

Benzocaine is a local anesthetic. It acts by blocking voltage-gated sodium ion channels in nerve endings. Benzocaine is available over-the counter for local anesthesia of oral and pharyngeal mucous membranes (sore throat, cold sores, mouth ulcers, toothache, sore gums, denture irritation), otic pain, and as a local anesthetic for surgical or diagnostic procedures. As a spray, benzocaine is used for temporary relief of pain and itching associated with minor burns, sunburn, minor cuts or scrapes, insect bites, or minor skin irritations. Topical application of benzocaine to gums or mouth may cause rare, but serious and potentially fatal adverse effect methemoglobinemia.

Enflurane (2-chloro-1,1,2,-trifluoroethyl-difluoromethyl ether) is a halogenated ether structural isomer of isoflurane. Developed by Ross Terrell in 1963, it was first used clinically in 1966. It was increasingly used for inhalational anesthesia during the 1970s and 1980s but is no longer in common use. Clinically, enflurane produces a dose-related depression of myocardial contractility with an associated decrease in myocardial oxygen consumption. Between 2% and 5% of the inhaled dose is oxidized in the liver, producing fluoride ions and difluoromethoxy-difluoroacetic acid. This is significantly higher than the metabolism of its structural isomer isoflurane. The exact mechanism of the action of general anesthetics has not been delineated. Enflurane acts as a positive allosteric modulator of the GABAA, glycine, and 5-HT3 receptors, and as a negative allosteric modulator of the AMPA, kainate, and NMDA receptors, as well as of nicotinic acetylcholine receptors.

Halothane, USP is an inhalation anesthetic chemically designated 2-Bromo-2-chloro-1,1,1-trifluoroethane. Halothane, sold under the brand name Fluothane among others, is a general anesthetic. It can be used to start or maintain anesthesia. One of its benefits is that it does not increase the production of saliva which can be particularly useful in those who are difficult to intubate. Side effects include an irregular heartbeat, decreased effort to breath (respiratory depression), and liver problems. It should not be used in people with porphyria or a history of malignant hyperthermia either in themselves or their family members. It is unclear whether use during pregnancy is harmful to the baby, and it is not generally recommended for use during a cesarean section. Fluothane is no longer commercially available in the United States.

Aniledrine is a narcotic pain reliver. The drug was prescribed as an analgesic in anaesthesia (Leritine brand name), however, it is no longer available on the market. Although the exact mechanism is not fully understood, aniledrine appears to elicit its action by binding to endorphine receptors in CNS.

Thiamylal is a barbiturate that is administered intravenously for the production of complete anesthesia of short duration, for the induction of general anesthesia, or for inducing a hypnotic state. Thiamylal, a barbiturate, is used in combination with acetaminophen or aspirin and caffeine for its sedative and relaxant effects in the treatment of tension headaches, migraines, and pain. Barbiturates act as nonselective depressants of the central nervous system (CNS), capable of producing all levels of CNS mood alteration from excitation to mild sedation, hypnosis, and deep coma. In sufficiently high therapeutic doses, barbiturates induce anesthesia. Thiamylal 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.

Trichloroethylene (or TCE), a synthetic chemical that does not occur naturally in the environment. TCE is used to make chemicals. Additionally, it is used for spot removal in dry cleaning operations. TCE is the most common organic contaminant in groundwater. It was revealed that the compound was a human carcinogen that caused liver cancer, kidney cancer, and non-Hodgkin's lymphoma (NHL).

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.

Vinyl ether (divinyl ether) is a clear colorless liquid with a characteristic odor. Less dense than water. Vapors heavier than air. Toxic by inhalation. Leake and Chen in 1930 demonstrated that vinyl ether possessed anaesthetic properties, and in 1931 a purer and more stable product was prepared in the research laboratories of Merck and Co. by Ruigh and Major and was used as ananaesthetic on dogs by Knoefel, Guedel, and Leake. These investigators found that dogs were more easily anaesthetized by vinyl ether than by chloroform. They also found that the period of recovery was rapid and free from vomiting; moreover, they did not notice any significant pathological effect on the various organs.The first experiments on human beings were conducted in 1933 by Gelfan and Bell. The first extensive account of vinyl ether anaesthesia in man was published in 1934, when Goldschmidt et al. reported having used it in operations in 461 mixed cases. In all these cases vinyl ether appeared to have no undesirable effect on respiration, the circulation, the liver, or the kidneys. Vinyl ether was widely used in Europe and North America for at least 30 years, until it was replaced by halothane. Vinyl ether was marketed under the name of Vinethine in the United States, Vinesthine in the United Kingdom, and Vinydan in continental Europe. Vinyl ether outlasted many of the inhalation agents introduced in recent years, and served a very useful purpose until safer, non-flammable agents, became available in the mid1960s.