Isoflurane (1-chloro-2, 2,2-trifluoroethyl difluoromethyl ether) a nonflammable liquid administered by vaporizing, is a general inhalation anesthetic drug. Isoflurane is a clear, colorless, stable liquid containing no additives or chemical stabilizers. Similar to many general anesthetics, the exact mechanism of the action has not been clearly delineated. Isoflurane reduces pain sensitivity (analgesia) and relaxes muscles. Isoflurane likely potentiates GABA-A and glycine receptor activity, which decreases motor function, inhibits receptor activity in the NMDA glutamate receptor subtypes and binds to glutamate receptors. Isoflurane is always administered in conjunction with air and/or pure oxygen. Often nitrous oxide is also used. Although its physical properties imply that anesthesia can be induced more rapidly than with halothane, its pungency can irritate the respiratory system, negating this theoretical advantage conferred by its physical properties. It is usually used to maintain a state of general anesthesia that has been induced with another drug, such as thiopentone or propofol.

Lorazepam (brand name Ativan) is indicated for the management of anxiety disorders or for the short-term relief of the symptoms of anxiety or anxiety associated with depressive symptoms. Anxiety or tension associated with the stress of everyday life usually does not require treatment with an anxiolytic. Lorazepam binds to an allosteric site on GABA-A receptors, which are pentameric ionotropic receptors in the CNS. Binding potentiates the effects of the inhibitory neurotransmitter GABA, which upon binding opens the chloride channel in the receptor, allowing chloride influx and causing hyperpolarization of the neuron. Studies in healthy volunteers show that in single high doses Ativan (lorazepam) has a tranquilizing action on the central nervous system with no appreciable effect on the respiratory or cardiovascular systems. Ativan (lorazepam) is readily absorbed with an absolute bioavailability of 90 percent. The mean half-life of unconjugated lorazepam in human plasma is about 12 hours and for its major metabolite, lorazepam glucuronide, about 18 hours. At clinically relevant concentrations, lorazepam is approximately 85% bound to plasma proteins. Lorazepam is rapidly conjugated at its 3-hydroxy group into lorazepam glucuronide which is then excreted in the urine. Lorazepam glucuronide has no demonstrable CNS activity in animal. Most adverse reactions to benzodiazepines, including CNS effects and respiratory depression, are dose dependent, with more severe effects occurring with high doses. Paradoxical reactions, including anxiety, excitation, agitation, hostility, aggression, rage, sleep disturbances/insomnia, sexual arousal, and hallucinations may occur. Small decreases in blood pressure and hypotension may occur but are usually not clinically significant, probably being related to the relief of anxiety produced by lorazepam.

Clorazepate is a water-soluble benzodiazepine derivative effective in the treatment of anxiety. It has also muscle relaxant and anticonvulsant actions. Studies in healthy men have shown that clorazepate dipotassium has depressant effects on the central nervous system. clorazepate is a prodrug since orally administered it is rapidly decarboxylated to form nordiazepam, there is essentially no circulating parent drug. Nordiazepam positively modulates GABAA receptors to produce anxiolytic and anticonvulsant effects.

Flurazepam (known under the brand names Dalmane and Dalmadorm) is a drug which is a benzodiazepine derivative. It is a hypnotic agent which does not appear to decrease dream time as measured by rapid eye movements (REM). Furthermore, it decreases sleep latency and number of awakenings for a consequent increase in total sleep time. Flurazepam binds to an allosteric site on GABA-A receptors. Binding potentiates the action of GABA on GABA-A receptors by opening the chloride channel within the receptor, causing chloride influx and hyperpolarization. Flurazepam is useful for the treatment of insomnia characterized by difficulty in falling asleep, frequent nocturnal awakenings, and/or early morning awakening. Flurazepam can be used effectively in patients with recurring insomnia or poor sleeping habits, and in acute or chronic medical situations requiring restful sleep.

Chlordiazepoxide (trade name Librium) is a sedative and hypnotic medication of the benzodiazepine class. Chlordiazepoxide is indicated for the management of anxiety disorders or for the short-term relief of symptoms of anxiety, withdrawal symptoms of acute alcoholism, and preoperative apprehension and anxiety. Anxiety or tension associated with the stress of everyday life usually does not require treatment with an anxiolytic. The effectiveness of Librium in long-term use, that is, more than 4 months, has not been assessed by systematic clinical studies. Chlordiazepoxide acts on benzodiazepine allosteric sites that are part of the GABAA receptor/ion-channel complex and this results in an increased binding of the inhibitory neurotransmitter GABA to the GABAA receptor thereby producing inhibitory effects on the central nervous system and body similar to the effects of other benzodiazepines. Chlordiazepoxide act via micromolar benzodiazepine binding sites as Ca2+ channel blockers and significantly inhibit depolarization-sensitive Calcium uptake in animal nerve terminal preparations. The withdrawal of chlordiazepoxide during pregnancy and breastfeeding is recommended, as chlordiazepoxide rapidly crosses the placenta and also is excreted in breast milk. Chlordiazepoxide is a long-acting benzodiazepine drug. The half-life of Chlordiazepoxide is 5 – 30 hours but has an active benzodiazepine metabolite (desmethyldiazepam), which has a half-life of 36 – 200 hours. The necessity of discontinuing therapy because of undesirable effects has been rare. Drowsiness, ataxia and confusion have been reported in some patients — particularly the elderly and debilitated. While these effects can be avoided in almost all instances by proper dosage adjustment, they have occasionally been observed at the lower dosage ranges. In a few instances syncope has been reported.

A centrally acting skeletal muscle relaxant whose mechanism of action is not completely understood but may be related to its sedative actions. Carisoprodol is indicated for the relief of discomfort associated with acute, painful musculoskeletal conditions in adults. Most common adverse reactions (incidence > 2%) are drowsiness, dizziness, and headache. Carisoprodol might be mixtured with Aspirin and Codeine Phosphate. Studies indicating increased risk of abuse or addiction led to withdrawal of the drug from the market in Norway and other EU countries in 2008.

Butalbital, 5-allyl-5-isobutylbarbituric acid, is a barbiturate with an intermediate duration of action. The different combinations with butalbital is approved. One of them is fioricet with codeine (butalbital, ccetaminophen, caffeine, and codeine phosphate) which is indicated for the relief of the symptom complex of tension (or muscle contraction) headache. Evidence supporting the efficacy and safety of fioricet with codeine in the treatment of multiple recurrent headaches is unavailable. Butalbital is well absorbed from the gastrointestinal tract and is expected to distribute to most tissues in the body. This compound in general may appear in breast milk and readily cross the placental barrier. Monoamine oxidase (MAO) inhibitors may enhance the CNS effects. The mechanism of action for butalbital is proposed the following: this compound 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.

Pentobarbital belongs to the class of a short-acting barbiturate is used as sedatives, hypnotics, for the short-term treatment of insomnia, since they appear to lose their effectiveness for sleep induction and sleep maintenance after 2 weeks; preanesthetics and anticonvulsant, in anesthetic doses, in the emergency control of certain acute convulsive episodes, e.g., those associated with status epilepticus, cholera, eclampsia, meningitis, tetanus, and toxic reactions to strychnine or local anesthetics. Pentobarbital 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. All of these effects are associated with marked decreases in GABA-sensitive neuronal calcium conductance (gCa). The net result of barbiturate action is acute potentiation of inhibitory GABAergic tone. Barbiturates also act through potent (if less well characterized) and direct inhibition of excitatory AMPA-type glutamate receptors, resulting in a profound suppression of glutamatergic neurotransmission.

Phenobarbital is a barbiturate derivative used to treat insomnia and anxiety, seizures, hyperbilirubinemia in neonates and cholestasis. Phenobarbital promotes binding to inhibitory gamma-aminobutyric acid subtype receptors, and modulates chloride currents through receptor channels.

Neboglamine is a functional modulator of the glycine site on the N-methyl-D-aspartate (NMDA) receptor. Neboglamine appeared to promote neuronal growth as measured by expression of Fos-like immunoreactivity, particularly in the prefrontal cortex, nucleus accumbens, and lateral septal nucleus. Neboglamine behaves as a potential antipsychotic. Neboglamine is in phase II clinical trials by Rottapharm for the treatment of schizophrenia and cocaine abuse.