Halothane

Halothane sold under the brand name Fluothane among others, is a general anesthetic. It can be used to start or maintain anaesthesia. 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. It is given by inhalation. Halothane sold under the brand name Fluothane among others, is a general anesthetic. It can be used to start or maintain anaesthesia. 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. It is given by inhalation. Side effects include an irregular heartbeat, decreased effort to breathe, and liver problems. Like all volatile anesthetics, it should not be used in people with a personal or family history of malignant hyperthermia. It appears to be safe in porphyria. It is unclear whether use during pregnancy is harmful to the baby, and it is not generally recommended for use during a C-section. Halothane is a chiral molecule that is used as a racemic mixture. Halothane was discovered in 1955. It is on the World Health Organization's List of Essential Medicines, the most effective and safe medicines needed in a health system. As of 2014, the wholesale cost in the developing world is about 22 to 52 USD for a 250 mL bottle. Its use in developed countries has been mostly replaced by newer anesthetic agents such as sevoflurane. It is no longer commercially available in the United States. Halothane also contributes to ozone depletion. It is a potent anesthetic with a MAC of 0.74%. Its blood/gas partition coefficient of 2.4 makes it an agent with moderate induction and recovery time. It is not a good analgesic and its muscle relaxation effect is moderate. Side effects include irregular heartbeat, decreased effort to breathe, and liver problems. It appears to be safe in porphyria. It is unclear whether use during pregnancy is harmful to the baby, and it is not generally recommended for use during a C-section. Halothane is a chiral molecule that is used as a racemic mixture.In rare cases, repeated exposure to halothane in adults was noted to result in severe liver injury. This occurred in about one in 10,000 exposures. The resulting syndrome was referred to as halothane hepatitis, and is thought to result from the metabolism of halothane to trifluoroacetic acid via oxidative reactions in the liver. About 20% of inhaled halothane is metabolized by the liver and these products are excreted in the urine. The hepatitis syndrome had a mortality rate of 30% to 70%. Concern for hepatitis resulted in a dramatic reduction in the use of halothane for adults and it was replaced in the 1980s by enflurane and isoflurane. By 2005, the most common volatile anesthetics used were isoflurane, sevoflurane, and desflurane. Since the risk of halothane hepatitis in children was substantially lower than in adults, halothane continued to be used in pediatrics in the 1990s as it was especially useful for inhalation induction of anaesthesia. However, by 2000, sevoflurane, excellent for inhalation induction, had largely replaced the use of halothane in children. Halothane sensitises the heart to catecholamines, so it is liable to cause cardiac arrhythmia, occasionally fatal, particularly if hypercapnia has been allowed to develop. This seems to be especially problematic in dental anaesthesia. Like all the potent inhalational anaesthetic agents, it is a potent trigger for malignant hyperthermia. Similarly, in common with the other potent inhalational agents, it relaxes uterine smooth muscle and this may increase blood loss during delivery or termination of pregnancy. People can be exposed to halothane in the workplace by breathing it in as waste anaesthetic gas, skin contact, eye contact, or swallowing it. The National Institute for Occupational Safety and Health (NIOSH) has set a recommended exposure limit (REL) of 2 ppm (16.2 mg/m3) over 60 minutes. Halothane activates GABAA and glycine receptors. It also acts as an NMDA receptor antagonist, inhibits nACh and voltage-gated sodium channels, and activates 5-HT3 and twin-pore K+ channels. It does not affect the AMPA or kainate receptors.