Anesthetic drugs can come in a variety of chemical states, including liquid, gas, and solid forms. Drugs in this class that are normally found as a liquid when kept at room temperature, and that can easily be converted into a gas that may be inhaled, are called volatile anesthetic substances. Medications in this category are used as general anesthetics, where they can cause an individual to temporarily lose consciousness while undergoing procedures that could be otherwise painful or unpleasant. Compounds that are commonly used in the medical world in this category include isoflurane, halothane, and desflurane. These compounds have several properties that make them desirable for use in medical situations, although they also have potential drawbacks and side effects.
Medications in the volatile anesthetic class are related by their chemical properties, but they may have slightly different ways of inducing anesthesia in the human body. Some of these drugs, such as halothane and sevoflurane, seem to interact with proteins called muscarinic receptors, which play a role in consciousness. These compounds, like other general anesthetics, could enhance inhibitory signals in the nervous system by binding gamma-aminobutyric acid (GABA) receptors. They may also dampen excitatory signals through the blocking of cellular ion channels used in conducting electrical messages.
Volatile anesthetic drugs, because they can be stored as liquids, can be kept in more compact containers than gases, and they tend to be more stable than many gases. Generally, they are not flammable, and they do not react with other materials commonly found in medical settings, such as steel, plastics, and rubber. Additionally, they tend to be easily converted into a vapor, which can then be inhaled through a mask; most individuals do not find them unpleasant to breathe in when they are mixed with oxygen. The volatile anesthetic substances currently in use tend to act quickly on most people, creating a rapid state of anesthesia which wears off soon after their administration stops.
Most drugs carry some potential for adverse events, however, and this holds true for volatile anesthetic substances. Halothane can create problems with blood flow to the brain, and may sometimes lead to heart arrhythmia, making it potentially dangerous for some individuals to use, particularly children. Isoflurane has the possibility of irritating different types of bodily tissue, and could damage the nervous system in sufficient doses. At times, these medications may not be able to induce anesthesia on their own, and they must be combined with other drugs like nitrous oxide, increasing the chances of dangerous side effects.