Halothane side effects

The newer volatile anesthetics, desflurane and sevoflurane, have physicochemical characteristics (ie, low blood gas partition coefficients) that are favorable to a more rapid onset and shorter duration of anesthetic actions compared with isoflurane and halothane. However, both of these newer agents also have certain limitations. The low volatility of desflurane necessitates the use of a specialized heated vaporizer, and the pungency of the drug leads to a high incidence of coughing and sympathomimetic side effects that make it less than ideally suited for induction of anesthesia. 

In the 1980s two more anaesthetics came into use enflurane and isoflurane. These were not metabolised by the liver to the same extent, 2% in the case of enflurane, and only 0.2% of isoflurane. Enflurane was introduced into clinical use in 1981, but isoflurane was delayed because some research appeared to show that it caused liver cancer in mice. This research was repeated by others and shown to be wrong and isoflurane came into general use in 1984. What operating theatre personnel did not like was its off-putting smell. Were there health risks associated with the new anaesthetics A statistical analysis of the side-effects experienced by 17,201 patients on whom they were used was compared with the effects experienced by a similar group on whom halothane had been used. Patients on the newer anaesthetics were more likely to suffer a heart attack and, with isoflurane, palpitations were more common. However, there was no increased risk of the patient dying. 

Halofluorocarbons and highly fluorinated ethers have been used as inhalation anesthetics for many years [91], The first anesthetic of this type was Halothane which was introduced clinically in 1956 [92], An excellent anesthetic with few unwanted side-effects, Halothane has the particular advantages of high chemical stability and non-flammability. Several alternative heavily fluorinated inhalation anesthetics have subsequently been introduced [93] (Scheme 4.42). 

Side effects of halothane include hypotension, cardiac arrhythmias and hangover. The high incidence of severe liver damage on repeated exposure to halothane has limited its use. The Committee on the Safety of Medicines (now the Commission on Human Medicines) recommends that repeated use of halothane should be avoided. 

CLINICAL USE Halothane is a potent, nonpungent and well-tolerated agent that usually is used for maintenance of anesthesia and is well tolerated for inhalation induction of anesthesia, most commonly in children, in whom preoperative placement of an intravenous catheter can be difficult. Anesthesia is produced by halothane at end-tidal concentrations of 0.7-1%. The use of halothane in the U.S. has diminished substantially since the introduction of newer inhalational agents with better pharmacokinetic and side-effect profiles. 

Cardiovascular System The most predictable side effect of halothane is a dose-dependent reduction in arterial blood pressure. Mean arterial pressure typically decreases -20-25% at MAC concentrations of halothane, primarily as a result of direct myocardial depression, and perhaps an inability of the heart to respond to the effector arm of the baroreceptor reflex. Halothane-induced reductions in blood pressure and heart rate generally disappear after several hours of constant halothane administration, presumably because of progressive sympathetic stimulation. 

A Similar to halothane, but hepatitis unlikely. Only 2 - 5% metabolized, released from fat stores more rapidly than halothane. Wide margin of safety, few side effects other than renal toxicity. ... 

It is quite potent, however, and produces good analgesia and muscle relaxation. The use of ether at present is rather limited, mainly because of its undesirable side effects. Halothane, CFsCHBrCI, comes closest to an ideal inhalation anesthetic at present, but halogenated ethers such as enflurane, CF2H—O—CF2CHCIF, are also used. 

One of the most widely used general anesthetics is halothane (2-bromo-2-chloro-l,l,l-trifluoroethane), also called fluothane. It has a pleasant odor, is nonexplosive, has few side effects, undergoes few reactions within the body, and is eliminated quickly fiom the hody. 

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