Halothane - Product Details
COMPOSITION
HALOTHANE is chemically 2-bromo-2 chloro 1:1:1 :- trifluoroethane to which 0.01 % thymol has been added.
PHARMACOLOGICAL CLASSIFICATION
A 2.1. Anaesthetics
INDICATIONSInhalation anaesthesia
CONTRA-INDICATIONSHypersensitivity to any of the ingredients. Safety during pregnancy and lactation has not been established. Not recommended for vaginal delivery unless uterine relaxation is required. Contra-indicated in porphyria. Adrenaline and most other sympathomimetic agents, and theophylline, should be avoided during halothane anaesthesia since they can produce cardiac arrhythmias; the risk of arrhythmias is also increased if halothane is used in patients receiving dopaminergic agents. The use of halothane is generally not recommended in obstetrics because of the increased risk of postpartum haemorrhage.
WARNINGSThe risk of halothane hepatitis has led to the following guidelines. A careful history should be taken to determine previous exposure and previous reactions to halothane. Repeated exposure within a period of at least 3 months should be avoided unless there are overriding clinical circumstances. Also a history of unexplained jaundice or pyrexia following exposure to halothane is an absolute contra-indication to its future use in that patient. . Patients should be advised of the possibility of psychomotor impairment following the use of halothane. Driving or performance of other tasks requiring alertness and co-ordination may be impaired for about 24 hours post-anaesthesia. The use of alcohol or central nervous system (CNS) depressants within 24 hours following anaesthesia must be avoided unless specifically prescribed or otherwise authorized by the physician or dentist.
SIDE-EFFECTSHalothane has a depressant action on the cardiovascular system and reduces blood pressure; signs of overdosage are bradycardia and profound hypotension. It is also a respiratory depressant and can cause cardiac arrhythmias; there have been instances of cardiac arrest. The sensitivity of the heart to sympathomimetic amines is increased. Adverse effects on the liver range from liver dysfunction to hepatitis and necrosis and are more frequent following repeated use. Halothane can produce nausea, vomiting and shivering. Malignant hyperpyrexia has been reported. Other adverse effects which may occur during general anaesthesia include involuntary muscle movements, hiccup, coughing, bronchospasm, larygospasm, hypotension and emergence reactions.
SPECIAL PRECAUTIONSHalothane should be used with caution in patients with phaeochromocytoma. The effects of competitive muscle relaxants such as gallamine and tubocurarine, and of ganglion blocking agents such as pentolinium, pempidine, and trimetaphan are enhanced by halothane and if required they should be given in reduced dosage. Morphine increases the depressant effects of halothane on respiration. Chlorpromazine also enhances the depressant effect of halothane. Patients who are known or are suspected to be susceptible to malignant hyperpyrexia should not be anaesthetized with halothane or any of the other halogenated inhalational anaesthetics. Halothane reduces muscle tone in the pregnant uterus and generally its use is not recommended in obstetrics because of the increased risk. of postpartum haemorrhage; the effects of ergometrine on the parturient uterus are diminished. Premedication with atropine has been recommended to reduce vagal tone and to prevent bradycardia and severe hypotension. Patients with impaired function of the adrenal cortex, such as those who are being treated or have recently been treated with corticosteroids, may experience hypotension with the stress of anaesthesia. Treatment with corticosteroids, pre-operatively and postoperatively, may be necessary. Patients taking other forms of long-term medication may require a change of dosage or cessation of therapy before major elective surgery. Such medications include aspirin, oral anticoagulants, oestrogens, monoamine oxidase inhibitors and lithium. Patients with chronic diseases such as diabetes or hypertension may require adjustment to their therapy prior to anaeshesia. Anaesethetic agents should be used with caution in patients with cardiac, respiratory, renal or hepatic impairment. Sensitisation of the myocardium to beta-adrenergic stimulation occurs with some anaesthetics and ventricular fibrillation may occur if sympathomimetic agents are administered concomitantly.
KNOWN SYMPTOMS OF OVERDOSE AND TREATMENTSee "Side-effects and special precautions" above.
Treatment is symptomatic and supportive.
A clean, bright, colourless liquid with a characteristic odour.
PRESENTATIONBottle of 250 ml.
STORAGE INSTRUCTIONSStore in airtight containers protected from light at a temperature not exceeding 25° C. Keep out of reach of children.
