Anaesthetics-general

Anaesthetics depress all excitable tissues including central neurones, cardiac muscle and smooth and striatal muscle. However, these tissues have different sensitivities to anaesthetics and the arca.s of the brain responsible for consciousness (middle. CD) arc among the most sensitive. Titus, il i.s possible to administer anaesthetic agents at concentrations that produce unconsciousness without unduly depressing the caidiova.scular and respiratory centres or the myocardium. However, for most nnaesthclias. the margin of safety is small. 

General anaesthesia usually involves the administration of dilTerenl drugs for 

1 the pteventinn of the parasympathomimetic effects of anaesthesia (bradycardia, bronchial secretion) and 

Prcmedicaiion is often omitted for minor openitiuns. If necessary, the appropriate drugs (c.g. hyoscine) are given intravenously at induction. 

This is a complex polysyiiapiie pathway in the brainstem reticular formation that projects diffusely to the cortex.. Activity in the R.AS is concerned with maintaining consciou.sncss and. because it is especially sensitive to the depressant action of anae.sthetics. it is thought to be their primary site of action. 

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Barbiturates are salts of barbituric acid. They can be used as hypnotics, sedatives, general anaesthetics, and... 

General anaesthetics have been in use for the last 100 years, yet their mechanism of action are still not yet clearly defined. For many years it was thought that general anaesthetics exerted their effects by dissolving in cell membranes and perturbing the lipid environment in a non-specific manner. This theory derived from the observation that for a number of drugs which induced anaesthesia, their potency correlated with their oil-water partition coefficients. This Meyer-Oveiton correlation was accepted for a number of years, however in the last 15-20 years evidence has shown that a more likely theory is that of specific interactions of anaesthetics with proteins, particularly those within the CNS that mediate neurotransmission [1]. 

General anaesthetics are administered for many surgical procedures where the patient is likely to undergo a severely painful procedure, and complete unconsciousness and immobility is required for the surgety to be performed. The most commonly used volatile anaesthetics are halothane, isoflurane and sevoflurane. Nitrous oxide is also commonly used, particularly during... 

Thompson SA, Watford KA (2001) Mechanism of action of general anaesthetics - new information from molecular pharmacology. Curr Opin Pharmacol 1 78-83... 

Krasowski MD, Harrison NL (1999) General anaesthetic actions on ligand-gated ion channels. Cell Mol Life Sci 55 1278-1303... 

Rudolph U, Antkowiak B (2004) Molecular and neuronal substrates for general anaesthetics. Nat Rev Neurosci 5 709-720... 

Inhalation general anaesthetics, such as halothane, stimulate CICR in a way similar to that of caffeine. Administration of these agents to patients with MH mutations in RyRl gene will cause the MH episodes. 

General Anaesthetics General Transcription Factors Genetic Polymorphism... 

Martindale W. 1977. Halothane and general anaesthetics. In WadeA, ed. The extra pharmacopoeia Incorporating Squire s "Companion." 27th ed. London Pharmaceutical Press, 714-715. 

Setting aside the general anaesthetics, which do not directly modify the function of any particular neurotransmitter, all the drugs that are used to induce sleep, i.e. the hypnotics , augment the function of GABA and so directly depress neuronal function and probably facilitate cortico-thalamic synchrony. Most of them are benzodiazepines... 

Inhalation (IH) The administration of volatile gases and vapours, followed by drug absorption in the lungs or nasal mucosa. Examples include general anaesthetics like nitrous oxide, nicotine from the tar droplets in tobacco smoke, cannabinoids from cannabis leaf smoke and various opiates from burning opium resin. 

Both of these general anaesthetics have long been known to oxidize in the presence of air and sunlight. Chloroform was shown to photo-oxidize to a peroxide of uncertain structure which collapsed to the poison gas phosgene. Anaesthetic chloroform is protected by the addition of ethanol, which intercepts the initial free radical and prevents the photodegradation [17]. Diethyl ether... 

Carla V, Moroni F. 1992. General anaesthetics inhibit the responses induced by glutamate receptor agonists in the mouse cortex. Neurosci Lett 146(l) 21-24. 

Haydon DA, Requena J, Simon AJB. 1988. The potassium conductance of the resting squid axon and its blockage by clinical concentrations of general anaesthetics. J Physiol 402 363-374. 

Commonly used solvent in chemical laboratories and in the chemical and pharmaceutical industries mainly used as an extractant for fats, oils, waxes and resins used for the manufacture of munitions, plastics, perfumes used in medicine as a general anaesthetic. 

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