Anaesthetic effects

Among other uses, these polymers have been employed in a variety of biomedical applications. Poly(phosphazenes) containing organic side chains, derived from the anaesthetics procaine and benzocaine, have been used to prolong the anaesthetic effect of their precursor drugs. They have also been used as the bioerodable matrix for the controlled delivery of drugs. 

Propane has a characteristic natural gas odour and is basically insoluble in water. It is a simple asphyxiant but at high concentrations has an anaesthetic effect. The TLV is 2500 ppm. It is usually shipped in low-pressure cylinders as liquefied gas under its own vapour pressure of ca 109 psig at 21°C. Its pressure/temperature profile is given in Figure 9.7. 

Anaesthetic effects may be evident loss of consciousness skin is clammy. 

A.S. Evers, B.A. Berkowitz, D.A. d Avignon, Correlation between the anaesthetic effect of halothane and saturable binding in brain. Nature 328 (1987) 157-160. 

The uptake, redistribution and protein binding of methohexitone are somewhat similar to that of thiopentone. Although methohexitone is less lipid soluble than thiopentone, a greater proportion (75%) is non-ionised at body pH and therefore available for pharmacological effect. Hepatic clearance (11 mL-kg-l-min-1) is higher for methohexitone than for thiopentone and the elimination half-life considerably shorter ( 4 hours). While cumulation is less likely to occur with repeated doses, prolongation of anaesthetic effect has been demonstrated when methohexitone was infused for longer than 60 minutes. 

A further property which is of central importance in diffusion is the tissue-binding capacity (or affinity) of a drug. Drugs that are highly lipid-soluble and protein-bound, such as bupivacaine and ropivacaine, are extensively bound to tissue. This limits the rate at which they are transferred from their intracellular sites of action to the vascular compartment. When tissue affinity is great the local anaesthetic effect is prolonged. 

The duration of action of a local anaesthetic is proportional to the time that the drug remains bound to the sodium channels. Measures that prolong contact time will prolong the duration of the local anaesthetic effect. Cocaine has a vasoconstricting effect on blood vessels and prevents its own absorption. Many local anaesthetics are prepared with adrenaline (epinephrine) in order to achieve this effect. Concentrations are usually of the order of 1 200000 or more dilute than this. Care should be exercised when using adrenaline-containing solutions in the presence of halothane as it is known to sensitise the myocardium to the effects of catecholamines. 

Amino-2,3-dihydrobenzofurans such as (501) and (502) are useful as antidepressants and hypotensives (70USP3513239). Substituted 5-acyl-2,3-dihydrobenzofuran-2-carboxylic acids of the type (503) possess diuretic and antitussive activities (69GEP1927393). Derivatives of the 3-phenyl-2 (3H)-benzofuranone type (504) exhibit musculotropic and anaesthetic effects. Amethone (505) is used against bronchial asthma and also shows antihistaminic activity (47JA980). 

The local anaesthetic effects of sila-mephenhydramine and sila-chlorphenox-amine are also of a shorter time as compared with their corresponding carbon compounds112. This could also be explained by a hydrolytic inactivation of the sila-phar-maca. 

On thermal stimulation l-(2 -perfluoropropyl-r-iodoethyl)silatrane produces the strongest effect. At the same time, l-(2 -perfluorohexyl-l -iodoethyl)silatrane increases the anaesthetic effect of sodium thiopental almost 5-fold. 

Clove oil is therefore used as a safe anaesthetic for channel catfish (Waterstrat, 1999). The anaesthetic effect of clove oil and eugenol for use in aquaculture and aquatic... 

Soltani, M., Omidbeigi, R., Rezvani, S., Mehrabi, M.R. and Chitsaz, H. (2001) Study of anaesthetic effects induced by clove flower (Eugina caryophillata) on rainbow trout (Oncorhynchus mykiss) under various water quality conditions. Journal of the Faculty of Veterinary Medicine, University of Tehran 56(4), ar85-ar89. 

OPIOIDS ANTIHISTAMINES Promethazine t analgesic and anaesthetic effects of opioids. However, it has an additive sedative effect Unknown Monitor vital signs closely during coadministration... 

Some P blockers have membrane stabilising (quinidine-like or local anaesthetic) effect. This property is clinically insignificant except that agents having this effect will anaesthetise the eye (undesirable) if applied topically for glaucoma (timolol is used in the eye and does not have this action), and in overdose. 

Cotton pledgets saturated Time required to produce with L in water/IPA/ anaesthetic effect glycerine... 

Volar forearm, dorsal hand and finger sites showed lower site-dependent baseline flux, but did vasodilate. Anaesthetic effect 3.6min for scrotum vs. 1 hr + for abdomen... 

Among various membrane functions that have been assigned to lipid bilayer perturbations, the anaesthetic effect has probably been the subject of most studies. The general anaesthetic effect can be induced by a wide range of chemically "inert" molecules (from noble gases to hydrocarboiis), whose lipophilic character is directly correlated to the anaesthetic potency. 

There are striking similarities between the anaesthetic effect discussed above and anti-microbial effects. Thus gases tiiat are general anaesthetics, even die inert noble gases, exhibit an anti-microbial effect. Furthermore this is correlated to the anaesthetic potency [57]. Moreover, it is possible to reverse this effect by hydrostatic pressiue. As discussed above there is an opposing effect of temperature on lipid phase transitions as compared to that of pressure, and this is also reflected in living systems. At 1,000 bar for example certain orgaiusms can survive at 104 C [57]. 

In the ripening process of certain plants, e.g. vegetables, ethylene is produced to increase the respiration rate. The mechanism is believed to be a nonspecific membrane lipid effect. Ethylene has an anaesthetic effect comparable to nitrous oxide, and it has even bem used as a general anaesthetic agent. It is therefore natural to assume that the corresponding membrane bilayer... 

In an abaxial sessamoid local anaesthetic model, the highest no-effect dose for the local anaesthetic effect of lidocaine was 4 mg (Harkins et al 1998). For caudal epidural anesthesia, dose rates of lidocaine alone of 0.25 (Csik-Salmon et al 1996) or 0.35mg/kg (Pikes et al 1989) have been proposed (i.e. 6-10 ml of a 2% solution). A maximum of 200 ml should be used for field blocks. The dose rates quoted for i.v. administration of either a 1% or 2% solution of lidocaine (without epinephrine (adrenaline)) are for loading doses of 0.65-5 mg/kg followed by a constant i.v. infusion of 25-100 gg/kg/min (Brianceau et al 2002, Doherty Frazier 1998). 

Ketamine, a dissociative anaesthetic, is administered as a racemic mixture (present in the parenteral preparation) and is initially metabolized by the liver to AT-desmethylketamine (metabolite I), which in part is converted by oxidation to the cyclohexene (metabolite II) (Fig. 1.5). The major metabolites found in urine are glucuronide conjugates that are formed subsequent to hydroxylation of the cyclohexanone ring. As the enantiomers differ in anaesthetic potency and the enantioselectively formed (metabolite I has approximately 10% activity of the parent drug) interpretation of the relationship between the anaesthetic effect and disposition of ketamine is complicated. On a pharmacodynamic basis, the S(+) enantiomer is three times as potent as the R(-) enantiomer (Marietta et al., 1977 Deleforge et al., 1991), while the enantiomer that undergoes N-demethylation (hepatic microsomal reaction) differs between species (Delatour et al, 1991). Based on the observed minimum anaesthetic... 

Deleforge, J., Davot, J.L., Boisrame, B. Delatour, P. (1991) Enantioselectivity in the anaesthetic effect of ketamine in dogs. Journal of Veterinary Pharmacology and Therapeutics, 14, 418-420. 

Camphor is a good example of the importance of the mode of application for the cutaneous effect. If camphor is massaged intensely in the skin the result will be an erythema, but if it is spread out carefully and lightly, a cooling effect is obtained, similar to the effect of menthol. Furthermore, camphor has a local anaesthetic effect. 

By inhalation a local anaesthetic effect and vasoconstriction of the vessels in the nasal mucosa are obtained. 

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