Ethanol physical dependence

Changes have also been reported to occur in the sub-unit composition of the GABA-A receptor following chronic exposure to barbiturates, neurosteroids, ethanol and benzodiazepine agonists. These changes may underlie the development of tolerance, physical dependence and the problems which are associated with the abrupt withdrawal of such drugs. 

The development of the benzodiazepine class of drugs for the treatment of a variety of neurological indications has proven to be an outstanting success story in the field of chemotherapy. However, these compounds often produce undesirable side effects when used as anti-anxiety or hypnotic agents. These side effects include sedation, physical dependence, amnesia, muscle relaxation, and ethanol potentiation. The development of a benzodiazepine receptor-based anxiolytic agent devoid of these side effects would constitute a major advance in the field and has been the focus of significant research efforts [284]. 

Recently, a new CBi receptor antagonist, namely SR147778, has been developed. This compound is able to reduce both ethanol and sucrose consumption in mice and rats (Rinaldi-Carmona et al. 2004), supporting the involvement of the CBi cannabinoid receptor in ethanol consumption. Taken together, these results suggest an involvement of endocannabinoids in die rewarding effects, physical dependence and craving induced by ethanol. Further studies must to be performed in order to clarify the apparent discrepancies observed in the different studies performed with CBi knockout mice. 

Chronic use leads to tolerance (cross with other S-H drugs), possibly via down-regulation of BZ receptors. Psychological and physical dependence occurs, but abuse liability and withdrawal signs are less intense than with ethanol or barbiturates. Rebound REM sleep, insomnia, and anxiety are common on discontinuance. 

Answer B. Buspirone has selective anxiolytic activity that is slow in onset The drug has no abuse liability and will not suppress withdrawal symptoms in patients who have become physically dependent on barbiturates, benzodiazepines, or ethanol. Bupropion is an antidepressant, also approved for management of dependence on nicotine. Baclofen is a spinal cord muscle relaxant that activates GABAfi receptors. Buprenorphine is a long-acting opioid analgesic with no effectiveness in GAD, and butabarbital is a barbiturate that may cause dependence. 

Tolerance and dependence Tolerance occurs mainly as a result of CNS adaptation but may be partly caused by an increased rate of ethanol metabolism. There is cross-tolerance to other sedative-hypnotic drugs. Both psychologic and physical dependence are marked, the latter demonstrated by an abstinence syndrome that occurs if a chronic user abruptly discontinues ethanol intake. 

The patient is experiencing symptoms of the withdrawal syndrome from physical dependency on ethanol. Since seizures are possible, it would not be appropriate to attempt sedation with a phenothiazine such as chlorpromazine. Thiamine is usually administered to counteract the symptoms of Wernicke-Korsakoff syndrome but will not alleviate withdrawal symptoms. Neither buspirone nor naltrexone has value in the immediate management of alcohol withdrawal states. The patient is indeed suffering from delirium tremens. The answer is (B). 

Biodiesel can be produced from various oilseed-yielding plants like castor, cotton, jatropha, palm, rape, soy, etc. The straight vegetable oils (SVO), which can be derived by physical and chemical treatment (milling/refining), are then converted into fatty acid methyl esters (FAME), also known as biodiesel. Similar to ethanol, these routes are established and proven, and their costs depend heavily on two factors ... 

The principle of extraction is based on a physical chemical phenomenon known as partitioning. If two fluids, one of which contains a solute that is soluble in both, come in contact with one another, the solute will migrate from the original fluid into the other fluid. The extent (but not the rate) to which it will migrate is governed by the relative solubilities of the fluids. See Table 4.2. If the solute is equally soluble in both fluids, half will continue to migrate until the concentrations in both fluids are the same. If the solute is much more soluble in one fluid or the other, the fluid in which the solute is most soluble will accumulate most of the solute. For instance, if ethanol is dissolved in water and contacted with a solvent, the amount of ethanol removed from the water depends on the solvent. 

The salt effects of potassium bromide and a series office symmetrical tetraalkylammonium bromides on vapor-liquid equilibrium at constant pressure in various ethanol-water mixtures were determined. For these systems, the composition of the binary solvent was held constant while the dependence of the equilibrium vapor composition on salt concentration was investigated these studies were done at various fixed compositions of the mixed solvent. Good agreement with the equation of Furter and Johnson was observed for the salts exhibiting either mainly electrostrictive or mainly hydrophobic behavior however, the correlation was unsatisfactory in the case of the one salt (tetraethylammonium bromide) where these two types of solute-solvent interactions were in close competition. The transition from salting out of the ethanol to salting in, observed as the tetraalkylammonium salt series is ascended, was interpreted in terms of the solute-solvent interactions as related to physical properties of the system components, particularly solubilities and surface tensions. 

Figure A1.4.1 Concentration dependence of refractive indices of sucrose, ethanol, and citric acid solutions at 20°C. Data based on tables in Handbookof Chemistry and Physics, 61st Edition (Weast, 1980).

Amestica and Wolf (12) in a study closely related to the one described herein, measured the conversion of Illinois No. 6 coal in toluene and ethanol. Their results clearly showed that conversions increased with temperature and solvent density but were not detailed enough to show the time dependence of the conversion. However, a result important to this study was that toluene converts coal to liquids without significantly reacting itself. After reaction, 98% of the toluene used was recovered versus only 73 -85% of the ethanol in runs using it. Ethanol is a hydrogen donor and reacts extensively with the coal. While toluene probably reacts with coal to a small extent, its effect was primarily physical in nature. As such, it is a good candidate for studying the effects of a supercritical solvent on coal liquefaction kinetics since the enhancement effect of supercritical conditions is physical in nature. 

Irrespective of the type of biomass used for ethanol production, the biomass needs to be pretreated to make the carbohydrates available for fermentation. However, which enzymes can be used depends on the source of the biomass. In addition, the biomass needs pretreatment before the enzymes are used. The first step of the pretreatment can be of a physical nature. Once the biomass is physically pretreated, the cellulose structures are open for enzyme action. In biomass from forests, the substance is mainly in the form of cellulose. Targeted enzymes are selective for the reaction of cellulose to glucose, and therefore there are no degradation byproducts, as occurs in acid conversion technology. There are at least three ways this can be performed. Firstly, in separate hydrolysis and fermentation, the pretreated biomass is treated with cellulase, which hydrolyzes the cellulose to glucose at 50 °C and pH 4.8. Secondly, in simultaneous fermentation and saccharification (SSF) the hydrolysis and fermentation take place in the same bioreactor. Thirdly,... 

---