Depressants are drugs that act on the brain and the spinal cord (known as the central nervous system or CNS). The action of these drugs changes the communication between brain cells by altering the concentration or the activity of chemicals called neurotransmitters.As a result they cause a decrease in brain activity that in turn influences the functioning of other parts of the body.
Low to moderate dose - calmness, relief from anxiety and very relaxed muscles
High dose - slurred speech, staggering gait, altered perception and sleep induced
Lethal dose - respiratory depression coma/death.
D.4.2 Discuss the social and physiological effects of the use and abuse of ethanol
Short term effect of ethanol abuse
- loss of self-restraint; memory, concentration and insight are impaired
- loss of balance and judgment
- violent behaviour associated with domestic abuse and family breakdown
- dangerous risk-taking behaviour leading to many accidents involving motor vehicles and machinery
- dehydration caused by increased urine output leading to 'hangover' and loss of productivity
- at high doses, can cause vomiting, loss of consciousness, coma and death
Long-term effects of ethanol abuse
- dependence known as alcoholism, associated with withdrawal symptoms
- liver disease, cirrhosis, liver cancer
- coronary heart disease
- high blood pressure
- fetal alcohol syndrome
- permanent brain damage
Ethanol in alcoholic drinks is an important part of many diets and cultures, adding a sense of occasion to meals, rituals and festivities. In low doses, it can help to create a mild excitement and users become more talkative, confident and relaxed. There is also some evidence that low doses of ethanol might might have a beneficial effect on the circulation and diminish cardio-vascular diseases, perhaps owing to its mild anti-clotting effect.
D.4.3 Describe and explain the techniques used for the detection of ethanol in the breath, the blood and urine
Breath
Ethanol is a volatile compound and at body temperature in the lungs it establishes equilibrium between being dissolved in the blood and released into the air in the exhaled breath.
The equilibrium constant for this reaction has a fixed value at a particular temperature so measurement of the ethanol in the breath can be used to assess the blood alcohol concentration.
The simplest test involves a roadside breathalyser which contains crystals of potassium dichromate (VI) which are orange, but are changed to green chromium (III) Cr3+ ions as they oxidize the ethanol to ethanal and ethanoic acid.
A more accurate technique for breath analysis uses infrared spectroscopy in an apparatus called an intoximeter. The principle here is that different molecules cause different absorption bands in the infrared part of the spectrum as a result of vibrations of their particular bonds and functional groups. Hence ethanol has a characteristic absorption band at 2950 owing to its C-H bonds.
Blood and Urine
The most established method for ethanol analysis is gas-liquid chromatography, which must be carried out in a labouratory. In this technique, blood or urine is vaporized and injected into a stream of an inert gas (the mobile phase) over the surface of a non-volatile liquid (the stationary phase). The components of the vapour, including ethanol gas, move at different rates depending on their boiling points and relative solubility in the two phases. As a result, each leaves the column holding the liquid phase after a specific interval of time known as its retention time. So a peak at the retention time corresponding to ethanol can be used to confirm its presence in the vapour. The area under the peak is a measure of ethanol concentration relative to a known standard in the mixture such as propan-1-ol. The method allows for an accurate assessment of ethanol levels.
D.4.4 Describe the synergistic effects of ethanol with other drugs
Ethanol has a the potential to increase the activity other drugs when taken at the same time. This effect is known as synergy. It means that care must be taken when consuming alcoholic drinks alongside other medications, as the synergistic effects can lead to very serious, even fatal, results. One of the problems is that because ethanol is such a widely consumed and socially available drug, many people do not consider its interaction with other prescription and non-prescription drugs.
- With aspirin, ethanol can cause increased bleeding of the stomach lining and increased risk of ulcers
- With other depressants such as barbiturates, including sleeping pills, ethanol can induce heavy sedation, possibly leading to coma
- With tobacco, ethanol appears to increase the incidence of cancers, particularly of the intestines and liver
- With many other drugs, ethanol can interfere with their metabolism by the liver, which can cause greater and more prolonged drug effects.
D.4.5 Identify other commonly used depressants and describe their structures
Benodiazepine are a major group of depressants. These drugs depress activity in the part of the brain that controls emotion and so are used as tranquilizers in the treatment of anxiety disorder and related insomnia. As well as being the most commonly used class of sleeping pill, they are also used as muscle relaxants. Although they are usually well tolerated by most people and cause relatively few side-effects, they can cause dependence. For this reason, they are used mostly in short-term treatments. Some widely used benzodiazepine drugs are diazepam, marketed as Valium and nitrazepam.
Thank you! Well structurized infomation :)
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