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Mol. mass

46.0684 g/mol

Alcohol, or more specifically, ethanol, is probably our very first synthetic (in a very loose sense of the word as it is not humans that synthesize it, but rather bacterial organisms) drug and has been used by humans for thousands of years (with the earliest record of such use dating further back than 10,000 BC),[1] despite this its pharmacology is so complex that even now we do not fully understand precisely how it elicits its various effects.[2][3]:28-29 It is very easily the most popularly consumed drug in the world, aside from caffeine. Approximately 3.3 million people die every year, worldwide, from alcohol consumption, accounting for 5.9% of worldwide deaths. In the age bracket 20-39 years it accounts for one in four deaths, worldwide. Alcohol consumption is causally related to over 200 different diseases and injuries (most of which are unintentional). Of these liver cirrhosis, alcohol dependence (‘alcoholism’), cancers and injuries are perhaps the best known. It accounts for 5.1% of global burden of disease and injury. While there is evidence for possible health benefits from light drinking,[4] there is also evidence for health dangers associated with light alcohol consumption.[5][6][7]:12

It is also worth noting that it is impossible to blind people with a convincing placebo in the any clinical trial involving alcohol, additionally many abstainers from alcohol are abstainers due to pre-existing illnesses that could be exacerbated by alcohol consumption, while others are abstainers because they once drank, it damaged their health and they gave it up as a result. Plus what many people consider to be drinking in moderation might actually be excessive.[8]

Short-term effectsEdit

  • Euphoria
  • Improved mood
  • Improved sociability
  • Impaired coordination and judgement
  • Stimulant effects, including increased movement[9]

Whereas moderate doses can produce:

  • Significantly impaired coordination, memory and judgement
  • Emotional or aggressive behaviours
  • Nausea or vomiting

And high doses can cause:

  • People to feel dizzy and potentially pass out.
  • Vomiting
  • Seizures
  • Coma
  • Respiratory depression

It also inhibits the production and the release of antidiuretic hormone (ADH), leading to diuresis which can cause dehydration. This is likely partially (but not fully, low blood sugar and sleep disturbances are also believed to contribute) responsible for the hangover effect the morning after a night of heavy drinking.[10]

Hangovers consist of the following symptoms: fatigue, headache, increased sensitivity to light and sound, redness of the eyes, muscle aches, thirst, increased blood pressure, nausea, vomiting, rapid heartbeat, tremor, sweating, dizziness, vertigo, memory impairment, depression, anxiety and irritability.[10]

Long-term consequences of alcohol consumptionEdit

Beneficial effectsEdit

Drinking in moderation may reduce one’s risk of the following diseases:[4]

  • Reduces the risk of developing Alzheimer’s disease/dementia by 25-40%
  • Asthma
  • Autoimmune hypothyroidism
  • Cardiovascular disease, reduced by, at most, 30%[6]
  • Colorectal cancer
  • Common cold
  • Ischaemic heart disease
  • Type 2 diabetes mellitus
  • Gallstones
  • Hearing loss
  • Liver cirrhosis
  • Low birth weight, prematurity
  • Lower urinary tract symptoms (in men)
  • Metabolic syndrome
  • Negative child development
  • Osteoporosis
  • Overweight
  • Psychiatric disorders
  • Renal cell cancer (RCC; the most common form of kidney cancer)
  • Rheumatoid arthritis
  • Stroke

It may also reduce one’s risk of death from any cause, improve general health status and cause an overall reduction in cancer-related mortality. But as mentioned above, it is impossible to blind anyone in these trials and many abstainers are abstainers for a medical reason, including the fact that alcohol has adversely affected their health in the past. It is also worth noting, however, these studies were all cohort/observational studies, not randomized placebo-controlled trials, hence, see these limitations.

Light wine consumption may protect from additional health conditions including:[4]

  • Stomach cancer
  • Lung cancer
  • Upper digestive cancers (probably oesophageal)
  • Hip fracture

It is worth noting, however, that a recently published observational study that followed 783 elderly patients over the period of 9 years found no evidence of improved survival or any other benefits imparted by the consumption of wine, in moderation.[11]

Harmful effectsEdit

Adverse consequences from alcohol consumption are far better studied than any health benefits from modest consumption. Light alcohol consumption is known to increase one’s risk of the following cancers: oesophageal (22% of deaths worldwide attributable to this cause are due to alcohol abuse), oropharyngeal (throat) (alcohol abuse accounts for 30% of deaths due to this cancer) and female breast cancers (8% of worldwide deaths can be attributed to alcohol abuse).[7]:12 It is worth noting that alcohol consumption is often understated when self-reported, hence as these studies were also observational it is possible that these results were for heavier consumption than what the participants reported. Whereas heavy alcohol consumption is associated with these risks, plus (the % in brackets is the percentage of worldwide deaths caused by said condition that are believed to be caused by alcohol abuse):[7]:12

  • Intentional physical injuries (it is estimated that 40% of such injuries are alcohol-related)[12]
  • Child abuse[13]
  • Cancer of digestive tract (including colorectal [10%]), pancreas and liver (12%).[14]
  • Liver cirrhosis (50%)[15][16]
  • Irreversible damage to the brain, heart and pancreas. Stroke (both ischaemic [4%] and haemorrhagic [11%]), hypertension and heart attacks are more common in those that heavily consume alcohol.[6][17][18][19][20] Alcohol is the second leading cause of dementia, after Alzheimer’s disease. Pancreatitis (swelling of the pancreas; 25%) is also more common in drunks.
  • Nerve damage
  • Alcoholism, also known as alcohol addiction[21][22][23][24]
  • Type II diabetes mellitus, especially common in binge drinkers[25]
  • Hormonal imbalances, including increased cortisol and aldosterone production, reduced testosterone levels (perhaps due to an increased production of oestrogen from testosterone) and reduced growth hormone production. This can lead to sexual dysfunction, amongst other effects.[26]
  • Domestic violence (22%)
  • Drowning (13%)
  • Tuberculosis (12%)
  • Pneumonia (4%)
  • HIV/AIDS (1%)
  • Seizures (12%)
  • Self-harm (22%)
  • Hypertensive heart disease (8%)
  • Poor judgement
  • Traffic accident (15%)
  • Fetal alcohol spectrum disorder (FASD; see below for details)
  • Nutritional deficiencies including of thiamine (vitamin B1) and niacin (vitamin B3).

Overall female alcoholics are, on average (across their potential ages), 4.6 times more likely to die during any given time period than their sober counterparts, whereas male alcoholics are 3.4 times more likely to die during any given time period than their sober counterparts.[21]

Fetal alcohol spectrum disorderEdit


A child with fetal alcohol syndrome

FASD is basically what it sounds like, it is a spectrum of potential birth defects or abnormalities that are seen in children exposed to alcohol in utero (in the womb). It is especially common in the children of alcoholics or binge-drinking mothers. They include fetal alcohol syndrome (FAS), partial fetal alcohol syndrome (pFAS), alcohol-related neuro-developmental disorders (ARND) and alcohol-related birth defects (ARBD).[27][28]

FAS is basically a constellation of symptoms due to alcohol exposure in utero (that is, in the womb), including craniofacial features (see figure 40), heart defects (potentially fatal ones too), stunted growth and neurodevelopmental defects (like mental retardation and behavioural anomalies). pFAS is, well what it sounds like, it is when a child exhibits some of the symptoms characteristic of FAS, but not all of them. ARND is when a child exhibits stunted development, including mental retardation and behavioural problems (both of which can closely resemble ADHD), but has no other physical abnormalities. ARBD are physical abnormalities experienced by some children exposed to alcohol in utero.[27][28]

As you can probably guess it is recommended by virtually every health organisation worldwide that pregnant women abstain from alcohol, this includes the World Health Organization and the National Health and Medical Research Council (NHMRC; an Australian government organisation that is concerned with medical research and health). Despite these warnings some 20-30% of women in English-speaking countries consume alcohol while pregnant.[27][28]

In the United States approximately 1% of children are afflicted by FASD, whereas in Australia this rate seems to be substantially less at 0.001-0.068%. South Africa has a FASD rate of 6.8-8.9%, Russia 14.1% and Italy 12%.[27][28]


It is a clear, colourless, very mobile and flammable liquid, with a mild, pleasant smell and a burning taste.[29] It has a density of 0.7893 g/cm3 (at 20℃), an acid dissociation constant (pK) of 15.9 and is miscible with water and most organic solvents.[29] Its melting point is -114.14℃ and its boiling point is 78.29℃.[29]

Metabolites of ethanol

Metabolites of ethanol

It is rapidly absorbed by the gut and reaches peak concentrations in the bloodstream within 30-60 minutes of oral administration.[2][3]:28 Its metabolism is in the liver and is via alcohol dehydrogenase (to acetaldehyde) and aldehyde dehydrogenase (from acetaldehyde to acetic acid) and is such that the time it takes to eliminate a quantity of ethanol goes up linearly with said quantity and in this case that relationship is such that twice as much alcohol takes twice as long for the body to eliminate[2][3]:28 is primarily excreted in urine, sweat and breath.[2][3]:28

Mechanism of actionEdit

It is believed to exert its effects via a variety of different mechanisms, including:[3]:29

  • GABAA receptor potentiation, especially of the α1,2,4,5 and β2 subunits, leading to anxiolysis, amnesia, incoordination, muscle relaxation, euphoria, sedation, etc.[23][30]
  • GABA release potentiation via a metabotropic mechanism.[31] Likely leading to the effects list above.
  • NMDA receptor antagonism. Likely leading to sedation, amnesia, euphoria, psychosis, analgesia and aggressive behaviour. This action might also be partly responsible for the brain damage caused by alcohol abused.[32]
  • AMPA receptor potentiation/antagonism.[32]
  • Potentiation of nAChRs, especially the α3β4 and α4β2 subtypes.[33][34] Probably contributing to the euphoria and potential for dependence produced by alcohol and potentially the ability of alcohol to induce seizures at higher doses and in susceptible individuals.[35]
  • Potentiation of glycine receptors, leading to muscle relaxation and potentially contributing to dependence.[36][37]
  • Induction of the release of endorphins, which act at the mu opioid receptors. Producing euphoria, anxiolysis and analgesia.[38][39]
  • Antagonism of adenosine receptors: A1 and A2A. Perhaps contributing to aggression.[40]
  • Potentiation of dopamine release, especially in the mesolimbic circuit, producing euphoria and dependence.[3]:29
  • Potentiation of 5-HT3 receptors, producing emesis and potentially potentiating the addictive potential of alcohol.[41]
  • Inhibition of AMPK, leading to liver damage.[15]

Medical usesEdit

Alcohol is very effective disinfectant at high concentrations, hence it is often used in hand sanitizers. Alcohol is also used in the treatment of methanol (a simpler, but far more toxic alcohol also known as wood alcohol) poisoning by competing with it for alcohol dehydrogenase and aldehyde dehydrogenase, slowing the toxic metabolism of methanol into formic acid.

Treatments for addictionEdit

The major treatment for alcohol abuse is psychosocial interventions like Alcoholics Anonymous. There are three drug treatments available for alcohol abuse that have received regulatory approval, naltrexone, acamprosate  and disulfiram. Acamprosate has complex effects at the NMDA receptors, serving as a partial agonist, so it increases activity of the receptor when glutamate is scarce, whereas when it is in abundance it reduces the activity of the receptor.167 Additional positive results in clinical trials have been achieved with the use of topiramate and baclofen.168-170 Unfortunately, their effectiveness is generally modest, hence the psychosocial interventions are still the cornerstones of the modern medical treatment of alcoholics.168-170 One treatment that is particularly promising, is depot naltrexone. See depots are long-acting injections of a drug that are made into a large muscle like those in one’s buttocks or thigh. They slowly release the drug into the body, over a period of weeks or months. In the case of depot naltrexone it is capable of reducing the pleasurable effects of alcohol over the period of a month. It is sort of a commitment for the alcoholics as there is no way for them to remove the depot themselves. Ondansetron and sodium oxybate might also reduce alcohol usage in alcoholics.

External linksEdit

Reference listEdit

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