Introduction
Alcohols, a term that often stirs up a cocktail of emotions, is an integral part of our lives. They are not just limited to the beverages we consume but extend to various sectors like healthcare, manufacturing, and even our household chores. This article aims to shed light on the multifaceted world of alcohol, its types, uses, and impacts on health and society.
What are Alcohols?
Alcohols are organic compounds characterized by one or more hydroxyl (-OH) functional groups attached to a carbon atom. They are classified into primary, secondary, and tertiary alcohols based on the attachment of the carbon atom. But, alcohols are not just about chemistry. They have a broader role in our lives.
Primary Alcohols
Primary alcohols are those where the carbon atom of the hydroxyl group is only attached to one alkyl group. Some common examples include ethanol and methanol. These alcohols are often used in solvents and fuels.
Secondary Alcohols
In secondary alcohols, the carbon atom of the hydroxyl group is attached to two alkyl groups. Isopropanol, found in rubbing alcohol, is a common example.
Tertiary Alcohols
Tertiary alcohols have the carbon atom of the hydroxyl group attached to three alkyl groups. They are often used in perfumes and flavorings.
Alcohols in Everyday Life
Alcohols have a wide range of applications in our daily lives. From the beverages we enjoy to the cleaning products we use, alcohols are everywhere.
Alcohols in Beverages
The most commonly known alcohol is ethanol, found in alcoholic beverages like beer, wine, and spirits. The process of fermentation, where yeast breaks down sugar into ethanol and carbon dioxide, is used to produce these beverages.
Alcohols in Cleaning Products
Alcohols like isopropanol and ethanol are commonly used in cleaning products due to their ability to kill bacteria and viruses. They are found in hand sanitizers, disinfectants, and household cleaners.
Alcohols in Healthcare
In healthcare, alcohols are used as antiseptics and disinfectants. They are also used in the manufacturing of medications and as a base for many medicinal creams and lotions.
The Science Behind Alcohols
Alcohols are fascinating from a scientific perspective. They exhibit unique chemical properties that make them versatile in various applications.
Chemical Properties of Alcohols
Alcohols are known for their polarity, high boiling points, and ability to form hydrogen bonds. These properties make them excellent solvents for both organic and inorganic substances.
Reactions of Alcohols
Alcohols undergo a variety of chemical reactions, including oxidation, reduction, and substitution reactions. These reactions are utilized in various industrial processes.
Production of Alcohols
Alcohols are primarily produced through fermentation and hydration of alkenes. The production process varies based on the type of alcohol being produced.
Health Impacts of Alcohols
While alcohols have many uses, they also have significant impacts on health, particularly when consumed in excess.
Effects of Ethyl Alcohol Consumption
Excessive consumption of ethyl alcohol can lead to a range of health issues, including liver disease, cardiovascular problems, and neurological damage. It can also lead to addiction and mental health problems.
Benefits of Moderate Alcohol Consumption
Moderate consumption of certain types of alcohol, like red wine, has been associated with some health benefits. However, these benefits should be weighed against the potential risks.
Pharmacological actions of ethyl alcohol/ethanol:
Local:
- Alcohol is a rubefacient and counterirritant to the skin.
- It causes irritation and a burning sensation on soft skin and mucus membranes.
- Injection of alcohol may cause pain, inflammation, and necrosis followed by fibrosis.
- Alcohol is astringent and antiseptic. It hardens the skin and dehydrates it when used at 100% concentration.
- Alcohol has no action on spores.
- If alcohol is injected around a nerve may cause permanent damage.
CNS:
- The acute effects of alcohol are primarily inhibitory.
- Alcohol produces apparent excitation and euphoria at lower concentrations.
- It is a depressant in a dose-dependent manner.
- The expected effects on plasma concentration range from anxiolytic, euphoria, and excitation to slurring of speech, loss of judgment, inhibition, and stupor and unconsciousness.
- Alcohol impairs performance, slowing of reflexes, and fine discrimination.
- The mechanism by which alcohol produces CNS depression is believed to be by altering the state of membrane lipids through a generalized membrane action, GABAA receptor-mediated synaptic inhibition and inhibition of the NMDA excitatory amino acid receptor.
CVS:
- Small doses of alcohol cause cutaneous vasodilatation and flushing.
- Moderate doses of alcohol cause tachycardia and a mild rise in blood pressure.
- Large doses of alcohol cause vasodilatation due to direct vascular smooth muscle dilatation and vasomotor center depression.
Other effects:
- Alcohol stimulates respiration through irritation of the pharyngeal and buccal mucosa but also depresses it centrally.
- Drinking alcohol in moderate amounts increases HDL-cholesterol levels and decreases LDL oxidation, which may be responsible for a lower incidence of coronary artery disease in such individuals.
- Alcohol is reputed to combat cold, but it actually increases heat loss in cold surroundings and depresses the temperature-regulating center at high doses.
- Dilute alcohol (optimum 10%) is a strong stimulant of gastric secretion, while higher concentrations inhibit gastric secretion and cause vomiting, mucosal congestion, and gastritis.
- Chronic alcoholism exposes the liver to oxidative stress, causing cellular necrosis followed by fibrosis, and increases lipid peroxidation and glutathione depletion.
- Alcohol has little direct effect on skeletal muscle, but fatigue is allayed by small doses, while muscle work is increased or decreased depending on the predominating central effect.
- Alcohol causes diuresis by increasing water ingestion and inhibiting ADH.
- Alcohol causes relaxation of uterine muscles and can induce aggressive sexual behavior due to loss of restraint and inhibition.
- Chronic alcoholism can cause impotence, testicular atrophy, gynaecomastia, and infertility in both men and women.
- Alcohol is rapidly absorbed from the small intestine and colon but slowly from the stomach and very fast from the intestines.
Pharmacokinetics:
- Ethanol undergoes first-pass metabolism in the stomach and liver.
- The maximal blood concentration of ethanol is achieved within 30 to 90 minutes.
- Ethanol can be absorbed through the lungs and skin.
- Ethanol is uniformly distributed throughout tissues and body fluids, and readily crosses the placenta and the blood-brain barrier.
- Ethanol is mainly metabolized (80-90%) and is also metabolized in small amounts by hepatic microsomal enzymes.
- The rate of ethanol metabolism is constant, and its concentration in the blood is zero order, at a rate of 8-12 ml/h of absolute alcohol.
- Ethanol is eliminated from the body through urinary excretion and exhalation (0.05% of blood concentration).
Interactions:
- Ethanol interacts with other drugs and medications, such as anxiolytics, anti-depressants, antihistamines, hypnotics, and opioids, and can cause disulfiram-like reactions when taken with sulfonylurea, cefoperazone, or metronidazole.
- Alcohol intake can enhance the hypoglycemic action of insulin and sulfonylureas and increase gastric bleeding caused by aspirin and other NSAIDs.
- Ethanol provides energy, yielding 7 calories per gram, but it cannot be stored.
Caloric Value:
- Regular alcohol intake can contribute to obesity by sparing carbohydrates and fats as an energy source.
- Ethanol does not supply essential constituents of food, making it an imperfect and expensive food.
- Ethanol is contraindicated in individuals with peptic ulcer, hyperacidity, GERD, epilepsy, severe liver disease, unstable personalities, and pregnant women (can produce fetal alcohol syndrome).
Acute adverse effects:
Acute effects of ethanol include nausea, vomiting, hangover, traffic accidents, CNS depression, decreased memory and concentration, poor judgment, emotional outbursts, decreased reflexes, decreased sexual response, and acute alcohol intoxication.
Chronic Alcoholism:
- Chronic alcoholism can cause various adverse effects, including gastritis, intestinal damage, liver cirrhosis, oxidative stress, cellular necrosis, polyneuritis, pellagra, tremors, seizures, loss of brain mass, Korsakoff’s psychosis, Wernicke’s encephalopathy, hypertension, cardiomyopathy, CHF arrhythmias, stroke, impotence, gynecomastia, infertility, acute pancreatitis, and fetal alcohol syndrome.
- Chronic alcoholism is characterized by craving, loss of control, tolerance, physical dependence, and withdrawal symptoms.
Click here to go to the detailed page on alcohol withdrawal symptoms and management
Alcohol Withdrawal Symptoms and its Management
Uses:
- Ethanol has various local uses, such as an antiseptic, rubefacient, counterirritant, antiperspirant, aftershave, and for reducing body temperature using alcohol sponges.
- Ethanol can stimulate appetite and aid in digestion as a carminative when taken in 30-60 ml of 7-10% concentration.
- Ethanol can be used to alleviate severe neuralgias, including cancer pain, by injecting it around the nerve.
- Ethanol can provide protection from the cold.
- Ethanol may have a protective effect against heart attacks and strokes, especially in frugivores.
- Ethanol can be used as an antidote to treat methanol, ethylene glycol, and diethylene glycol poisoning.
Contraindications:
- Peptic ulcer, hyperacidity, and GERD
- Epileptics
- Severe liver disease
- Unstable personalities
- Pregnant women (can produce foetal alcohol syndrome)
Disulfiram:
- Disulfiram, also known as Antabuse, is an ALDH enzyme inhibitor that is marketed internationally to help chronic alcoholics overcome their addiction using an aversion technique.
- When taken with alcohol, disulfiram increases the concentration of aldehyde in the blood and tissues, causing a distressing aldehyde syndrome with symptoms such as flushing, burning sensation, throbbing headache, perspiration, dizziness, vomiting, visual disturbance, mental confusion, fainting, and circulatory collapse.
- Disulfiram is only recommended for motivated persons who abstain from alcohol overnight and start with 1 gram on the first day, followed by 0.75 grams the next day and 0.50 grams the following day, and so on. Its effects start within a few hours of the first dose and last for two weeks.
- Disulfiram works by irreversibly inhibiting ALDH, and the synthesis of new enzymes takes time, causing the person to resolve not to drink alcohol due to the distressing symptoms.
Methanol Poisoning:
- Methanol poisoning can be caused by unscrupulous mixing of alcoholic beverages, and formic acid, which is toxic, can cause blindness even at 15 ml.
- Symptoms of methanol poisoning include vomiting, epigastric pain, dyspnoea, bradycardia, acidosis, permanent retinal damage, and death.
- Ethanol saturates alcohol dehydrogenase enzyme and prevents the metabolism of methanol to formic acid.
- Methanol poisoning treatment includes patient isolation in a dark room, ventilation, and BP supportive measures, gastric lavage with sodium bicarbonate if brought in immediately, IV sodium bicarbonate to combat acidosis, Ethanol 10% in water through a nasogastric tube, potassium chloride if hypokalemia occurs, folinic acid or calcium leucovorin injection to enhance the oxidation of formic acid, Fomepizole (4-methyl pyrazole) as a specific inhibitor of ALD until methanol level is <20 mg/dL, and hemodialysis.
Ethanol is a neuronal depressant and can cause long-term adaptive changes in the neuronal system, while chronic alcoholism can cause toxic effects on all organs, especially the liver.
Alcohols – the Key Points
- Alcohols are hydroxy derivatives of aliphatic hydrocarbons.
- ‘Alcohol’ refers to ethyl alcohol or ethanol.
- Alcohol is mostly known for its presence in beverages.
- Alcoholism and alcohol intoxication are major concerns associated with alcohol.
- Alcohol is manufactured by the fermentation of sugars.
- Fermentation is the process of converting sugar into alcohol and carbon dioxide.
- Yeasts are living microorganisms that are used in the fermentation process.
- Starch is converted into maltose and then alcohol during the production process.
- Alcoholic beverages include malted liquors, fortified wines, and spirits.
- Malted liquors are produced by fermenting germinating cereals like barley.
- Wine is produced by fermenting natural sugars found in grapes, apples, and other fruits.
- Fortified wines can have an alcohol content of up to 22%.
- Spirits like rum, whisky, brandy, and gin typically have an alcohol content of 40-55% v/v.
- Absolute alcohol is 99% w/w ethanol and is also called dehydrated alcohol.
- Rectified spirit is 90% w/w ethyl alcohol produced from fermented molasses by distillation.
- Methylated spirit, also known as denatured spirit, is produced by adding wood naphtha (methyl alcohol) to rectified spirit to make it unfit for drinking.
- Alcohol has pharmacological actions such as being a rubefacient, counterirritant, and astringent.
- Alcohol does not have any action on spores and can cause permanent damage if injected around a nerve.
- Alcohol is a CNS depressant and can cause ataxia, disorganization of thought, and impairment of memory.
- Alcohol can induce sleep but is not an ideal hypnotic or analgesic.
- Small doses of alcohol can cause cutaneous vasodilation and flushing.
- Moderate doses can cause tachycardia and mild rises in blood pressure.
- Large doses can cause vasodilation due to direct vascular smooth muscle dilatation and vasomotor center depression.
- Drinking alcohol in moderate amounts can increase HDL-cholesterol levels and decrease LDL oxidation.
- Drinking alcohol in moderation may decrease the incidence of coronary artery disease. However, drinking more than three drinks daily can nullify the protective effects of alcohol on coronary artery disease.
FAQs about Alcohols
What are the different types of alcohols?
There are three types of alcohols: primary, secondary, and tertiary. They are classified based on the attachment of the carbon atom in the hydroxyl group.
What are the uses of alcohols?
Alcohols are used in a wide range of applications, including beverages, cleaning products, healthcare, and industrial processes.
How are alcohols produced?
Alcohols are primarily produced through fermentation and hydration of alkenes.
What are the health impacts of alcohols?
While moderate consumption of certain alcohols can have health benefits, excessive consumption can lead to a range of health issues, including liver disease, cardiovascular problems, and neurological damage.
What role does alcohol play in society?
Alcohol plays a significant role in social and cultural events. However, it also poses societal challenges, including addiction, drunk driving, and social issues.
What are the chemical properties of alcohols?
Alcohols are known for their polarity, high boiling points, and ability to form hydrogen bonds.
