Specific Poisonings: Ethanol and Its Effects

Specific Poisonings

• Ethyl alcohol (ethanol) is the active constituent in alcoholic beverages.
• Ethanol concentration varies across different beverages:
  • Beers: 4% to 5%
  • Wines: 7% to 12%
  • Cordials: 20% to 40%
  • Distilled beverages (whiskey, vodka, rum): 40% to 60%
• Ethanol is a clear, volatile liquid that burns easily and has a slight characteristic odor.
• It's highly soluble in water, mixing in all proportions.

Causes of Poisoning or Death

• Accident:
  • Direct effect on body tissues
  • Inhalation of vomitus
  • Ingesting other poisons or drugs
  • Associated pathology in organs (e.g., drowning, burning, falling)
  • Road traffic accidents
• Committing a crime:
• As a catalyst in assaults and homicides

Fate of Ethanol in the Body

• When alcohol is consumed, it is diluted by stomach juices and quickly distributed throughout the body.
• Ethanol doesn't require digestion before absorption into the bloodstream.
  • Some diffuses directly into the bloodstream through the stomach wall.
  • The remainder enters the small intestine for rapid absorption and circulation.

Alcohol Absorption

• Alcohol is absorbed from all parts of the gastrointestinal tract via simple diffusion into the blood.
• The small intestine is the most efficient absorption region due to its large surface area.
• Absorption speed varies based on the type of beverage and the person's stomach state.
  • Fasting individuals: 20-25% from the stomach, 75-80% from the small intestine; peak blood alcohol concentrations in 0.5-1.0 hours.
  • Non-fasting individuals (presence of food, especially fatty foods): delayed absorption; peak concentrations in 1.0-6.0 hours.
  • Alcohol with carbonated beverages: absorbed more rapidly.

Alcohol Distribution

• Absorbed alcohol is distributed to all parts of the body.
• Distribution is proportional to the water content of tissues and organs.
• Greater concentration in blood and brain, with lower concentration in fat and muscle.

Alcohol Metabolism & Elimination

• Over 90% of alcohol is metabolized in the liver, oxidizing it to acetaldehyde and then acetic acid, releasing carbon dioxide and water.
• Alcohol dehydrogenase (ADH) converts alcohol to acetaldehyde, a highly toxic substance.
• Aldehyde dehydrogenase transforms acetaldehyde into acetic acid.
• Acetic acid is finally oxidized to CO2.
• Metabolism rate depends on alcohol use history; heavy drinkers metabolize faster than light drinkers or nondrinkers.
• Approximately 5-10% of a dose of ethanol is excreted in the urine unchanged.
• The remainder is eliminated via excretion in breath, sweat, milk, and saliva.

Primary Pharmacological Effect of Alcohol

• Alcohol is a central nervous system (CNS) depressant.
• The degree of CNS impairment corresponds to the concentration of blood alcohol.

Signs and Symptoms of Acute Alcohol Intoxication

• Symptoms depend on blood alcohol content (BAC).
• BAC ranges and associated clinical manifestations are shown in the table on page 14.

Causes of Death

• Most deaths from acute alcohol intoxication occur when BAC exceeds 300mg%.
• Death can result from direct depressive effects on the brain stem's respiratory centers or secondary events (accidents like traffic accidents, falling, inhalation of vomitus).

Alcoholism

• Alcoholism is a disabling, addictive disorder.
• It entails compulsive and uncontrolled alcohol consumption despite adverse effects on the drinker's health, relationships, and social standing.
• Long-term alcohol abuse leads to physiological changes in the brain, including tolerance and dependence.
• Alcoholism involves a cycle of tolerance, withdrawal, and excessive alcohol use.
• Alcohol damages nearly all organs in the body.
• Detoxification is conducted to help the addict withdraw from alcohol, often using cross-tolerance drugs like benzodiazepines to manage withdrawal symptoms.

Signs and Symptoms of Alcoholism

• Poor nutrition, weight loss, lack of appetite.
• Liver damage (jaundice, ascites, cirrhosis)
• Pancreatitis
• Peripheral neuritis, tremors
• Insomnia, memory loss, impaired judgment (alcoholic dementia)
• Loss of vitality, recurrent infections
• Increased risk of cardiovascular disease, malabsorption, alcoholic liver disease, and cancer.

Liver Pathology

• Liver Mallory bodies: a characteristic of alcoholic hepatitis (alcoholic hyaline).
• Portal fibrosis: observed along with pericellular fibrosis in alcoholic liver tissue.

Corrosive Agents Poisoning

• Corrosive agents cause significant tissue damage on contact due to chemical action.
• Alkaline agents: cause liquefactive necrosis (deep tissue damage ).
• Acid agents: cause coagulative necrosis (primarily superficial injury) by dehydrating tissues.
• Common strong inorganic acids include sulfuric, hydrochloric, and nitric acid.
• Common organic acids include phenol (carbolic acid), Lysol, and cresol.
• Common strong alkalis include sodium and potassium hydroxide, and ammonia.

Symptoms of Caustics (Corrosive agents)

• Ingestion rapidly results in severe burning and intense dysphagia.
• Associated airway edema can obstruct airways and cause asphyxia.
• Alkali ingestion can lead to esophagus perforation, mediastinitis, and death.
• Acid ingestion can affect the esophagus, but gastric necrosis and perforation with peritonitis are more common.

Carbon Monoxide Poisoning

• Chemical Properties: Colorless, odorless, tasteless gas, slightly lighter than air, produced by incomplete combustion.
• Major Sources: Cigarette smoke, Coal gas, automobile exhaust, defective/ faulty heating appliances (furnaces, stoves, water heaters), and smoke from conflagrations.
• Toxic Effects: CO binds to hemoglobin more strongly than oxygen (200-300 times stronger), generating carboxyhemoglobin (COHb). This renders hemoglobin unable to carry oxygen, leading to hypoxia.
• Disposition of CO: Absorbed through the lungs; eliminated through the lungs without undergoing metabolic processes. COHb is displaced by the mass action of oxygen. Half-lives are 5-6 hours at normal oxygen levels, 30-90 minutes with 100% oxygen, and just 30 minutes under hyperbaric conditions.
• Clinical Effects of CO Toxicity: Symptoms depend on CO concentration in inspired air, individual activity levels, duration of exposure, and COHb accumulation rate. Symptoms vary. Mild to severe and sometimes fatal.
• Treatment: Immediate removal from the environment; high concentrations of oxygen; and, in severe cases hyperbaric oxygen therapy.
• Autopsy Findings: Characteristic cherry-red coloration of blood, fingernails, mucous membranes, visceral organs, and skin.

Organophosphates Poisoning

• Organophosphates are insecticides.
• They are widely used, but degrade fairly quickly in the environment.
• Mechanism of Action: Inhibit cholinesterase. This prevents the breakdown of acetylcholine – resulting in an accumulation of acetylcholine and its corresponding excitation responses in the nervous systems and muscles.
• Exposure Routes: Inhalation, ingestion, dermal absorption.
• Metabolism: In the liver via action of esterases.
• Excretion*: In the urine.
• Signs and symptoms: Various symptoms from mild to fatal.
  • Bronchospasm, bronchorrhea, chest discomfort, wheezing, pulmonary edema
  • Loss of consciousness, incontinence, convulsions, respiratory depression
  • Tachycardia, hypertension, sweating, lacrimation, rhinorrhea, vomiting, abdominal cramps, diarrhea, miosis (constricted pupils).
  • Anxiety, restlessness
• Autopsy findings: External cyanosis, inflamed/ congested mucosa of the stomach and intestines, edema of lungs, brain, and respiratory tract. Low levels of cholinesterase in red blood cells and plasma.
• OPIDN – Organophosphate-Induced Delayed Neuropathy: A rare toxicity. Proximal muscle weakness; numbness/ tingling, pain in the lower legs frequently develops 1-4 weeks after exposure.
• IMS (Intermediate Syndrome): A neurological dysfunction in the 24-96 hours range following exposure. Characterized by weakness of proximal limb muscles.

This quiz covers the properties of ethanol, its concentration in various alcoholic beverages, and the different causes of ethanol poisoning. Additionally, it discusses the impact of ethanol on the human body and its fate after consumption. Test your knowledge on ethanol and its physiological effects.