Alcohol

Alcohols

  • Alcohol is the world's most popular recreational drug, available to adults legally and widely used for pleasure and relaxation with no consequences.

    • Ethanol: A substance of abuse, chronic drinking leads to dependence and craving for alcohol, with serious consequences for the individual and society.
    • Overconsumption of alcohol is frequently a catalyst and contributing factor in violent crimes such as physical and sexual assault and homicide.
    • Binge-drinking and intoxication have become significant public health issues.
    • In forensic examinations of unnatural deaths, alcohol ranks as the most common psychoactive substance found.

  • Forensic investigators need to know how alcohol affects the body and how it can lead to bad behavior.

    • It is also necessary to convert a person's blood-alcohol concentration (BAC) into the amount of alcohol consumed.
    • Retrograde Extrapolation: When prosecuting drunk drivers, an investigator might ask an expert to extrapolate a person's blood alcohol content (BAC) from when they were sampled to an earlier time, such as when they were driving.
    • Ethanol is produced naturally in the body. This happens when fermentation of carbohydrates in the gut or during some minor biochemical reactions happens.

  • Absorption is the process by which a drug enters the bloodstream and travels to all organs, fluids, and tissues in the body.

    • Alcohol is absorbed through the entire digestive system, depending on how much surface area there is on the stomach and intestine where the alcohol is absorbed, and how concentrated the alcohol is.
    • Alcohol is first absorbed in the stomach, but the upper small intestine absorbs it much more quickly.
    • When gastric emptying is quick, the pyloric sphincter is less likely to block the passage of alcohol into the small intestines, which speeds up absorption.

  • Ethanol is absorbed into the body and the concentration reached in all body fluids and tissues at equilibrium depends primarily on the water content of these fluids and tissues.

    • Sweat, saliva, and urine, which are nearly 100% water, will have a higher concentration of ethanol than whole blood, which is 80% water.
    • The levels of ethanol in plasma and serum (which contain 93% water) are higher than those in whole blood.

  • The metabolism of ethanol occurs mainly in the liver, where it is released as energy in the form of heat. This process is more energy-rich than the energy released from breaking down proteins or carbohydrates.

    • Acetaldehyde is created during the enzymatic oxidation of ethanol and is then changed into acetate by the mitochondrial enzyme low Km aldehyde dehydrogenase (ALDH).
    • Cytochrome P450 monooxygenases: A large family of proteins being responsible for oxidation and reduction of xenobiotics — that might enter the body, these includes atmospheric pollutants, industrial solvents, as well as diverse pharmaceutical agents.
Biochemical Markers of Alcohol Consumption
  • Biochemical markers can be used to detect organ and tissue damage caused by heavy drinking so that treatment can begin before liver cirrhosis and death occur.
  • Mean corpuscular volume (MCV): Red blood cell enlargement, another commonly used marker of chronic drinking in combination with enzyme markers.
  • Carbohydrate deficient transferrin (CDT): It is another marker of excessive drinking that is used in clinical medicine but also has forensic applications due to its high sensitivity and specificity.
    • It is the preferred marker for spotting heavy drinkers before their livers are irreparably damaged, and it supports the findings of clinical interviews and questionnaires.
    • Transferrin: A plasma protein synthesized and secreted by the liver that serves to transport iron in the body.
  • The following techniques are now much better for determining serum CDT:
    • capillary electrophoresis and
    • high performance liquid chromatography (HPLC)
  • Results of CDT analysis are now more consistently reported between laboratories.
Ethanol Tolerance
  • Dispositional tolerance: The first and most basic type of tolerance involves altered ethanol absorption, distribution, metabolism, or excretion during chronic treatment.
  • Metabolic tolerance: This is faster elimination of certain drugs from the body after chronic exposure.
  • Acute tolerance: It develops during a single exposure to ethanol.
    • After consuming a known amount of ethanol, the subjective and objective levels of intoxication vary with the passage of time.
    • The drug's effect on the descending phase of the BAC curve is lessened compared to the ascending phase when the blood or brain concentration is the same.
    • Acute tolerance to alcohol is also referred to as the Mellanby effect, after Sir Edward Mellanby, a British pharmacologist who first observed the phenomenon and published the results of his experiments on alcohol intoxication in dogs.
  • Chronic tolerance: It is a more gradual process that results in a lessening intoxicating effect after several days or weeks of constant heavy drinking without a period of abstinence.
  • Behavioral/Functional tolerance: The type of tolerance that develops after long-term use of alcohol, it relates to an altered sensitivity of the brain to the effects of the drug.
  • All pharmaceutical products are considered to be legal drugs, despite the fact that many of them, including opiates and benzodiazepines, are narcotics and can be abused.