Psychopharmacology Week 10: Alcohol Effects

Course Information

• Course code: PYB260
• Course name: Psychopharmacology of Addictive Behaviour
• Week: 10
• Topic: Action & Effects of Alcohol

Lecture Outline

• What is alcohol?
• History of alcohol
• Administration, distribution & excretion of alcohol
• Effects of alcohol - physiological & performance
• Conditioning, tolerance & withdrawal
• Harmful effects of alcohol
• Pharmacotherapies for alcohol dependence/ relapse prevention

Reflection Questions

• You and your friend weigh the same, different sexes at birth, and show different acute effects. If both are light social drinkers, what factors explain the difference in absorption, distribution, or excretion?
• If your friend had alcohol dependence, what metabolic differences might explain this?
• What are the long-term effects of alcohol use?
• What does alcohol withdrawal look like?
• Describe one psychopharmacological treatment for ceasing alcohol use.
• Describe one neuropharmacological effect of alcohol that leads to greater inhibition.

What is Alcohol?

• Types: Isopropyl, Methanol, Ethanol
• Fermentation: Sugar dissolved in water, yeasts multiply and convert sugar into ethanol & CO2. Alcohol content about 10-15%.
• Distillation: Fermentation → heated → alcohol given off in vapour → vapour cooled. Alcohol content ~ 40-50%.

Measurement of Alcohol

• BAL/BAC: Concentration of alcohol in whole blood, usually measured as mg alcohol/100ml whole blood (or % of alcohol in the blood).
  • Example: 50mg/100ml = 0.05%
• SI units: mmol/L
• Conversion: mg/100ml / 4.607 = mmol/L

What is a Standard Drink?

• Various types of drinks with different alcohol percentages and volumes (e.g., Light Beer, Mid Strength Beer, Full Strength Beer, Sparkling Wine, Wine, Fortified Wine, Spirits, etc.)
• Informational graphics displaying volumes and alcohol content for each standard drink.

History of Alcohol Use

• Been around since the dawn of time
• 6000 BC: Neolithic people cultivated grains & grapes
• 3500 BC: Egyptian Book of the Dead
• 2225 BC: Code of Hammurabi (Assyria)
• Roman Empire introduced grapes to Britain
• Taverns & alehouses established in Britain
• 1066: Wine reintroduced to Britain
• Spirits first distilled about 1000 years ago
• 16th century: Irish settlers in Britain introduced distillation
• 1660: Licensed distilleries (esp. gin)
• 1684-1727: Consumption increased from 0.5 million to 3.5 million gallons/year
• 1742: Distillation banned in Britain
• American Colonies, colonial and revolutionary eras, impacts on regulation.
• Late 1890's: Temperance Movement
• WW1: Licensing hours introduced to control factory workers
• Prohibition (1917-18th Amendment), Al Capone, and Roosevelt's amending of the 18th amendment (21st Amendment) in 1933.
• Alcohol consumption patterns in Australia.

Trends in Type of Alcohol Consumed in Australia

• Volume of pure alcohol consumed (in millions of liters) over time.

Australians 14+ Alcohol Drinks Status

• Data shows trends in daily/weekly/monthly alcohol consumption patterns amongst Australians.

Risky Alcohol Consumption Trends in Australia

• Data (by age groups) on the percentage of risky drinking behaviours (e.g., exceeding lifetime/single-occasion risk guidelines).

Risky Alcohol Consumption Trends by Remoteness

• Data shows trends in risky alcohol consumption by remoteness in Australia (e.g., major cities, inner regional areas, outer regional areas, remote/very remote areas.)

Most Recent Australian Stats (2022-2023)

• Alcohol accounted for 59% of drug-related hospitalisations, males highest.
• 1742 alcohol-induced deaths (1245 males)
• Highest rates in 55-64 yr olds
• chronic conditions (incl. alcoholic liver cirrhosis).
• Acute alcohol-induced deaths (154 deaths)
• consistent since records begin (2002-2003).
• Top 3 concerns for clients: Male (60%); First Nations people (16%); Clients aged 30-39 or 40-49.
• Most common referrals: Self (41%); Health services (37%)
• Most common treatment: Counselling (33%); assessment only (23%); and withdrawal management(14%).
• Median treatment duration: Just under 4 weeks (27 days).

Administration, Absorption, Distribution & Excretion of Alcohol

• Generally oral administration

• pH levels have no effect on absorption

• Readily dissolves in water & passes into blood from stomach lining.

• 1st pass metabolism - alcohol dehydrogenase in stomach.

• Stomach contents, body fat/age, female sex, medication, and alcohol concentration and usage all affect absorption.

• Plateau phase, Peak levels in BAC.

• Impact of drink type on absorption

• Expectancy effects.

• Distribution of alcohol: alcohol dissolves in water, distributed entirely in body water, crosses blood-brain barrier and placental barrier,

• Excretion: Some alcohol is excreted through breath, sweat & urine; most alcohol is metabolized in the liver (~90-98%) at a rate of ~1 standard drink/hr

Metabolism of Alcohol

• Alcohol is metabolized by the liver in a 2-step process:
  • Conversion of alcohol to acetaldehyde by alcohol dehydrogenase.
  • Conversion of acetaldehyde to acetate, which goes into the bloodstream; some acetate is converted into acetyl-coenzyme A.
  • Acetyl-coenzyme A is converted into water and CO2 via the Krebs cycle.
• Excretion rates vary greatly between individuals, typical range is 10-20 mg/100ml/hour.
• Non-drinkers metabolize alcohol slightly slower; eating speeds alcohol metabolism.
• Excretion of methanol: formaldehyde & formic acid.
• Microsomal ethanol-oxidizing system (MEOS) is involved in alcohol metabolism; more activity with continuous drinking, enabling faster metabolism.
• MEOS also metabolizes barbiturates – cross-tolerance.

Effects of Alcohol

• Alcohol affects a variety of tissues.
• Large doses needed to have an effect.
• No drugs act as complete antagonists (all) to alcohol's effects.
• Conclude that alcohol does not only work directly on specific receptor sites, but affects many sites of action.
• Affects receptors of many NTs & their ion channels (glutamate (excitatory NT), including NMDA receptor and (blocks ion channels); hippocampus (NDMA receptors), and PFC)
• Affects GABA (inhibitory NT), including GABAA-receptor–ionophore complex and orthosteric and allosteric sites);
• also affects other transmitters such as cerebrobellum, GABAB (metabotropic) receptors, and 5-HT3 receptors.
• Alcohol affects second messengers, monoamine oxidase, glycine, acetylcholine and endogenous opioid systems.
• Dilates blood vessels, increases urination, induces sleep.
• Affects the amount and phases of sleep
• Affects sensitivity to light, sensory perceptions such as visual acuity, peripheral vision and sensitivity to smells, tastes, and pain.
• Slowed reaction time, impaired coordination, reduced vigilance and performance, decreased storage/retrieval memory (en bloc blackout, and grayout).
• Sensitivity to balance is affected (Romberg sway test).
• Affects behavior: Disinhibition, talkativeness, excitability, cheerfulness, sleepiness, unconsciousness, nausea, and vomiting.
• Impaired driving performance.
• Significant impact on relation to accidents.
• Relative risk of traffic accident by blood alcohol levels (BAL)

Conditioning, Discrimination, Tolerance & Withdrawal Effects of Alcohol

• Conditioning: Reinforcing properties are dose dependent, shock avoidance, & increased response rates when paired with shock.
• Discriminative properties: Easy discrimination from saline, generalization to barbiturates.
• Self-administration: Rats/humans usually consume high amounts of alcohol intermittently with periods of abstinence, varying by culture.
• Tolerance:
  • Acute & selective tolerance: occurs when drinking, subjective feeling of intoxication. Develops quickly within weeks for humans.
  • Does not develop equally for all effects.
  • Metabolic tolerance: stimulation of alcohol dehydrogenase, conditioned tolerance and hypothermic effects, and environmental factors.

Harmful Effects of Alcohol

• Alcohol poisoning, symptoms, and dangers.
• Dangers when combined with other conditions like epilepsy, heart disease, or diabetes.
• Socio-cultural effects like accidents, relationship difficulties.

Harmful Effects of Alcohol (Continued)

• Reproduction: Small doses decrease inhibitory/ increase inhibitions and sexual arousal with large doses. Chronic use causes loss of interest, impotence, shrinking testes, menstrual issues and Spontaneous abortion. Fetal alcohol spectrum disorder (FASD).
• Liver function: Hepatitis and Cirrhosis; ↓ immune functioning.
• Nervous System: Korsakoff’s syndrome, epilepsy, dementia, peripheral neuropathy.
• Cancer: Risk increased for mouth, throat and liver, especially with smoking.
• Heart Disease; Alcoholic cardiomyopathy.
• Dependence described.

Pharmacotherapies

• Acamprosate (Campral).
• Naltrexone
• Disulfiram (Antabuse)

Exam Prep

• Tutorial topics covered in the week and next week.
• How to prepare notes for assessments.
• Upcoming exam prep workshops, tutors, and student voice surveys.

Other

• Additional questions and explanations on reflection and related questions.

Explore the action and effects of alcohol in this quiz focused on psychopharmacology. Delve into the physiological and performance impacts, conditioning, tolerance, and pharmacotherapies related to alcohol dependence. Reflect on important questions regarding alcohol's effects on the body and mind.