Drugs of abuse: Alcohol

Question 1

How is the absolute amount of alcohol calculated?

Answer 1

% ABV x 0.78 = g alcohol/100ml

ABV = alcohol by volume

Question 2

How are units of alcohol calculated?

Answer 2

(% ABV x volume (ml))/1000
1 unit = 10ml or 8g of absolute alcohol.
No consistency.

Question 3

What is the safe level (low risk) of alcohol consumption?

Answer 3

Men and women < 14 units per week.

Question 4

What is classified as binge drinking?

Answer 4

> 8 units in one sitting.

Question 5

What is the usual route of administration of alcohol?

Answer 5

Oral

Question 6

Where is alcohol absorbed from?

Answer 6

20% stomach

80% small intestine

Question 7

How does drinking on an empty or full stomach affect the rate at which alcohol enters the bloodstream?

Answer 7

Speed of onset is proportional to gastric emptying.
Much more effectively absorbed from small intestine.
Fluid stimulates gastric emptying.
Full stomach delays gastric emptying, so alcohol stays in stomach and is much less effectively absorbed, so enters bloodstream at much slower rate.

Question 8

What percentage of alcohol is metabolised?

Answer 8

90%.

10% is not metabolised at all, which is why the breath test is used.

Question 9

What percentage of alcohol that is metabolised is metabolised in the liver?

Answer 9

85%

Question 10

What are the 2 main enzymes that metabolise alcohol in the liver?

Answer 10

Alcohol dehydrogenase (75%)
Mixed function oxidase (25%)

Question 11

What is alcohol converted to in the liver?

Answer 11

Acetaldehyde- toxic.

Question 12

How does tolerance to alcohol arise?

Answer 12

Up-regulation of mixed function oxidase enzymes.

Question 13

Where is alcohol metabolised, other than in the liver?

Answer 13

15% is metabolised in the GI tract (stomach) by alcohol dehydrogenase intro acetaldehyde. Females tend to have less alcohol dehydrogenase in the stomach than males.

Question 14

What happens to acetaldehyde?

Answer 14

Metabolised by aldehyde dehydrogenase in the liver and stomach into acetic acid.

Question 15

What is used as aversion therapy for alcoholics, and what does it mimic?

Answer 15

Disulfiram
Increases the amount of acetaldehyde building up in the blood due to ineffective or less aldehyde dehydrogenase.
Mimics genetic polymorphism- Asian flush, headaches and nausea, etc.

Question 16

Discuss the potency of alcohol.

Answer 16

Low pharmacological potency.
Poor affinity and efficacy, very simple molecule (ethanol is C2H5OH). Need much larger doses than other drugs (e.g. nicotine or cocaine) to see effects.

Question 17

What are the acute effects of alcohol on the CNS?

Answer 17

Depressant effect.
CNS agitation may occur.
Dependent on degree of CNS excitability, which depends on personality and environment (social or non-social setting).

Question 18

How may alcohol cause euphoria?

Answer 18

When intranasal (sniffed), binds to opioid receptor to switch off GABA and increase dopamine release from the nucleus accumbens.

Question 19

What areas of the brain can alcohol affect?

Answer 19

Corpus callosum- passes information from the left brain (rules, logic) to the right brain (impulse, feelings) and vice versa.
Hypothalamus- controls appetite, emotions, temperature, and pain sensation.
Reticular activating system- consciousness.
Hippocampus- memory.
Cerebellum- movement and coordination.
Basal ganglia- perception of time.

Question 20

What are the acute effects of alcohol on the cardiovascular system?

Answer 20

Cutaneous vasodilation- red face, acetaldehyde is the problem.
Decreased calcium entry.
Increased prostaglandins.
Tachycardia- centrally mediated decrease in baroreceptor sensitivity lead to acute increase in HR.
Chronic alcohol- increased BP.

Question 21

What are the acute effects of alcohol on the endocrine system?

Answer 21

Diuresis (polyuria)- stimulated by acetaldehyde, which inhibits ADH production- fewer AQP2 in collecting duct, lose more fluid.

Question 22

What are the chronic effects of alcohol on the CNS?

Answer 22

Thiamine deficiency- Wernicke-Korsakoff syndrome. Wernicke’s encephalopathy and Korsakoff’s psychosis.
Dementia- cortical atrophy/ decreased volume of cerebral white matter.
Ataxia- cerebellar cortex degeneration.

Question 23

What are the chronic effects of alcohol on the liver?

Answer 23

NAD+ is overused for metabolism of alcohol. It is needed for glycolysis and the Kreb’s cycle. Pyruvate is converted to lactate and acetyl CoA to ketones when there is not enough NAD+ available. Acidosis and ketoacidosis.
Build up of fat in the liver
Free oxygen radicals released into blood.
HEPATITIS.
CIRRHOSIS.

Question 24

What is the acute presentation of liver problems related to alcohol?

Answer 24

Fatty liver.

Inability to sufficiently metabolise fats and lipids in the liver, stored there, reversible.

Question 25

What is cirrhosis?

Answer 25

Inflammatory environment of the liver gets so bad that fibroblasts (connective tissue cells) begin to infiltrate- supportive framework.
Decreased hepatocyte regeneration.
Increased fibroblasts.
Decreased active liver tissue.
Eventually need liver transplant.

Question 26

What are the chronic effects of alcohol on the cardiovascular system?

Answer 26

Low levels of alcohol semi-regularly may be beneficial.
Decreased mortality from coronary artery disease
Increased HDLs
Increased tPA levels
Decreased platelet aggregation
Polyphenols may be protective.

Question 27

What are the chronic effects of alcohol in the GI tract?

Answer 27

Damage to gastric mucosa.
Carcinogenic- increased risk of stomach cancer.
Ulceration common- linked to acetaldehyde.

Question 28

What are the chronic effects of alcohol on the endocrine system?

Answer 28

Increased ACTH secretion.

Decreased testosterone secretion.