Ethanol and Methanol

Question 1

Medical uses of ethanol

Answer 1

Antiseptic

Analgesic

Weak general anesthetic

Question 2

What cells does ethanol act on

Answer 2

Almost all cells

Lipid and water soluble

Question 3

Mechanism of ethanol

Answer 3

General depressant action on most cells

Inhibits glutamine

Activates GABA

May activate DA pathways (pleasure center)

Question 4

How does ethanol affect the CNS?

Answer 4

• Inhibits higher cortical function
• Inhibits critical faculties (judgement making)→excitement, euphoria
• Lack of critical judgement→decreased social inhibitions
• Memory impairment
• Slows rxn time
• Decreased visual acuity
• Decreased visual tracking ability
• Motor incoordination→slurred speech
  
  • Inhibited REM sleep is bad for motor fxn
• Impairs medullary fxn
  
  • Loss of balance
  • Nausea and vomiting
  • Decreased resp
  • Decreased sexual performance
    *

Question 5

Ethanol and cardiovascular system

Answer 5

Skin vasodilation

due to inhibition of reflex vasoconstriction

Question 6

Ethanol and GI tract

Answer 6

Low conc-increased gastrin and HCl secretion (good for digestion)

High conc-gastric irritation

Question 7

Ethanol and liver

Answer 7

Direct toxic effect-interacts w/ other liver toxicants

Chronic use→Fatty livers

Decreases test. synth and increases its metabolism

Question 8

Ethanol and kidney

Answer 8

Inhibits ADH secretion

Decreased uric acid excretion→gout

Question 9

Pharmacokinetics of ethanol–absorption

Answer 9

Rapidly absorbed from SI

Slightly absorbed from stomach

Factors that delay stomach emptying lower rate of absorption.

Such as:

• Exercise
• Food
• Anti-cholinergic agents
• Pts w/ gastrectomy→rapid absorption
• Carbonation may increase stomach emptying→drunk faster

Question 10

Pharmacokinetics of ethanol–distribution

Answer 10

Rapid equilibration w/ all tissues

Can pass placental barrier

• Newborns can undergo withdrawls
• There may be developmental damage-FAS

Question 11

Pharmacokinetics of ethanol–metabolism

Answer 11

Primarily in the liver

Ethanol–(AlcDH)–>Acetaldehyde–(AcetDH)–>AcetylCoA

NAD+→NADH during both enzymatic rxns

AlcDH: Zero order rxn

Rate of metabolism is constant, ind. of ethanol conc.

Rate limiting factor: Availability of NAD+

Best measure of alcohol exposure is a blood test

Question 12

Pharmacokinetics of ethanol–excretion

Answer 12

Lungs (minor)

Kidneys

Breathlyzer accurate +/- 10%

Question 13

Potency of ethanol

Answer 13

Very low

50g of ethanol=1 mol of ethanol

4 avg drinks=56g

2 drinks=.03%

6 drinks=.1%

Question 14

Tolerance of ethanol

Answer 14

Metabolic tolerance-increased AlcDH

Tissue Tolerance-increase glutamate receptors

Behavioral tolerance

Question 15

Ethanol dependence

Answer 15

Physical

• Withdrawl→headache, dizziness, nausea, sweating=hangover
• Severe=seizure, cramps, delerium tremens (DTs)-shakes and tremors

Psychological

Question 16

Ethanol drug interactions

Answer 16

Any drug that enters CNS

Question 17

Disulfiram

Answer 17

Inhibits acet.DH→buildup of acetaldehyde

Get severe hangover right away

Question 18

Acamprosate

Answer 18

Decreased craving for ethanol

Question 19

Ethanol addiction sequelae

Answer 19

Neurological and mental

• Brain damage
• Memory loss
• Sleep disturbances
• Psychosis
• Family

Nutritional

• Alcoholics have poorest nutrition of any group in US
• Thiamine deficiency→Wernickes encepholopathy
• Disorientation, vision changes, polyneuritis

Cardiomyopathy

• Nutrition, alcohol, lack of exercise?

Liver damage

• Cirrhosis
• Fatty liver

FAS

• CNS disfunction
• Facial abnormalities
• Immune system abnormalities

Question 20

Methanol metabolism and toxicity

Answer 20

Methanol–(AlcDH)–>Formaldehyde–(AcetDH)–>Formic Acid

Toxicity:

• Metabolic acidosis
• Blindness-formic acid kills cells in retina

Metabolism=slower than alcohol

They compete for the same enzymes so treatment of methanol ingestion is ethanol ingestion b/c body preferentially degrades ethanol

Question 21

Fomepizole

Answer 21

Specific inhibitor of alcDH

Prolongs effects of alcohol