Ethanol and Methanol Flashcards
Medical uses of ethanol
Antiseptic
Analgesic
Weak general anesthetic
What cells does ethanol act on
Almost all cells
Lipid and water soluble
Mechanism of ethanol
General depressant action on most cells
Inhibits glutamine
Activates GABA
May activate DA pathways (pleasure center)
How does ethanol affect the CNS?
- 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
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Ethanol and cardiovascular system
Skin vasodilation
due to inhibition of reflex vasoconstriction
Ethanol and GI tract
Low conc-increased gastrin and HCl secretion (good for digestion)
High conc-gastric irritation
Ethanol and liver
Direct toxic effect-interacts w/ other liver toxicants
Chronic use→Fatty livers
Decreases test. synth and increases its metabolism
Ethanol and kidney
Inhibits ADH secretion
Decreased uric acid excretion→gout
Pharmacokinetics of ethanol–absorption
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
Pharmacokinetics of ethanol–distribution
Rapid equilibration w/ all tissues
Can pass placental barrier
- Newborns can undergo withdrawls
- There may be developmental damage-FAS
Pharmacokinetics of ethanol–metabolism
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
Pharmacokinetics of ethanol–excretion
Lungs (minor)
Kidneys
Breathlyzer accurate +/- 10%
Potency of ethanol
Very low
50g of ethanol=1 mol of ethanol
4 avg drinks=56g
2 drinks=.03%
6 drinks=.1%
Tolerance of ethanol
Metabolic tolerance-increased AlcDH
Tissue Tolerance-increase glutamate receptors
Behavioral tolerance
Ethanol dependence
Physical
- Withdrawl→headache, dizziness, nausea, sweating=hangover
- Severe=seizure, cramps, delerium tremens (DTs)-shakes and tremors
Psychological
Ethanol drug interactions
Any drug that enters CNS
Disulfiram
Inhibits acet.DH→buildup of acetaldehyde
Get severe hangover right away
Acamprosate
Decreased craving for ethanol
Ethanol addiction sequelae
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
Methanol metabolism and toxicity
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
Fomepizole
Specific inhibitor of alcDH
Prolongs effects of alcohol
