Ethanol and Methanol Flashcards

1
Q

what are the medicinal uses of ethanol?

A

very limited- antiseptic, analgesic, weak general anesthetic

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2
Q

what is the structure of ethanol?

A

both lipid and water soluble, can get anywhere in body and act on any cell

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3
Q

what is the general action of ethanol on most cells?

A

depressant

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4
Q

what does ethanol do to the glutamine pathway?

A

ethanol inhibits the excitatory glutamine (NT) pathway

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5
Q

what does ethanol do to the GABA pathway?

A

ethanol activate the inhibitory GABAnergic (NT) pathway

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6
Q

what other pathway might ethanol activate?

A

dopanergic pathways- pleasure center

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7
Q

what are the sites of action of ethanol in the CNS?

A

ethanol inhibits higher cortical functions
inhibits critical faculties- increase in excitement, euphoria
lack of critical judgment- decrease social inhibitions
often memory impairment
slows reaction time
decrease visual acuity
decrease visual tracking ability
motor incoordination- staggering, speech slurring
impairs medullary function- loss of balance, nausea, vomiting, decrease respiration
decrease sexual performance
inhibits REM sleep

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8
Q

what are the sites of action of ethanol in the cardiovascular system?

A

skin vasodilation- due to inhibition of reflex vasoconstriction- why we feel warmer in winter but actually causing more heat loss

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9
Q

what are the sites of action of ethanol in the GI tract?

A

low concentrations- increase gastrin secretion, HCL acid secretion- good for digestion
high concentrations- gastric irritant

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10
Q

what are the sites of action of ethanol in the liver?

A

direct toxic effect on the liver
taking tylenol (acetaminophen)- interact with other liver toxicants
chronic use- fatty liver, decrease testosterone synthesis, increase testosterone metabolism

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11
Q

what are the sites of action of ethanol in the kidney?

A

weak diuretic- inhibit ADH secretion- water in collecting duct not absorbed
decrease uric acid excretion- can cause gout

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12
Q

what are the absorption characteristics of ethanol?

A

rapidly absorbed in small intestines
slightly absorbed from stomach
px with gastrectomies have more rapid absorption
carbonation may increase stomach emptying

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13
Q

what are the factors that delay stomach emptying (lower rate of absorption)?

A

exercise, food, anticholinergic agents

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14
Q

what are the distribution characteristics of alcohol?

A

rapidly equilibrated in all tissues
ethanol can pass through the placenta
newborns can undergo withdrawal- developmental damage- fetal alcohol syndrome

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15
Q

where is alcohol primarily metabolized?

A

in the liver

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16
Q

what are the oxidation reactions of ethanol?

A

ethanol is oxidized to acetaldehyde by alcohol dehydrogenase
acetaldehyde is oxidized to acetyl coa by acetaldehyde dehydrogenase
both steps transfer a hydrogen to NAD+ to make NADH

17
Q

what is special about alcohol dehydrogenase?

A

it is a zero order reaction- rate of metabolism is constant, regardless to amount of ethanol

18
Q

what is the average amount of metabolism pf ethanol?

A

1 ounce every 3 hours

19
Q

what is the rate of limitation of ethanol metabolism?

A

amount of NAD+ limited

need to be regenerated via other means

20
Q

what are the excretion characteristics of alcohol?

A

lungs (minor)
kidney (acetyl coa to water and co2)
breathelizer- lungs- accurate +/- 10%
best measure of alcohol exposure- blood test

21
Q

what is the toxicity of alcohol?

A
potency is very low 
50 grams of ethanol= 1mole of ethanol
4 average drinks= 56 grams
aspirin- 1 mole=300 tablets
2 drinks = 0.03% blood concentration
0.08%= legal limit in ohio 
6 drinks- 0.1%
12 drinks- 0.2% 
18 drinks- 0.3%- unconscious
22
Q

how do you gain tolerance of ethanol?

A

metabolic tolerance- increase alcohol dehydrogenase
tissue tolerance- increase # of excitatory neurons
behavioral tolerance- watching their slurring, staggering etc

23
Q

what are the symptoms of physical alcohol dependence?

A

withdrawal- headache, dizziness, nausea, sweating- hangover

severe- tremors, nausea, seizures, cramps, delirum tremens (shakes, see things)

24
Q

what kind of drug can ethanol interact with?

A

any drugs that enters the CNS

25
Q

how does ethanol interact wth disulfiram?

A

inhibits aldehyde dehydrogenase
leads to build up of acetaldehyde
used to help people stay off alcohol
headache nausea, severe hangover if taken with alcohol

26
Q

how does ethanol interact with acamprosate?

A

mechanism unknown- decrease the craving of ethanol

27
Q

neurological and mental sequelae of ethanol addiction

A

brain damage, memory loss, sleep disturbances, psychosis, strain on family

28
Q

nutritional sequelae of ethanol addiction

A

alcoholics have the poorest nutrition of any group in the us
drinking- calories from ethanol- develop thiamine deficiencies, wernicke’s encephalopathy- disorientation, polyneuritis, severe vision changes

29
Q

cardiomyopathy sequelae of ethanol addiction

A

more congestive heart failure etc than control group

diet or not enough exercise?not sure

30
Q

liver damage sequelae of ethanol addiction

A

cirrhosis/ fatty liver

31
Q

fetal alcohol syndrome

A

CNS dysfunction, facial abnormalities, immune system abnormalities, still birth, spontaneous abortions

32
Q

what are the oxidation reactions of methanol?

A

methyl alcohol is oxidized by alcohol dehydrogenase into formaldehyde
formaldehyde is oxidized by acetaldehyde dehydrogenase into formic acid

33
Q

what is the toxicity of oxidations reactions of methanol?

A

metabolic acidosis

blindness- formic acid destroys ganglion cells in retina

34
Q

how does the metabolism of methanol compare to ethanol?

A

slower

35
Q

what is the treatment of the toxic formic acid?

A

ethanol

enzyme preferentially breakdown ethanol= no build up of formic acid - methanol is given time to be cleared first

36
Q

fomepizole

A

specific inhibitor of alcohol dehydrogenase- prolong effect of ethanol