Ethanol and Methanol Flashcards
name the medical uses of ethanol
antiseptic, analgesic, anesthetic, weak general anesthetic
describe pharm of ethanol
both lipid and water-soluble: goes where it wants
CH3-CH2-OH
MoA? and sites of action?
has a general depressant action on most cells
ethanol inhibits excitatory (glutamine) pathways and appears to activate GABAergic pathways
may also activate DA pathways in “pleasure center”
Name sites of action for alcohol / effects
ethanol inhibits higher cortical functions (inhibits critical faculties) -> excitement and euphoria
- lack of critical judgement and decreased social inhibtions
- often memory impairment
- slows reaction time
- decreased visual activity
- decreased visual tracking ability
- decreased motor skills, staggering
- slurred speech
- impaired medullary function = loss of balance, nausea, vomiting, decreased respiration
- decreased sexual performance
- inhibits REM sleep
Describe alcohol’s effect on cardiovascular system
skin vasodilation due to inhibition of reflex vasoconstriction = heat lost
what is alcohol’s effect on GI tract?
at low concentrations:
-increased gastrin secretion, HCL acid secretion
at high concentrations:
-directly irritates gastric tissue
what is ethanol’s effect on liver?
direct toxic effect on liver - interacts with other liver toxicants
chronic use:
- fatty liver
- decreased testosterone synthesis
- increased testosterone metabolism
what is ethanol’s effect on the kidney?
- weak diuretic
- inhibits ADH secretion: H2O @ collecting duct not reabsorbed as well
- decreased uric acid secretion -> gout (deposition of crystals in joints)
Describe the absorption of ethanol
- rapidly absorbed in S.I.
- slightly absorbed from stomach
- factors that delay stomach emptying, lower the rate of absorption (food, exercise, anticholinergic agents)
px with gastrectomies have more rapid absorption
carbonation may increase stomach emptying (champagne get you drunk)
describe systemic distribution of ethanol
- rapidly equilibrated with all tissues
- ethanol can pass placenta
- newborns can undergo withdrawal - there may be developmental damage aka fetal alcohol syndrome
describe metabolism of ethanol
explain reasoning behind fatty liver side effect
what order reaction is the first enzyme of metabolism?
what is the rate limiting component of ethanol metabolism?
primarily metabolic site is liver
CH3-CH2-OH ———-> acetaldehyde via alcohol dehydrogenase, a NAD+ —> NADH as well
–fomepizole acts here to inhibit alc. dehydro
acetaldehyde ———> acetyl CoA via acetaldehyde dehydrogenase, a NAD+ —–> NADH once again
–disulfiram acts here to inhibit acetaldehyde dehydro
fatty liver: NADH goes into fat production, much of which is made
alcohol dehydrogenase is a zero-order rxn = rate of metabolism is constant and independent of ethanol concentration (1 oz / 3 hr)
NAD+ availability is rate-limiting
describe excretion of ethanol
lungs (minor) and kidneys
best measure of concentration is blood sample
acetyl CoA —> water and CO2
comment on toxicity of ethanol
potency: effect vs. concentration
- alcohol potency is very low
50g of ethanol = 1 mol ethanol
4 avg. drinks = 56 g
for aspirin, 1 mol = 300 tablets
2 drinks = .03% blood conc
6 drinks = 0.1%: 50% decrease in reaction time
12 drinks = 0.2%
18 drinks = 0.3%
What are the three kinds of ethanol tolerance and what are their effects?
metabolic: increase in alc. dehydrogenase
tissue: increase in # of excitatory neurons
behavior: trained to be soberz
Effects of ethanol dependence?
physical:
-withdrawal: headache, nausea, dizziness, sweating
-severe withdrawal: tremors, seizures, cramps, delirium tremens
psychological effects do present
Can ethanol interact with other drugs?
yes, any drug that enters CNS
For what is disulfiram used?
inhibits aldehyde dehydrogenase = buildup of acetaldehyde
for what is acamprosate used?
decreased craving for ethanol
what are the neurological and mental consequences of ethanol addition?
- brain damage
- memory loss
- sleep disturbances
- family life
- psychosis
what are the nutritional consequences of ethanol addition?
alcoholics have the poorest nutrition of any group in U.S.
thiamine deficiencies ->
- wernicke’s encephalopathy
- disorientation polyneuritis
- severe vision changes
what are the cardiomyopathy consequences of ethanol addition?
more congestive heart failure
what are the liver consequences of ethanol addition?
- cirrhosis
- fatty liver
what are the fetal consequences of ethanol addition?
fetal alcohol syndrome:
- CNS dysfunction
- facial abnormalities
- immune system abnormalities
- still birth
describe metabolism of methyl alcohol
toxicity?
treatment of toxicity?
CH3-OH ———> formaldehyde via alcohol dehydrogenase
formaldehyde ——> formic acid via acetaldehyde dehydrogenase
toxicity: metabolic acidosis
- blindness: formic acid kills retinal cells (ganglion cells)
metabolism of methanol is slower than ethanol
so, as treatment, drink ethanol
for what is fomepizole used?
specific inhibitor of alcohol dehydrogenase
