Alcohols

Question 1

What is an osmol gap?

Answer 1

• difference between the measured osmolality and the calculated osmolarity

Question 2

What is osmolarity?

Answer 2

measure of the total number of particles in 1 litre of solution (molar concentration)

Question 3

What is osmolality?

Answer 3

differs from osmolarity only in that the number of particles is expressed per kilo of solution (molal concentration)

Question 4

What is the formula for calculating osmolarity?

Answer 4

2(Na) + (glucose) + (BUN)

BUN= blood urea N

Question 5

What can circulating alcohol do to the serum osmolality?

Answer 5

• can increase the serum osmolality (alcohol and other low MW substances)
• since these substances are not included in the calculated osmolarity, there will be a gap proportional to their serum concentrations when comparing calculated vs measured values

Question 6

What is the normal range for the osmol gap?

Answer 6

• 10 +/- 6 mOsm

Question 7

How is most of ethanol eliminated?

Answer 7

• by enzymatic oxidation

Question 8

What is the MOA of CNS depression with ethanol?

Answer 8

• membrane fluidification
• enhancement of GABA-nergic function
• inhibition and up regulation of NMDA receptors and increase in dopamine release
• functional tolerance (habituation)

Question 9

In non-tolerant individuals, impairment of judgement can be detected at levels as low as ______

Answer 9

25 mg/dL

Question 10

What are the s/s of acute ethanol intoxication?

Answer 10

• flushed face
• tachycardia
• increased sweating
• mydriasis
• muscular incoordination
• ataxia
• altered consciousness
• euphoria
• agitation
• n/v
• impaired cardiac output
• coma
• resp depression

Question 11

What are some of the metabolic changes that can happen with ethanol intoxication?

Answer 11

• hypoglycemia
• metabolic acidosis (due to lactate and/or ketoacids)
• hypomagnesemia

Question 12

What are some of the supportive care measures to give to someone with acute ethanol toxicity?

Answer 12

• sedatives potentially
• glucose, oxygen and thiamine
• electrolytes (Mg)
• anion gap and osmol gap

Question 13

What happens with alcoholic liver disease?

Answer 13

• fatty liver (90% of chronic drinkers, happens when the mobilization of fatty acids and inhibition of lipoprotein synthesis)
• alcoholic hepatitis (hepatocyte degeneration and necrosis)
• alcoholic cirrhosis

Question 14

Alcoholism causes enzymatic _____

Answer 14

induction (increases the clearance of certain drugs)

Question 15

What medications does alcohol increase the clearance of?

Answer 15

• phenytoin
• methadone
• tolbutamide
• isoniazide
• warfarin

Question 16

What causes alcohol withdrawal?

Answer 16

• habituation to the CNS depressant effects, uncompensated state of overstimulation (up regulation of NMDA receptors)

Question 17

What can be used as treatment of an alcoholic patient?

Answer 17

• diagnosis
• serotonin uptake inhibitor
• naltrexone
• acamprosate calcium
• bromocriptine
• lithium
• disulfiram
• non-pharms

Question 18

What is the mechanism of methanol elimination?

Answer 18

• zero order kinetics at high concentrations
• first order kinetics at low concentrations
• 10-20% eliminated unchanged by the lungs
• 3% unchanged in the urine
• primarily liver metabolism

Question 19

Affinity of ADH for ethanol is _______ than its affinity for methanol

Answer 19

4x greater

Question 20

The conversion of formaldehyde to formic acid is ______

Answer 20

very rapid (formaldehyde does not accumulate in the blood)

Question 21

What is the toxic components of methanol?

Answer 21

methanol itself is not toxic, its metabolites formaldehyde and formic acid are the toxic metabolites

Question 22

What are the effects that methanol can cause that are toxic

Answer 22

• direct effect on metabolic acidosis
• indirect effect (mitochondrial toxicity, binding to cytochrome oxidase, intereference with intracellular respiration, tissue hypoxia, anaerobic metabolism)

Question 23

What causes ocular toxicity?

Answer 23

• formic acid

Question 24

______ increases toxicity by favouring diffusion

Answer 24

acidosis

Question 25

What is the primary site of toxicity with ocular toxicity associated with methanol?

Answer 25

• retina
• formate concentration usually >20-30 mg/dL
• retinal ganglion cells and retrotubular optic nerve are secondary sites

Question 26

What are the characteristics associated with methanol induced ocular toxicity?

Answer 26

• blurred vision
• “snow field” vision
• fundoscopic examination shows hyperemia of the optic disc and retinal edema
• reduced pupillary response to light

Question 27

What are the permanent effects of ocular toxicity?

Answer 27

• optic atrophy
• peripheral constriction of visual fields
• central scotoma
• reduced visual acuity
• loss of colour vision
• blindness

Question 28

What is the treatment of methanol toxicity?

Answer 28

• standard supportive care
• correction of academia (iv sodium bicarb)
• fomepizole or ethanol
• iv folinic acid
• hemodialysis

Question 29

What is preferred - folic acid or folinic acid?

Answer 29

• folinic acid- because it does not require metabolic reduction

Question 30

What is the treatment regimen for ethylene glycol?

Answer 30

• ethanol
• fomeprizole (competitive inhibitor of ADH)
• thiamine and pyridoxine (100 ng 50 mg respectively)
• folates
• hemodialysis