"Bad" Alcohols

Question 1

lab investigation - if looking to see if there is alcohol consumption what do we test?

Answer 1

1st - osmolality and osmolal gap

2nd- pH = acid/base disorder?

3rd - pCO2, HCO3 = helps physician determine if acidosis coming from organic molecule or resp in nature?

4th - anion gap (Na, K, Cl, HCO3) = CATMUDPILES

5 - toxic alcohol identification = GC-FID, headspace or serum analysis)

6 - ethanol enzymatic assay (is it a contributing osmol?)

Question 2

acidosis

Answer 2

pH <7.35

Question 3

is the acidosis metabolic or respiratory?

Answer 3

decrease in HCO3 = metabolic
increase in CO2 = respiratory

Question 4

is there an anion gap?

Answer 4

AG = Na - HCO3 - Cl
> 12 mmol/L

Question 5

CATMUDPILES

Answer 5

cyanide, Co2
aminoglycosides
theophylline
methanol
uremia
diabetic ketoacidosis
paraldehyde
isoniazid
lactate
ethylene glycol
salicylic acid

Question 6

pathophysiology of methanol poisoning

Answer 6

1. formic acid production => metabolic acidosis
2. formic acid destruction of optic nerve/retina => blindness; unique!!
3. irritation of GI lining => nausea and abdominal pain

in addition to alcohol mediated CNs depression

Question 7

competitive inhibitor of alcohol dehydrogenase

Answer 7

Fomepizole
- 8000x greater affinity than ethanol

Question 8

Fomepizole

Answer 8

diluted in total body water
elimination:
- 97% hep metabolism (<3% unchanged in urine)
- induces own metabolism (dose increased after 5th)
- zero order pre-induction; 1st order post-induction
- t1/2 =16-17h

Question 9

T or F. Alcohols can freely traverse cell membranes (small, uncharged, organic properties)

Answer 9

T!
the number and location of hydroxyl group is relevant to metabolism and toxicity of each alc

Question 10

methanol clinical presentation

Answer 10

CNS: headache, vertigo, lethargy, confusion, coma, seizures, NO BUZZ
GI: nausea, vomiting, ab pain
acid/base balance: met acidosis
ocular: blurred vision -> blindness
cardiac: bradycardia
renal: myoglobiunria, possible renal failure

Question 11

ethylene glycol clinical presentation

Answer 11

CNS: depression (1-12 hr), coma, seizures, transient exhiliration
GI: nausea, vomiting
acid/base balance: met acidosis
ocular: nystagmus
cardiac: tachycardia, mild hypertension
renal: oligouria, acute tubular necrosis, renal failure, oxalate crystals (24-72 hr)

Question 12

pathophysiology of ethylene glycol poisoning

Answer 12

1. 0.5-2 hrs = cute CNS depression
2. 12-24 hrs = glycolic, glyoxylic and oxalic acid => met acidosis
3. 24-72 hrs = CaOxalate formation => AKI with oliguria

Question 13

these impact the PCT of the nephron

Answer 13

calcium oxalate monohydrate and dihydrate crystals
(ethylene glycol)

Question 14

treatment for methanol

Answer 14

folic acid
to turn formate to CO2

Question 15

treatment for ethylene glycol

Answer 15

thiamine, pyridoxine

Question 16

treatment for BOTH methanol and ethylene glycol

Answer 16

supportive

ethanol
- methanol = 1/10 ADH affinity
- eth glycol = 1/100 ADH affinity

correct acidosis with NaHCO3

hemodialysis

Fomepizole

Question 17

folic acid

Answer 17

vit B9

Question 18

vit B6

Answer 18

pyridoxine

Question 19

thiamine

Answer 19

vitamin B1

Question 20

progressive ethylene glycol and methanol testing

Answer 20

• perform initial diagnosis and treatment = supportive care focus; assess for toxic syndromes
• request eth glycol &/or methanol, Na, urea, glucose, osm, ethanol
• lab performs all except eth glyc and methanol
• determine: calc osm, osm gap, unaccounted osm gap
• is unaccounted osm gap greater than or equal tp decision level???

> eth glyc = 2
methanol = 5

if yes, performed eth glyc and methanol analysis

if not, cancel tests

Question 21

T or F. MeOH elimination during hemodialysis is zero order

Answer 21

F! first order

Question 22

T or F. Fomepizole prolongs methanol and ethylene glycol half-life

Answer 22

T! patient may need several infusions to adequately eliminate the alcohol; fomepizole to stop metabolism and dialysis to get rid of everything

Question 23

T or F. Ethylene glycol is volatile

Answer 23

F! methanol is but not ethylene glycol
- not excreted in lungs unchanged

Question 24

exclusions to cancelling toxic alc request if does not fall lower than threshold (<2 eth glycol; <5 methanol)

Answer 24

if stat request subsequent to an initial pos result
if ped patient <11y/o

Question 25

does presence of ethanol affect Kd of methanol hemodialysis?

Answer 25

no, there is a generally flat line; Kd is not changing even if there is ethanol (no matter how much)

Question 26

antizol

Answer 26

fomepizole brand name in Canada

Question 27

T or F. Fomepizole induces its own metabolism

Answer 27

T; causes CYP enzymes to be induced … then zero -> first = will have constant half-life so constant dosing