CNS depressants: Alcohol and glycols

Question 1

CNS depressants

Answer 1

Ethanol
Methanol
Ethylene glycol 
Isopropyl alcohol 
Barbiturates
Benzodiazepines
Opioids

Question 2

Organ-selectivity of ethanol, methanol and ethylene glycol

Answer 2

Ethanol - effect on CNS in normal doses.

Methanol and glycol - effect on multiple organ systems at small doses.

Question 3

Metabolism of ethyl alcohol

Answer 3

Oxidized by alcohol dehydrogenase to form acetate. Acetate enters citric acid cycle and oxidizes to CO2 and H2O.
Depletion of nicotinamide adenide dinuclease (NAD).
Zero-order kinetics.
At higher/chronic doses: metabolized by CYP2E1 - contributes to alcohol tolerance.

Question 4

BAC - what is it?

Answer 4

Blood alcohol concentration - calculated by exhaled air which contains 0.05% of the concentration of alcohol in the blood.

Question 5

Ethanol - MOA

Answer 5

Potentiates GABA.
Inhibits release of ACh from CNS neurons (sedation, delirium).
Inhibits ADH

Question 6

Ethanol - CNS effects

Answer 6

Sedative-hypnotic
Anxiolytic
Amnesic
Anticonvulsant effects (Long-term use/withdrawal may lower the threshold).
Sedation
Delerium.
Low doses: disinhibition, mild euphoria - rate dopamine increases in accumbens.

Question 7

Ethanol - effects outside CNS

Answer 7

Vasodilation.
Increased heat loss (interferes with hypothalamus)
(Diuresis)
Blood pressure fluctuations
Long-term: alcoholic cardiomyopathy and cardiac arrhythmia

Question 8

Long-term alcohol use - symptoms

Answer 8

Alcoholic cardiomyopathy, cardiac arrhythmia.
Nerve demyelination: thiamine deficiency (secondary to poor diet).
Peripheral neuropathies, paresthesia, reduced sensory acuity.
Wernicke-Korsakoff syndrome - thiamine deficiency.
NAD deficiency: cirrhosis, impaired glycogenolysis.
Megaloblastic anemia.
Overall tissue damage.

Question 9

Wernicke-Korsakoff syndrome - signs

Answer 9

Confusion
Severe anterograde and retrograde amnesia
ataxia
nystagmus
ophthalmoplegia

Question 10

Fetal alcohol syndrome - signs

Answer 10

Low birth weight
Microcephaly
Facial abnormalities (flattening)
Mental retardation
Heart defects

Question 11

Methanol intoxication - signs

Answer 11

Anion gap metabolic acidosis.

Optic nerve damage and blindness (formate)

Question 12

Methanol - metabolism

Answer 12

Converted to formaldehyde and then to formate.

Question 13

Alcohol dehydrogenase inhibitor

Answer 13

Fomepizole

Question 14

Isopropyl alcohol - signs

Answer 14

More CNS depression

Question 15

Ethylene glycol intoxication - signs

Answer 15

Anion gap metabolic acidosis.

Kidney, lung and CNS toxicity

Question 16

Alcohol intoxication - signs

Answer 16

Ataxia, incoordinatino, loquacity, slurred speech.
Euphoria, impaired attention, irritability, mood changes, sedation.
Flushed face
Nystagmus

Question 17

Alcohol withdrawal - signs

Answer 17

Altered perceptions, insomnia, irritability, seizures.
Tremor.
Hypertension and tachycardia.
Delerium tremens, nausea, sweating

Question 18

Treatment of alcohol intoxification

Answer 18

Supportive care
Ethanol - Supportive, fomepizole, hemodialysis
Methanol - give ethanol or fomepizole.
Isopropyl alcohol - Supportive
Ethylene glycol - Supportive, ethanol or formepizole, manage acidosis, hemodialysis