Ethanol and CNS Depressants

Ethanol (EToH), or alcohol, is a central nervous system (CNS) depressant.
SI refers to the liver.
80 proof indicates the alcohol per volume (ABV).
Beer has an ABV of 4%-10%. A beer contains roughly the same amount of alcohol as a shot.
GABA is an inhibitory transmitter in the central nervous system.
Figure 1 illustrates its effects on the cortex.
Blood Alcohol Concentrations (BAC):
- 0.08%: Legal intoxication limit where one cannot operate machinery due to impairment. Inhibits motor functions and impairs divided attention tasks.
- 0.10%: Motor impairments are greater, and brain function is further depressed.
- 0.15%: Visible signs of intoxication, including impaired driving ability (slowed reaction time) and motor instability (e.g., inability to walk heel-to-toe, wobbly stance).
- 0.20%: Sensory alterations and blackouts occur. Blackouts involve short-term memory impairment, leading to periods of amnesia.
Combining CNS depressants results in a synergistic effect, where 1 + 1 = 5. Example: Alcohol + Valium.
0.3: Significant CNS and motor impairment
0.4: Alcohol poisoning begins, affecting the brain stem.
0.5: Likely to be fatal due to respiratory failure. The brain stem controls respiratory function, and its depression leads to asphyxiation.
Excitatory Phase: Initial feeling of euphoria due to disinhibition.
Tolerance:
- Metabolic
- Functional: Desensitization of receptors to the drug.
  - Upregulation: Occurs when there is a low amount of primary cell messenger which results in an increase of receptors
  - Downregulation: Occurs when there is a high amount of primary cell messenger, leading to a decrease in the number of receptors.
  - High tolerance to a drug results in a decrease in the number of receptors.
- Genetic Disposition: Variations in alcohol dehydrogenase (ADH) production. Some individuals, like those in certain Asian populations, produce less ADH.
Acetaldehyde: A byproduct that causes hangovers.
Alcohol Excretion:
- Excreted in breath (volatile pulmonary excretion).
- Metabolized in the blood.
- Some urinary excretion.
- Volatile excretion via alveolar spaces in the breath is the most important route.
Breathalyzers: Directly correlate blood alcohol concentration with breath alcohol concentration.
0. 10% is equivalent to 0.1 g/100 mL.
Alcohol is distributed in plasma water, thus the volume of distribution (VOD) is 0.65 for males and 0.33 for females.
BAC = \frac{Dose (mL) \times 0.8}{Weight of person (kg) \times VOD}
- Females tend to have a higher BAC than males due to differences in body composition and water distribution.
- 0.8 is the gravity of alcohol.
Example Calculation:
- 10 L is equivalent to 10 ml
- 30 mL of 40% alcohol contains 12 mL of pure alcohol (40% of 30 mL).
- For a 70 kg individual: BAC = \frac{12 mL \times 0.8}{70,000 g \times .55}
6 hours -> .25%
Conversion Example: 100 lbs
Formula Application: 0.08 = \frac{x \times 0.8}{kg \times 0.55}, and 0.08 = \frac{24 mL}{kg}

Sympathomimetic Drugs (CNS Stimulants)

Sympathomimetic toxidromes mimic the sympathetic nervous system's