Alcohol Pharmacology + Forensic Issues

What is the prefered specimen for clinical testing?

Plasma/Serum

What analytes make up the typical basic profile of interest for alcohol?

- Ethanol
- Methanol
- Acetone
- Isopropanol

What are the effects of alcohol as a social lubricant?

Loss of inhibitions
Altered judgment
Relaxation
Increased confidence
Expansiveness

What are the depressant effects of alcohol

Slurred speech
Ataxia
Sedation
Stupor
Coma
Death

At a LOW BAC what are the effects on CNS

Stimulant effect, depression of inhibitory processes

What BAC % is Death

>0.45%

What is considered a low dose

BAC < 0.05%

Low dose alcohol impairment, what are the effects

Dynamic visual acuity
Divided attention
Complex reaction time
Voluntary eye movements

At a moderate dose, what is the BAC range

0.05 - 0.08%

What is affected at a moderate dose alcohol impairment

Attention
Vigilance
Tracking
Information processing
Reaction time
Psychomotor performance

Why is 0.08 the legally impaired %

All drivers are impaired at this BAC

At what BAC is tracking and reaction time impaired

0.05 g/dL

Is ethanol lipid soluble?

Poor solubility

Is ethanol soluble in water

Yes

What are the properties of ethanol?

- Small colorless
- Miscible with water
- Poor solubility in fats/lipids
- Negligible protein binding
- Readily passes biological membranes

What is the route of absorption in the body

Mouth to esophagus to stomach to pyrolic sphincter to small intenstive

Where is alcohol primarily absrobed

Small intenstine

Absorption at each site depends on:

Quantity of alcohol
Time in contact
Vascularity
Surface area

Absoption is affected by

gastric emptying

What factors affect stomach emptying?

- Food in stomach
- Meal size/composition
- Dose of alcohol/concentration
- Beverage type
- Anatomy of gut
- Time of day

How does food in the stomach affect stomach emptying?

It is one of the variables that influence stomach emptying.

What is the average BAC in DWI

0.15 - 0.17 g/dL

Effect of food in blood alcohol concentration

Empty stomach makes peak BAC occur earlier
Food will compete with ethanol for sites in small intesntine, slows absorption

If fasting, peak BAC occurs

0.5-2 hrs

If non-fasting, peak BAC occurs

1 -6 hr

An increase water content, will have INCREASED OR DECREASED alcohol content

INCREASED

What are the issues with clinical BAC results

Serum not whole blood
COC
Replicate analysis
Enzymatic assays
Forensic defensibility
Hematocrit

Urine as a specimen

Ratio of UAB/BAC varies
during absorptive phase
• Post-absorptive phase typically
1.3
• Two samples collected ('VOID"
and "SAMPLE", 30-60 mins
later)

Breath as a specimen

Deep lung air (alveolar air)
• Saturated with water
• Henry's Law
• EtOH in 2100 mL breath = 1 mL
whole blood at 34°C (expired
air temp)
• Burping, vomiting

Widmark equation

A = C P R

What is retrograde extrapolation

Allows estimaton of theoretical BAC in linear phase

Estimation of BAC at the time of death is complicated by:

Quality and location of samples
Trauma
Timeline
Presence of microorganisms
Diffusions
Environemental conditions

A negative VAC and positive BAC suggests

PM production

If BAC >> VAC then it suggests

pre-equilibrium death (rapid death)

What is the average elimination

0.015 g/dL

What is the range of elimination rates to cover pop variations

0.01 - 0.02 g/dL

In acute tolerance, effects of alcohol are perceived to be ____ when BAC is ___ rather than ___

greater when BAC is ascending rather than descending

In chronic tolerance, tolerance is lost within ____ days of abstinence

5-7 days

Why is vitreous fluid the preferred specimen for decomps and traumatic injury

It is anatomically isolated and more protected from bacterial putrefaction