DiMaio - Drugs Flashcards
Name 5 possibles sources of blood for tox testing, in descending order of preference
Femoral blood
Subclavian vessels
Root of aorta
Pulmonary artery
Superior vena cava
Heart
What additive should be use for samples of blood for tox testing?
Sodium fluoride (preservative)
Potassium oxalate (anticoagulant)
What additive should be use for samples of blood for DNA analysis?
EDTA
What additive should be use for samples of blood for CO testing?
EDTA
Why is blood from the femoral vessels the preferential blood for testing?
To prevent possibility of postmortem release (redistribution and diffusion)q
2 factors why tox done on blood after hospital stay may give wrong data
Dilution from fluid administration
Metabolism of drug
Possible samples for tox in a decomp case
Muscle
Liver
Maggots
What are the 2 broad categories of testing in tox
Screening:
- Immunoassay
- Spectrophotometry
- Gas or liquid chromatography
Confirmatory
How does immunoassay work?
Blood pass on a solid phase with antibodies specific to that substance
The analyte binds to the antibody
Another andibody (with a reporter) is washed on that solid phase and then detection is done to know if present or not
How does spectrophotometry work?
Wavelength pass through the blood, and depending of the profile, allow to identify presence of a substance
How does chromatography work?
Drugs are dissolved in gas or liquid, which then pass through a stationary phase (column), alowing separation of the constituent of the solution
What is the gold standard for confirmatory testing of drugs?
Gas or liquid chromatography + mass spectrometry
Allows for mass spectral analysis of analytes after they have been separated
Fragmentation of a molecule by different ionization techniques, allowing for fragmentation pattern and ion ratio
Autopsy findings in drug use
Cocaine:
- Nasal septum perforation
IV drug use:
- Needle tracks
Subcutaneous injection:
- Skin popping scars
Opioids or depressant:
- Cerebral edema, pulmonary edema, full bladder, foam cone
Stimulants:
- Cardiomegaly in a young man
What is postmortem distribution of drugs?
As death occur, blood starts to separate, causing a change in hematocrit and distribution of drug within the blood (bound to protein, pH change, cell wall lysis)
Can cause diffusion of drugs both in and out of blood
Where does absorption of ROH occurs?
Stomach (20-25%)
GI tract (75-80%)
Metabolites of ethanol
Acetaldehyde –>
Acetic acid –>
CO2
Usual treshold for death 2nd to acute ethanol toxicity
0.400
Metabolites of methanol
Formaldehyde
Formic acid
Long term complication of methanol toxicity
Blindness
4 alcohols than are of forensic interest
Ethanol (acetaldehyde and acetic acid)
Methanol (formaldehyde and formic acid)
Isopropanol
Ethylene glycol (oxalic acid)
Which alcohol is found in rubbing alcohol?
Isopropanol
Which alcohol is found in antifreeze
Ethylene glycol
Difference between opiates and opioid
Opiates: derived from poppy plant (morphine, codeine, papaverine)
Opioid: natural or synthetic drugs that have the same actions as opiates
Heroin: stimulant or depressant?
Depressant
Metabolites of heroin (diacetylmorphine)
6-monoacetylmorphine (half life: 9 min)
Morphine (half life: 38 min)
2 mechanisms of toxicity in stimulant use
CNS: systemic excitation and decrease in the seizure treshold
Cardiovascular:
- increased heart rate, blood pressure and cardiac contractility (arrythmias)
- coronary spasm
- ischemic or hemorrhagic strokes
- Ruptured aortic and cerebral aneurysms
- myocardial infarct
