what can pm tox tell us 9 2

Question 1

Interpretation of pm

Answer 1

 Interpretation of postmortem blood drug conc was thought a relatively simple process
 Conc of drug measured at autopsy compared to established therapeutic and toxic conc
ranges in living subjects
 Underlying assumption as drug conc dud not change during or after death
o Wrong

Question 2

Why is interpretation challenging

Answer 2

o No randomized controlled human studies
o Must rely upon
 Basic science of pharmacology
 Animal data
 Antidotal human case reports

Question 3

IS there an absolute rules for interpretation

Answer 3

o absolute rules for interpretation of tox. Results
Don’t waltz in with the Red Book
Disposition of toxic drugs and chemicals in man

Question 4

Must consider multiple factors and sources of information for interpretation

Answer 4

Scene investigation
Medical history
Autopsy findings
Histological and toxicological studies
Limits of toxicological analyses
Knowledge on how the postmortem interval may impact the findings

Question 5

“how much drug did the decedent take?”

Answer 5

Historically: toxicologists relied upon published case reports of fatal intoxications
More recently: pharmacokinetic equations been used to estimate ingested dose from measured blood concentration
HOWEVER: investigation of numerous drug-related deaths have shown these equations to yield unreasonable and obviously overestimated dose

Question 6

Additional factors for consideration for interpretation

Answer 6

Postmortem redistribution
Parent: metabolite ratio
Serum/plasma: whole blood ratio
Clinical “therapeutic” concentrations vs postmortem “therapeutic” concentrations
Tolerance