C - Toxicology Flashcards
list sources of tox samples
antemortem serum / blood
post mortem blood - femoral vein
vitreous humour
stomach contents
liver
urine
hair
list 9 of the most common drugs of abuse in tox
ethanol
heroin
cocaine
amphetamines
methadone
benzos
cannabis
pregbalin
new psychoactive compounds
in what cases is ethanol tox found
OD
RTAs
liver cirrhosis
how can ethanol cause death if other drugs are taken too
additive effects with other depressants
who dies of rapid death from heroin
naive users
high tolerane ppl who have quit
what do heroin users die from
resp depression
aspiration pneumonitis
what does prognosis with heroin depend on
TOLERANCE
describe half-life of heroin products with timings
diacetylmorphine (3 mins) –> 6-MAM (30 mins)—> morphine (6 hours)
what is actually measured in heroin blood screen
morphine
what is a speedball
depressant + stimulant (usually cocaine)
acute dangers of cocaine
cardiac dysrhythmias
acute heart failure
myocardial infarction
chronic dangers of cocaine
myocardium damage
ventricular arrhythmias
suddendeath
which group is most at risk from cocaine death
body packers - bag splits in their stomach so OD
how can the effects of cocaine be prolonged
mix with ethanol to get cocaethylene
why is cocaine difficult to measure PM
degrades in blood
how is cocaine result PM interpreted
with witness behaviour, cardiopathology and pattern of drug use
what causes death in amphetamine OD
direct toxic effect on heart
complications of amphetamine use
hyperthermia
rhabdomyolysis –> muscle necrosis –> renal failure
how long does it take to die from methadone OD once ingested
4-6 hours
what doses can kill a child / adult with methadone
5mL child, 60mL adult
what is maintenance dose of methadone
5 to 200mL
what does the dose of maintenane methadone depend on
heroin tolerance
how common in benzo death
very rare alone
is cannabis fatal
no
how can you determine if cannabis was the cause of a RTA
investigation of impairment that dose would cause
what is the ‘lethal combination’ with cannabis
cannabis + alcohol + driving
what % of coroners cases have pregablabin present
9%
when is pregablin used
heroin users to cause euphoria
prescribed for epilepsy / neuropathic pain
give examples of new psychoactive compounds
stimulants
synthetic cannabinoids - spice
synthetic opioids - carfentanil, isotonitazene
hallucinogenic compounds
what is carfentanil normally used for
elephant tranquilliser
how does carfentanil potency compare to morphine
10,000x more potent
how does isotonitazene potency compare to morphine
500x more potent
what is the problem with new psychoactive compounds
+++ potency vs original drugs
severe ADRs even in low doses
what are the problems with interpretation of tox results
need lots of Hx info to interpret results!!
- tolerance
site dependence
PM redistribution of drugs
individual variation in response
stability of drugs
how can PM redistribution of blood affect drug conc
drugs released from tissues into blood after death
relates to volume distribution
how can the ratio of parent drug:metabolite be used to determine if chronic use or OD
the closer 1:1, then the more likely to be chronic use
why is hair used for analysis
only sample that can detect chronic use
for how long can drugs be detected in blood
12 hours
for how long can drugs be detected in urine
2-3 days
how can hair analysis show chronic use
drugs incorporated into hair from blood during growth
hair grows 1cm/month therefore every 1cm that contains a drug = 1 month of use
limitation of hair use in analysis
limited by hair length - if 5cm hair only, can only see 5 months of drug use
contamination by smoke/powder
cosmetic Tx can remove drugs from hair
darker hair incorporates more drug
can not be used to determine cause of death as it takes 5-10 days for hair to come above scalp
to what scenarios can hair analysis be applied
child custody cases
Ix spiked drinks defencefs
drug naive deaths
monitoring drug use in employment / driving
