toxicology/therapeutic windows

week 3 stibs

drug

medicine/other substance which has a physiological effect when ingested or otherwise introduced into the body

poison

substance that is capable of causing illness/death of a living organism when introduced or absorbed

toxicology

science dealing with properties, actions, toxicity

forensic toxicology: study of chemical and physical properties of toxic substances and their effect on living organism

therapeutic index

• therapeutically effective dose to toxic dose of pharmaceutical agent

margin of safety

• ratio of toxic dose to 1% of population

blood

• anti mortem: provides closest correlation to dose

• post mortem blood may contain clots, fatty deposits

• decomposition

urine

• 99% water

• determining past use

• large sample volume

• useful for POCT

urine: post mortem

advantages:

• longer detection window

• post mortem ethanol production

• large sample volume

disadvantages:

• parent compound may not be detectable

• poor correlation with blood

oral fluid

• consists of saliva, cellular debris and blood

• detection window relates to administration

• anti mortem sample used in POCT

oral fluid- post mortem

advantages:

• non invasive sample

• difficult to adulterate

• good for pharmacokinetic studies

disadvantages:

• passive contamination

• less fluid than urine

• dry mouth

• buffers

vitreous humour

advantages:

• analyte stability

• remains sterile for days after death

• strong correlation between blood alc conc

disadvantages:

• small sample vol

• not all drugs cross blood retina barrier

stomach analysis

• stomach wash out

• useful for identifying fungi and plants

• cyanide

hair analysis

• drugs incorporated via

  1. blood

  2. sweat

  3. external

• advances in instrumentation have resulting in analysis of organic molecules