Stability of drugs of forensic interest in post mortem blood

Lutfi, Layal Anton (1998) Stability of drugs of forensic interest in post mortem blood. PhD thesis, University of Glasgow.

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The stability study of drugs of forensic interest in human post-mortem
blood is an important forensic study, because in some cases, a requirement for
the laboratory to undertake a full drug screening is after a few months of
storage due to a need for new evidence. Therefore, it is necessary and
important to know if drugs are stable over a period of time under different
conditions to enable a solid interpretation to be made from any results.
Some studies have been published on the stability of drugs at different
temperatures but none had covered the whole set of drugs that has been studied
in this thesis. The periods of study that have been covered by other studies
varied from a few days to a maximum of 70 weeks, but again not all drugs have
been covered.
The drugs studies in this thesis are two sets of drugs, benzodiazepines
and tricyclic antidepressants, their stability being determined over twelve
months and at three different temperatures 25,5 and -20°C.
In this thesis, blood was 'spiked' with eight drugs, Diazepam,
Temazepam, Triazolam, Desmethyldiazepam, Amitriptyline, Nortriptyline,
Imipramine and Chlorpromazine. The samples were stored with blanks at
different temperatures for different storage times. Each month a number of
samples were removed from storage and analysed to test the effect of storage
time and temperature on drug concentration.
Different solid phase and liquid-liquid extraction methods were tested
for the determination of benzodiazepines. Liquid-liquid extraction methods for
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the determination of Diazepam, Temazepam, desmethyldiazepam and
Triazolam proved after study to be tedious and time-consuming. A method
based on solid phase extraction was used to determine the four benzodiazepine
drugs. The extraction method gave good recoveries and was highly efficient.
The method of analysis used for the determination of stability of
benzodiazepine drugs was the high performance liquid chromatography
(HPLC) method.
Tricyclic antidepressant drugs are the other drugs studied for their
stability in blood. Different solid phase extraction methods were used for the
determination of drugs in post-mortem blood but gave poor recoveries. The
best method of extraction used was a liquid-liquid extraction method which
yielded high recoveries and proved to be quick. The method of analysis used
for the determination of tricyclic antidepressants for the purpose of stability of
the study was gas chromatography (GC).
At a recognised toxic level for each drug under study a reasonable
amount of the drug was found to be detectable after one year at storage
regardless of the storage temperature or media. The decrease rate of each drug
concentration with time at the three storage conditions (25, 5 and -200e) was

Item Type: Thesis (PhD)
Subjects: R Medicine > RA Public aspects of medicine > RA1001 Forensic Medicine. Medical jurisprudence. Legal medicine
Colleges/Schools: College of Medical Veterinary and Life Sciences
Supervisor's Name: Oliver, Doctor John S.
Date of Award: June 1998
Depositing User: Mrs Marie Cairney
Unique ID: glathesis:1998-7085
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 11 Feb 2016 12:08
Last Modified: 22 Apr 2016 12:08

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