TOXICOLOGY Flashcards
• Branch of science which deals with the study of the effect of drugs on biologic systems
PHARMACOLOGY
biologic systems
o Routes of drug administration
o Pharmacokinetics
o Drug actions
o Drug interactions
I. ROUTES OF DRUG ADMINISTRATION
- Oral
- Sublingual
- Rectal
- Intravenous
- Intramuscular
- Subcutaneous
- Inhalation
- Topical
- Transdermal
– below the tongue; in cases of cardiovascular diseases
- Sublingual
– suppository: drug delivery system inserted in the rectum
- Rectal
– IV fluid, anti-fungal, antibiotic
- Intravenous
– insulin shots
- Subcutaneous
– asthmatics
- Inhalation
- Vicks
- Topical
• Fate of an administered drug
PHARMACOKINETICS
– movement of drugs into the bloodstream after administration
- Drug absorption
- movement of drugs to and from the blood and other tissues or organs of the body
- Drug distribution
- biotransformation mainly occurring in the liver
- Drug metabolism
– metabolites of drugs move out of the body through urine; happens in the kidneys
- Drug excretion
– rate of excretion of drugs and its metabolites
- Drug clearance
Drug response depends on both the affinity of a drug for its receptors and the drug’s efficacy
RECEPTOR THEORY
- strength of binding between a drug and its receptor
• Affinity
- the degree to which a drug is able to induce maximal effects
• Efficacy
– addition of multiple drugs produces different effect for each
- Addition
– combination of multiple drugs produces singular effect for all
- Synergism
– addition of one drug will increase the effect of another
- Potentiation
- addition of one drug will reduce/block the effect of another
- Antagonism
• Study of exogenous clinical compounds that profoundly influence bodily functions, either in a deleterious way or for therapeutic benefits
TOXICOLOGY
CLINICAL TOXICOLOGY LABORATORY 3 Functions :
- Therapeutic drug monitoring (TDM)
- Identification of drugs in acute intoxication
- Urine testing for drugs of abuse
- enables physicians to adjust and optimize the dosage on an individual basis
- Therapeutic drug monitoring (TDM)
- identify the offending drug/s
- Identification of drugs in acute intoxication
- establish diagnosis, assess level of intoxication, suggest course of therapy
- Identification of drugs in acute intoxication
- pre-employment and medico-legal cases
- Urine testing for drugs of abuse
Vol for urine drug testing: –
Patient:
Donor
Freshly voided urine sample temp: –
Analytes tested: –
: Evidences
Chain of Custody
Most common drugs of abuse measured in the Ph/Two-parameters:
Marijuana, Methamphetamine
4 areas :
- drugs of abuse
- therapeutic drugs
- environmental carcinogens
- toxins
• Toxicity of chemicals is determined in the [?]
laboratory
• The normal procedure is to expose test animals
1. By [?], or some other method which introduces the material into the body
2. By placing the test material in the [?] of the test animals’ environment
ingestion, application to the skin, by inhalation, gavage
water or air
Toxicity is measured as clinical “endpoints” which include:
o Mortality (death)
o Teratogenicity (ability to cause birth defects)
o Carcinogenicity (ability to cause cancer), and,
o Mutagenicity (ability to cause changes in the DNA)
(death)
o Mortality
(ability to cause birth defects)
o Teratogenicity
(ability to cause cancer), and,
o Carcinogenicity
(ability to cause changes in the DNA)
o Mutagenicity
• The amount (dose) of a chemical which produces death in 50% of a population of test animals to which it is administered by any of a variety of methods mg/kg
LD50
• Normally expressed as mgs of substance per kg BW of animal
LD50
• The concentration of a chemical which produces death in 50% of en. exposed population of test animals in a specified time frame mg/L
LC50
• Normally expressed as mgs of substance per liter of air or water (or as ppm)
LC50
OPTIMAL TIME FOR BLOOD SPECIMENS
Steady state concentration
Trough or pre-dose period
Peak or post-dose level
• Received regular maintenance doses of the drug for about five half-lives of the drug
Steady state concentration
• Just before the next dose
Trough or pre-dose period
• For most orally taken drugs
Trough or pre-dose period
• Shortly after receiving the drug
Peak or post-dose level
Peak or post-dose level IV -
30 minutes after infusion
Peak or post-dose level IM -
60 minutes after injection
• For patients who exhibit toxic symptoms
Peak or post-dose level
TECHNIQUES FOR DRUG ANALYSIS
Immunologic
Chromatographic
Spectrophotometry
Ab-antigen
Immunologic
Separation technique
Chromatographic
Absorbance
Spectrophotometry
Immunologic:
• Enzyme immunoassay systems
• Fluorescence immunoassay
• Radioimmunoassay
Chromatographic:
• HPLC
• GLC
• TLC
Spectrophotometry:
• Visible spectrum, ultraviolet spectrum and fluorescence
• Serum + antibody + enzyme-labelled drug + substrate
ENZYME MULTIPLIED IMMUNOASSAY TECHNIQUE (EMIT)
• Measured enzyme activity : drug concentration (directly proportional)
ENZYME MULTIPLIED IMMUNOASSAY TECHNIQUE (EMIT)
• More rapid than RIA ENZYME MULTIPLIED IMMUNOASSAY TECHNIQUE (EMIT)
ENZYME MULTIPLIED IMMUNOASSAY TECHNIQUE (EMIT)
• 1st homogenous Enzyme Immunoassay
ENZYME MULTIPLIED IMMUNOASSAY TECHNIQUE (EMIT)
: most useful; less likely to be affected by serum constituents
• MDH & G-6-PD
• Measures drugs (mg/L) & drug metabolites in biological fluids
ENZYME MULTIPLIED IMMUNOASSAY TECHNIQUE (EMIT)
• Some drugs detected:
Cocaine & metabolites, cannabinoides, opiates & barbiturates
• Drug to be measured is the hapten
ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA)
• Specific antibodies bound to a solid state carrier
ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA)
• Separation of the bound drug from the unbound
ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA)
• Digoxin and digitoxin tests
ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA)
• Principle: Sandwich Immunoassay
ENZYME-LINKED IMMUNOSORBENT ASSAY (ELISA)
• Drug bound to a fluorogenic substrate :
umbelliferyl-ßgalactoside
(Enzyme:)
B-galactosidase
• Fluorogenic reagent + antibody + beta-galactosidase — incubated w/ serum sample
FLUORESCENCE IMMUNOASSAY
• Drug and DFS compete for binding
FLUORESCENCE IMMUNOASSAY
SUBSTRATE-LABELED FLUORESCENT IMMUNOASSAY (+)
Flourescence
• Fluorescent product
UMBELLIFERONE
formed when the substrate is cleaved by Bgalactosidase
UMBELLIFERONE
Enzyme cannot cleave the DFS when it is reacted with the specific antibody
UMBELLIFERONE
• Separation of free from antibody bound drug
RADIOIMMUNOASSAY
• Counting the radioactivity in either free or antibody bound fraction
RADIOIMMUNOASSAY
• Calculating amount of drug in serum from a standard curve of % antibody bound vs drug concentration
RADIOIMMUNOASSAY
• Incubation of serum + antibody + radiolabeled drug (competition for antibody binding sites)
RADIOIMMUNOASSAY
• Adsorption of drug to a solid support and elution by means of a mobile, liquid phase
- screening for drug identification
• Thin Layer Chromatography
- primarily for quantitating serum drug levels in TDM and also for confirming drug identification
• High-Performance Liquid Chromatography and Gas-Liquid Chromatography
: gold standard for drug testing
• Gas Chromatography-Mass Spectrometry
: NRL for drug testing
• East Avenue Medical Center (Q. C.)
: tentative identification of tentative
Spectral scan
Quantitative analysis:
- Visible spectrum –
salicylate
- Ultraviolet spectrum
barbiturates
Fluorescence –
quinidine
Visible spectrum Wavelength:
Ultraviolet spectrum Wavelength:
340 to 700 nm
< 340 nm