Clinical Chemistry- Toxicology Questions and Answers Already Passed

Clinical Chemistry- Toxicology Questions and Answers Already Passed The main function of toxicology is to: identify drugs in cases of acute intoxication and/or poisoning Is there a specimen of choice for toxicologic analysis? No, there is no true specimen of choice as the type of specimen is dependent on the desired test and/or suspected toxic agent Most widely used specimen for toxicology screening tests Urine T or F: Urine is regularly used for quantitative toxicology analysis F. urine is rarely used for quantitative analysis as urine drug concentration and serum concentrations do not correlate This is the preferred specimen for Blood Alcohol and carbon monoxide cases Whole Blood This is the most widely used specimen for toxicology quantitative testing Serum/Plasma In cases of violent death, blood or urine may be unavailable so this can be used to screen and quantitate drug levels Body Tissues/Homogenates Alcohol is composed of what two things? methyl and ethyl This is the #1 drug abused in the US, and is frequently seen in toxicology testing, and acts as both a depressant and vasodilator Alcohol This family of drugs is classified as mild analgesics, pain relievers, and antipyretics such as aspirin; frequently seen in accidental overdose by children Salicylates Also known as tylenol, mild analgesic and antipyretic, also seen in overdose cases Acetaminophen Common names are speed, "uppers", stimulants; first synthesized an anti-asthmatics; act to increase CNS activity Amphetamines Commonly known as "downers" or sedatives; Frequently seen in drug abuse and suicide attempts Barbiturates Classified as mild tranquilizers; most frequently prescribed drug in the US; Two commonly seen: Valium and Librium Benzodiazepines Many have a narrow margin between therapeutic range and the toxic level; may not be taken correctly or taken too much putting the patient in a toxic condition Therapeutic Drugs Most of these agents come from sources in the environment; public health problem in lower socio-economic housing areas where lead-based paint still exists Heavy Metals Method of toxicology testing include: -EIA -FPIA -Chromatography This method of toxicology testing involves antibodies directed against the drug to produce a color in which the color is proportional to the drug concentration EIA and FPIA This is the most specific toxicology testing method to date but is primarily limited to forensic labs due to cost, time, and demand Chromatography The assay of serum drug concentrations for drugs displaying a high correlation between their serum concentrations and their pharmacologic effect; assays drug levels on those drug which must be at a certain level in the blood stream before they work properly Therapeutic Drug Monitoring (TDM) What are the benefits of TDM? -Aids proper dosing of prescriptions -Helps ensure patients compliance w/ meds -Allows investigation of symptoms related to toxicity of the meds The time required for a 50% decrease in plasma drug concentration Plasma half-life The drug concentration achieved when rate of intake is equal to the rate of elimination Steady-state concentration Steady-state usually occurs after @ least how many half-life (doses) of a drug? 5 The maximum drug concentration reached following one dosage of a drug Peak concentration The lowest drug concentration reached, usually occuring during the "pre-dose" period Trough Concentration Specimen of Choice for TDM: Serum Time of serum collection for a TDM is dependent on drug administration. Explain. Orally- most valuable after patient reaches steadystate Intramuscularly(IM)- 1 hour after injection Intravenously(IV)- 30 min. after infusion is complete Commonly assayed Therapeutic drugs include: -Digoxin -Theophylline -Carbamazepine -Quinidine -Phenytoin -Gentamicin -Common name: Lanoxin -Used to strengthen cardiac concentration and slow heart rate -Commonly used to treat congestive heart failure and atrial tachycardia Digoxin -Common name: Lenophyllin -Causes relaxation of bronchial muscles and pulmonary vessels -Commonly used for asthma, chronic bronchitis, emphysema Theophylline -Common name: Tegretol -Stabilizes neural membranes to limit seizure activity -Commonly used to control grand mal and other psychomotor seizures Carbamazepine -Common name: Quiniglute -Stabilizing effect on the "pacemaker" membranes of the heart -Commonly used for atrial fibrilation Quinidine -Common name: Dilantin -Has a stabilizing effect on neural membranes to reduce seizure activity, much like Tegretol -Commonly used to treat epilepsy and post-head trauma seizures Phenytoin -Powerful IV administered antibiotic -Can cause liver failure in high doses Gentamicin TDM test methodology most commonly used EIA Grain alcohol Ethyl Alcohol Ethyl Alcohol Metabolism: -Metabolized into acetaldehyde by __________. -Acetaldehyde is converted to __________ by _________ -By products of ethyl alcohol metabolism include: CO2, H20, ATP, Cholesterol, Fatty Acids Alcohol dehydrogenase Acetic Acid, Acetaldehyde dehydrogenase Methyl Alcohol Metabolism: -Metabolized to formaldehyde by ____________ -Formaldehyde breaks down into _________ which can cause _________ Alcohol dehydrogenase Formic acid, blindness Wood alcohol Methyl alcohol -Strictly for medical reasons -Ordered by a physician -No special handling or COC -Results given to physician -CANNOT be used for legal purposes MEDICAL BAT -Done for purposes of legal actions -Only base commander may authorize but others acting on their behalf may execute -Must have individual consent of civilians and dependents -Consent of military member is not required -Results ONLY given to appointed individuals -DIRECTOR OF PATIENT AFFAIRS is responsible for releasing the results to proper authorities -Must use NON-ALCOHOLIC SKIN PREP LEGAL BAT -Must be established @ time of collection -Legal paperwork that must accompany BAT at all times -Ensures specimen integrity (legal) -If not established, specimen becomes INVALID as evidence in court of law -Specimen must be safe-guarded (secured) until the assay is complete Chain of Custody (COC) BAT Method: -Mixed in a potassium dichromate solution -Principle used in the "breathalyzer" Dichromate Reduction BAT Method: -Most commonly performed method in AF lab -Ethanol converted to acetaldehyde by alcohol dehydrogenase -Acetaldehyde then reacts w/ NAD Alcohol Dehydrogenase (ADH) BAT Method: -Method of choice for FORENSIC studies Gas Chromatography Under the influence: Legally intoxicated: Potentially fatal: 0.04g% 0.08g% >0.4g% Two important factors that affect these values are: Body Weight Fasting vs. Non-fasting