Toxicology Flashcards
therapeutic drug monitoring
-practice of measuring concentration of a drug or its metabolites in order to optimize the dosing of that drug to an individual pt and/or to assess pt compliance with a dosing schedule
-may be required for drugs with narrow TI, significant SE, or low margin of safety
-monitoring is useful when the therapeutic range for a drug significantly overlaps the toxic range, when a drug cant be dosed based on clinical observation or when pts have compliance problems
-not all drugs require monitoring
detection of drugs of abuse
-an abused drug is any compound that is consumed in greater amounts or in a way that is neither approved nor supervised by medical staff
-used for euphoria, stimulant, sedative, or other effects
-analysis is intended to detect past used by the pt
-DUI, AMS, overdose, workers comp
detection of environmental toxins
-environmental toxins are potentially hazardous substances that contaminate the air, water, or soil
-exposure to environmental toxins may be monitored by specific tests for clinical dx and tx
-radon, lead, carbon monoxide, water
indications for drug monitoring
-clinical reasons:
-overdose
-therapeutic monitoring for max efficacy
-legal
-forensic:
-cause of death
-athletic testing
-DUI
-employment testing
therapeutic drug monitoring
-optimum dosing
-improve drug therapeutic effect while avoiding SE or toxic effects
-appropriate therapeutic dosing for condition (renal function, pregnancy, newborn, geriatric)
-blood serum or plasma, urine
-trough concentrations (due for next dose)
-peak concentrations (30-60 min post dose)
pharmacokinetic principles
-LADME
-Liberation
-Absorption- PO, IV, SQ
-Distribution
-Metabolism- first pass
-Elimination- half life
-vancomycin only tx c diff orally, but covers many things IV
lab methods
commonly monitored drugs
-Methotrexate
-Cyclosporin
-Aminoglycosides- ototoxic, trough?
-Vancomycin- MRSA IV, c diff PO, red man syndrome (quick infusion rxn-not allergic)
-Dilantin (phenytoin)- uncontrolled eye movement
-Tegretol- seizure disorder, preg cat D, avoid grapefruit
-Valproic Acid- cat X, pancreatitis
-Tricyclic Anti-depressants- prolonged QT, narrow TI
-Lithium- monitor every 2-3 weeks, tremor, confusion, slurred speach
-Prozac- QT prolongation
-Digoxin- hypokalemia, hypomagnesium
-Acetaminophen- liver failure -> NAC
-Aspirin- reye syndrome
-Methadone- bleeding, synthetic opiod -> naloxone
alcohols
-Acute intoxication
-Chronic abuse:
-Pancreatic disease
-Liver cirrhosis
-Peak 30 -75 min post ingestion
-1 oz liquor, 4 oz wine, 12 oz beer (25-30 mg/dL)
-15- 25 mg/dL/hour
-ETOH in pregnancy
-Metabolism
-Breath Test & Blood Test
alcohols: methanol
-Moonshine, washer fluid
-Impaired vision up to blindness, vomiting, seizures, coma
alcohols: ethylene glycol
-Antifreeze
-Anuria, vomiting, seizures, coma
alcohols: isopropanol
-Rubbing alcohol
-Vomiting, abdominal pain, hematemesis, melena, coma
environmental toxins
-Occupational exposure:
-Heavy metals
-Gases
-Caustic compounds
-Contamination:
-Soil
-Ground water
-Examples:
-Carbon monoxide
-Mercury
-Cyanide
-Insecticides
-Lead
environmental toxins: carbon monoxide
-4,000 deaths per year, leading cause of accidental & deliberate poisoning
-Binding of Carbon monoxide to oxygen binding sites on hemoglobin
-Adults heart, CNS and lungs, vision, hearing, peripheral nerve conduction. Myocardial ischemia, headache, permanent neurological impairment.
-Children presentation mimics gastroenteritis!
-Carboxyhemoglobin Relative to Total Hemoglobin (%)
-0.1–0.9 Normal range for nonsmoking adults
-1.5–10 Smoking adults
-10–30 As concentration elevates, increasingly severe headache and greater dyspnea on exertion
-40–50 Very severe headache and dyspnea with tachycardia; may be fatal
-60–70 Coma, seizures, often fatal80Rapidly fatal
algorithm for using normobaric and hyperbaric oxygen following carbon monoxide exposure
-hyperbaric O2 chamber- just this
-not on test
effect of carboxyhemoglobinemia on O2 content and delivery
-can have 50% drop
signs and symptoms of lead toxicity
lead screening
-test- risk, other family members, symptoms, 1&2 years old test (they do it but its not required)
-follow up- iron studies, neurodevelopmental monitoring, GI
-45-69- watch Hmg, hct
-chillation therapy- binds iron to excrete it
-pregnant- not needed
-children 5 years and younger- not needed in asymptomatic
-area of concern - test
drugs of abuse testing
-Testing for illicit drugs, addictive and harmful therapeutic agents.
-Goal to detect past exposure by detecting metabolites.
-Present or Absent
-Urine, Serum, Meconium, breath, saliva, hair, nails
-Class screening- look for metabolites of class of drug not specific drug
summary of common urine drug immunoassays
