TDM & Toxicology Flashcards
What does TDM stand for?
Therapeutic Drug Monitoring
TDM involves the measurement of drugs and/or metabolites to maintain therapeutic benefits.
What is the therapeutic range?
The dose or concentration of a drug which produces the desired therapeutic effect
Too low or too high levels can lead to decreased efficacy or toxicity.
When is TDM typically performed?
When a drug has a narrow therapeutic range or critical adverse effects
It helps ensure correct dosing and identify drug-drug interactions.
What are pre-analytical variables?
Factors that can affect the accuracy of drug measurements before analysis
These include timing of specimen collection and patient adherence.
What is bioavailability?
The fraction of the dose that reaches the site of action
It is crucial for determining the effectiveness of different routes of drug administration.
What does ‘first pass effect’ refer to?
The metabolism of a drug in the liver before it reaches systemic circulation
This can significantly reduce the concentration of the drug.
What is the significance of free vs bound drugs?
Only free or unbound drugs interact with the site of action
Bound drugs cannot exert therapeutic effects.
What influences free drug levels in the body?
Protein levels and other analytes that compete for binding sites
Conditions like renal failure can increase free drug levels, potentially leading to toxicity.
What is the importance of specimen collection timing in TDM?
Accurate timing ensures that trough and peak levels are assessed correctly
Trough levels are drawn right before the next dose, while peak levels vary based on administration route.
What are aminoglycosides used for?
To treat gram-negative and some gram-positive infections
Examples include gentamicin, tobramycin, and amikacin.
What is the reference range for Digoxin?
1-2.6 nmol/L
Digoxin is used for cardiac arrhythmias and CHF.
What is the primary route of exposure for toxic substances?
Ingestion
Other routes include inhalation and transdermal exposure.
What is the difference between acute and chronic toxicity?
Acute toxicity results from a single short-term exposure, while chronic toxicity results from repeated exposure over time
Both can be assessed using urine and blood tests.
What does HPLC stand for?
High-Performance Liquid Chromatography
It is a reference method for testing substances like acetaminophen.
What is the reference range for acetaminophen toxicity?
992-1323 umol/L
Toxic levels exceed 1323 umol/L.
What is the significance of the osmolal gap?
It helps determine the presence of specific substances in the body
Used in assessing toxicology and drug monitoring.
Which drugs require monitoring for potential toxicity due to protein binding?
Phenytoin and lithium
Fluctuating protein levels can lead to misleading therapeutic ranges.
What are some common agents associated with toxicity?
- Alcohols
- Salicylates
- Acetaminophen
- Methanol
- Isopropanol
- Ethylene Glycol
Each has distinct metabolic pathways and toxic effects.
What is the primary concern with carbon monoxide exposure?
It binds to hemoglobin, forming carboxyhemoglobin
This significantly reduces oxygen transport in the body.
What is the reference range for lithium?
0.5-1.2 mmol/L
Lithium is commonly used to treat bipolar disorder.
What are the potential effects of salicylate toxicity?
- Disruption to GI function
- Hyperventilation leading to respiratory alkalosis
- Metabolic acidosis
Critical levels for salicylates are above 3 mmol/L.
