13. Therapeutic Drug Monitoring Flashcards
Drug category?
- phenytoin
- valporic acid
anti-epileptics
Half-life of methotrexate
8-10 hrs
Drug category?
- thiopurines
- methotrexate
antimetabolites
Number of half-lives to reach steady state
5-7 half-lives
Folic acid antagonist; mimics DNA nucleotides
methotrexate
Drug category?
- digoxin
- lidocaine
cardioactive
Relaxes smooth muscle cells surrounding bronchioles
theophylline
Drug category?
- theophylline
bronchodilator
4 methods/organs for drug excretion
Liver - total metabolism
Kidneys - via urine (water-soluble)
Bile and feces - for lipid-soluble
Lungs - volatile metabolites
Drug category?
- cyclosporine
- tacrolimus
immunosuppressants
Half-life of vancomycin
6 hrs
3 reasons why a drug level may be falsely low and require a recovery dilution
- interfering substances
- non-compliance
- hook effect
When are ‘peak’ samples usually drawn for oral, IV, and IM after administration?
Oral = 2 hrs IV = 30 mins IM = 1 hr
4 factors that affect drug disposition
Absorption
Distribution
Metabolism
Excretion
5 common analytical methods for determination of therapeutic drugs
MR HEG
Mass spec Radioimmunoassay HPLC Electrophoresis Gas liquid chromatography
Half-life of theophylline
8 hrs
Number of half-lives required to eliminate 99% of a drug
7.5 half-lives
Half-life of lithium
22 hrs
Half-life of cyclosporine
4-6 hrs
Half-life of digoxin
40 hrs
3 factors that influence absorption of drug
- drug interactions
- solubility
- food or co-administered drugs
Used for treating leukemias, lymphomas
Methotrexate
Concentration range of the drug in blood where the drug has been shown to be effective without causing toxic effects in most people
Therapeutic range
Example of an inhibition metabolism
Morphine vs alcohol (compete for same enzyme active site)
