therapeutic drug monitoring

Question 1

what is TDM

Answer 1

measure [drug] and [metabolites] to investigate the dosing to specific patients

Question 2

when to perform TDM (4 reasons)

Answer 2

1. low/narrow therapeutic range
2. low patient compliance with drugs
3. symptoms and toxicity of drug is hard to distinguish
4. has pharmacokinetic variability

Question 3

what pharmocokinetic variability can be measured by TDM

Answer 3

1. inter-individual
2. non-linear order drug kinetics
3. drug-drug interactions
4. physiological conditions (e.g. pregnancy) or underlying diseases

Question 4

specimens for TDM

Answer 4

1. serum/plasma
2. EDTA-whole blood
3. urine
4. saliva/oral fluid

Question 5

TDM measurements

Answer 5

1. trough levels, prior to next dose to evaluate therapeutic effect
2. peak levels at varying times to avoid toxic risks

Question 6

methotrexate is monitored because

Answer 6

toxicity is common in high dose therapy
immune suppression, renal failure, myelosuppression, liver toxicity, neurological toxicity, GI toxicity, death

Question 7

digoxin (heart failure drug) monitored because

Answer 7

low therapeutic index
GI distress, confusion, visual impairment, hyperkalemia, cardiac toxicity

Question 8

phenytoin (anticonvulsant) monitored for

Answer 8

non-linear kinetics and inter-individual ability
ataxia, tremor, lethargy, seizure exacerbation, neuropsychiatric changes

Question 9

lithium (bipolar disorder)

Answer 9

narrow therapeutic index, wide inter-individual variations
lethargy, weakness, slurred speech, ataxia, tremor, myoclonic jerks

Question 10

aspirin monitored for

Answer 10

likely to overdose
nausea, vomiting, increased respiratory rate (alkalosis)

Question 11

respiratory acidosis

Answer 11

1. increased CO2
2. unable to remove via respiration

Question 12

metabolic acidosis

Answer 12

1. increased acid
2. kidney unable to clear
3. underlying: diabetes, lactic acidosis, aspirin toxicity, dehydration

Question 13

respiratory alkalosis

Answer 13

1. decreased CO2
2. hyperventillation, lack O2, high alttitude, aspirin poisoning