Drug Monitoring Flashcards
which drugs with a narrow therapeutic index usually require monitoring?
- digoxin
- theophylline
- lithium
- phenytoin
- Abx (gentamicin and vancomycin)
features of digoxin toxicity?
monitor?
confusion
N
visual halos
arrhythmias
creatinine (renal dysfunct)
features of Li+ toxicity?
safe serum level?
how to monitor?
- early:
TREMOR, diarrhoea - intermediate: TIRED
- late: ARRHYTHMIA, seizures, coma, renal failure and diabetes insipidus
0.4-0.8
take 12 hours post dose
serum level weekly - if stable - 3 months
advise patient not to drop sodium intake
features of phenytoin toxicity?
how to monitor?
- gum hypertrophy
- ataxia
- nystagmus
- peripheral neuropathy and teratogenicity
serum levels, if IV use, monitor ECG and BP
(trough levels immediately before dose should be checked if:
-adjustment of phenytoin dose
-suspected toxicity
-detection of non-adherence to the prescribed medication)
features of gentamicin toxicity?
ototoxic
nephrotoxic
features of vancomycin toxicity?
what to monitor?
ototoxic
nephrotoxic
renal function - serial creatinine
what do if evidence of drug toxicity? (3)
1) stop drug +/- alternative
2) supportive measures (IV fluids)
3) antidote
how is gentamicin given and monitored?
its given IV once daily (unless renal problems then 12 hourly)
gentamicin levels are measured between 6-14 hours after dose given “high trough”, and a normogram is used to plot hr-after against the conc
this plot will show whether to give next dose at 24/36/48 hours
normal range for gentamicin?
if Tx endocarditis?
5-10mg/L
3-5mg/L
Tx paracetamol OD?
- NAC (N-acetyl cysteine)
- IV fluids
nomogram is used: > 4hr after ingestion, if the plasma paracetamol level is below the line, the patient does NOT require NAC; if the plasma level is above the line,
they DO
(if staggered OD, or time is unknown, Tx with NAC)
paracetamol toxic metabolite?
NAPQI
what is measured in aminophylline THERAPEUTIC monitoring?
O2 sats
what is measured in aminophylline TOXIC monitoring?
serum aminophylline
how to monitor S/E of statins?
- full lipid profile (non-fasting), TSH, U&E, LFTS ( ALT must be <3x upper limit)
+/- high risk: Hx/FHx muscular disorders/toxicity, ↑alcohol, renal ↓, ↓thyroid, elderly) then DO baseline CK!
check at 3m and 12mths, if marked ↑ in Sx or CK: STOP
how to monitor ACEi when starting?
do renal function 1-2 weeks after
how to monitor methotrexate when starting?
what if wbc ↓?
what if abnormal LFTs?
do liver/renal 1-2 weeks at first, then 3 monthly
avoid in liver/renal dysfunct
STOP!
due to liver cirrhosis risk, Tx with methotrexate should not be started if LFTs abnormal
trimethoprim + methotrexate =?
agranulocytosis!
what to be particularly wary of in antipsychotics? CLOZAPINE
agranulocytosis!
what to monitor in olanzapine?
fasting BM
what to monitor in clozapine?
weekly FBC for 18 weeks
+ registration with a clozapine monitoring service
what to monitor if existing CVD and starting antipsychotic Tx?
ECG: long QT syndrome
monitoring requirement of amiodarone?
CXR (ILD) and K+ before
TFTs LFTs before treatment and then every 6 months
what to monitor in COCP?
BP
what monitoring for in carbimazole?
agranulocytosis!
how to monitor tacrolimus for derm?
trough level
how to monitor theophylline?
serum level 5 days after starting
how to monitor cyclosporin?
monitor renal function
when should statins be used with caution?
liver impairment (check transaminases aren’t >3x upper limit)
check ALT/AST 3 and 12 months after Tx
how to monitor lithium?
does sodium intake affect Li+?
serum Li+ level 12 hours after dose (0.4–0.8), then done weekly until stable, then 3monthly (1st yr) then 6monthly
yes! Sodium depletion ↑risk of toxicity
how to monitor Na valproate?
LFTs before therapy and during first 6 months (especially if at risk)
(NOT serum valproate)
how to monitor NOAC/rivaroxaban?
check creatinine clearance (accurate)
can’t use eGFR (body weight, could be significantly wrong)
dangers of NOAC Tx?
if you miss a tablet; not anticoagulated
must be compliant
monitoring ciclosporin?
trough levels immediately before dose
monitoring digoxin?
at least 6 hrs post-dose
for gentamicin - when to increase time between, and when to change dose?
If the pre-dose (‘trough’) concentration is high, the interval between doses must be increased.
If the post-dose (‘peak’) concentration is high, the dose must be decreased.
