Therapeutic Drug Monitoring
Monitoring of Anticoagulation Therapies
Warfarin: Monitoring of this anticoagulant therapy is best achieved by Protime
(PT) testing and the subsequent calculation of the INR.
Unfractionated Heparin: This anticoagulant is monitored by Anti-Xa and only while admitted in
the hospital.
Low Molecular Weight Heparin: This anticoagulant is monitored by Anti-Xa.
***Disclaimer: Currently there are no available techniques to monitor the "New"
Oral Anticoagulants (NOAs) on the market i.e. Pradaxa (dabigatran), Xarelto
(rivaroxaban), or Eliquis (apixaban). Based upon literature, it is suggested
that patients wait 24 hours before beginning coagulation testing. Of note:
The dose of these NOAs does not correlate well with the measured PT/INR
and hence, anticoagulant testing when using these NOAs may be an unreliable
guide to antithrombotic efficacy.
***
|
Therapeutic Drug Monitoring
(Chart includes only drugs tested at MMC)
|
Make sure the drug is not hanging or infusing as you are drawing the level. If drawing through an existing catheter, make sure the line has been flushed
appropriately.
The following information has been reviewed and updated by MMC pharmacy.
|
| Drug |
Therapeutic
Range
|
Sampling Times |
(APTT) Activated Partial Thromboplastin Time
(Heparin®)
|
Normal 24-35 seconds
Therapeutic range- 60.2-103 seconds
|
Per Heparin Protocol
IV: 6 hours after initiation or changes in dose
|
Aminoglycosides Including:
Gentamicin
Tobramycin
Amikacin – levels are sendouts and desired levels are different than gent
& tobra trough/peak levels, but timing of the sample is the same.
|
Trough: Less than 2 mcg/mL
Peak: 5-10 mcg/mL(depending on indication)
Random: See Nomogram if EID
|
Trough: IV or IM therapy: within 30 minutes prior to dose
Peak: IV: 30 minutes after 30 minute infusion
IM: 1 hr after injection
Random: 8-12 hours after 60 minute infusion for extended interval dosing (EID)
|
|
*Carbamazepine
(Tegretol®/Carbatrol)
|
4-12 µg/mL |
Trough: 15 minutes prior to dose
Peak: 6-8 hours post dose
|
| Digoxin |
0.8-2.0 ng/mL |
Trough:
(Oral) 15 minutes prior or 12 hours post dose
(IV) 15 minutes prior or 6-12 hours post dose
|
|
Phenytoin – Total (Dilantin)*
Fosphenytoin
(Cerebyx) Free Phenytoin
(only in pts with altered protein binding-ex .uremia, hepatic disease,
late pregnancy, postpartum or head injury)
|
10-20 mcg/mL
10-20 mcg/mL
1-2.5 mcg/mL
|
ORAL
Trough: 15 min prior to dose
Peak: 6-8 hours post dose
IV/IM
Trough:15 min prior to dose
Peak: 2 hours after IV dose; 4 hours after IM dose.
|
|
Lithium *
|
0.5-1.5 mEq/L |
Trough: 15 minutes prior to dose
|
Lovenox (enoxaparin)
Therapeutic
One (Dose?) Daily
Two (Doses?) Daily
Prophylactic
|
1-2 IU/mL
0.6-1 IU/mL
0.2-0.5 IU/mL
|
Peak (Factor Xa level):Four hours after dose is administered
|
|
Phenobarbital *
|
10-30 mg/mL
>40 Critical
|
Trough: 15 minutes prior to dose
|
|
Prothrombin Time (INR) (Coumadin Therapy)
|
INR: Therapeutic 2-3 or 2.5-3.5, depending on indication |
Preferable to keep the time of draws consistent
16-18 hours after dose.
|
Theophylline
Liquid or fast release tab
Slow-release product
|
10-20 µg/mL |
ORAL:
Trough: just before dose
Peak: 1 hour after dose
IV: 30 minutes post loading dose, then 18-24 hours after initiation
|
|
Valproic
Acid (Depakene®/ Depakote®) *
|
50-100 µg/mL |
Trough: 15 minutes prior to dose
|
Vancomycin
Peak levels are only indicated in certain situations –contact pharmacy
for more info
|
Trough: 10-15 mcg/mL
|
Trough: within 30 minutes prior to dose
Peak: 1 hr after completion of 1 hour infusion
|
| For pheumonia, osteomyelitis, etc. 15-20 mcg/mL |
|
Peak: 30-40 mcg/mL
|
*A trough level is appropriate for routine evaluation. For evaluation of
toxicity, a peak sample is recommended. (REVISED by MMC Pharmacy 5/2005,11/2006,
1/2009, 3/2013)
REFERENCES
1) Young L, Koda-Kimble M, eds
Applied Therapeutics: The Clinical Use of Drugs Eighth Edition. Vancouver: Applied Therapeutics, 2005.
2) Interpretation of Diagnostic Tests. Jacques Wallach, M.D. Lippencott
Williams & Wilkins 2000
3) Lexi-Comp Online, accessed January 2009
4) Micromedex ® Drug Information, accessed January 2009
5) Basic Clinical Pharmacokinetics 3rd edition. Winters ME. Applied Therapeutics,
Inc Vancouver, WA.1994.
|