Therapeutic Drug Monitoring Guidelines
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| TABLE Q: THERAPEUTIC DRUG MONITORING GUIDELINES |
| DRUG | WHEN TO SAMPLE | RANGE | TIME TO SS | COMMENT |
| Amikacin |
IM |
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| Peak: 15-30 minutes
after infusion.
Trough: Just prior to the next dose. |
Peak:
20-30 mcg/ml
Trough: <8 mcg/ml |
3-4 doses |
Prolonged high serum concentrations are associated with renal and ototoxicity | |
|
IV |
||||
| Peak: 30 minutes after
30 minute IVPB. 15 minutes after 60 minute IVPB.
Trough: Just prior to the next dose. |
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| Carbamazepine | Immediately prior to the next dose |
4-10 mcg/ml |
4-8 days | Levels affected by phenytoin & valproic acid |
| Chloramphenical | Peak: 1.5 hours post
infusion.
Trough: just prior to the next dose. |
Peak:
10-25 mcg/ml
Trough: <4-8 mcg/ml |
3-4 doses | Time of peak is variable; reversible bone marrow suppresion occurs with levels <25 mcg/ml |
| Digoxin | 12-24 hours post dose | 0.8-2 ng/ml | 7 days | Quinidine, verapamil & amiodarone can cause an increase in digoxin levels. |
| Disopyramide | Immediately prior to the next dose | 3-6 mcg/ml | 2 days | Toxicity < 9 mcg/ml; Phenytoin may increase clearance. |
| Gentamicin | See Amikacin | Peak:
5-10 mcg/ml
Trough: < 2 mcg/ml |
3-4 doses | Same as Amikacin |
| Lidocaine | After LD: 2 hours, no LD: 6-12 hours | 1.5 - 5 mcg/ml | 5-10 hours | b-blockers & cimetidine can cause increased levels. |
| Lithium | Immediately prior to the first dose of the day. | 0.6-1.2 mcg/ml | 3-7 days | Renal disease and dehydration increase serum levels. Many ADRs. |
| Phenobarbital | Immediately prior to the next dose. | 15-40 mcg/ml | 10-14 days | Many drug interactions, valproice acid increases phenobarbital levels. |
| Phenytoin | Immediately prior to the next dose. | 10 - 20 mcg/ml | 5 days (variable) | SS variable, many drug interactions. Small changes in dosing can cause large changes in serum levels. |
| Procainamide | IV: 2 hours into maintenance infusion. PO: Immediately prior to the next dose. | 4 - 8 mcg/ml
NAPA: 15 - 25 mcg/ml |
1-2 days | Procainamide toxicity < 12 mcg/ml |
| Quinidine | Immediately prior to the next dose. | 2 - 5 mcg/ml | 2 days | Cimetidine increases levels; Pb & Phenytoin decrease levels. |
| Theophylline | Peak: IVPB: 30 minutes post infusion. IV INFUSION: 12-18 hours after start. PO: 2 hours post dose for regular release and 4 hours post dose for sustained release. Trough: immediately prior to the next dose. | 8 - 20 mcg/ml | 1-2 days | Ciprofloxacin, cimetidine, erythromycin, increase levels. Time to SS is also affected by smoking, cardiac decompensation, liver disease, and pulmonary decompensation. |
| Tobramycin | Same as Amikacin | Peak: 5 - 10 mcg/ml Trough: < 2 mcg/ml | 3-4 doses | Same as Amikacin |
| Valproic Acid | Immediately prior to the next dose. | 50 - 100 mcg/ml | 2-3 days | Valproic acid levels decreased by phenytoin |
| Vancomycin | Peak: 1 hour post
infusion.
Trough: Immediately prior to the next dose. |
Peak: 25 - 40 mcg/ml Trough: 5-10 mcg/ml | 3-4 doses | Dosage adjustment required for renal disease. |
LD = Loading Dose SS = Steady State ADR = Adverse Drug Reaction PO = Oral