Monitoring
Serum creatinine
- Baseline
- Two - three times weekly
Aminoglycoside serum concentrations
- Order pre (trough) and post (peak) levels at steady state (usually after 3-4 doses in patients with normal renal function)
- If using gentamicin for synergy in the treatment of Gram positive infections (e.g. endocarditis), recommend trough level monitoring only in patients:
- with poor renal function
- on concurrent nephrotoxic drugs
- receiving prolonged therapy (> 5 days).
Aminoglycoside Therapeutic Drug Monitoring – Adults, Infants > 44 weeks PCA & Children
| Antibiotic | Specimen | Order on Requisition | Sampling Times | Notes |
|---|---|---|---|---|
| Gentamicin and Tobramycin and Amikacin | Pre (trough)
AND |
Pre (trough) | 0-60 minutes before dose | DO NOT collect DURING infusion |
| Gentamicin and Tobramycin and Amikacin | Post (peak) | Post (0.5-1h after dose end) | 30-60 minutes after END of IV infusion. At least 60 minutes post IM injection |
DO NOT collect sooner than 30 minutes after END of infusion. Result will be uninterpretable. |
Desired Serum Levels
| Infection | Desired Peak (mg/L) | Desired Trough (mg/L) |
|---|---|---|
| Gentamicin/Tobramycin | ||
| Synergy for Gram positive infections (e.g. endocarditis) | NA | < 1 |
| Lower UTI | 3 - 4 | < 1 |
| PID/chorioamnionitis Pyelonephritis Peritonitis Soft tissue infections |
6 - 7 | < 2 |
| Sepsis Neutropenia Burns Pneumonia Pseudomonas (non-urinary) infections |
8 - 11 | < 2 |
| Cystic Fibrosis | 12 - 15 | < 2 |
| Amikacin | ||
| Moderate infections | 20 - 25 | < 4 |
| Severe infections | 25 - 30 | < 8 |
Frequency of Serum Levels
- Once weekly (may need more frequently if renal function changing or concurrent nephrotoxic drugs)
- If creatinine changes (increase of > 40µmol/L, or 50% of baseline), draw trough aminoglycoside level to assess need for dosing change.
Ototoxicity
May be irreversible.
- Patients should be advised to watch for and report signs & symptoms of cochlear (e.g. tinnitus, sense of fullness in ears, loss of hearing) and/or vestibular (e.g. dysequilibrium, oscillopsia, cognitive dysfunction, visual sensitivity, nausea/vomiting, vertigo, headache, nystagmus) toxicity. AG should be discontinued immediately if any signs/symptoms of toxicity develop.
- Audiometry and vestibular testing recommended for patients receiving ≥ 7 days of aminoglycoside therapy, or at any time if ototoxicity suspected. Contact Audiology.