Contents
Dosing
NOTE: Anecdotal clinical and pharmacokinetic evidence at UW Medicine dating back to the early 1990s suggests that the clearance of enoxaparin is compromised in the presence of the calcineurin inhibitors (CNI) cyclosporine and tacrolimus. It is our practice to reduce full dose enoxaparin by one level (from 1mg/kg SQ q12h to 0.85mg/kg SQ q12h, or from 0.85mg/kg SQ q12h to 1mg/kg SQ q24h) in patients on concurrent CNI therapy.
Monitoring For Initial LMWH Therapy, Including Bridging
- Baseline PT/aPTT
- Baseline hematocrit and q2-5 days during first 2 weeks of LMWH therapy, and prn if bleeding is suspected or confirmed
- Baseline platelet count, and q2-5 days during first 2 weeks of LMWH therapy
- Baseline serum creatinine, and q2-5days during first 2 weeks of LMWH therapy, and prn if a change in renal function is suspected, or if bleeding is suspected or confirmed
Monitoring For Long-Term LMWH Therapy
| Patient weight | q1-3 months and adjust LMWH dose if needed |
|---|---|
| Platelet count | q1-3 months |
| Hematocrit | q1-3 months |
| Serum creatinine/CrCl | q1-3 months (and PRN if change in renal function is suspected or if bleeding is suspected or confirmed) and adjust LMWH dose if needed |
| Trough antiXa level | Consider assessment if clinical circumstances suggest over-anticoagulation (e.g. bleeding complications, worsening renal function, anemia, thrombocytopenia, etc) Goal: <0.5 unitsl/mL (adjust LMWH dose or dosing interval if needed) |
| Peak antiXa level | not correlated with efficacy monitoring not recommended for therapeutic failures (recurrent thrombosis despite adequate weight-based LMWH dosing), adjust LMWH dosing frequency (from q24h to q12h) or increase LMWH dosing (does not need to be guided by peak antiXa levels) |
Monitoring with Anti-Xa Levels
Routine monitoring of Anti-Xa levels is not recommended as there is no “therapeutic range” for LMWH. For more specific guidance see Monitoring of Antithrombotic Therapy.
Monitoring LMWH in Pregnancy
| For Use of LMWH in Pregnancy during 3rd Trimester | |
|---|---|
| Patient weight | q2 weeks |
| Platelet count | q2 weeks |
| Hematocrit | q2 weeks |
| Serum creatinine/CrCl | q2 weeks and adjust LMWH dose if needed |
| Trough antiXa level | q1 month if CrCl > 60ml/min or q2 weeks if < 60ml/min Goal: <0.5 units/ml (adjust LMWH dose or dosing interval if needed) |
| Peak antiXa level | q2 weeks (check 4 hrs after dose) Goal: 0.5-1 units/ml (for q12h dosing of LMWH) Adjust LMWH dosing if needed, according to suggestions below |
LMWH dosage adjustments based on peak antiXa levels
[from Monagle P et al. Chest 2001; 119 (suppl 1): 344-370]
| Peak antiXa level (units/ml) | Hold next dose | Dosage change | Next antiXa level |
|---|---|---|---|
| <0.35 | No | Increase 25% | 4hrs after next dose |
| 0.35-0.49 | No | Increase 10% | 4hrs after next dose |
| 0.5-1 | No | None | Next day, then within 1 week |
| 1.1-1.5 | No | Decrease 20% | Before next dose |
| 1.6-2 | For 3 hours | Decrease 30% | Before next dose and 4hrs after next dose |
| >2 | Until antiXa level <0.5 | Decrease 40% | Before next dose and q12h until antiXa level <0.5 |
Monitoring LMWH in Obesity
- For patients who weigh >190 kg and require treatment doses of enoxaparin, dose based on total body weight and consider anti-Xa measurement, especially in those at high risk of bleeding or dose accumulation, e.g., renal impairment, extended duration of therapy:
-
- Suggested initial dose based on renal function:
- CrCl >60: 1 mg/kg q12h
- CrCl 30-60: 0.85 mg/kg q12h
- CrCl <30: UFH preferred or 1mg/kg q24h
- Measure peak anti-Xa level 3-4 hours after a dose (expected value, 0.5-1.2 units/mL) once therapy has reached steady state (typically after 5th or 6th dose)
- Measure trough anti-Xa level 30 min prior to next dose (expected value, <0.5 units/mL) once therapy has reached steady state expected value (typically after 5th or 6th dose) to monitor for accumulation
- If levels are out of the expected range, consider consulting Hematology
- Based on anti-Xa monitoring studies, enoxaparin doses of 0.7-1 mg/kg BID have achieved expected anti-Xa levels in obese patients with normal renal function
- Suggested initial dose based on renal function:
- Enoxaparin 1.5mg/kg once daily dosing should be avoided in patients who weigh >120 kg
- Routine anti-Xa measurements are not recommended as levels have not been shown to correlate with efficacy or safety outcomes
Patient Education
