General dosing guidelines

Please see the attached document for dosing guidelines for LMWHs at UW Medicine.

NOTE:  anectodal 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 LMWHs in pregnancy

Use of LMWH in pregnancy 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