| Enter Age (years) |
|
| Enter Height in |
|
| Enter Actual Weight in
|
|
| Select Sex |
|
| Enter Most Recent
Serum Creatinine (mg/dl) |
|
Enter Previous Serum
Creatinine (mg/dl)
Use the same value twice if
renal function is stable. |
|
| Enter time between serum
creatinines (hours). Use 24 if renal function is stable.
Creatinines should be > 1 T1/2 apart
to accurately determine creatinine clearance when renal function is
changing. |
|
|
There is no antidote for Arixtra; protamine does
not reverse its anticoagulant effects. The manufacturer recommends fresh
frozen plasma and factor VIIa. Arixtra continues to be active until it is
excreted from the body and is not consumed during inactivation of factor
Xa. Arixtra is renally eliminated unchanged and is not metabolized.
Arixtra's half-life is dependent on renal function. Arixtra's
anticoagulant effect, inhibition of thrombin generation, is directly
related to serum levels. Excessive peak levels are to be avoided. This
dosing tool adjust the dose based on patient's dosing weight (lean
body weight or actual weight, which ever is less) and renal function. Goal
mid point levels are 1 mcg/ml for DVT/PE treatment and 0.33 mcg/ml for VTE
prophylaxis in orthopedic and abdominal surgery. The
tool predicts serum levels at the mid point of the dosing
interval and minimizes peak to trough flucuations. As renal
function declines smaller doses are given to obtain the same mid
point level, while the peak decreases and the
trough increases. Mid point levels are dependent on drug
clearnace and are independent of volume of distribution. Mid point levels
also decrease serum level sampling error, due to timing
of drug administration and blood level drawing, which is inherent in
peak serum levels. When ordering levels please order a mid point
level. Steady state or non steady state levels may be fit. Non steady
state fitting assumes all doses are the same before the level. |
|
| Dosing for
Treatment of DVT/PE or Prophylaxis for abdominal or orthopedic
surgery. |
|
| Select Drug |
|
| |
|
| Calculated Lean Body Weight
(kg) |
|
| Calculated Drug Dosing
Weight (kg) |
|
| Calculated Creatinine
Clearance (ml/min) |
|
| Calculated T1/2 for
CREATININE (hours) |
|
| Calculated Drug K
(hours-1) |
|
| Calculated Drug T1/2
(hours) |
|
| Calculated Drug Vd
(liters) |
|
| Calculated Drug Clearance
(liters/hour) |
|
Calculated Loading Dose
(mg)
For
peak level of 1.5 mcg/ml based on Dosing Weight assuming no drug
on board, only for PE/DVT Treatment. |
|
Calculated Daily Dose (mg)
For mid
point level of 1 mcg/ml for Treatment of DVT/PE or
0.33 mcg/ml for VTE Prophylaxis for Abdominal and Orthopedic
Surgery |
|
| Enter Rounded Dose (mg) |
|
|
Select Dosage
Interval
Daily dosing is recommended to minimize peaks
and reduce peak to trough flucuations. |
|
| |
|
| A therapeutic
level for DVT/PE treatment at the mid point of the dosing
interval is 1 mcg/ml. This is based on the level obtained by a 75 kg
patient with a creatinine clearnance of 120 ml/min receiving 7.5 mg per
day. The usual mid point level for VTE Prophylaxis for orthopedic
and abdominal surgery is 0.33 mcg/ml and is based on the level
obtained by a 75 kg patient with a creatinine clearnance of 120 ml/min
receiving 2.5 mg per day. |
|
|
Calculated Steady
StatePeak (mcg/ml) |
|
|
Calculated Steady State
Trough (mcq/ml) |
|
| AUC mg/hour/liter |
|
Calculated Steady State Mid Point Level
(mcg/ml)
Treatment of DVT/PE: 1 mcg/ml, (0.8-1.2
mcg/ml)
VTE Prophylaxis: Orthopedic or
Abdominal Surgery 0.33 mcg/ml, (0.26-0.4 mcg/ml) |
|
|
Calculated Steady
State Mid Point Anti Xa Level (units/ml)
Treatment of DVT/PE: 0.666 units/ml,
(0.53-0.799 units/ml)
VTE
Prophylaxis: Orthopedic or Abdominal Surgery 0.22 units/ml,
(0.177-0.266 units/ml) |
|
| Serum level
analysis: Please complete the input boxes below if you have
an actual fondaparinux anti-Xa level and the time is was drawn.
Levels at the mid point of the dosage interval are
recommended. These values along with the entered dosage
history will be used to calculated the patient's elimination rate constant
(K) and clearance. |
|
| Enter the Number of Doses
given before the level was drawn or enter 99 if the level was drawn
at steady state. Steady state is acheived when 5 half-lives have
passed from the start of the regimen. Non steady state levels may be
fit if the number of doses administered is known. |
|
Enter Actual Measured
Fondaparinux Level in mcg/ml. Note 1 mcg/ml of fondaparinux
equals 0.666 anti Xa units/ml.
Steady State Mid Point levels are
recommended. |
|
| Enter the time in
hours that the level was drawn after the PREVIOUS DOSE. |
|
| |
|
| K (hours-1) Fit (Fit using
level, time of level, dosage form, and entered dosage history.) |
|
| Thanks for using
the program. If you have any comments, suggestions or questions
please call 804-764-6307 or 804-287-7921. |
|