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Tositumomab Dosage

Applies to the following strengths: 14 mg/mL

Usual Adult Dose for non-Hodgkin's Lymphoma

Dosimetric dose : Tositumomab 450 mg IV infusion over 60 minutes followed by I-131 tositumomab 5 mCi I-131 and 35 mg protein IV infusion over 20 minutes

Therapeutic dose: Tositumomab 450 mg IV infusion over 60 minutes followed by I-131 tositumomab dose calculated to deliver 75 cGy total body irradiation for patients with normal platelet count (platelet count greater than 150,000/mm3 obtained within 28 days prior to dosing) 7 to 14 days after dosimetric step

Comments:
-Do not administer the therapeutic dose if biodistribution is altered.
-See manufacturer's product information for instructions on assessing dosimetry and biodistribution and calculating the therapeutic dose.

Renal Dose Adjustments

Data not available

Liver Dose Adjustments

Data not available

Dose Adjustments

Platelet count between 100,000/mm3 and 149,000/mm3 (obtained within 28 days prior to dosing): Calculate therapeutic dose to deliver 65 cGy total body irradiation.

Precautions

Consult WARNINGS section for dosing related precautions.

Dialysis

Data not available

Other Comments

Administration advice:
-Begin a thyroid protective pre-medication regimen 1 day prior to dosimetric dose and continue daily dosing for a minimum of 14 days following the therapeutic dose. The manufacturer recommends: Saturated solution of potassium iodide (SSKI) 4 drops orally 3 times daily or, Lugol's solution 20 drops orally 3 times daily or, Potassium iodide tablets 130 mg orally once daily. Do not administer dosimetric dose unless patient has received at least 3 doses of SSKI, 3 doses of Lugol's solution, or 1 dose of 130 mg potassium iodide tablet.
-Premedicate with acetaminophen 650 mg orally and diphenhydramine 50 mg orally 30 minutes prior to dosimetric dose.
-Administer 450 mg tositumomab in 50 mL 0.9% sodium chloride using a 0.22 micron inline filter for administration. Keep the same filter for tositumomab and I-131 tositumomab infusions.
-Use a syringe pump to deliver the entire dose of I-131 tositumomab over 20 minutes.
-Flush the IV line with 0.9% sodium chloride for injection upon completion of I-131 tositumomab infusion.
-Determine the combined residual activity of the syringe and infusion set components by assaying these items in a suitable radioactivity calibration system upon completion of administration of all components of the dosimetric dose.
-Calculate and record the dose delivered to the patient by subtracting the residual activity in the syringes and the infusion set components from the activity of I-131 tositumomab in the syringe prior to infusion.

Storage requirements:
-Store tositumomab at 36F to 46F (2C to 8C). Protect from strong light.
-Store I-131 tositumomab in the original lead pot at -4F (-20C) or below until thawed prior to administration.
-Do not shake or freeze.
-Diluted tositumomab is stable for up to 24 hours refrigerated and 8 hours room temperature.
-Thawed I-131 tositumomab is stable for up to 8 hours at 36F to 46F (2C to 8C) or at room temperature.

Reconstitution/preparation techniques:
-For information about the preparation of dosimetric and therapeutic doses of tositumomab, see the manufacturer's product information.

General: Discard unused portion of Iodine I-131 tositumomab and infusion set components according to federal and state laws regarding radioactive and biohazardous waste.

Monitoring:
-Monitor for infusion reactions. Decrease the infusion rate by 50% for mild to moderate reactions. Interrupt infusion for serious reactions, and resume at 50% of previous rate if the severe reaction completely resolves
-Monitor for 3 month after treatment, and for persistent cytopenias beyond 3 months
-Life-long monitoring for hypothyroidism

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

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