Iodinated I-131 Albumin

FDA Drug Information • Also known as: Megatope, Volumex

Brand Names: Megatope, Volumex
Route: INTRAVENOUS
Dosage Form: INJECTION, SOLUTION
Product Type: HUMAN PRESCRIPTION DRUG

Description

DESCRIPTION Chemical Characteristics MEGATOPE (iodinated I 131 albumin) injection is a sterile, nonpyrogenic, radioactive diagnostic agent for intravenous use. Each mL contains albumin human (approximately 10 mg), dibasic sodium phosphate (16 mg), guanidine hydrochloride (not more than 0.4 mg), monobasic sodium phosphate (1.6 mg), sodium chloride for isotonicity, and benzyl alcohol (9 mg) as a preservative. The stabilizers acetyltryptophanate and sodium caprylate have a concentration of less than 0.89 mM. The pH has been adjusted to 7.2 to 7.8 with sodium hydroxide or hydrochloric acid. Each vial contains 37 MBq/mL (1,000 microCi/mL) of radioactivity as iodinated I 131 albumin at time of calibration (see HOW SUPPLIED). Physical Characteristics Iodine-131 decays by beta and gamma emissions with a physical half-life of 8.02 days. Photons that are useful for detection and imaging studies are listed in Table 1. 1 Evaluated Nuclear Structure Data File of the Oak Ridge Nuclear Data Project DOE (1985). External Radiation The specific gamma ray constant for iodine-131 is 2.2 R/hour-millicurie at 1 cm. The first half-value layer is 0.24 cm lead (Pb). A range of values for the relative attenuation of the radiation emitted by this radionuclide that result from interposition of various thicknesses of Pb is shown in Table 2. To facilitate control of the radiation exposure from this radionuclide, the use of a 2.55 cm thickness of Pb will attenuate the radiation emitted by a factor of about 1,000. To correct for physical decay of iodine-131, the fractions that remain at selected intervals after the time of calibration are shown in Table 3. * Calibration time MegaT-1 MegaT-2 MegaT-3

What Is Iodinated I-131 Albumin Used For?

INDICATIONS AND USAGE MEGATOPE is indicated in adults for use in determinations of total blood and plasma volumes.

Dosage and Administration

DOSAGE AND ADMINISTRATION Premedication Administer 10 drops of Strong Iodine Solution, USP (e.g., Lugol’s Solution) three times daily, beginning at least 24 hours before administration of MEGATOPE and continue for 1 week or 2 weeks thereafter to minimize the uptake of iodine-131. Recommended Dosage The recommended dose of MEGATOPE for total blood or plasma volume determination in adult patients is from 0.185 MBq to 1.85 MBq (5 microCi to 50 microCi) administered intravenously. When a procedure such as a blood volume is to be repeated, do not exceed 7.4 MBq (200 microCi) in any 1 week. Administration Instructions

Measure the patient dose using a suitable dose calibrator immediately prior to administration.

Use a shielded syringe for withdrawing and injecting MEGATOPE.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration whenever solution and container permit. MEGATOPE is a colorless to very pale yellow solution. Do not use MEGATOPE if excessive coloration is present.

The expiration date given on the MEGATOPE vial label pertains to the stability of MEGATOPE and not to the radioactivity level. Blood Volume Determination Preparation of Reference Solution 1. Remove the amount from the vial to be used in the procedure identical in volume to the dose to be administered to the patient. 2. Prepare a reference solution using 0.9% Sodium Chloride Injection, USP as a diluent. The recommended dilution is 1:4,000 [Dilution Factor (DF) = 4,000]. 3. Determine the radioactivity concentration (net cpm/mL) of the reference solution. 4. Assay the reference solution and the blood samples (Step 3 of Administration of Dose ) using the same geometric configuration. Administration of Dose 1. Inject the dose into a large vein in patient’s arm. Measure the residual radioactivity in the syringe and needle. 2. Do not reuse the syringe. Dispose the syringe in accordance with the US Nuclear Regulatory Commission or Agreement State regulations pertaining to the disposal of radioactive waste. 3. At 5 minutes and 15 minutes after injecting the dose, withdraw blood samples from the patient’s other arm with a sterile heparinized syringe. Calculation of Blood Volume 1. Take a known aliquot from each blood sample and determine radioactivity concentration in net cpm/mL. 2. Plot the 5-minute and 15- minute sample counts (net cpm/mL) on semilog graph paper using the average count value of each sample and determine the radioactivity concentration at injection time (zero time) by drawing a straight line through the 15-minute and 5-minute points to zero time. The x ordinate of the graph is the sample withdrawal time and the logarithmic y ordinate is radioactivity concentration in net cpm/mL. 3. Calculate patient’s blood volume (in mL) using the following formula: Net cpm/mL reference solution x DF* = blood volume (in mL) Net cpm/mL patient's blood sample *DF: Dilution factor of reference solution Sample Blood Volume...

Side Effects (Adverse Reactions)

ADVERSE REACTIONS The following adverse reactions have been identified with the use of radioiodinated albumin products. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure. Immune System Disorders: Hypersensitivity

Warnings and Precautions

WARNINGS Aseptic meningitis and pyrogenic reactions have been reported following cisternography with MEGATOPE. The safety and effectiveness of MEGATOPE for cisternography have not been established. MEGATOPE is not approved for this use.

Contraindications

CONTRAINDICATIONS None Known.

How Supplied

HOW SUPPLIED MEGATOPE (iodinated I 131 albumin) injection is a colorless to very pale yellow solution available in multiple-dose vials containing the following amounts of radioactivity on the date of calibration: Complete radioassay data for each vial are provided on the MEGATOPE vial label. MegaT-5

About This Information

This drug information is sourced from FDA-approved labeling via the openFDA database. It is intended for educational and reference purposes only. This is not medical advice. Always consult your healthcare provider before making decisions about medication. Drug information may be updated by the FDA; check with your pharmacist for the most current information.

What are side effects?

Side effects are unwanted reactions that can occur when taking a medication. They range from mild (headache, nausea) to severe (allergic reactions, organ damage). Not everyone experiences side effects, and severity varies. Report any concerning side effects to your doctor.

What are drug interactions?

Drug interactions occur when a medication is affected by another drug, food, or supplement. Interactions can make medications less effective or cause dangerous side effects. Always tell your doctor about all medications and supplements you take.