Thallous Chloride Tl 201 Injection may be useful in myocardial perfusion imaging using either planar or SPECT (Single Photon Computed Tomography) techniques for the diagnosis and localization of myocardial infarction. It may also have prognostic value regarding survival, when used in the clinically stable patient following the onset of symptoms of an acute myocardial infarction, to assess the site and size of the perfusion defect.

Thallous Chloride Tl 201 Injection may also be useful in conjunction with exercise stress testing as an adjunct in the diagnosis of ischemic heart disease (atherosclerotic coronaryartery disease).

It is usually not possible to differentiate recent from old myocardial infarction, or to differentiate between recent myocardial infarction and ischemia.

Thallous Chloride Tl 201 Injection is indicated also for the localization of sites of para-thyroid hyperactivity in patients with elevated serum calcium and parathyroid hormone levels. It may also be useful in pre-operative screening to localize extrathyroidal and mediastinalsitesof parathyroid hyperactivity and for post-surgical reexamination. Thallous Chloride Tl 201 Injection has not been adequately demonstrated to be effective for the localization of normal parathyroid glands.

The recommended adult dose of intravenous Thallous Chloride Tl 201 Injection for planar myocardial imaging is 37 to 74MBq (1-2mCi). The recommended intravenous doses for SPECT myocardial imaging are 74 to 111 MBq (2-3mCi). The efficacy of a 1.0 mCi dose SPECT imaging has not been well established.

Parenteral drug products should be inspected visually for particulate matter and discoloration prior to administration, whenever solution and container permit.

The patient dose should be measured by a suitable radioactivity calibration system immediately prior to administration.

For patients undergoing resting thallium studies, imaging is optimally begun within 10-20 minutes after injection. Several investigators have reported improved myocardial-to-background ratios when patients are injected in the fasting state, in an upright posture, or after briefly ambulating. The upright position reduces the hepatic and gastric Thallium Tl 201 concentration.

Best results with thallium imaging performed in conjunction with exercise stress testing appear to be obtained if the thallium is administered when the patient reaches maximum stress and when the stress is continued for 30 seconds to one minute after injection. Imaging should begin within ten minutes post-injection since target-to-background ratio is optimum by that time. Several investigators have reported significant decreases in the target-to-background ratios of lesions attributable to transient ischemia by two hours after the completion of stress imaging.

For the localization of parathyroid hyperactivity, Thallous Chloride Tl 201 Injection may be administered before, with or after a minimal dose of a thyroid imaging agent such as sodium pertechnetate Tc99m or sodium iodide l 123 to enable thyroid subtraction imaging.

RADIATION DOSIMETRY

Table 4. Radiation Dose Estimates for Thallous Chloride Tl 201 Injection (plus contaminants)

Based on data gathered in humans by Krahwinkel et al. (J Nucl Med 29(9):1582-1586, 1988) and data gathered in humans by Gupta et al. (Int J Nucl Med & Biol 8:211-213, 1981).

Bladder voiding interval 4.8hr. Contaminants assumed: Tl-200 (0.3%), Tl-202 (0.84%), Pb-203 (0.2%). Includes dose from Tl-201 Auger electrons. Estimate calculated using phantom of Cristy & Eckerman (Report ORNL/TM-8381/V1 & V7). Radiation Internal Dose Information Center.

Thallous Chloride Tl 201 Injection for intravenous administration is supplied as a sterile, non-pyrogenic solution containing at calibration time, 74MBq/ml (2mCi/ml) of Thallous Chloride Tl 201, 9mg/ml sodium chloride, and 9mg/ml of benzyl alcohol. The pH is adjusted with hydrochloric acid and/or sodium hydroxide solution. Vials are available in the following quantities of radioactivity:

(NDC# 11994-427-24) 162.8
(NDC# 11994-427-26) 244.2
(NDC# 11994-427-28) 325.6
(NDC# 11994-427-11) 407.0
(NDC# 11994-427-15) 569.8
and 732.6 MBq (NDC# 11994-427-19)
(4.4, 6.6, 8.8, 11.0, 15.4 and 19.8 mCi) of Thallous Chloride Tl 201 Injection.

Store at controlled room temperature 20° to 25°C (68° to 77°F) [See USP].

Preparation and Handling Procedures for Thallous Chloride Tl 201 Injection

a. Waterproof gloves should be worn during the handling and injection period.

b. Adequate shielding during the life of the radioactive drug should be maintained by using the lead shield and cover and by using a syringe shield for withdrawing and injecting Thallous Chloride Tl 201 Injection.

This radiopharmaceutical is approved for distribution to persons licensed pursuant to the Code of Massachusetts Regulations 105 CMR 120.100 for the uses listed in 105 CMR 120.533 or under equivalent licenses of the U.S. Nuclear Regulatory Commission, an Agreement State, or a Licensing State.

Bristol-Myers Squibb
Medical Imaging, Inc.
331 Treble Cove Road
N. Billerica, Massachusetts 01862 USA
For ordering call Toll Free: 800-225-1572
All Other Business: 800-362-2668
(For Massachusetts and International,
call 978-667-9531)
Printed in U.S.A.

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