Thallous Chloride

Radiation Safety

Thallous Chloride Tl 201 Injection emits radiation and must be handled with appropriate safety measures and in accordance with the “as low as reasonably achievable” (ALARA) principle of radioactivity dosing.

Use the lowest dose of Thallous Chloride Tl 201 Injection necessary to obtain the intended diagnostic image. Individualize the dose and consider factors such as body size, and the equipment and technique to be employed. 

Recommended Dose

Myocardial perfusion

• Planar scintigraphy: 37 to 74 MBq (1 to 2 mCi) administered intravenously
• SPECT: 74 to 111 MBq (2 to 3 mCi) administered intravenously

Parathyroid hyperactivity localization

Planar or SPECT: 75 to 130 MBq (2 to 3.5 mCi) administered intravenously

Drug Administration and Imaging

For resting myocardial studies, begin imaging 10 to 20 minutes after injection of Thallous Chloride Tl 201. Myocardial-to-background ratios are improved when patients are injected upright and in the fasting state; the upright position reduces the hepatic and gastric thallium Tl-201 concentration.

For exercise stress testing administer Thallous Chloride Tl 201 Injection at the start of a period of maximum stress which is sustained for approximately
30 seconds after injection. Begin imaging within ten minutes after administration to obtain maximum target-to-background ratios. Within two hours after the completion of the stress testing the target-to-background ratios may decrease in lesions that are attributable to transient ischemia.

For localization of parathyroid hyperactivity, administer Thallous Chloride Tl 201 Injection before, with or after a minimal dose of a thyroid imaging agent such as sodium pertechnetate Tc 99m or sodium iodide I-123 to enable thyroid subtraction imaging. 

Radiation Dosimetry

The estimated absorbed radiation doses at calibration time to a 70 kg patient from an intravenous injection of Thallous Chloride Tl 201 are shown in Table 1. The estimates were calculated based on human data from Krahwinkel et al.1  and Thomas et al.2  Assumed percentages of 98.3% 201Tl, 0.3% 200Tl, 1.2% 202Tl, and 0.2% 203Pb. The effective dose was calculated using ICRP 103 tissue weighting factors and assumptions on the biodistribution data based on data from Krahwinkel et al. and Thomas et al.

Table 1. Radiation Dose Estimates for Thallous Chloride Tl 201  (includes contaminants)

Drug Handling

• Do not use this drug after six (6) days from the calibration date, or nine (9) days from date of manufacture, whichever comes first.
• Limit the use of this drug, to physicians who are qualified by training and experience in the safe use and handling of radionuclides.
• Wear waterproof gloves during the handling procedures.
• Aseptically withdraw the material for use with a shielded sterile syringe.
• Measure the patient dose with a suitable radioactivity calibration system immediately prior to administration.
• Visually inspect the drug for particulate matter and discoloration prior to administration, whenever solution and container permit.  Do not use if contents are turbid.
• Minimize radiation exposure to the patient and ensure minimum radiation exposure to occupational workers.
   

Thallous Chloride Tl 201 Injection is supplied as a sterile, non-pyrogenic solution for intravenous administration.

Table 2. Strengths Available

None. 

Drugs that increase or decrease myocardial blood flow or potassium uptake might correspondingly alter the biodistribution of Thallous Chloride Tl 201.

In the event of the administration of a radiation overdose with Thallous Chloride Tl 201, the absorbed dose to the patient should be reduced where possible by increasing the elimination of the radionuclide from the body by forced diuresis with frequent voiding and stimulation of the gastrointestinal passage.

Applies to thallous chloride, tl-201: intravenous solution

Along with its needed effects, thallous chloride, tl-201 may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor or nurse immediately if any of the following side effects occur while taking thallous chloride, tl-201:

• Blurred vision
• chest pain or discomfort
• chills
• confusion
• cough
• difficulty with breathing
• difficulty with swallowing
• dizziness
• dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
• fainting
• fast, slow, or irregular heartbeat
• feeling of warmth
• fever
• hives, itching, or skin rash
• inability to speak
• nausea
• noisy breathing
• pain or discomfort in the arms, jaw, back, or neck
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• redness of the face, neck, arms, and occasionally, upper chest
• seizures
• severe or sudden headache
• shakiness in the legs, arms, hands, or feet
• slurred speech
• sweating
• temporary blindness
• tightness in the chest
• trembling or shaking of the hands or feet
• unusual tiredness or weakness
• vomiting
• weakness in the arm or leg on one side of the body, sudden and severe

Some side effects of thallous chloride, tl-201 may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

• Bleeding, blistering, burning, coldness, discoloration of the skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at the injection site
• burning, dry, or itching eyes
• discharge or excessive tearing
• mild diarrhea
• redness, pain, or swelling of the eye, eyelid, or inner lining of the eyelid

Applies to thallous chloride, tl-201: intravenous solution

Cardiovascular

Frequency not reported: Hypotension[Ref]

Dermatologic

Frequency not reported: Pruritus, flushing, diffuse rash, itching[Ref]

Gastrointestinal

Frequency not reported: Nausea/vomiting, mild diarrhea[Ref]

Musculoskeletal

Frequency not reported: Tremor[Ref]

Ocular

Frequency not reported: Conjunctivitis, blurred vision[Ref]

Other

Frequency not reported: Chills, fever, sweating[Ref]

Respiratory

Frequency not reported: Shortness of breath[Ref]

Some side effects of thallous chloride, tl-201 may not be reported. Always consult your doctor or healthcare specialist for medical advice. You may also report side effects to the FDA.