Thallous chloride tl 201

Uses

Thallous Chloride is a diagnostic radiopharmaceutical for myocardial perfusion testing and tests of parathyroid function.

For use as a diagnostic radiopharmaceutical. It is indicated to help diagnose heart disease (eg, coronary artery disease, heart attack). It is also used for the diagnosis of parathyroid problems.

Thallous chloride tl 201 is also used to associated treatment for these conditions: Ischemic Heart Disease, Myocardial Infarction, Myocardial Ischemia

How Thallous chloride tl 201 works

Thallous Chloride TI201 without carrier, accumulates in the heart (myocardium) in a similar way to that of potassium. Thallous Chloride Tl 201 images have been found to visualize areas of infarction as “cold” or nonlabeled regions which are confirmed by electrocardiographic and enzyme changes. Regions of transient myocardial ischemia corresponding to areas perfused by coronary arteries with partial stenoses have been visualized when Thallous Chloride Tl 201 was administered in conjunction with an exercise stress test. Anatomic configurations may interfere with visualization of the right coronary artery.

Toxicity

LD50 (mouse): 24 mg/kg. Minimum lethal dose (Human): 8 mg/kg. Thallium inhibits enzymes, but nothing is really known of a biochemical lesion. In fatal cases, there usually is extensive peripheral paralysis and cardiovascular involvement. The immediate cause of death may be peripheral respiratory failure of cardiac arrest.

Volume of Distribution

3–10 L/kg

Elimination Route

After IV administration, thallous chloride clears rapidly from the blood, with maximum concentration in the myocardium after about 10 min. Only 5-8% of injected activity remained in the blood, following 5 minutes of intravenous administration.

Half Life

91% of the blood radioactivity has a t1/2 of 5 min. 9% has t1/2 of 40 hours.

Clearance

Approximately 4-8% of the injected dose was excreted in the urine in the first 24 hours. The whole body disappearance half-time was 9.8 ± 2.5 days. Kidney concentration was found to be about 3 percent of the injected activity and the testicular content was 0.15 percent. Net thyroid activity was determined to be only 0.2 percent of the injected dose, and the activity disappeared in 24 hours. From anterior and posterior whole-body scans, it was determined that about 45 percent of the injected dose was in the large intestines and contiguous structures (liver, kidneys, abdominal musculature).

Elimination Route

Thallous Chloride Tl 201 is excreted slowly and to an equal extent in both feces and urine.

Innovators Monograph

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