Drug Guide
Technetium Tc-99m Sulfur Colloid
Classification
Therapeutic: Diagnostic imaging agent
Pharmacological: Radioisotope
FDA Approved Indications
- Liver/spleen imaging to evaluate organ size, shape, and function
- Gastric emptying studies
- Lymphoscintigraphy
Mechanism of Action
Technetium-99m emits gamma radiation detectable by a gamma camera. When bound to sulfur colloid, it localizes in the reticuloendothelial system, particularly in the liver, spleen, and lymph nodes, allowing imaging of these structures.
Dosage and Administration
Adult: Typically 2-10 mCi administered intravenously, depending on the study and patient size.
Pediatric: Dosing varies based on age and weight; consult specific protocols.
Geriatric: Adjust dose as needed based on renal or hepatic function, similar to adult dosing.
Renal Impairment: Use with caution; may require dose adjustment depending on severity.
Hepatic Impairment: Use with caution; hepatic function may influence distribution.
Pharmacokinetics
Absorption: Not applicable (administration is intravenous).
Distribution: Localizes in liver, spleen, lymph nodes via reticuloendothelial system.
Metabolism: Metabolized by the reticuloendothelial system; radioactive decay is by physical half-life.
Excretion: Excreted via biliary and/or renal pathways, depending on organ uptake.
Half Life: Approximate physical half-life of 6 hours for Tc-99m.
Contraindications
- Allergy to sulfur colloid or technetium-99m
Precautions
- Use caution in pregnancy unless benefits outweigh risks, as radiation exposure may harm fetal development.
- Ensure proper patient identification and radiation safety procedures.
Adverse Reactions - Common
- Local injection site pain or swelling (Rare)
- Transient nausea or allergic reaction (Rare)
Adverse Reactions - Serious
- Radiation-induced tissue damage or allergic reactions (Very rare)
Drug-Drug Interactions
- None specifically noted; however, interactions with other radiopharmaceuticals should be considered.
Drug-Food Interactions
- No significant interactions
Drug-Herb Interactions
- No known interactions
Nursing Implications
Assessment: Confirm patient identity, allergy status, and pregnancy status.
Diagnoses:
- Risk for radiation injury
- Impaired tissue perfusion
Implementation: Ensure proper preparation and administration per protocol, observe for immediate adverse reactions.
Evaluation: Monitor for adverse reactions post-administration; verify quality of imaging results.
Patient/Family Teaching
- Explain that the procedure involves a small amount of radioactive material, which is generally safe but requires safety precautions.
- Advise on minimal contact and handling of bodily fluids for a specified period after the procedure.
- Inform about possible temporary side effects, such as mild discomfort at injection site.
Special Considerations
Black Box Warnings:
- Radiation risk to fetus; pregnancy should be avoided in women of childbearing age unless absolutely necessary.
Genetic Factors: No specific genetic considerations reported.
Lab Test Interference: May interfere with certain lab tests measuring radiation-sensitive substances.
Overdose Management
Signs/Symptoms: Radiation sickness symptoms such as nausea, vomiting, or skin tingling may occur with overdose.
Treatment: Supportive care, symptomatic treatment, and possibly chelation if indicated; consult radiation safety protocols.
Storage and Handling
Storage: Store at room temperature away from light and moisture; radioactive material must comply with institutional and regulatory requirements.
Stability: Stable for use within shelf life; check expiration date and storage conditions before use.