Drug Guide
Ammonia N-13
Classification
Therapeutic: Diagnostic agent for PET imaging
Pharmacological: Radioactive diagnostic agent
FDA Approved Indications
- Use in PET imaging to evaluate myocardial perfusion and cerebral blood flow
Mechanism of Action
N-13 ammonia is a positron-emitting radiotracer that mimics ammonia in the body. It is taken up by tissues with high blood flow, allowing imaging of perfusion in the heart and brain through PET scans.
Dosage and Administration
Adult: Typically, 370-740 MBq (10-20 mCi) administered intravenously; imaging performed shortly after injection.
Pediatric: Dosing varies based on weight and clinical indication; specific protocols are used.
Geriatric: No specific dose adjustment generally required but evaluate renal and hepatic function.
Renal Impairment: Use caution; renal function may influence clearance.
Hepatic Impairment: No specific adjustments well established.
Pharmacokinetics
Absorption: Injected intravenously, immediate availability in bloodstream.
Distribution: Rapidly distributed to myocardial or cerebral tissue depending on the imaging site.
Metabolism: Minimal metabolism; remains mostly as unchanged N-13 ammonia.
Excretion: Rapidly cleared by the lungs and excreted via respiration.
Half Life: Approximately 10 minutes, reflecting the half-life of N-13.
Contraindications
- Known hypersensitivity to ammonia or radionuclides
Precautions
- Use with caution in pregnant or breastfeeding women due to radiation exposure; is generally avoided unless necessary.
Adverse Reactions - Common
- None expected due to low pharmacological activity of tracer (Rare)
Adverse Reactions - Serious
- Radiation exposure risks, including radiation dermatitis or tissue damage (Very rare)
Drug-Drug Interactions
- None specific; interactions primarily related to radiation precautions.
Drug-Food Interactions
- None
Drug-Herb Interactions
- None
Nursing Implications
Assessment: Verify renal and hepatic function, allergy history, and pregnancy status.
Diagnoses:
- Risk of radiation exposure
Implementation: Ensure proper timing and injection protocol, follow radiation safety procedures.
Evaluation: Assess imaging results within context of clinical findings and ensure protocols adhered to.
Patient/Family Teaching
- Inform about the nature of the test, radiation exposure, and precautions post-procedure.
- Advise on hydration and voidance to minimize radiation after the procedure.
Special Considerations
Black Box Warnings:
- Potential radiation exposure; use only when clinically indicated.
Genetic Factors: None specified.
Lab Test Interference: Radiotracer may interfere with certain diagnostic tests involving radionuclides.
Overdose Management
Signs/Symptoms: Radiation overdose symptoms are unlikely due to short half-life; overexposure may increase radiation risks.
Treatment: Supportive care, symptomatic treatment, and chelation generally not necessary due to rapid decay.
Storage and Handling
Storage: Store in lead-shielded container at room temperature; away from light.
Stability: Stable for a short duration (a few hours) due to short half-life; prepare fresh as needed.