Iobenguane I-123

Name: Iobenguane I-123

Adverse Effects

Frequency Not Defined





Injection site hemorrhage

Postmarketing Reports



Mechanism of Action

Iobenguane is similar in structure to guanethidine and the neurotransmitter norepinephrine (NE), and is therefore subject to the same uptake and accumulation pathways as NE

Diagnostic radiopharmaceutical contains only a small quantity of iobenguane that is not expected to produce a pharmacodynamic effect

Iobenguane is taken up by the NE transporter in adrenergic nerve terminals and stored in the presynaptic storage vesicles; accumulates in adrenergically innervated tissues (eg, adrenal medulla, salivary glands, heart, liver, spleen, lungs) as well as tumors derived from the neural crest


Metabolic process not well characterized and pharmacologic activity of metabolites has not been studied

Metabolites: Radioiodinated metabolite m-iodohippuric acid (MIHA); free radioiodide


Half-life: 13.2 hr (I 123)

Dialyzable: No

Excretion: 70-90% (unchanged iobenguane) in urine within 4 days

How is this medicine (Iobenguane I 123) best taken?

Use this medicine as ordered by your doctor. Read all information given to you. Follow all instructions closely.

  • It is given as a shot into a vein.
  • Drink lots of noncaffeine liquids before the test and for at least 48 hours after the test as your doctor has told you.

What do I do if I miss a dose?

  • Call your doctor to find out what to do.

What are some other side effects of Iobenguane I 123?

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

  • Flushing.
  • Dizziness.
  • Headache.
  • Irritation where the shot is given.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-FDA-1088. You may also report side effects at

Consumer Information Use and Disclaimer

  • If your symptoms or health problems do not get better or if they become worse, call your doctor.
  • Do not share your drugs with others and do not take anyone else's drugs.
  • Keep a list of all your drugs (prescription, natural products, vitamins, OTC) with you. Give this list to your doctor.
  • Talk with the doctor before starting any new drug, including prescription or OTC, natural products, or vitamins.
  • Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
  • Check with your pharmacist about how to throw out unused drugs.
  • Some drugs may have another patient information leaflet. Check with your pharmacist. If you have any questions about this medicine, please talk with your doctor, nurse, pharmacist, or other health care provider.
  • If you think there has been an overdose, call your poison control center or get medical care right away. Be ready to tell or show what was taken, how much, and when it happened.

This information should not be used to decide whether or not to take iobenguane I 123 or any other medicine. Only the healthcare provider has the knowledge and training to decide which medicines are right for a specific patient. This information does not endorse any medicine as safe, effective, or approved for treating any patient or health condition. This is only a brief summary of general information about this medicine. It does NOT include all information about the possible uses, directions, warnings, precautions, interactions, adverse effects, or risks that may apply to iobenguane I 123. This information is not specific medical advice and does not replace information you receive from the healthcare provider. You must talk with the healthcare provider for complete information about the risks and benefits of using this medicine.

Review Date: October 4, 2017

What is the most important information I should know about iobenguane I-123?

Tell your doctor if you have ever had any type of reaction to iodine, to a contrast agent, or to potassium.

What should I discuss with my healthcare provider before receiving iobenguane I-123?

You should not be treated with iobenguane I-123 if you are allergic to it.

To make sure iobenguane I-123 is safe for you, tell your doctor if you have:

  • kidney disease;

  • a thyroid disorder;

  • Parkinson's disease or other neurologic disorder;

  • high blood pressure;

  • if you are dehydrated or unable to urinate; or

  • if you are allergic to iodine.

Older adults may need kidney function tests before receiving iobenguane I-123. Your kidney function may also need to be watched closely after you have received this medication.

It is not known whether Iobenguane I-123 will harm an unborn baby. Tell your doctor if you are pregnant.

It is not known whether iobenguane I-123 passes into breast milk or if it could harm a nursing baby. You should not breast-feed within 6 days after receiving iobenguane I-123. If you use a breast pump during this time, throw out any milk you collect. Do not feed it to your baby.

What happens if I overdose?

Since this medication is given by a healthcare professional in a medical setting, an overdose is unlikely to occur.