Phentolamine

What is phentolamine?

Phentolamine is used during a test for pheochromocytoma. It is used to treat high blood pressure due to pheochromocytoma. Phentolamine is also used to treat skin problems from some drugs. It is used to reverse the effects of some drugs. Phentolamine may be given to you for other reasons. Talk to your doctor.

Description

Phentolamine Mesylate for Injection, USP, is an antihypertensive, available in vials for intravenous and intramuscular administration. Each vial contains phentolamine mesylate USP, 5 mg and mannitol USP, 25 mg in sterile, lyophilized form.

Phentolamine mesylate is m-[N-(2-Imidazolin-2-ylmethyl)-p-toluidino]phenol monomethanesulfonate (salt), and its structural formula is:

Molecular Formula  C17H19N3O•CH4O3S                                 

                                                                                                   M.W.  377.47

Phentolamine mesylate USP is a white or off-white, odorless crystalline powder. Its solutions are acid to litmus. It is freely soluble in water and in alcohol, and slightly soluble in chloroform. It melts at about 178°C.

Before taking phentolamine, tell your doctor:

• If you are allergic to phentolamine; any part of this medicine; or any other drugs, foods, or substances. Tell your doctor about the allergy and what signs you had.
• If you have ever had any of these health problems: Chest pain or pressure, diseased arteries in the heart, or heart attack.

This is not a list of all drugs or health problems that interact with phentolamine.

Tell your doctor and pharmacist about all of your drugs (prescription or OTC, natural products, vitamins) and health problems. You must check to make sure that it is safe for you to take phentolamine with all of your drugs and health problems. Do not start, stop, or change the dose of any drug without checking with your doctor.

What are some things I need to know or do while I take phentolamine?

For all uses of phentolamine:

• Tell all of your health care providers that you take phentolamine. This includes your doctors, nurses, pharmacists, and dentists.
• Heart attack and blood vessel problems in the brain have happened after phentolamine was given. Most of the time, this happened in people with low blood pressure. Talk with the doctor.
• Tell your doctor if you are pregnant or plan on getting pregnant. You will need to talk about the benefits and risks of using phentolamine while you are pregnant.
• Tell your doctor if you are breast-feeding. You will need to talk about any risks to your baby.

Mouth:

• Do not eat or drink while your mouth feels numb.

How is phentolamine best taken?

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

• It is given as a shot.

What do I do if I miss a dose?

• Call your doctor to find out what to do.

What are the side effects of phentolamine that I need to call my doctor about immediately?

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Weakness on 1 side of the body, trouble speaking or thinking, change in balance, drooping on one side of the face, or blurred eyesight.
• Chest pain or pressure or a fast heartbeat.
• A heartbeat that does not feel normal.
• Very bad dizziness or passing out.
• Very bad headache.

What are some other side effects of phentolamine?

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:

• Feeling tired or weak.
• Dizziness.
• Flushing.
• Stuffy nose.
• Upset stomach or throwing up.
• Diarrhea.
• Pain where the shot was 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 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

If overdose is suspected:

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.

How do I store and/or throw out phentolamine?

• If you need to store phentolamine at home, talk with your doctor, nurse, or pharmacist about how to store it.

Label

PACKAGE LABEL PRINCIPAL DISPLAY PANEL

PACKAGE LABEL PRINCIPAL DISPLAY PANEL