Rapaflo

Generic name: silodosin
Drug class: Alpha-adrenoreceptor antagonists

Medically reviewed by A Ras MD.

What is Rapaflo?

Rapaflo is a prescription medicine that is used to treat the signs of an enlarged prostate. Rapaflo may be given to you for other reasons.

Description

RAPAFLO is the brand name for silodosin, a selective antagonist of alpha-1 adrenoreceptors. The chemical name of silodosin is 1-(3-Hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2-trifluoroethoxy)phenoxy]ethyl}amino)propyl]-2,3-dihydro-1H-indole-7-carboxamide and the molecular formula is C25H32F3N3O4 with a molecular weight of 495.53. The structural formula of silodosin is:

Silodosin is a white to pale yellowish white powder that melts at approximately 105 to 109°C. It is very soluble in acetic acid, freely soluble in alcohol, and very slightly soluble in water.

Each RAPAFLO 8 mg capsule for oral administration contains 8 mg silodosin, and the following inactive ingredients: D-mannitol, magnesium stearate, pregelatinized starch, and sodium lauryl sulfate. The size #1 hard gelatin capsules contain gelatin and titanium dioxide. The capsules are printed with edible ink containing FD&C Blue No. 1 Aluminum Lake and yellow iron oxide.

Each RAPAFLO 4 mg capsule for oral administration contains 4 mg silodosin, and the following inactive ingredients: D-mannitol, magnesium stearate, pregelatinized starch, and sodium lauryl sulfate. The size #3 hard gelatin capsules contain gelatin and titanium dioxide. The capsules are printed with edible ink containing yellow iron oxide.

Mechanism of Action

Silodosin is a selective antagonist of post-synaptic alpha-1 adrenoreceptors, which are located in the human prostate, bladder base, bladder neck, prostatic capsule, and prostatic urethra. Blockade of these alpha-1 adrenoreceptors can cause smooth muscle in these tissues to relax, resulting in an improvement in urine flow and a reduction in BPH symptoms.

An in vitro study examining binding affinity of silodosin to the three subtypes of the alpha-1 adrenoreceptors (alpha-1A, alpha-1B, and alpha-1D) was conducted. The results of the study demonstrated that silodosin binds with high affinity to the alpha-1A subtype.

Before taking Rapaflo, tell your doctor:

If you are allergic to Rapaflo; 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 any of these health problems: Kidney disease or liver disease.
If you take any drugs (prescription or OTC, natural products, vitamins) that must not be taken with Rapaflo, like certain drugs that are used for HIV, infections, or depression. There are many drugs that must not be taken with Rapaflo. Your doctor or pharmacist can tell you if you are taking a drug that must not be taken with Rapaflo.
If you are taking or will be taking another drug like this one.

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

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 Rapaflo 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 Rapaflo?

Tell all of your health care providers that you take Rapaflo. This includes your doctors, nurses, pharmacists, and dentists.
Avoid driving and doing other tasks or actions that call for you to be alert until you see how Rapaflo affects you.
To lower the chance of feeling dizzy or passing out, rise slowly if you have been sitting or lying down. Be careful going up and down stairs.
If you are having cataract surgery or other eye procedure, talk with your doctor.
Have blood work checked as you have been told by the doctor. Talk with the doctor.
Check your blood pressure as you have been told.
Have a rectal exam (to check prostate gland) and blood work (PSA test). Talk with your doctor.
Talk with your doctor before you drink alcohol.
This medicine is not approved for use in children. Talk with the doctor.
This medicine is not approved for use in women. If you are a woman using Rapaflo, talk with your doctor if you are pregnant, plan on getting pregnant, or are breast-feeding.

How is Rapaflo best taken?

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

Take with a meal.
You may sprinkle contents of capsule on applesauce. Do not chew. Swallow right away and follow with cool water.
If mixing on applesauce, the applesauce should not be warm. Do not sprinkle on other liquids or foods.

What do I do if I miss a dose?

Take a missed dose as soon as you think about it, with a meal.
If it is close to the time for your next dose, skip the missed dose and go back to your normal time.
Do not take 2 doses at the same time or extra doses.

What are the side effects of Rapaflo 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.
Very bad dizziness or passing out.

What are some other side effects of Rapaflo?

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:

Orgasm with less or no semen.
Dizziness.

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 Rapaflo?

Store at room temperature.
Protect from light.
Store in a dry place. Do not store in a bathroom.
Keep all drugs in a safe place. Keep all drugs out of the reach of children and pets.
Throw away unused or expired drugs. Do not flush down a toilet or pour down a drain unless you are told to do so. Check with your pharmacist if you have questions about the best way to throw out drugs. There may be drug take-back programs in your area.