How does this medication work? What will it do for me?

Alprostadil belongs to a class of medications known as prostaglandins. Prostaglandins like alprostadil cause increased blood flow to certain areas of the body by causing the blood vessels in the area to widen.

In particular, an alprostadil injection causes increased blood flow to the penis. It allows more blood to flow into the penis and helps to produce an erection. Alprostadil is used to treat erectile dysfunction (also known as male impotence). The goal is to achieve erections that last up to one hour.

This medication may be available under multiple brand names and/or in several different forms. Any specific brand name of this medication may not be available in all of the forms or approved for all of the conditions discussed here. As well, some forms of this medication may not be used for all of the conditions discussed here.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. If you have not discussed this with your doctor or are not sure why you are being given this medication, speak to your doctor. Do not stop using this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to use this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

20 µg/vial kit
Each case contains a single-dose vial of alprostadil 20 µg sterile powder, 1 mL prefilled syringe of BWFI (bacteriostatic water for injection) diluent, a 27-gauge 0.5 inch needle, 2 alcohol swabs, and a patient administration leaflet. These cases are fitted with a lock designed for safe and convenient disposal of the contents after use. Once reconstituted, each mL contains alprostadil 20 µg, lactose monohydrate 172 mg, sodium citrate dihydrate 47 µg, benzyl alcohol 8.4 mg, and sterile water for injection qs.

How should I use this medication?

Alprostadil is given by injection into the blood-filled spaces of the penis. Your doctor will determine the appropriate dose of alprostadil by assessing the nature of the impotence. Your doctor will give an initial injection and then slowly increase the dose over the course of the next injections until the lowest dose for an effective erection is found. Erection should occur within 5 to 20 minutes after injection.

The initial dose of alprostadil is usually around 1.25 µg to 2.5 µg (depending on the cause of the erectile dysfunction). The amount of medication will be increased until the lowest effective dose is reached. The maximum daily dose should not exceed 60 µg. Alprostadil should be used no more than once a day and no more than 3 times a week, with at least 24 hours between each dose.

If the erection lasts for 2 hours, try to reduce the erection by methods suggested by the doctor. A prolonged erection (3 hours or more) should be reported to the doctor immediately.

Do not inject alprostadil into an erect penis. Never increase or decrease the dose without consulting your doctor. Once the correct dose has been found, the first few injections will take place at your doctor's office so you can learn how to inject the medication properly. Once your doctor is assured that you are comfortable with the procedure, you will be given a prescription for a kit to use at home.

Refer to the package insert for details on how to mix the medication and inject it properly. Everything you need to use the medication comes with the kit. It is important to visit your doctor regularly, at least once every 3 months during treatment, to ensure that the medication is working safely and effectively.

Many things can affect the dose of a medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are using the medication without consulting your doctor.

It is important to use this medication exactly as prescribed by your doctor.

Store unused vials of this medication between 2°C to 30°C and do not let it freeze. Once mixed, the solution must be used immediately. Keep it out of the reach of children.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not use alprostadil (Caverject®) if you:

  • are allergic to alprostadil (Caverject®) or to any of the ingredients of the medication
  • are under 18 years of age
  • are a man for whom sexual activity is inadvisable
  • are a woman
  • have a condition called priapism, where erections are painful and last for over 4 hours
  • have conditions that increase the risk of priapism, such as sickle cell anemia, multiple myeloma, or leukemia
  • have deformations of the penis, such as angulation, fibrosis, or Peyronie's disease
  • have penile implants

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent. The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • bruising or clotted blood in penis at site of injection (if injected incorrectly)
  • burning sensation or tension in the penis
  • discomfort or irritation
  • pain and/or swelling at site of injection
  • painful erection (usually mild-to-moderate intensity)
  • prolonged erection
  • short-term bleeding at site of injection
  • skin rash or redness

Although most of these side effects listed below don't happen very often, they could lead to serious problems if you do not check with your doctor or seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • abnormal ejaculation
  • curving of penis with pain during erection
  • nodules or hard tissue appearing in the penis
  • inflammation of the tip of the penis
  • dizziness or faintness
  • headache
  • pain in the testicles or at the base of the penis
  • bleeding from the urethra

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • prolonged erection (erections that last for 3 hours or more)
  • changes in blood pressure
  • fast or irregular heart beat

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Blood-borne diseases: The injection of alprostadil may cause a small amount of bleeding at the injection site. For those with a blood-borne disease, this may increase the risk of transferring the disease between sexual partners.

Prolonged erection: If the erection lasts for 2 hours, try to reduce the erection by methods suggested by your doctor. A prolonged erection (3 hours or more) or priapism (a painful erection lasting longer than 6 hours) should be reported to your doctor immediately.

What other drugs could interact with this medication?

There may be an interaction between alprostadil (Caverject®) and any of the following:

  • anticoagulants (e.g., warfarin, heparin)
  • phosphodiesterase 5 inhibitors (e.g., sildenafil, tadalafil, vardenafil)

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.