Caverject Impulse

Generic Name: Alprostadil
Product Name: Caverject Impulse

Indication: What Caverject Impulse is used for

Caverject Impulse contains the active component alprostadil which is used in the treatment of male erectile dysfunction. Caverject Impulse is injected directly into the side of the penis to have its effect. Caverject has been shown to be beneficial for the treatment of erectile dysfunction due to varied causes including vascular, pychogenic and nervous.

Caverject Impulse is intended for adult male use only and has no indications for use in females or children. You should however not use this medication if you have been advised not to have sex for health reasons. Injected alprostadil is also used by your doctor to help in the diagnosis of erectile dysfunction.

Action: How Caverject Impulse works

Caverject Impulse contains the active compound alprostadil, also known as prostaglandin E1 (PGE1), that normally occurs naturally within the body at various sites. PGE1 has numerous effects in the body, the most important of which is dilation of vessels and inhibition of platelet clumping (small particles used to plug vessels when they bleed).

In the penis PGE1 causes an increase in blood flow due to relaxation of blood vessels and muscular tissue. The spongy erectile tissue contained within the corpus cavernosum therefore gets filled with blood. This blood gets trapped due to the blockage or draining venules and causes the penis to swell and become hard. Generally Caverject Impulse will produce an erection within 5-20 minutes of its injection. This erection lasts for around 30-60 minutes.

Dose advice: How to use Caverject Impulse

Caverject Impulse should only be used in men (not women or children) who are considered safe and suitable to have sexual intercourse. It should not be used in the following circumstances:

• You have an allergy to alprostadil or other ingredients in the device (alfadex, lactose, sodium citrate, hydrochloric acid and sodium hydroxid).
• Your penis is scarred, bent and you have painful erections (Peyronie’s disease).
• You have a penile implant.
• You are predisposed to priapism (prolonged erections) due to sickle cell anaemia or trait, multiple myeloma (tumour of the bone marrow) or leukaemia (cancer of the blood cells).

In addition, if you suffer blood or clotting disorders or are taking blood thinning medications (such as warfarin) you may have increased bleeding following injection.

Caverject Impulse comes as a pre-filled syringe device with a glass cartridge containing a whitish powder (alprostadil- the active medication) separate to a clear fluid. Each syringe contains either 10 micrograms or 20 micrograms of the drug per 0.5ml.

The entire dose can be injected or for better flexibility of dosing, quarterly increments can be injected.

The medication needs to be injected into the shaft of an outstretched penis to have an effect. It should not be injected into the top or underside of the penis or into any visible veins. Following injection, the device is discarded even if the entire tube contents aren’t used.

The first dose should always be administered by an experienced medical practitioner but it may be possible for you to learn how to self-administer for later doses. All Cavererject Impulse packets come with detailed administration instructions.

The usual starting dose depends on the expected cause for the erectile dysfunction.

If the doctor thinks it is due to psychological (emotional) factors or nerve damage or if the doctor is using the injection for diagnostic purposes, an initial dose of 2.5 micrograms is given. The next doses can be adjusted by increments of 2.5 micrograms to find the best dose to maintain an erection sufficient for sexual intercourse. If the erection lasts too long (greater than an hour), the dose will need to be halved.

For other cases where the doctor is sure of a physical cause or vascular problem (poor circulation), a starting dose of 5 micrograms is given and increased by 5 microgram increments as needed. Most patients end up using around 10-20 micrograms but your doctor will decide the best dose for you.

You should be followed up by your doctor to ensure you do not develop scarring or thickening of the tissues of the penis. This can be reduced by rotating the injection sites and alternating sides for each dose.

You should not use more than one injection in 24 hours and should not exceed 3 doses per week.

If your partner becomes pregnant or intends to in the future, you should advise the treating obstetrician.

Also remember Caverject Impulse provides no protection against sexually transmitted infections so barrier contraception methods may still be required.

Schedule of Caverject Impulse

S4 (prescription required).

Side effects of Caverject Impulse

Common side effects

Like all medications Caverject Impulse can cause side-effects in some patients. In most case these will be mild and disappear after a short period of time. Some patients can have some more serious side effects but it is impossible to predict who this will be beforehand. If you have any symptoms that you think may be due to the medication or that are worrying you, be sure to see your doctor.

The most common side effects form Caverject Impulse injections are listed below:

• Penile pain- This can occur in nearly 40% of patients treated with Caverject Impulse. However in most cases the pain will not even be severe enough to interfere with sexual intercourse but a small number of patients will discontinue treatment with Caverject Impuls and only a very small number of patients actually stop the treatment due to pain.
• Prolonged erection- Erections lasting four to six hours occur in around 4% of patients. A very small number of patients experience erections lasting longer than 6 hours which is called priapism. If your erections last longer than one hour you may need a smaller dose. If an erection lasts longer than four hours you should contact your doctor immediately as it may lead to permanent damage.
• Penile fibrosis or hardening- This occurs in around 3% of patients and may be associated with prolonged use of the medication. Occasionally thickening around the injection site can cause penile deformity. Your doctor will check for this regularly and if thickening does occur will stop the medication.
• Disorders at the injection site- Redness, itching, swelling or bruising may occur at the injection site often due to poor injection techniques.
• Penile rash- 1%.
• Penile oedema (swelling)- 1%.

Uncommon side effects

Rarer but potentially serious side effects of Caverject impulse include:

• Allergic reactions.
• Urinary symptoms- The urge to pass urine more frequently or difficulty passing urine.
• Cardiovascular problems- Occasionally Caverject Impulse may upset the rhythm of your heart or cause a change in blood pressure. These effects are more common at higher doses.
• Scrotal or testicular disorders- This can involve pain, redness or swelling.
• Dizziness, headache or fainting.
• General neurological symptoms- weakness of limbs, numbness, cramping or increased sensitivity to pain.
• Nausea and dry mouth.
• Yeast infection.
• Pupil dilation.

Remember that most patients will have no side effects at all so do not become worried about the long list of possible side effects. Likewise not all side effects have necessarily been reported from this medication so you may have symptoms beyond those listed above.

Do not hesitate to see your doctor for any worrying symptoms or other concerns you have regarding this medication.

References

1. Australian Medicine Handbook. Chapter 13.3.2 Alprostadil. AMH Pty Ltd.2006.
2. Caverject (R) Impulse- Consumer Medicine Information. Pfizer Australia Pty Ltd 2003.
3. Caverject Impulse (R)- Prescribing Information. Pharmacia AB 2003. Available at URL: http://www.caverject.com/CaverjectImpulseUSPISept2003.pdf
4. MIMS Online Prescribing Information- Caverject Impulse. MIMS Australia Pty Ltd 2003.

For further information talk to your doctor.