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Medically reviewed by
Dr Daniel Atkinson
GP Clinical Lead
on August 02, 2022.
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What is alprostadil?

Alprostadil is an erectile dysfunction medication that’s prescribed for those who are unable to tolerate oral ED medication. In some cases, it can also be used by those who find the likes of Viagra and Cialis don’t work as effectively as they would like. 

Alprostadil is indicated as a powerful erectile dysfunction treatment in its own right, with decades of use preceding the more modern ED treatments that come in pill form. Alprostadil brand names include Caverject, Vitaros, Viridal and MUSE

How does alprostadil work in the body?

Alprostadil prostaglandin e1 belongs to a group of medications known as vasodilators. This group of drugs work to relax the blood vessels around the penis to allow for better blood flow. In order to get an erection, you need blood to flow freely into the penis and remain there, so using alprostadil makes it easier to get and maintain erections.

Alprostadil use for erectile dysfunction started back in the early 1980’s after being isolated a few decades before. It’s mechanism of action is proven clinically and is considered safe for the majority of men to use. 

What different forms of alprostadil are there?

Alprostadil is available in several different forms. The fact that there are several methods of application for alprostadil means that you have some leeway if you’re uncomfortable with one method or find one more convenient, or discreet, compared to the others.

Caverject and Viridal Duo are alprostadil injections, whereas Vitaros is an alprostadil cream. For MUSE, alprostadil comes in the form of a suppository. Each of these products have their own advantages and disadvantages, so you might want to try each of them to find which one works best for you.

What is Caverject?

Caverject is an injectable alprostadil treatment, applied directly to the penis, that’s available as a dual chamber injection and in individual vials.

The dual chamber device automatically mixes the solution and is used as needed. The Caverject injection kit is also straightforward but requires a little more prep in order to mix the powder and solution so that it’s ready for use.

Before you use this medication for the first time a doctor or nurse will show you how to apply Caverject treatments safely. Because alprostadil in Caverject is in powder form and mixed with the solution before the injection, this means it doesn’t need to be kept in the fridge. Although it must be used straight after mixing. The Caverject kit will include all these instructions that you can refer to as needed.

You can also buy the powder separately and mix Caverject injections that way. Caverject is manufactured by Pfizer, who provide everything you need to use it safely. When using alprostadil in the form of Caverject, be sure to follow the instructions provided by your doctor carefully.

Do you need a prescription for Caverject?

It’s not possible to get Caverject without a prescription in the UK. Being a prescription only treatment allows your doctor to properly monitor its use and adjust or change your treatment if needed. Caverject prescriptions are only given when your prescribing clinician thinks it safe for you to use.

While it’s possible to buy Caverject online with no prescription from disreputable sources, illegal pharmacies mean you can never be sure what it is you’re taking. Always buy online medications from a registered pharmacy.

How to use Caverject

There are two products available to choose from: Caverject powders (which come in vials) and Caverject Dual Chamber. The instructions are different for each type, so be sure to follow the correct one for your treatment as you’ll need to know how to correctly mix Caverject powder for the injection. Pfizer provides Caverject instructions with each product, so you can always refer to these if you’re not sure.

Using Caverject Dual Chamber can be easier for some as it comes with the device that mixes the powder and solution by twisting the plunger. Then you only need to gently shake the mixture before use. 

For the Caverject powder injection method, you need to fix the needle onto the syringe then push it through the top of the vial and push the plunger. After giving it a gentle swirl the mixture should become clear. If the mixture remains cloudy you shouldn’t use it. Draw out the mixture into the syringe by pulling the plunger and it’s ready to use.

For Caverject administration, try to relax before using it. You can start by undressing and lying on your bed. Swab the injection area with the antiseptic pad then gently hold yourpenis from the front at a slight angle so that the injection area, the side of the penis, sticks out. 

Taking care to avoid any veins, push the needle into the bulging part of the shaft and slowly press the plunger without forcing the solution. The Caverject needle size will be long enough to reach the area it’s designed for, just be sure that it’s not bent before use.

For full information about how to use Caverject Impulse injections, your medication will come with a Caverject package insert with all the information you need. Your doctor will make sure you know how to use Caverject before prescribing the treatment, so this should only act as a backup. 

If you’re still unsure about how to administer Caverject in either of its forms, speak with your prescribing clinician.

Where does Caverject need to be injected?

Now we have explained how to inject Caverject, a little more information on the Caverject injection site. This is important as the medication will not work as it should if this aspect of the process is incorrect.

Along the shaft of the penis, the part that leads up to the head, runs two parallel chambers called the corpora cavernosa. It’s here where you need to inject Caverject, past the superficial layer of skin. 

There is little difference between how to inject Caverject Dual Chamber and the manual needle and vial version.

Does Caverject need to be refrigerated?

Caverject doesn’t need to be refrigerated as it comes in a powdered form, but once you’ve mixed it with the solution, it needs to be used straight away in the case of the vials. For the Caverject Dual Chamber device, it can be mixed up to 24-hours before use and kept below 25°C.

Vials should be used within three months from when you’ve been provided with the medication. Always check the use by date before injecting Caverject.

Can you use Caverject and Viagra together?

Despite the fact that they’re different medications, you shouldn’t take Caverject and Viagra together. When combined these drugs lower blood pressure even further than they would separately, causing dizziness, a rapid pulse and fainting. 

Taking alprostadil and Viagra together also won’t provide any benefits. If one drug isn’t working by itself, then trying the other separately is the only way to know if it’s a good replacement. You should speak with your doctor if you want to change your erectile dysfunction medication.

How much Caverject should I use?

Everyone is different and how they process any medication is unique to them. Some men find that the lowest dosages of Caverject are effective and that they won’t need to take the higher ones. Others might have toleration issues with the standard dose and lowering still provides the benefits of the medication without the side effects.

Prescription dosages typically start between 1.25mcg and 2.5mcg. These are very low dosages that are prescribed to see if you are able to tolerate it. If all goes well, your doctor will begin titration, which is where the dosage is increased slowly to see which strength allows you to get the maximum benefits from the medication with the minimum of side effects.

Most men will find that a dosage of between 5mcg and 20mcg is effective enough to treat their erectile dysfunction. You should be able to find the right dosage for you, with a little patience and guidance from your prescribing clinician.

How well does Caverject work?

Caverject results from various studies show that the majority of men will gain significant benefits from the treatment. One study reported satisfaction rates at 87% in the men that participated . Caverject doesn’t always work for every man. This can be for several reasons, including the cause of the condition and its severity.

When comparing Caverject vs Viagra, Viagra is preferred to alprostadil by most men, but many found that Caverject worked best for them . This suggests some trial and error is recommended if you’re having issues with one or other of the treatments. Oral PDE5 inhibitors will usually be the first line of treatment for men with ED but it’s important to note that there are several other non-oral options available. 

So how long do Caverject and Viagra last? You should be able to get the benefits of Caverject for up to an hour, which is shorter than Viagra at five hours.

Caverject does not increase your size and it cannot cause arousal. It’s prescribed to help you achieve erections during sex. None of the erectile dysfunction treatments have aphrodisiac properties. 

If Caverject doesn’t work for you, always remember that there are many other options available. These include alprostadil creams and suppositories as well as oral treatments such as Viagra, Cialis, Levitra and Spedra

How long will my erection last using Caverject?

Like other erectile dysfunction treatments, Caverject only works if you’re sexually aroused so it won’t work if you’re not ‘turned on’. But if you are then there’s a good chance your erection will last for a long as you need it to. Occasionally some men can have prolonged erections when using injectable ED medications, this can be serious so it’s worth remembering to only use the dose prescribed for you by your doctor. 

If your erection persists, becomes painful or lasts longer than four hours, you need urgent medical attention so call 999 or get yourself to the local A+E department straight away.

What is Vitaros Cream?

Vitaros cream contains the same active ingredient as Caverject – alprostadil. Only it’s applied urethrally (through the top of the penis) instead of being injected. Using Vitaros alprostadil as a cream might be better suited for those that are unsure about using other methods of application, like injections. Vitaros alprostadil cream’s manufacturer is Ferring, which is based in Switzerland. The cream has been approved for the treatment of erectile dysfunction since 2016.  Many men have found that using Vitaros cream for erectile dysfunction is the most effective method with the least amount of side effects.

How to use Vitaros Cream

It’s important to know how Vitaros is applied before you use it so you can get the best results from the treatment. Vitaros application is straightforward, but timing, dosage and preparation are still key. Vitaros cream begins to take effect between five and 30 minutes, applying it 30 minutes in advance is recommended. It should remain effective for between one and two hours, so you may also need to factor this into the timing of the application. Before using Vitaros, wash your hands and make sure the Accu Dose applicator is at room temperature. You can do this by rubbing the device between your hands if needed. If possible, remove the cream from the refrigerator beforehand.  Then, twist the Accu Dose to remove the cap, take hold of the tip of the penis and gently squeeze it so the opening widens. Insert the Accu Dose device into the opening and press the plunger so that the cream enters the penis.  Vitaros can also be effective when simply rubbed into the head of the penis, rather than applied into the urethra (the opening at the tip of the penis), and some men may find this a more comfortable way of using it For full advice on how to use alprostadil cream, read the Vitaros patient information leaflet that comes with your medication. It contains all the information you need on how to use the treatment, including Vitaros side effects and interactions.

How well does Vitaros work?

The most important information you’re likely to want to know is does Vitaros cream work? The short version is yes, it does for the majority of men using it. One study found that close to 75% of participants ‘demonstrated an overall improvement in erectile function’ When comparing Vitaros cream vs Viagra, oral medications are more effective, but alprostadil might be more suitable for those who have issues with ED pills such as Viagra. If Vitaros does not work for you, speak with your prescribing clinician about other options. These might include oral ED treatments or other versions of alprostadil.

What is Viridal Duo?

The Viridal Duo injection is another alprostadil erectile dysfunction medication that’s similar to Caverject. Unlike Caverject, which is made by Pfizer, Viridal Duo is manufactured by Advanz Pharma.

This treatment is also injected into the penis and comes in two glass vials. One for the powder that contains the active ingredient, and one containing the solvent that’s mixed with it for the injection.

Like all alprostadil medications, it works by opening up the blood vessels to allow blood to flow freely into the penis. This helps you to achieve and maintain an erection for sexual intercourse.

How to use Viridal Duo

The Viridal Starter Pack comes with all the equipment you need, including Viridal Easy Duo injector instructions. Before you’re prescribed the treatment, your clinician will make sure that you fully understand how to use Viridal injections safely.

Start by placing the needle on the tip of the injector and screw on clockwise. Then, holding the syringe upright, push the Viridal Duo plunger so that the two grey stoppers inside it are touching. It’s here that the solution will fill the rest of the syringe. 

You can now remove the protector on the needle. Holding the injector upwards, flick the syringe so that any bubbles have been dislodged and gently push the plunger so that a small amount of liquid comes out. You should never touch the needle after removing the protective barrier.

You can then set the dosage by moving the plunger to the dosage marked on the syringe. After cleaning the injection site with the swab, insert the needle into the side of the penis and slowly push the plunger. You should look to empty the contents of the syringe within five to ten seconds. 

How well does Viridal Duo work?

Viridal Duo contains the same active ingredient as all the other treatments listed here – alprostadil. It uses an injection as the method of application. It should therefore work in the same way, producing the same results. 

In the case of alprostadil injections, Viridal has been found to be among the most effective treatments . There are three different Viridal Duo dosages to choose from, so if the lower strengths prove ineffective, there are options that can be discussed with your prescribing clinician.

What is MUSE?

MUSE alprostadil is an erectile dysfunction medication with a slight difference. Instead of using an injection or cream, MUSE uses alprostadil urethral sticks, which make the process of application more straightforward for some.

MUSE alprostadil is manufactured by Meda Pharmaceuticals in the UK, and is available in four different dosages. Each MUSE alprostadil suppository will have the dosage clearly marked on the packaging. 

How to use MUSE urethral sticks

Your doctor will be able to show you how to use the alprostadil urethral stick applicator before you first use this treatment. Once you’ve a complete understanding of how it works, you can begin using MUSE with confidence.

Begin by washing your hands after urinating. You should shake the penis several times to ensure that the urethra is clear. Open the foil patch that MUSE comes in and allow the applicator to fall out onto your hand. Do not pull the treatment from the packaging. You can then remove the applicator from its cover.

Apply the MUSE urethral stick lying down or standing, whichever makes you feel more comfortable. Start by stretching the penis to its full length then squeeze the tip of it gently so that the opening widens. You can then insert the alprostadil urethral suppository until it reaches the collar of the device.

Slowly and gently push the button on the applicator and wait five seconds. Lastly, ensure that you’re not stretching the urethra by slowly removing the device.

For full instructions on how to use alprostadil suppositories, read the packaging of the medication. 

How well does MUSE work?

MUSE alrostadil urethral sticks are effective for the majority of mean and remain a good option for those that have issues tolerating oral ED medication like Cialis, Viagra, Levitra and Spedra.

Unfortunately, as is the case for all erectile dysfunction medications, there’s no guarantee that MUSE alprostadil urethral suppositories will be effective and some trial and error might be required. 

Your prescribing clinician will likely start you on a dosage of 500mcg, which can be increased to 1,000mcg if needed. Likewise, if you find you’re having issues tolerating it, lowering the dosage is also an option.

Are there generic versions of alprostadil?

While alprostadil is the active ingredient for each of these treatments, there’s no generic alprostadil product that goes by that name. All products containing this specific active ingredient are branded, so you won’t be able to find a generic Vitaros cream.

That’s not to say there aren’t options. There might not be a Caverject Impulse generic, but Viridal availability offers an alternative to Caverject injections in the UK. Outside of the UK, Caverject can also be bought as Edex, which is also essentially the same treatment.

What about Edex?

There’s no difference between using Caverject or Edex, apart from the branding and device. Edex alprostadil is available in some countries, but there’s no advantage to using it over Caverject or Viridal Duo.

The only difference between the treatments is in how the medication is applied. Viridal uses the Easy Duo applicator, Caverject the Dual Chamber and Edex cartridges and vials. You might have a preference relating to these devices, but the action of the medications is the same.

What about Invicorp?

Invicorp is another injectable ED treatment but it contains a different active ingredient to alprostadil. In fact, it contains two – aviptadil and phentolamine mesilate. They work to increase blood flow to the penis to help you obtain and sustain an erection. Invicorp can be a good option if alprostadil-based products haven’t worked.

Which type of alprostadil should I use?

There are many considerations to take into account before choosing which product to use. Firstly, the method of administration. Do you prefer an injection to a suppository? If the suppository is preferable, would you prefer Vitaros cream, which has an applicator, or MUSE, which uses a urethral stick?

For injections, is the Caverject Dual Chamber device more suitable than Caverject vials? Or does the Viridal Duo Easy device sound best?

Then there’s pricing, what is the alprostadil cost per dose for each product?

The truth is, the only way to truly know which one’s best for you is trial and error. With a little luck, you’ll find the right ED product and dose for you at the first try. But don’t worry if it doesn’t give you the results you want, there are lots of ED treatment options so it’s likely that you’ll find something suitable with a little guidance and patience.

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This page was medically reviewed by Dr Daniel Atkinson, GP Clinical Lead on August 02, 2022. Next review due on August 01, 2024.

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