There are two forms of Caverject available: Caverject Vials and Caverject Dual Chamber.

The main difference between them is that when using Caverject Vials, the user has to prepare the vial and mix the powder and liquid solution together themselves; whereas with Caverject Dual Chamber, everything is contained in one device, and the medicine is mixed together by turning the plunger.

But aside from the way they are administered, the two are mostly very similar.

They are both made by the same company (Pfizer), contain the same medicine (alprostadil which is similar to the natural substance in your body called prostaglandin E1) and work in the same way: by widening your blood vessels so that blood can flow in your penis more easily, thus making it easier to get and keep an erection.

In this post, we’ll run through the differences and similarities between the two, including:

and what to do if you aren’t sure which form is best for you.

How are they administered?

The injections are given to the same area (the tissue on the side of the shaft of the penis), but there are slight differences in the way each one is prepared.

Both contain alprostadil in ‘lyophilized form’. This means that it has been freeze-dried so that it has an increased resistance to heat, light, and other external influences.

In Caverject Vials, the freeze-dried medicine and the water for injection solutions are supplied separately. Two needles are also provided.

The larger needle is affixed carefully to the syringe containing the solution. The user then injects the solution into the vial containing the freeze-dried medicine, through the rubber stop. Once all the liquid is in, the user swirls the vial to mix it together, before pulling the plunger back out to draw the now-mixed solution back into the syringe.

The used needle is then removed and replaced with the smaller needle, ready to be administered. When injecting the medicine, the user ensures they are using the right amount (and correct dose).by injecting the appropriate line on the side of the syringe.

In Caverject Dual Chamber, both the injection solution and the freeze-dried powder are contained in one device, but in separate chambers. The user mixes these together by simply twisting the plunger until it clicks, and then gently shaking it. The dose is selected by turning a dial at the end of the plunger.

Are there different doses available?

Yes. Caverject Dual Chamber is available in 10mcg and 20mcg concentrations.

Caverject Vials is available in 10mcg, 20mcg and 40mcg concentrations. A 5mg concentration used to be available, but has been discontinued.

When injecting with Caverject Vials, the user has to administer it to the line manually. Caverject Dual Chamber on the other hand, has a twistable switch at the end of the syringe where the user selects the dose they need to use.

A doctor will usually advise ‘titration’ with Caverject, which means that the patient will start with a low dose (equivalent to 1.25 or 2.5 mcg for example) and gradually increase the amount they use until they get a sufficient response.

Do they work differently?

No. They both contain the same active ingredient, so once injected the body, they work in the same manner.

Alprostadil is a synthetic ingredient, similar to a natural chemical in the body, called PGE1 (which is short for prostaglandin E1). Erectile dysfunction is caused by tightened blood vessels, restricting blood flow to the penis. PGE1 helps to loosen these blood vessels, which allows blood to flow more easily into the penis, and allow for firmer erections.

Caverject Vials vs Dual Chamber: Which is cheaper?

It depends where you get it from. If you’re entitled to branded treatment for ED on the NHS, then both forms (whichever you are issued) will cost the same (the price of the prescription levy), or be free (if you’re entitled to free treatment).

If you’re buying Caverject privately, prices for each can vary. When you buy Caverject online from for example, Caverject Vials is more expensive per injection. Two dual chamber injections costs £39, whereas two vials injections costs £55.

You can find a full list of prices on our Caverject page.

Which should I use?

It ultimately depends which one you’re more comfortable with, and which one your doctor recommends. If you’re not sure about the best form or want to switch from one form to another, speak to your doctor for advice.

Page last reviewed:  24/08/2018