What’s the Difference Between Caverject and Muse for Erectile Dysfunction?

Erectile dysfunction (ED) is when you’re regularly unable to have or maintain an erection. ED may be due to different factors affecting blood vessels, nerves, or hormones. Mental health factors can also play a role. It’s estimated that over 150 million men experience ED worldwide. 

Phosphodiesterase type 5 (PDE5) inhibitors, like sildenafil (Viagra) and tadalafil (Cialis), are often first-choice medications to treat ED. But they might not work for everyone, and some people can’t take them. This is where medications like Caverject or Muse may come in.

Read on to learn more about Caverject and Muse for treating ED. We’ll cover key similarities and differences to help you decide which may be better for you.

What is Caverject?

Caverject (alprostadil) is an ED medication that’s injected into the penis. It’s available as single-dose vials in 20 mcg and 40 mcg strengths that you’ll store at room temperature. Each vial contains powder that you’ll need to mix with a solution before use.

Alprostadil injections are also available as a dual chamber cartridge (Edex) and dual chamber syringe (Caverject Impulse). Both of these products can make it easier to mix the powder before injection.

What is Muse?

Muse (alprostadil) is a suppository that’s inserted into the urethra of the penis. The urethra is the tube below the bladder that allows urine to exit the body.

Muse is available in four different strengths:

• 125 mcg

• 250 mcg

• 500 mcg

• 1,000 mcg

Unlike Caverject, Muse suppositories need to be stored in the refrigerator. They’re only good for 14 days if you keep them at room temperature.

How do Caverject and Muse work for ED?

Caverject and Muse contain alprostadil. Alprostadil is a lab-made form of prostaglandin E1 (PGE1). PGE1 is a naturally-occurring chemical in the body that sends signals that cause smooth muscles to relax.

Alprostadil works by dilating — or widening — the blood vessels in the penis. When the smooth muscles become relaxed, more blood flows into the penis. This helps people achieve erections.

How are Caverject and Muse dosed and given?

While Caverject and Muse contain the same active ingredient, they’re dosed and given differently. More on these differences below.

Caverject

Caverject is given as an injection into a part of the penis known as the corpus cavernosum. This part is made up of two spongy tissues that run along the body of the penis. It’s important to change sides of the corpus cavernosum with each dose. Rotating injection sites can help minimize scar tissue.

The starting dose is typically 1.25 mcg to 2.5 mcg. An erection should happen within 5 to 20 minutes of your dose. If you only partially respond or don’t respond at all, your healthcare provider will provide instructions for what to do next. This may include giving yourself a higher dose.

You’ll want to use the lowest effective dose of Caverject. This is typically the dose that provides an erection suitable for sex lasting up to 1 hour. Once you find an effective dose, you can use Caverject up to 3 times per week. But you’ll want to wait at least 24 hours between injections.

Your healthcare provider will want to make sure you understand how to give yourself the injections. So, they’ll typically walk you through the process in their office. They’ll also give you tips to minimize side effects, like applying pressure to the injection site.

Some people may respond differently to Caverject. So, it’s important to talk to your healthcare provider if you’re having trouble finding a dose that works. 

Muse

Unlike Caverject, Muse isn’t injected into the penis. Instead, it’s placed in the urethra where alprostadil can be absorbed. Muse comes with an applicator to help you administer the medication. Your healthcare provider will instruct you how to use it properly.

The starting dose of Muse is 125 mcg to 250 mcg, with a dosing range from 125 mcg to 1,000 mcg. Your healthcare provider will help adjust your dose until you achieve erections that allow for sexual intercourse. Just like Caverject, you’ll want to find the lowest effective dose.

It takes about 5 to 10 minutes for Muse to take effect. Once it kicks in, the effects usually last for about 30 to 60 minutes. But this may vary from person to person. Don’t use more than 2 doses of Muse per day.

How effective are Caverject and Muse for ED?

Both Caverject and Muse can be effective for ED. Let’s take a look at how they stack up.

A 1996 study looking at alprostadil injections (like Caverject) found the medication to be effective in 94% of injections. Sexual experiences were reported to be satisfactory for about 87% of injections. Side effects were also reported. About 11% of injections resulted in mild penile pain. And 5% of people experienced prolonged erections.

A 1997 study found Muse to be effective for about 65% of men using it. Around 11% of injections were reported to cause mild penile pain. And low blood pressure occurred in a little over 3% of men receiving the medication.

A 2007 study compared both medications. The study found that most people (70%) using Muse reported poor erection quality. This is compared to 12% of people using alprostadil injections. Plus, 77% of people reported worse erections with Muse compared to alprostadil injections.

Other head-to-head studies also suggest that alprostadil injections, like Caverject, may be more effective than Muse. But injections may not be right for everyone. Muse might be a better option if you’re afraid of needles or unable to give yourself injections.

What are the known side effects of Caverject and Muse?

Caverject and Muse can be used to help achieve erections. But they can also cause a variety of side effects. 

What are the serious side effects of Caverject and Muse?

Carject and Muse can sometimes cause serious side effects.

• Very low blood pressure and fainting. Caverject injections can sometimes cause alprostadil to move into the bloodstream. This can cause very low blood pressure (hypotension) and lead to fainting. See how you respond to the injection before driving.

• Erections lasting longer than desired. Sometimes, Caverject and Muse provide an erection that lasts longer than intended. If it lasts longer than 4 hours (called priapism), seek medical attention right away. This is considered a medical emergency.

• Scar formation on penis (penile fibrosis). Scars may form on the penis from Caverject injections. Rotate injections sites with each dose to help minimize scarring.

Before using Caverject or Muse, talk with your healthcare provider about the potential side effects and risks of these medications. 

What interactions do Caverject and Muse have?

People using Caverject and Muse should talk with their healthcare providers about using them with blood pressure medications. That’s because alprostadil can also lower blood pressure.

Make sure to talk to your healthcare provider first before taking PDE5 inhibitors at the same time as Caverject or Muse. They’re sometimes recommended together for additive effects. But you shouldn’t try this unless instructed to do so.

How to save on Caverject and Muse

Caverject and Muse are only available as brand-name medications. But GoodRx can help you navigate ways to save on your prescription.

• Save with patient assistance programs. If you’re uninsured or underinsured, you may be eligible for the Caverject or Muse patient assistance programs, which offer the medication at no charge.

• Save with a copay savings card. If you have commercial insurance and meet eligibility requirements, Caverject’s price is as little as $20 if you use the manufacturer’s savings card. You can also save up to $50 per fill on Muse if you use the manufacturer’s savings card.

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Written by:

Kevin Le, PharmD, BCPS, BCPPS

Kevin Le, PharmD, BCPS, BCPPS is a clinical pharmacy specialist in solid organ transplant at Ann & Robert H. Lurie Children’s Hospital of Chicago. He has been working as a pediatric pharmacist since 2016.

Edited by:

Alyssa Billingsley, PharmD

Alyssa Billingsley, PharmD, is the director of pharmacy content for GoodRx. She has over a decade of experience as a pharmacist and has worked in clinical, academic, and administrative roles.

Reviewed by:

Christina Aungst, PharmD

Christina Aungst, PharmD, is a pharmacy editor for GoodRx. She began writing for GoodRx Health in 2019, transitioning from freelance writer to editor in 2021.

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