Caverject

How Does Caverject Work?

Alprostadil is a Prostaglandin E1 (PGE1) agonist. When injected into the corpus cavernosum, it binds to prostaglandin E receptors (EP2 and EP3) on smooth muscle cells, activating adenylate cyclase and increasing intracellular cyclic AMP (cAMP). The elevation of cAMP causes smooth muscle relaxation in the corpus cavernosum and cavernosal arteries, significantly increasing blood flow into the penis.

Unlike oral PDE5 inhibitors (Viagra, Cialis) which amplify the natural arousal-induced nitric oxide/cGMP pathway, alprostadil works through an independent pathway and does not require sexual stimulation to produce an erection. This makes it particularly effective for men with neurogenic or severe vascular ED where the nitric oxide pathway is compromised.

After injection, alprostadil is metabolized primarily locally within the penile tissue. Approximately 80% of any drug that enters systemic circulation is cleared in a single pass through the lungs. This limits systemic exposure and explains why serious systemic side effects are relatively uncommon with intracavernosal alprostadil.

How Hard Is It to Find Caverject in Stock?

Finding alprostadil injection has been challenging for patients over the past several years. A major 2023 supply disruption by Pfizer — caused by manufacturing capacity being diverted to another essential medication — left many patients unable to access Caverject for extended periods. This was compounded by Pfizer's decision to permanently discontinue the Caverject brand in July 2025.

As of 2026, generic alprostadil injection is available from multiple manufacturers (including Meitheal Pharmaceuticals, which launched in March 2025), but local pharmacy stocking remains inconsistent during the market transition. Alprostadil injection is a specialty drug not carried at every pharmacy — patients are most likely to find it at specialty pharmacies, compounding pharmacies, or through mail-order. Standard retail chains may not stock it or may only carry it at select locations.

To find which pharmacies near you carry alprostadil injection, use medfinder — a service that calls pharmacies on your behalf and texts you results, saving you significant time.

Who Can Prescribe Caverject?

Caverject (alprostadil injection) is not a controlled substance, so it can be prescribed by any licensed prescriber with authority to write prescriptions. However, FDA guidelines require that the first dose be administered in a medical office with medical supervision and dose titration before home self-injection is permitted. In practice, alprostadil injection is most commonly prescribed by specialists.

Urologists — the primary specialists for ED; most experienced with intracavernosal therapy and in-office titration

Men's health clinic providers — specialists in male sexual health and hormonal issues

Primary care physicians (PCPs) — some experienced PCPs prescribe alprostadil injection, particularly for established patients

Endocrinologists — for patients whose ED is associated with hormonal or metabolic conditions

Nurse practitioners and physician assistants — with full prescribing authority in most states, particularly in urology and men's health settings

Some telehealth platforms offer ED consultations, but intracavernosal therapy requires at least one in-person visit for dose titration and injection training before home self-administration is approved.

Is Caverject a Controlled Substance?

No. Alprostadil (Caverject) is not a controlled substance under the DEA scheduling system. It is not assigned to any DEA schedule (I through V) and has no recognized potential for abuse or dependence. This means Caverject and generic alprostadil injection can be prescribed by any licensed healthcare provider — including PCPs, urologists, NPs, and PAs — without DEA restrictions.

Prescriptions for alprostadil injection can typically be written for 30-day or 90-day supplies without the refill restrictions that apply to Schedule II–V controlled substances. Insurance prior authorization requirements still apply for many plans, but these are based on medical necessity criteria, not controlled substance regulations.

Common Side Effects of Caverject

The most common side effects of Caverject (alprostadil injection) include:

Penile pain (most common, ≥10% in clinical trials; up to 20–40% in real-world use)

Bruising or bleeding at the injection site

Mild dizziness or lightheadedness

Redness or swelling at the injection site

Serious side effects that require immediate medical attention:

Priapism (erection lasting more than 4 hours) — a medical emergency; go to the ER immediately

Penile fibrosis — scarring causing curvature with long-term use; report new curvature to your doctor

Significant hypotension — dizziness, fainting; more common in patients on antihypertensives

Needle breakage — rare; use proper technique and never reuse needles

Final Thoughts on Caverject

Caverject (alprostadil injection) is a highly effective, FDA-approved treatment for erectile dysfunction with over 40 years of clinical use. Over 80% of men in clinical studies achieved erections sufficient for intercourse, and alprostadil works independently of sexual arousal — making it effective even for men with neurogenic or severe vascular ED where oral medications fail. The 2023 shortage and 2025 brand discontinuation were significant challenges for patients, but generic alprostadil is now entering the market and supply should improve over time.

The main challenges in 2026 are cost and local availability. At retail prices historically exceeding $1,000 for a six-vial pack, prior authorization from your insurer is important to pursue. Discount cards (GoodRx, SingleCare) provide meaningful savings, and compounded Trimix may offer a more affordable and even more effective alternative for many men.

If you have a valid prescription and are struggling to find alprostadil injection locally, medfinder can help. Enter your medication, dose, and zip code — medfinder calls pharmacies near you and texts you which ones can fill your prescription. It's the fastest way to find your medication without spending hours on hold.