Trimix questions answered: how to inject it, storage, needle size, and cost

Trimix is injected into the side of the shaft of the penis (an intracavernosal injection) with a very short, very fine insulin syringe, using the exact site, volume, and frequency your prescriber sets. Most urology practices teach the technique in person and give the first dose in the office so they can watch the response before you inject at home. Everything below explains what the terms on your prescription and your vial label mean, not what dose you should use.

The preparation itself is compounded trimix injection, which combines alprostadil, papaverine, and phentolamine in one solution, prepared by Bayview Pharmacy to the strength written on the prescription. It is prescription-only and is not an FDA-approved product. Your prescriber decides whether it is appropriate for you and what dose you use.

What is trimix?

Trimix is a compounded injectable that contains three active ingredients in a single vial:

• Alprostadil (prostaglandin E1), a vasodilator that relaxes smooth muscle, per MedlinePlus.
• Papaverine, a smooth-muscle relaxant that widens blood vessels, per MedlinePlus.
• Phentolamine, a non-selective alpha-adrenergic blocker that reduces the signals constricting blood vessels, per the DailyMed label.

The three act locally on the blood vessels and smooth muscle inside the penis. Injectable therapy is one of several erectile dysfunction options described in the American Urological Association ED guideline, and providers often consider it when oral medications are not suitable or have not worked well enough. There is no mass-produced trimix product, which is why it comes from a compounding pharmacy: the pharmacy prepares the combination and concentration the prescriber orders.

Bimix, trimix, and quadmix: what is the difference?

The injectable combinations differ in how many active ingredients they contain. The table describes composition and form only. It is not a statement that any option is better, stronger, faster, or more effective, and it is not a recommendation.

Bimix contains no prostaglandin, all four injectables are solutions, and every one of these is compounded and not FDA-approved.

How to inject trimix: the steps a prescriber teaches

Injection technique is taught by the prescriber or a nurse in the office, usually with a demonstration and a supervised first dose. What follows is the general shape of that training so the instructions are familiar when you hear them. Follow your own prescriber's instructions wherever they differ from this outline.

1. Wash your hands. Take the vial out of the refrigerator and let it come toward room temperature if you were told to.
2. Wipe the vial stopper with an alcohol swab and let it dry. Wipe the injection site with a fresh swab.
3. Draw up the exact volume your prescriber wrote, using a new sterile syringe and needle every time. Insulin syringes in the 29 to 31 gauge range are commonly used because the needle is short and fine.
4. Inject into the side of the shaft, into the corpus cavernosum, in the area your prescriber identified. Avoid the top of the penis, the underside where the urethra runs, and any visible vein.
5. Alternate sides and rotate the site within the taught area from one dose to the next, rather than using the same spot repeatedly.
6. Withdraw the needle and hold firm pressure on the site for the length of time your prescriber specified. This is what limits bruising.
7. Put the used syringe straight into an approved sharps container. Never reuse or share a needle.

Call your prescriber if you are not confident about any step, and call before you change anything about how or how much you inject. A Bayview pharmacist can answer questions about the prescription itself, but the pharmacy does not provide consultations and does not set doses.

What size needle for trimix injection?

Prescribers commonly have patients use an insulin syringe in the 29 to 31 gauge range, where the needle is fine and short and the barrel is marked in units. Higher gauge means a thinner needle. The specific syringe, needle length, and gauge are part of your prescriber's instructions, and the syringe you are told to use also determines how the volume is measured out, which is the source of most of the confusion about "units."

Is 20 units of trimix a lot?

That question cannot be answered outside of your prescriber's office, and the honest answer is that "a lot" is defined by the individual, the concentration in the vial, and the response observed during titration. Two people holding vials labeled 20 units are not necessarily receiving the same amount of drug, because the concentration differs. The prescriber sets the starting dose, watches the response, and adjusts.

What can be explained is the arithmetic. On a standard U-100 insulin syringe, 100 units equals 1 mL, so 1 unit equals 0.01 mL. Twenty units on that syringe is 0.2 mL of whatever solution is in your vial. That is a volume, not a strength. The amount of each active ingredient you receive is that volume multiplied by the concentration on your label.

Terms you will see on the label

Units measure volume and not drug strength (1 unit is 0.01 mL), and the beyond-use date on your label governs whatever else you have read.

What is the maximum dose of trimix, and what is the strongest trimix?

Both are prescriber decisions, made for one person at a time, and neither has a single published answer that applies to everyone. A maximum dose is written on your prescription by the clinician who titrated you to it, along with a maximum frequency. Do not exceed either, and do not change your dose on your own.

"Strongest" usually means the highest concentration rather than anything about how well a preparation performs. Bayview compounds 27 validated trimix strengths, with alprostadil from 2.5 to 100 mcg/mL, papaverine at 30 mg/mL, and phentolamine from 1 to 6 mg/mL. A higher concentration is not a better preparation, and there is no correct strength to ask for. The prescriber selects the concentration and the volume together, which is why titration usually starts low and moves in small steps under supervision.

How long does trimix last?

Two different questions get asked with the same words. If you mean how long an individual dose acts, that is specific to the person, the concentration, and the volume, and it is a question for the prescriber who is titrating you. Onset and duration are exactly what they are watching during that in-office titration.

If you mean how long the vial keeps, the answer is on the label. Which brings up the question below.

How long does trimix last in the refrigerator?

Store the vial as directed on your label, which for trimix is generally refrigerated, protected from light, and away from heat and moisture. Keep it out of the reach of children.

The beyond-use date printed on your label is the one that governs. It is assigned for your specific preparation, and no number you find in a forum, on another pharmacy's page, or in an old prescription applies to the vial in your refrigerator. If the vial has passed its beyond-use date, if it has been left out, or if the solution looks cloudy or discolored, call the pharmacy rather than using it. Dispose of needles and syringes in an approved sharps container.

Priapism: the one thing to plan for before your first dose

A prolonged erection is a medical emergency. Your prescriber will tell you the time limit that applies to you; 4 hours is the threshold commonly cited in the urology literature and on the Urology Care Foundation's priapism page. An erection lasting beyond that point can cause permanent damage if it is not treated promptly, so go to the emergency room or seek immediate care rather than waiting to see whether it resolves.

Know before your first injection where you would go and who you would call. For urology practices that manage priapism in the office, Bayview compounds a phenylephrine priapism rescue preparation on a prescriber's order. That is a clinician-administered preparation, not something a patient keeps at home.

Other reported effects of penile injection therapy include pain or aching at the injection site, which can be associated with the alprostadil component, bruising or minor bleeding, dizziness or flushing, and, with long-term use, scarring or firm areas (fibrosis) in the penile tissue. Report new or worsening penile pain, curvature, or lumps to your provider promptly. Injection therapy is not appropriate for everyone, and extra caution applies with conditions that raise the risk of prolonged erection such as sickle cell disease, leukemia, or multiple myeloma.

How much does trimix cost?

At Bayview, compounded trimix injection starts at $100 for a 2.5 mL multi-dose vial. What you pay depends on the strength your prescriber orders and the quantity dispensed, since the higher-concentration validated strengths and the larger vial sizes are priced differently. Prices are cash prices and are subject to change, so call with your prescription in hand for a quote on your specific strength and quantity.

Compounded preparations are generally not billed through insurance, which is covered in more detail in do compounding pharmacies take insurance. A cash price is the whole price, with no deductible or prior authorization in the way.

What Bayview compounds for this

On a prescriber's order, Bayview prepares trimix injection in 2.5 mL multi-dose vials, compounded in our USP 797 sterile lab. Papaverine is held at 30 mg/mL while alprostadil (2.5 to 100 mcg/mL) and phentolamine (1 to 6 mg/mL) vary across 27 validated strengths, so a prescriber can titrate in small steps. The related injectables (bimix without the prostaglandin, quadmix and atropine trimix with a fourth active) and the needle-free Triple-P urethral gel are prepared the same way. The rest of the line is in our compounded medications catalog.

Talk to your prescriber

If injectable therapy is something you want to ask about, that conversation belongs with a urologist or your prescribing provider, who can decide whether it is appropriate, teach the injection technique, and set your dose. If they write for trimix, they can e-prescribe, fax, or phone the order to Bayview Pharmacy in Warwick, Rhode Island, and we can fill and ship it to the states where Bayview is licensed. Details are on our FAQ page, and a pharmacist is available for questions about your prescription.