Injectable ED Medications:
- Pharmacologic Category: Anti-erectile dysfunction preparation: vasodilator, prostglandin, & alpha-adrenergic receptor antagonist.
Tri-mix is administered as a penile self-injection, typically considered to be the most powerful class of anti-erectile dysfunction agents. While the components of Tri-mix are, on there own, indicated for a vast number of different conditions (papaverine, phentolamine, PGE1 monographs), the practice of bringing them together in concert to treat erectile dysfunction has become commonplace in sexual medicine and is now considered to be the go-to treatment if conventional PDE5 inhibitors are contraindicated or nonresponsive. and is now considered the go-to treatment if a patient is not responsive to conventional PDE5 inhibitors such as Viagra or Cialis.
Indications: Tri-Mix is indicated in the treatment of erectile dysfunction in males. Tri-Mix contains three drugs from complimentary classes designed to act synergistically, mixed into a sterile injection. They are:
Papaverine: A drug that causes blood vessels to expand (vasodilator); it produces an erection by allowing for increased blood flow to the penis. Papaverine interacts with adenylate cyclase resulting in increased cyclic adenosine monophosphate (cAMP) production, ultimately resulting in increased erectile capacity by relaxation of penile smooth muscle. This drug was one of the first effective therapies for erectile dysfunction administered by penile injection. Papaverine works by inhibiting phosphodiesterase non-specifically, there are also multiple other mechanisms by which this drug acts to improve erectile capacity.
Phentolamine: When injected into the penis, it induces an erection by relaxing and dilating the blood vessels of the penis, as well as by elevating cardiac output.
Phentolamine is classified as an Alpha-Adrenoceptor Antagonists. Noradrenaline effects the smooth muscle tone of the penile tissues by keeping the corpora cavernosa in a contracted state. By blocking the functional noradrenaline receptors, the Alpha-Adrenoceptor, erectile response can be achieved. Phentolamine competes with endogenous norepinephrine for the Alpha1-Adrenoceptor and Alpha2-Adrenoceptor. Phentolamine has similar binding capacities to both receptors. The current literature suggests that this is the main mechanism by which phentolamine exerts its physiological effects. Phentolamine also blocks 5-HT receptors, inducing the release of histamine from mast cells. Some studies also show that NOS activation could possibly be involved in another mechanism, inducing increased vasodilation.
The Alpha-Adrenoceptor Antagonist of phentolamine is considered to be complex. The non-selective receptor blocking action interacts with adrenergic nerves in a complex fashion. Phentolamine action on adrenergic nerves has not been fully established. It is thought that there might be counteracting regulation on pre-and post-junctional nerves.
Prostaglandin E1 (Alprostadil): A potent hormone-like substance that induces erection by relaxing the penis’s blood vessels and dilating cavernosal arteries-dilation of the cavernosal arteries is accompanied by increased arterial inflow velocity and increased venous outflow resistance allowing for more blood into the penis and less blood out.
Prostaglandin E1 is administered intracavernosally. This drug is prescribed as a second-line treatment, after oral PDE5 inhibitors have been ineffective for treatment of erectile dysfunction. Currently the body of medical literature demonstrates that 40 to 70% of erectile dysfunction patients respond to treatment with prostaglandin E1. The failure to respond to prostaglandin E1 has not been established. The demonstration that prostaglandin E1 with S-nitrosoglutathione in combination is more effective than prostaglandin E1 alone may shed light on the lack of efficacy in some patients .
Medications to activate alternative relaxant pathways in addition to by prostaglandin E1 may be necessary in patients who fail to respond to prostaglandin E1. Relaxation of smooth muscle is a critical component of erectile capacity. Additional agents to work in combination with prostaglandin E1 might have significant therapeutic benefits. Prostaglandin E1 with S-nitrosoglutathione or other erectile dysfunction medications, might have advantages in the treatment of male erectile dysfunction.
Reasons not to take this medicine: Do not take this medicine with any of the following medications: hypersensitivity or allergy to any component of this formulation; conditions predisposing you to priapism (painful erection lasting 4 hours or more): sickle cell anemia, multiple myeloma or leukemia; anatomical deformation of the penis or penile implants; direction by your physician that sexual activity is inadvisable or contraindicated
Key warnings before taking this medicine? Tell your doctor if you have a condition or are taking a medicine that interferes with blood clotting.
What are t/he precautions when taking this medicine? Give your health care provider a list of all the medicines, herbs, non-prescription drugs, or dietary supplements you use. Some items may interact with your medicine.
How is it best taken? Ideally, the injection should be administered just prior to foreplay. It is administered via intravavernosal injection and should produce an erection in 5 to 20 minutes and can be expected to last up to one hour. To prevent bruising, apply firm pressure to the injection site for 5 minutes after injecting. Do not use Tri-mix Injection more than two times a week; use at least 24 hours apart. There is a possibility of needle breakage with use of Tri-mix Injection: you should pay careful attention to your doctor’s instructions and handle syringe and needle properly. If the needle breaks during injection, you should promptly contact your doctor.
What do I do if I miss a dose? Do not take double or extra doses. This medicine should only be taken 5 to 20 minutes before intercourse.
What are some possible side effects of this medicine? Mild to moderate pain during injection; painful sensation with erection; small amount of bleeding at the injection site. Call your healthcare provider if you notice any redness, lumps, swelling, tenderness or curvature of the erect penis. If you experience an erection lasting more than 2 hours, you may take 2 – 4 pseudoephedrine 30 mg by mouth once and apply an ice pack. If your erection does not go away within the next hour, seek professional help immediately. Erections that last more than 6 hours can cause serious damage to the penile tissue.
How should I store this medicine? The mixture is not stable for long periods at room temperature. Once reconstituted keep this medicine in a refrigerator below 41°F (5°C). It is important to note that improper storage does not result in harmful chemicals: the only thing to suffer is the potency – the preparation may not be as strong as when fresh. Keep all medicine out of the reach of children. Throw away any unused medicine after the expiration date. Do not flush unused medications or pour down a sink or drain.
General statements: Do not share or take any one else’s medicine. Talk with your healthcare provider before starting any new medicine, including over-the-counter, natural products, or vitamins. This medication was compounded specifically for you. This patient information summarizes the most important information about your medication; if you would like more information, talk with your doctor.