The effects of nitroglycerin on the penis have been known for many years. Researchers in 1989 published a paper based on a study they conducted comparing a 2% nitroglycerin paste to a placebo. In this small study, 18 of 26 men had a significant increase in penile circumference after using the nitroglycerin. Using an ultrasound, researchers were able to detect an increase in blood flow in the cavernous arteries after application of the paste. Further studies over the years since have confirmed these results – that nitroglycerin applied topically is safe and effective for treating ED.
Nitrates and Vasodilation
Nitrates are a class of drugs that are typically prescribed for treating heart conditions. These drugs are well known vasodilators that exert relaxant effects on vascular smooth muscle. Nitroglycerin is a nitrate that absorbs easily through the skin. Its vasodilatory properties combined with its high absorption make it an excellent candidate for the topical treatment of ED.
Vasodilation is a primary mechanism targeted by drugs that are used to treat erectile dysfunction. ED is thought to have both psychological (often referred to as psychogenic) causes and organic, physiological causes. Most cases of ED have some psychological component. Even if these issues are resolved the physical issues may remain. Blood flow to the penis is one of the primary factors determining whether an erection occurs. The most common treatments for ED – PDE5 inhibitors like sildenafil and tadalafil – work by improving blood flow to the penis. This is accomplished through the relaxation of smooth muscle, which allows for increased blood flow.
ED is extremely common in men suffering from chronic coronary artery disease. An estimated 75% of men with chronic coronary artery disease also have erectile dysfunction. Nitroglycerin may be effective for some of these men however nitrates are contraindicated for use with certain common heart medications. Drugs like PDE5 inhibitors can not be used with nitroglycerin, which means patients should not combine a drug like oral sildenafil with a nitroglycerin cream.
How Does Nitroglycerin for ED Work?
The studies have shown that nitroglycerin topical is effectively absorbed through the glans penis, which consists of a thin squamous mucosal epithelium. Nitroglycerin is known to dilate blood vessels, which allows more blood to flow into the penis. Blood flow into the penis is what helps maintain an erection. However nitroglycerin does not only work by increasing blood flow.
When nitroglycerin is applied topically to the penis, it leads to a rapid signaling and release of endogenous nitric oxide (NO) into the corpus cavernosum. NO is an essential part of obtaining and maintaining an erection as it is associated with the relaxation of smooth muscle. This relaxation allows blood to flow into the penis and prevent it from flowing out to maintain an erection. Nitric oxide production decreases with age and can be impaired by the use of certain medications or particular diets. It is not the only factor affecting an erection but it is one important target of topical treatments for ED.
Through multiple mechanisms, nitroglycerin topical both increases blood flow to the penis and also prevents the outflow of blood to help men maintain an erection.
MED 2005 and Commercial Development
A nitroglycerin topical has been developed using a proprietary dermal delivery system. In clinical trials so far, nitroglycerin has effectively improved erections for many men. This new nitroglycerin topical is being marketed in other countries already and is currently being reviewed for FDA approval. It is possible that a nitroglycerin topical for ED will be available by prescription or over the counter at some point in the near future. In the meantime, a topical nitroglycerin for ED can only be made by a compounding pharmacy with a prescription.
Nitroglycerin has been made in various forms including sublingual, oral, patch, powder, and spray. Many of these forms are available for use in treating heart conditions. To avoid more significant systemic effects and to target the treatment area more directly, a topical has won out as the preferred drug form for treating erectile dysfunction.
Application of Nitroglycerin Topical for ED
Nitroglycerin creams and gels are applied directly to the penis and allowed to absorb for a few minutes. A small, pea-sized amount is applied to the head of the penis. The effects are usually noticed fairly quickly. Most men will be able to notice the start of an erection within 10 minutes, and around half of men will notice an erection in only 5 minutes.
Adverse Effects and Precautions
One important contraindication of nitroglycerin cream is that it should not be used with PDE5 inhibitors. The combination of these drugs can significantly trigger vasodilation and severe hypotension. The most common side effect that has been found to-date with nitroglycerin topical cream and gel is headache. This is also a potential side effect of PDE5 inhibitors. Patients have also reported nasopharyngitis (having a stuffy nose). These side effects can sometimes occur in the man’s sexual partner as well.
The risk of a sudden drop in blood pressure is one that patients should discuss with their doctor. Patients should also talk with their doctors about all medications they are taking and all health conditions before starting a new treatment like nitroglycerin cream.
Articles
Topical nitroglycerin: a potential treatment for impotence – The Journal of Urology, 1989
Nitroglycerin Ointment in the Treatment of Impotence – The Journal of Urology, 1993
Erectile dysfunction in the cardiac patient: how common and should we treat? – The Journal of Urology, 2003
Drug Interactions With Phosphodiesterase-5 Inhibitors Used for the Treatment of Erectile Dysfunction or Pulmonary Hypertension – Circulation