With only a year or so to go before its 20th anniversary, Viagra remains one of the best-selling erectile dysfunction drugs on the market. Although Pfizer’s little blue pill is out of patent in several countries, generic formulations of the drug are top sellers as well.
In the years since its introduction, medical researchers have found that sildenafil citrate — Viagra’s active ingredient — can ease the symptoms of other health conditions as well. Such conditions include pulmonary arterial hypertension — a form of high blood pressure that targets the lungs, Raynaud’s syndrome, altitude sickness, and prostate cancer.
Mouth Spray in the Works
Now comes word that scientists are hard at work on the development of a sildenafil mouth spray that some reports say produces the desired results in as little as a minute or so, much more rapidly than the little blue pill that takes 30 to 60 minutes to become effective.
The idea of delivering sildenafil in a mouth or nasal spray isn’t new, but when it first surfaced five or six years ago, it was little more than talk, Now, it seems, preliminary scientific tests have been conducted that could lead to the introduction of consumer health products over the next few years.
Taiwanese Study
Most recently, a team of Taiwanese scientists mixed minute amounts of sildenafil with food-grade propylene glycol in a spray that was tested on male rabbits (who knew rabbits needed any help with erections?). A couple of spritzes of the spray beneath the rabbits’ tongues, and they were ready for action in 78 seconds on average. Before live testing on the rabbits, scientists first conducted laboratory tests to find the ideal mixtures of the active ingredient and delivery agent for use in live testing.
A few years earlier, another team of Taiwanese researchers, some of whom later worked on the sublingual (under the tongue) spray, conducted similar experiments on rabbits using sildenafil in a nasal spray. For that experiment, which was done first in the laboratory and later on live rabbits, the active ingredient was mixed with a variety of oils, surfactants, and cosurfactants to determine which produced the most rapid onset and longest duration of action.
Australian Firm Tests Spray
SUDA Ltd., based in Osborne Park, Western Australia, has also been working on a proprietary mouth spray delivery system for sildenafil. It recently announced the successful completion of a pilot pharmokinetic clinical trial comparing the mouth spray with oral sildenafil in the form of a tablet. SUDA’s SUD-003 spray formulation was acquired in July 2013 when the Australian company purchased virtually all the assets — including intellectual property — of New Jersey-based NovaDel Pharma Inc. The sildenafil spray technology had been code-named NVD-401 by NovaDel. Should SUDA’s sildenafil spray be approved for sale by regulatory authorities, the product will be brand named DuroMist.
One of the primary goals of SUDA’s clinical trial was “to assess the relative bioavailability and safety of one, two, and three sprays of 10-milligram/0.12-milliliter of DuroMist, compared to a 25-milligram Viagra tablet.” SUD-003 came through with flying colors, according to SUDA. Two 10-milligram spritzes of SUD-003 was bioequivalent to a 25-milligram Viagra tablet taken orally. However, a single 10-milligram spray of SUD-003 produced only about 40 percent of the systemic exposure produced by a 25-milligram oral tablet. Three spritzes of SUD-003 resulted in 40 percent higher systemic exposure than the 25-milligram oral tablet.
Study’s Findings Published
Findings from the Taiwanese study on the sublingual sildenafil spray were published in the September 2016 issue of “Journal of Pharmaceutical Sciences.” Part of the motivation for developing alternatives to oral ED drugs was to speed the onset of action, get more benefits from lower levels of the active ingredient, and reduce the adverse side effects experienced when taking the oral tablet.
The researchers involved in sublingual spray study noted that sildenafil in tablet form has a first-pass effect (also known as presystemic metabolism) of 70 percent. This indicates that 70 percent of the active ingredient is metabolized in the liver and thus never becomes systemically active or bioavailable. The mouth spray formulation ensures that more of the active ingredient becomes bioavailable and thus allows increased results from lower amounts of the active ingredient.
Side Effects of Sildenafil
While the side effects of Viagra in tablet form are generally mild and often disappear upon continued use, some users find them troublesome and discontinue use of the drug. The most common side effects include abnormal vision, cardiac risk, diarrhea, dizziness, fainting, nasal congestion, upset stomach, rash, and urinary tract infections.
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In the earlier Taiwanese study of the nasal sildenafil spray, researchers found that nasal absorption of the active ingredient was fairly rapid — in some cases almost instantaneous. Moreover, the duration of action averaged three hours. Findings from the nasal spray study were published in the March 2011 issue of “Xenobiotica.”
In all these studies of spray technologies, sildenafil is the active ingredient that’s being used, although it’s conceivable that similar delivery systems could be developed for the active ingredients in other popular ED medications. All these active ingredients belong to a family of medications known as PDE5 inhibitors, so called because they temporarily disable an enzyme known as phosphodiesterase-5. To understand why this matters, it’s helpful to know a bit about the erectile function.
Erections Begin in Brain
Erections begin not in the genitals but in the brain, which reacts to physical stimuli to erogenous zones or feelings of sexual desire by sending a flood of nitric oxide coursing toward the pelvic region. As this nitric oxide makes its way to its destination, it triggers other chemical reactions, one of which produces a compound known as cyclic guanosine monophosphate, or cGMP.
The role of cGMP is critical in erectile function, because it relaxes the smooth muscle tissue lining the arteries that supply the penis. As this muscle tissue relaxes, the arteries expand, increasing the flow of blood into the penis. As this fresh rush of blood engorges the spongy erectile tissue within the penis, an erection is produced. At the same time, the veins that carry blood away from the penis temporarily contract, trapping the blood in the penis until sexual activity is complete.
PDE5 Enzyme vs. cGMP
In men with no vascular problems, all these processes are carried out with little or no interference from the PDE5 enzyme, which is charged with the responsibility of breaking down cGMP. However, for men whose vascular systems are already compromised, the PDE5 enzyme often kills off cGMP faster than it can be replaced, thus sabotaging the erection process.
Viagra and the other PDE5 inhibitors temporarily hold the PDE5 enzyme at bay so that the erection process and sexual activity can be completed before the enzyme goes back to work breaking down cGMP. Viagra’s effects usually last four to five hours, which is more than enough time for an erection to develop and sexual activity to be completed.
If this article has piqued your interest and you’d like to read more about sexual health and function, as well as other topics of interest to health consumers, check out our blog.
Frequently Asked Questions
Can I take Viagra pills with other medications?
Taking Viagra pills with other medications can be risky, especially if you’re on nitrates, alpha-blockers, or certain blood pressure drugs, as it may cause severe drops in blood pressure. Always inform your healthcare professional about all medications and supplements you take to ensure the safe use of Viagra.
Are Viagra pills safe for long-term use?
Viagra pills are generally safe for long-term use when taken as prescribed by doctors. However, regular check-ups with your healthcare provider are essential to monitor for any side effects or underlying conditions that may require attention.
Is it safe to switch between Viagra 25mg and Viagra 100mg doses?
Switching between Viagra 25mg and Viagra 100mg doses should only be done under medical supervision. Factors like your health, age, and response to the medication determine the safest dose. Consult your doctor before making any changes to your dosage.
Is Viagra 25mg effective for treating erectile dysfunction?
Yes, Viagra 25mg can be effective for treating erectile dysfunction, especially for men who are sensitive to higher doses. It provides the same mechanism of action as larger doses but with a reduced risk of side effects. Discuss with your doctor if this dose is suitable for you.
How long does it take for Viagra to work after taking it?
It usually takes about 30 to 60 minutes for Viagra to start working, but this can vary depending on aspects like metabolism and whether it’s taken on an empty stomach. Knowing how long does it take for Viagra to work helps you plan its use effectively.
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