Have you ever wondered what the difference is between Viagra and Cialis? Do you need to know which medication is suitable for which situation? Are you looking for an easy way to find the differences between these popular erectile dysfunction medications? We spoke to a pharmaceutical expert to find out more.

Generic Name

Viagra is a short-acting drug originally developed by Pfizer back in the 1960s. It was originally approved for use in the United States in 1985 and was subsequently approved for use across the world. In 2011 alone, Viagra was prescribed for some 48 million daily doses in the U.S., according to the pharmaceutical data firm IMS.

Cialis is a second-generation drug, developed by a French pharmaceutical company, and was approved for use in humans in 1994. Like Viagra, Cialis is a short-acting drug that works by inhibiting an enzyme called PDE5, which is responsible for breaking down cGMP and causing blood vessels in the penis to relax and expand, thereby creating an erection sufficient for sexual intercourse.

Key Differences

While both Viagra and Cialis are effective in treating erectile dysfunction, they differ in important ways, as outlined below.

Time Of Effect

Viagra has a quick onset of action, with effects typically lasting for about an hour or so. Cialis, on the other hand, takes a bit longer to take effect. It has been known to take 30 to 45 minutes to start working and to last for up to four hours. It should be noted that the effect of Cialis also tends to be more gradual than that of Viagra.

Dosage

The standard dose of Viagra is one pill per day, taken on an empty stomach in the morning. The recommended starting dose of Cialis is one pill per day, taken as needed. Some patients may experience desirable effects with lower dosages than usual (e.g., one pill every other day). However, as with any medication, trying a lower dose first may increase the chance of side effects appearing. The ideal dose of Cialis varies by body-type and medical history, but is usually between 10 and 40 mg daily, taken as needed.

Viagra’s label does not include a maximum dose, but Pfizer recommends against taking more than one pill per day, and preferably not more than half of a pill per day, due to the risk of overdose. Similarly, Cialis’s label suggests avoiding doses above 15 mg daily due to the risk of side effects, such as headache, diarrhoea, flushing, or heart issues. Some patients may require a starting dose of 5 mg daily, and the recommended maximum dose is 20 mg daily.

Route Of Administration

While oral administration of Viagra and Cialis is possible, sublingual absorption is highly preferred, as this allows molecules to readily enter the systemic circulation. Sublingual administration of Viagra (which is available as a tablet, a powder suspended in a gel, or a liquid) improves drug absorption and effectiveness compared to oral administration. The same goes for Cialis (tablet or liquid).

Active Ingredients

The active ingredients in Viagra and Cialis are sildenafil and tadalafil, respectively. Both are PDE5 inhibitors, which work by boosting cGMP levels in the blood and genital tissues. Sildenafil is the active ingredient in the widely-used drug Viagra, while tadalafil is the active ingredient in the oral treatment Cialis. Drugs containing these ingredients have been proven to be effective in treating erectile dysfunction in both men and women. In clinical trials to date, sildenafil showed an average improvement in erectile dysfunction severity of 72% in men and 55% in women. Tadalafil showed an average improvement in erectile dysfunction severity of 70% in men and 55% in women (source: sildenafilcitrate and tadalafil citrate product monographs, respectively, from the US FDA).

Research

While both Viagra and Cialis are safe and effective treatment options for erectile dysfunction, they are not entirely without risk. The main concern with both medications is that they can cause kidney damage in rare cases, particularly when prescribed by inexperienced practitioners or in excess. Patients should also avoid taking either drug with nitrates, which are found in some recreational drugs (e.g., amyl nitrates, butyl nitrates, and nitroglycerin), as this can cause severe, and sometimes fatal, reactions (e.g., due to hypotension and bradycardia).

According to the UK’s Medicines and Healthcare Products Regulatory Agency, men with diabetes, liver disease, or hypertension are at increased risk of developing side effects from PDE5 inhibitors, such as sildenafil and tadalafil. Similarly, patients with severe kidney disease are at risk of developing kidney damage from these medications.

If you’re interested in trying either Viagra or Cialis for erectile dysfunction, make sure you consult with your personal physician. They will be able to advise you of the risks and benefits of each particular medication. Hopefully, this article will help you make the right choice for your situation.

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