Mild to moderate erectile dysfunction affects around 50% of men aged 40+ years, making it one of the most common disorders in older men worldwide. An erection is a carefully orchestrated physical response to sexual stimulation. Sensory nerve signals in the brain compel the smooth muscles in the penis to relax which increases blood flow to the male sex organ. As a consequence, the penis expands and becomes erect. Erections are started and stopped with the help of nitric oxide and phosphodiesterase-5 (PDE-5). Whilst nitric oxide promotes relaxation of the penis muscles, PDE-5 blocks an erection after intercourse.
In men with erectile dysfunction, these processes are disrupted, but luckily medications are available. PDE-5 inhibitors are effective in up to 63% of men. There are three main types of PDE-5 inhibitors – sildenafil (Viagra, Revatio), vardenafil (Levitra) and tadalafil (Cialis). All of these drugs act by inhibiting PDE-5, the enzyme responsible for shutting down an erection. When PDE-5 is blocked, the smooth muscles of the penis relax, and an erection can occur and is maintained.
Technically, sildenafil is the active ingredient in Viagra. In other words, there is no difference. But sildenafil is also a compound of a drug called Revatio which treats pulmonary hypertension.
Revatio can technically be prescribed for the treatment of erectile dysfunction, but it exists only as a 20 mg dose. Doctors may prescribe Revatio instead of Viagra, but it is at their discretion to do so. Patients could take multiple Revatio to reach a higher dose. For example, your doctor may order you to take four Revatio (for a total of 80 mg). This may give patients more flexibility if they suffer mild to moderate or occasional erectile dysfunction.
Viagra is available in three doses: 25 mg, 50 mg, and 100 mg and is a branded prescription drug. However, Pfizer’s patent of the drug expires in 2019, which means that cheaper generic versions of sildenafil will be available in 2020. Pfizer has already partnered with Teva Pharmaceuticals to produce a generic version of Viagra that costs half the retail price of the branded pill ($65-$70).
Erectile dysfunction prescription medications usually differ in the time it takes for them to work, the length of their action, their side effects and contraindications.
Although all three medications share a similar mode of action, that is, they inhibit PDE-5, they vary when it comes to effectiveness.
Viagra and Levitra are effective within one hour after ingestion, whilst Cialis takes a little longer (2-4 hours). But the action of Cialis lasts considerably longer at up to 18 hours compared to 3-5 hours for Viagra and Levitra.
Viagra and Levitra are best taken on an empty stomach because food may delay absorption. Cialis can be taken alongside food and is a better option for men who may not know when intercourse will occur. Cialis has also been approved for the treatment of an enlarged prostate. In which cases may Cialis be a better option?
For example, a man may take Cialis during dinner because it allows him to prepare for the possibility of sex at the end of a romantic evening. Cialis is available in a dose as low as 2.5 mg which can be increased to 20 mg. The recommended starting dose for Cialis is 2.5 mg per day. This is preferable for many men because the timing issue disappears.
Side effects can vary from pill to pill. Headaches, runny nose, upset stomach, flushing, and back pain are common for all three erectile dysfunction medications. Nausea and dizziness are more often experienced in men who take Viagra. Vision changes are also a concern for those on Viagra. But indigestion is a more commonly seen side effect for Levitra and Cialis.
It’s important to discuss side effects with a doctor before committing to a prescription drug. Patients may also wish to try a few different medications or vary their doses depending on their symptoms. Finding the perfect erectile dysfunction drug that works best for you can be a case of trial and error.
All three prescription drugs can interact with certain blood pressure medications and nitrates. Beta and alpha-blockers, anti-fungal and anti-bacterial drugs are also known to interact with erectile dysfunction medications. Read the package insert and discuss your medical conditions with a doctor.
The answer to that question will vary from patient to patient and is highly dependent on the severity of erectile dysfunction, the desired effect and whether a patient suffers from any other medical conditions.
One research study found that patients taking sildenafil (Viagra) or tadalafil (Cialis) were similarly satisfied with their resulting erections. But a meta-analysis of 16 separate drug trials noted that although both drugs improved erectile dysfunction symptoms in men, sexual confidence was higher in those taking Cialis. Both men and women preferred Cialis over sildenafil for the treatment of erectile dysfunction.
A comparison of the biochemical and physiological effects of Viagra and Levitra found Levitra to be preferable for efficacy and a better choice for men who cannot take Viagra or where Viagra does not produce the desired effect.
Ultimately, the choice between Viagra, Levitra and Cialis should be dependent on patient medical history and side effects.
Avanafil is a relatively new PDE-5 inhibitor. It was approved by the US Food and Drug Administration in 2012 and is available in a dose of 50 mg, 100 mg or 200 mg.
Avanafil has been shown to act more rapidly compared to sildenafil and vardenafil. Marketed under the name Stendra by Mitsubishi Tanabe, avanafil acts within 30 minutes after ingestion and lasts up to six hours. It is less affected by food. Some studies have shown successful intercourse after only 15 minutes of taking the drug, making it an excellent option for men seeking a quick-acting PDE-5 inhibitor.
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