Viagra (sildenafil) and Levitra (vardenafil) are prescription medications used to treat erectile dysfunction and pulmonary arterial hypertension. Viagra was introduced by Pfizer Pharmaceuticals in March 1998 as a treatment for pulmonary arterial hypertension. The clinical trials revealed that the active ingredient — generically known as sildenafil citrate — also relaxed the muscle tissues in the penis, allowing for increased blood flow. Levitra, introduced in 2003 by Bayer Pharmaceuticals and marketed by GlaxoSmithKline to treat erectile dysfunction, works similarly.
In appearance, Viagra tablets are blue, rounded diamonds that are available in 25 mg, 50 mg, and 100 mg doses. Levitra has orange-colored tablets in 2.5 mg, 5 mg, 10 mg, and 20 mg doses. It is recommended that both medications be taken 30 to 60 minutes before sexual activity is intended.
|Price||Tablets (Levitra). 5 mg (10): $101.55. 10 mg (10): $98.98. 20 mg (10): $103.94||25 mg (10 tablets): $288-$383. 50 mg (10): $288-$360. 100 mg (10): $283-$360. Prices vary by region, store, and available discounts.|
|Selling Point||May work faster, and for men for whom Viagra failed.||Good track record. Has been around five years longer than Cialis and seven years longer than Levitra.|
|How does it work?||Inhibits an enzyme called phosphodiesterase type 5 (PDE-5), making muscle in the penis more likely to relax and allowing blood to flow in, causing an erection.||Inhibits an enzyme called phosphodiesterase type 5 (PDE5). This relaxes muscles and increases blood flow, allowing those suffering from erectile dysfunction to experience an erection during sexual stimulation.|
|How fast does it work?||Levitra label says to take it 60 minutes before sexual activity, but studies show it can work faster. May be more likely to work the first time.||Varies by person, but users are recommended to take the pill at least 30 minutes to an hour prior to sex.|
|How does it look?||Flame-orange coloured, rounded tablets||Viagra pills are blue-colored, film-coated, and in the shape of elongated diamonds with rounded corners. "Pfizer" is engraved on one side of the pill and "VGR" and a dosage amount are printed on the other side (e.g., VGR50 for 50 mg).|
|Dosage||Comes in 2.5, 5, 10 and 20 mg tablets||Comes in 25, 50, and 100 mg tablets.|
|Consumption instructions||Can be taken with or without food; For most it is 10mg per day 60 min before intercourse.||Can be taken with or without food. Users are advised to avoid eating grapefruit and drinking grapefruit juice, as they might alter how the drugs work. Taking the pills with greasy or fatty foods can also alter absorption.|
|Storage instructions||Should be stored at room temperature between 15-30°C (59-86°F).||Should be stored at a reasonable room temperature and away from moisture. Recommended room temperature range is between 15 and 30C (59-86F).|
|Generic Names||Vardenafil hydrochloride||Sildenafil citrate, which is not approved for sale as a generic yet.|
|Function||To treat erectile dysfunction||To treat erectile dysfunction, pulmonary heart disease.|
|Half Life||4-5 hours||4 hours.|
|Side effects||acial flushing (reddening), headaches, stomach upset, diarrhea, flu like symptoms and nausea. Vardenafil also may cause chest pain, low blood pressure, blurred vision and changes in color vision, abnormal ejaculation and priapism (painful erection).||Facial flushing, headaches, stomach pain, nasal congestion, nausea, diarrhea, and an inability to differentiate between the colors green and blue.|
|FDA Approval||On 20th August, 2003||March 27, 1998.|
|Brand owners||Manufactured by Bayer Corp. and distributed by GlaxoSmith Kline.||Viagra is the product of the drug manufacturing company Pfizer.|
|Named after||Levitate, or la vita which means 'life'||Vigor or Niagara|
|Excretion||Feces (91% to 95% as metabolites); urine (2% to 6%)||Over 80% of the drug is excreted through feces, and more than 13% is excreted through urine.|
|US Sales||$174 Million(2004)||$919 Million(2004)|
When to Take Levitra or Viagra
Levitra and Viagra are taken as needed, anywhere from 30 minutes to as much as 4 hours before initiating sexual activity. However, neither medication should be taken more than once a day, unless cleared by a doctor based on a person's medical profile. The need to "plan" sexual encounters can make Levitra and Viagra less convenient for some than erectile dysfunction drugs like Cialis, which can be taken in a low, daily dose and enable performance at any time, without any necessary planning.
The initial recommended dosage of Viagra for most patients is 50 mg about one hour before sexual activity. However, a person can take Viagra as little as 30 minutes or up to 4 hours before sexual activity. The initial 50 mg dose, taken no more than once daily, can be adjusted later depending on a person's responsiveness to the medication. Doses can be lowered to 25 mg or increased to as much as 100 mg daily.
Patients taking Levitra are usually started on a 10 mg dose, which they take no more than once daily, about one hour before sexual activity. It can take as little as 30 minutes for Levitra to work in some patients. Like with Viagra, Levitra dosages are adjusted depending on a person's reaction, with doctors generally decreasing doses to to 2.5 mg or increasing them to no more than 20 mg once a day.
Both medications require sexual stimulation for effectiveness. Although Viagra and Levitra can be taken with or without food, those taking the medications shouldavoid grapefruit and grapefruit juice, as both can diminish drug effectiveness. Similarly, greasy or fatty foods can delay absorption and effects.
How Levitra and Viagra Work
More than half the incidences of impotence (erectile dysfunction) are considered to arise from medical (physical) causes, such as diabetes and circulatory, neurological, or urological conditions. The rest are considered to be caused bypsychological problems. Levitra and Viagra treat the physical limitation that reduces blood flow to the penis. An erection occurs when blood flow into the penis increases while outflow decreases. With sexual stimulation, the body produces and releases nitric oxide in the penis. This activates an enzyme known as guanylate cyclase and causes the production of cyclic guanosine monophosphate (cGMP). The monophosphate cGMP directly affects erections by altering blood flow rates into and out of a penis.
Viagra and Levitra both inhibit the presence of phosphodiesterase-5 (PDE5), an enzyme that breaks down cGMP. This allows the cGMP to accumulate in larger quantities and have a longer-lasting effect, increasing the potential and persistence of an erection.
The following video features a physician explaining how PDE5 inhibitor drugs like Cialis, Viagra, and Levitra work and how they differ:
Vardenafil and sildenafil are effective in treating erectile dysfunction and pulmonary arterial hypertension. They are well-tolerated by patients, with few suffering from serious side effects. Additionally, Viagra (sildenafil) has recently been found to treat the symptoms of several other health conditions.
Levitra vs. Viagra Studies
- Levitra very slightly outperformed Viagra in one study of men with erectile dysfunction and risk factors for cardiovascular disease, with more men preferring Levitra over Viagra (39% to 35%). Neither drug caused significant side effects.
- A 2011 comparison of studies of Cialis, Levitra, and Viagra concluded that there was "insufficient data" to decide which drug was best at treating erectile dysfunction. The researchers suggested doctors have patients try all three drugs to decide which works best for them personally.
- A meta-analysis of eight randomized, double-blinded, placebo-controlled clinical trials found Levitra greatly improved erectile function in men who also suffered from hypertension.
- In a randomized, double-blinded study of Japanese men suffering from erectile dysfunction, 90% of patients on Levitra saw significant improvements in achieving an erection. Furthermore, patients experienced no serious side effects. Mild side effects, such as flushing and headaches, were reported, however, and were more common on higher doses of the drug.
- A combination of Levitra, the antidepressant Zoloft (sertraline), and behavioral psychosexual therapy were found to moderately improve the symptoms of men suffering from premature ejaculation.
- Levitra improved erectile function in men with renal transplants, a demographic that frequently suffers from erectile dysfunction. Side effects experienced from taking Levitra were relatively mild and did not alter the results of renal function tests.
- In a study of 979 men who were taking Viagra, over 94% of participants reported improved erectile function over the course of 4 years of using the drug. Side effects and discontinuation of the drug due to "insufficient response" were rare. Long-term use of Viagra was shown to be effective and safe.
- An overview of clinical studies of Viagra found the drug to be safe and effective, even in some "difficult-to-treat" populations, such as patients with diabetes mellitus. Furthermore, the drug appears to have "beneficial effects" on the symptoms of several other chronic conditions, including some forms of premature ejaculation.
- While Viagra has not been found to treat sexual dysfunction in women, at least one study has found the drug is effective in treating symptoms associated with interstitial cystitis (bladder pain syndrome) in women.
The common side effects of Viagra are usually mild and last a few hours, and may include facial flushing, an upset stomach, and headaches. Less common side effects are blurred vision, or perceiving a bluish tint in one's vision, and sensitivity to light. Levitra has shown additional common and usually mild side effects, including dizziness and nasal congestion.
Most side effects experienced from taking these drugs are temporary. Clinical studies have revealed that the frequency of these side effects decreases over time. However, a rare side effect, vision loss, has been reported with people who have used PDE5 inhibitors, including Viagra, Levitra, and Cialis. This loss of vision could be permanent and thus any vision-related side effects require an immediate visit to a doctor or medical facility. There is no evidence as yet that PDE5 inhibitors are the direct cause of vision loss.
The dependence or addiction liability of Viagra and Levitra is low. Many patients are able to have erections without these medications, though often not as easily or frequently.
Those wanting to take Viagra or Levitra should get a prescription for the medication, based on a complete medical history. A person should reveal if he has an allergy to sildenafil or vardenafil, or any other medication, and report any incident of allergic reactions, such as a rash, hives, itching, shortness of breath, wheezing, coughing, or swelling of face, lips, tongue and throat.
Cardiovascular conditions should also be mentioned to doctors, as well as any renal or hepatic condition. Past and current drug use or addiction should be shared as well.
Viagra and Levitra can interact with other medications, so other prescribed treatments need to be discussed. A person should not take Viagra or Levitra with alcohol (liquor, beer, or wine) or in conjunction with Isosorbide dinitrate, isosorbide mononitrate, nitroglycerin, or drugs called "poppers", like amyl nitrate and butyl nitrate. If a person has been told not to have sex by a healthcare provider, this recommendation needs to be discussed with a doctor before using Viagra or Levitra. As neither drug prevents sexually transmitted diseases, use of a condom for protection is advised.
Patients taking medication to lower blood pressure should use Viagra and Levitra under medical advice and with caution, Both medications enhance the effects of lowering blood pressure, so patients with hypertension and angina who are taking nitrates such as isosorbide dinitrate (Isordil), isosorbide mononitrate (Imdur, Ismo, Monoket), and nitroglycerin (Nitro-Dur, Transderm-Nitro), as well as alpha-blocking drugs such as terazosin (Hytrin), should avoid Viagra and Levitra, unless cleared by a doctor. A common side effect of Viagra and Levitra in these patients is chest pain and lowered blood pressure, conditions that require prompt medical attention.
Other medications, such as Cimetidine (Tagamet), erythromycin, ketoconazole (Nizoral), itraconazole (Sporanox), and mibefradil (Posicor), can cause significant increases in the amount of sildenafil and vardenafil in the body, leading to a sudden drop in blood pressure. Patients on these medications should be observed carefully when taking Viagra or Levitra. Similarly, Rifampin decreases the blood levels of sildenafil and can reduce its effectiveness.
Vardenafil excretion is inhibited by erythromycin, ketoconazole (Nizoral), itraconazole (Sporanox), indinavir (Crixivan) and ritonavir (Norvir), so these drugs increase the concentration of vardenafil in the blood. To avoid potential complications, the dose of vardenafil should be reduced. Vardenafil reduces the concentration of ritonavir and indinavir in the blood, and can reduce the effect of these drugs.
Viagra and Levitra should be stored at room temperature and away from rooms with excessive moisture (e.g., bathroom, kitchen). Neither drug should be exposed to direct sunlight.
Sildenafil citrate is a powder, white to off-white in color, soluble in water at 3.5 mg/ml. The molecular weight is 666.7 g/mol. Viagra tablets combine sildenafil citrate with inactive ingredients such as microcrystalline cellulose, anhydrous dibasic calcium phosphate, croscarmellose sodium, magnesium stearate, hypromellose, titanium dioxide, lactose, triacetin, and FD & C Blue #2 aluminum lake. Tablets are formed as rounded blue diamonds, coated in soluble film, in doses of 25 mg, 50 mg and 100 mg. Tablets are to be taken orally.
Vardenafil, the main ingredient in Levitra, is a pale solid with a solubility in water of 0.11 mg/ml. The molecular weight is 579.1 g/mol. A Levitra tablet blends vardenafil primarily with these inactive ingredients: crospovidone, microcrystalline cellulose, colloidal silicon dioxide, hypromellose, polyethylene glycol, magnesium stearate, yellow ferric oxide, titanium dioxide, and red ferric oxide. The end result is an orange tablet in 2.5 mg, 5 mg, 10 mg and 20 mg doses. Tablets are to be taken orally.