Viagra vs Levitra
Viagra and Levitra are drugs to combat erectile dysfunction. Both belong to the class of PDE-5 inhibitors and are approved by FDA. Viagra is more popular among the lot. The underlying mechanism of these drugs is the same. They help to increase the blood flow and cause erection.
Viagra
The chemical compound in Viagra is sildenafil citrate. The drug takes about half an hour to start its course of action and the effects last for approximately four hours. The dosage required to get the biological action is higher. It is the first approved drug among the PDE-5 inhibitors.
PDE-5 inhibitors inhibit the action of phosphodiesterase type 5 which causes degradation of cyclic GMP in smooth muscle cells. The enzyme is present in the smooth muscle cells of the penis as well as the arterial lining of the lungs. Hence the drug is known to be effective in treating pulmonary hypertension also.
Levitra
Levitra is the brand name of vardenafil hydrochloride. The drug is primarily used to treat erectile dysfunction and the effects are reported to be lasting long. The duration for the onset of biological action is also low. The drug is effective at smaller doses of 10-20 mg. Contraindications and side effects are known to be reported.
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Difference between Viagra and Levitra 1. Drug class – both belong to the same class of drugs PDE-5 inhibitors. 2. Mechanism of action – they are found to block the degradative action of Phosphodiesterase type 5 on cyclic GMP found in smooth muscle cells of the penis as well as arterial walls of lungs. A high cGMP level allows relax of smooth muscle cells and better flow of blood. The blood flow increases substantially causing the erection. 3. Time for onset of biological action– Both take similar time periods for starting the course of biological action. However, the effects are more pronounced if Viagra is taken atleast 1 hour before sex. Levitra on the other hand should be taken before half an hour. 4. Duration of efficacy – Viagra effects are known to last approximately for four hours whereas L:evitra gives a higher duration lasting up to 6 hours. 5. Approval by FDA- Both drugs are approved by FDA and are prescription drugs. Viagra is sold without prescription also in some countries. 6. Side effects – Most of the side effects are common for both the drugs and include headache, abnormal or blurred vision, diarrhea, difficult urination etc. Levitra is found to have comparatively less side effects attributed mainly to the low dosage. 7. Contraindications – The drugs are not advisable on patients on nitrate medications and certain cardiovascular diseases. |