Dosing
| Patient Type | Viagra | Cialis | Levitra |
|---|---|---|---|
| Unrestricted | Patients are usually advised to start with 50mg dose an hour before sexual activity. Range: 25-100 mg doses | 10mg starting dose is recommended and dose is optimized based on patient response. Can be given the full range 2.5mg-20mg | Patients are usually advised to start with 10mg dose before sexual activity. Can be recommended full range: 5-20mg mg. |
| Patients over 65 | Recommended starting dose of 25mg and upped if necessary. | No dose adjustment necessary. Same as 'unrestricted' | Recommended starting dose of 5mg. |
| Patients with liver problems | Recommended starting dose of 25mg and upped if necessary. | Mild to moderate impairment: Usually best not to exceed 5mg. Severe liver problems: Not Recommended | Recommended starting dose of 5mg. |
| Patient with kidney problems | Recommended starting dose of 25mg and upped if necessary. | Dosage not to exceed 10mg | No dose adjustment necessary. |
Drug Interaction
Viagra, Cialis and Levitra are all metabolized by CYP3A4 and this means that medicines that control or affect this particular isozyme can potentially inhibit the clearance of all 3 PDE5 inhibitors in question.
So what medicines contain CYP3A4 inhibitors? Medicines used to treat HIV infection such as ritonavir and amprenavir, anti-fungal medicines like ketoconazole and itraconazole and even antibiotics like erythromycin contain CYP3A4 inhibitors. Continue reading
Radiotherapy is commonly prescribed treatment to prostate cancer patients. Recent studies have observed a 38% post radiotherapy erectile dysfunction (ED) rate after a span of 3 years. Lets look at some clinical trial results that discussed the efficacy of Cialis in such patients 
In the United Kingdom’s official supply chain, some mock versions of Cialis(Tadalafil) have been known to come up from time to time. Counterfeits are a real problem and the problem has been growing ever since mock versions of ranitidine (Zantac) were discovered in 1994.
In the age of E commerce, when everything from house hold commodities to travel to gadgets everything is available online in hoards it’s only obvious that a need based commodity like Viagra where most men prefer anonymity will have high demand online.
National Health Service from Great Britain has evoked some attention and criticism with a declaration that might come like the below the belt joke of the year at the year end. A similar directive was overruled by the high court in the year 1999. Mangers at NHS are instructing the General Practitioners and Doctors to restrict the limit of sildenafil based drugs such as Viagra, Vardenafil (Levitra) and Tadalafil (Cialis) to two per fortnight in lieu of saving on the shortage of funds.
Skin cancer is the most identifiable form of cancer as the malignancies start to show on the upper most layer of the skin- epidermis. It is also the most prevalent form of cancer and globally over 2 million cases are diagnosed each year.
Viagra works by inhibiting the PDE enzymes that lead to degradation of cyclic guanosine monophosphate, which relax the vascular muscles leading to an increased blood flow to the penis causing good strong erections in men and for these activating purposes, it is very commonly known as the “miracle pill”. There are however certain cases of Erectile Dysfunctions where in Viagra fails to work. We will in this article try to identify the reasons for such failure. 
Depression is one of the causes of erectile dysfunction in men and unfortunately the anti-depressant medications used to treat the condition can themselves trigger erection and libido problems. This research investigates Viagra’s efficacy when it comes to psychiatric patients. 