Generic Viagra

Consistent with its known effects on the nitric oxide/cGMP pathway, VIAGRA was shown to potentiate the hypotensive effects of nitrates, and its administration to patients who are using organic nitrates, either regularly and/or intermittently, in any form is therefore contraindicated.

After patients have taken VIAGRA, it is unknown when nitrates, if necessary, can be safely administered. Based on the pharmacokinetic profile of a single 100 mg oral dose given to healthy normal volunteers, the plasma levels of sildenafil at 24 hours post dose are approximately 2 ng/mL (compared to peak plasma levels of approximately 440 ng/mL). In the following patients: age >65, hepatic impairment (e.g., cirrhosis), severe renal impairment (e.g., creatinine clearance <30 mL/min), and concomitant use of potent cytochrome P450 3A4 inhibitors (erythromycin), plasma levels of sildenafil at 24 hours post dose have been found to be 3 to 8 times higher than those seen in healthy volunteers. Although plasma levels of sildenafil at 24 hours post dose are much lower than at peak concentration, it is unknown whether nitrates can be safely coadministered at this time point.

VIAGRA is contraindicated in patients with a known hypersensitivity to any component of the tablet.

VIAGRA is not indicated for use in newborns, children, or women.
Pregnancy Category B

No evidence of teratogenicity, embryotoxicity or fetotoxicity was observed in rats and rabbits which received up to 200 mg/kg/day during organogenesis. These doses represent, respectively, about 20 and 40 times the MRHD on a mg/m2 basis in a 50 kg subject. In the rat pre- and postnatal development study, the no observed adverse effect dose was 30 mg/kg/day given for 36 days. In the nonpregnant rat the AUC at this dose was about 20 times human AUC. There are no adequate and well-controlled studies of sildenafil in pregnant women.
Geriatric Use

Healthy elderly volunteers (65 years or over) had a reduced clearance of sildenafil. Since higher plasma levels may increase both the efficacy and incidence of adverse events, a starting dose of 25 mg should be considered

I am a 39 year old male and in good health and fairly fit, but realized a while back that sometimes I had a hard time maintaining an erection. I am single, but I do date a lot and I believe many times the problem was due to anxiety and pressure to perform with someone new. I bought three 100mg Viagra pills online and a $4.00 pill splitter. After doing extensive research, I decided to split the pills and take only 25mg last night. WOW-WOW-WOW…it kicked in after about 20-30 minutes and that was just perfect, as I knew where the evening was going. I had alcohol and dinner before I took it. She is a beautiful woman with a great body and I did not think I needed it with her, but let me just say…after the 5th time…I am not kidding, she said: Please no more…lol…..unbelievable. I felt like a stud and since I took an Advil with the pill to prevent headaches afterwards, I had absolutely no side affects. - Age 39, USA

VIAGRA is rapidly absorbed after oral administration, with absolute bioavailability of about 40%. Its pharmacokinetics are dose-proportional over the recommended dose range. It is eliminated predominantly by hepatic metabolism (mainly cytochrome P450 3A4) and is converted to an active metabolite with properties similar to the parent, sildenafil. The concomitant use of potent cytochrome P450 3A4 inhibitors (e.g., erythromycin, ketoconazole, itraconazole) as well as the nonspecific CYP inhibitor, cimetidine, is associated with increased plasma levels of sildenafil. Both sildenafil and the metabolite have terminal half lives of about 4 hours.

Absorption and Distribution

VIAGRA is rapidly absorbed. Maximum observed plasma concentrations are reached within 30 to 120 minutes (median 60 minutes) of oral dosing in the fasted state. When VIAGRA is taken with a high

Based upon measurements of sildenafil in semen of healthy volunteers 90 minutes after dosing, less than 0.001% of the administered dose may appear in the semen of patients.
Metabolism and Excretion

Sildenafil is cleared predominantly by the CYP3A4 (major route) and CYP2C9 (minor route) hepatic microsomal isoenzymes. The major circulating metabolite results from N-desmethylation of sildenafil, and is itself further metabolized. This metabolite has a PDE selectivity profile similar to sildenafil and an in vitro potency for PDE5 approximately 50% of the parent drug. Plasma concentrations of this metabolite are approximately 40% of those seen for sildenafil, so that the metabolite accounts for about 20% of sildenafil’s pharmacologic effects.

After either oral or intravenous administration, sildenafil is excreted as metabolites predominantly in the feces (approximately 80% of administered oral dose) and to a lesser extent in the urine (approximately 13% of the administered oral dose). Similar values for pharmacokinetic parameters were seen in normal volunteers and in the patient population, using a population pharmacokinetic approach.

If you notice any changes in your vision while taking this drug, notify your prescriber or health care professional as soon as possible. Stop using sildenafil right away if you have a loss of sight in one or both eyes. Contact your healthcare provider immediately.

Contact you physician immediately if the erection lasts longer than 4 hours or if it becomes painful. This may be a sign of priapism and must be treated immediately to prevent permanent damage.

If you experience symptoms of nausea, dizziness, chest pain or arm pain upon initiation of sexual activity after sildenafil use, you should refrain from further activity and should discuss the episode with your prescriber or health care professional as soon as possible.
Do not change the dose of your medication. Please call your prescriber or health care professional to determine if your dose needs to be reevaluated.

Using Viagra® (sildenafil) does not protect you or your partner against HIV infection (the virus that causes AIDS) or other sexually transmitted diseases.