01What does alcohol do with a 4-hour VIAGRA swallow?
Sildenafil and alcohol are both vasodilators. A large alcohol load can add dizziness and a drop in blood pressure to the same swallow. The US label still places the usual 50 mg tablet from 30 minutes to 4 hours before activity, once per day.
02Can a second VIAGRA tablet go down the same day?
The maximum recommended dosing frequency is once per day. The 16-man program used a single 100 mg dose before the 4-hour stimulation clock.
03How long after VIAGRA before a nitrate can be considered?
VIAGRA is contraindicated with organic nitrates. The interval from the last dose to a nitrate, when a nitrate later looks medically necessary, has not been determined on that label. Plasma levels at 24 hours after 100 mg were about 2 ng/mL versus a peak near 440 ng/mL.
04What does a high-fat meal do to that swallow?
A high-fat meal delayed the time to peak plasma concentration by 60 minutes and reduced Cmax by 29 percent in the US VIAGRA prescribing information. When taken on an empty stomach, peak plasma concentrations are reached within 30 to 120 minutes, median 60 minutes.
05Does VIAGRA work without stimulation?
Sexual stimulation is required for VIAGRA to work. The 4-hour program started 60 minutes of visual sexual stimulation at the 4-hour mark and counted men who had a grade 3 or 4 erection, or rigidity over 60 percent, as responders.
06What else sits on the sildenafil clock besides a 4-hour half-life?
Mean steady-state volume of distribution is 105 L. Plasma clearance is 41 L/h. After a 100 mg fasted dose, peak plasma levels sat near 440 ng/mL. At 24 hours those levels were about 2 ng/mL. About 96 percent of sildenafil in plasma is bound to proteins. Sildenafil is cleared predominantly by hepatic CYP3A4, with CYP2C9 as a minor route.
07When does the US label say to swallow VIAGRA?
The recommended dose is 50 mg taken, as needed, approximately 1 hour before sexual activity. VIAGRA may be taken anywhere from 30 minutes to 4 hours before sexual activity. Based on effectiveness and toleration, the dose may be increased to a maximum recommended dose of 100 mg or decreased to 25 mg.
08Who starts at 25 mg?
A 25 mg start is considered for people 65 and older, for hepatic impairment, for severe renal impairment, and when a potent CYP3A4 inhibitor is already on the chart. With ritonavir, the labelled sildenafil dose is 25 mg, and a repeat dose is not recommended within 48 hours.
09What if an erection lasts more than 4 hours after VIAGRA?
An erection lasting longer than 4 hours needs emergency care. Priapism, if not treated promptly, can damage erectile tissue. VIAGRA is used with caution in sickle cell anemia, multiple myeloma, leukemia, and anatomical deformation of the penis.
10What about sudden vision or hearing changes?
Non-arteritic anterior ischemic optic neuropathy has been reported rarely in postmarketing use of PDE5 inhibitors, including sildenafil. Sudden decrease or loss of hearing, sometimes with tinnitus and dizziness, has also been reported. Either of those changes needs the tablet stopped and urgent care.
11Which effects showed up most in the VIAGRA trials?
The most common adverse reactions in flexible-dose trials included headache, flushing, dyspepsia, nasal congestion, abnormal vision, diarrhea, dizziness, and rash. Headache was the most frequent. Those events were generally transient and mild to moderate.
12What about a blue-green color tinge after VIAGRA?
Sildenafil is a weak inhibitor of PDE6, which sits in the retina. Some men reported a change in color discrimination, often a blue-green tinge, or light sensitivity. Those visual changes were usually transient and mild. A sudden loss of vision in one or both eyes is a different event and needs the tablet stopped and urgent care.
13What if an alpha-blocker is already on the chart with VIAGRA?
Alpha-blockers and VIAGRA are both vasodilators. The person should be stable on the alpha-blocker before VIAGRA is added, and VIAGRA starts at 25 mg. Symptomatic hypotension can still occur.
14What is the terminal half-life?
The terminal half-life of sildenafil is about 4 hours on the US VIAGRA label. The 16-man program still found 13 of 16 responders when stimulation began 4 hours after 100 mg.
15Which CYP3A4 inhibitors drop VIAGRA to 25 mg?
Ritonavir, ketoconazole, itraconazole, erythromycin, and cimetidine raise sildenafil levels. Grapefruit juice can do the same. The labelled start in that setting is 25 mg. With ritonavir, a repeat dose is not recommended within 48 hours.