If the patient is diagnosed with liver disease, then the daily dose is reduced by half. viawom.com/how-to-take-lady-era-correctly.html. In diseases of the kidneys, the dosage depends on the level of the glomerular filtration rate:• 30-80 milliliters per minute – the dosage of Sildenafil is 50 milligrams per day;• Less than 30 milliliters per minute – the dosage of sildenafil is 25 milligrams per day.