Dapoxetine is a active constituent present in Prejac. It is a selective serotonin reupyake inhibitor which produces a fast action. It is generally administered to the patients who are between 18-64 years of age. It is a recently developed formulation for treating premature ejaculation. A single tablet of 60mg has to taken once a day. The action of this medicine is witnessed wihinh 1-3 hours and it continues for a period of 1-2 hours.