A Phase II Study to Evaluate: Delay in Intravaginal Ejaculatory Latency Time (IELT), Safety, Tolerability, Pharmacokinetics and Pharmacodynamics of Two Oral Doses of GSK557296 in a Randomized, Double Blind, Placebo-Controlled, Parallel Group Study in Men with Premature Ejaculation

There are no clear definitions of premature ejaculation. A premature
ejaculation can be a psychological, emotional or relational problem. A method
or means to delay ejaculation can be very useful.

Current research often uses the "intravaginal ejaculation latency time
'(IELTS). This is the time measured from the penetration of the vagina until
the beginning of ejaculation.

The cause of premature ejaculation is not yet fully known. In the past it was
often thought that premature ejaculation had a psychological cause or had been
taught. The last ten years there are increasing indications that premature
ejaculation can also be caused by a disturbance of serotonin receptors in the
brains. This is possibly congenital. Recent research shows that substances that
affect serotonin receptors (antidepressants or SSRIs) are beneficial in
extending the IELTS and thus delaying ejaculation. The disadvantage of these
drugs is that they must be taken every day and may therefore cause more side
effects.

To determine if an on demand dosing of 50 or 150 mg of GSK557296 demonstrates
superior efficacy with respect to duration of IELT during an 8 week study period
compared to placebo in men with premature ejaculation.

To assess safety and tolerability of 50 mg and 150 mg of GSK557296.
To assess change in the Index of Premature Ejaculation (IPE) from baseline and
at
the end of the 8 weeks of treatment
To characterize the pharmacokinetics of GSK557296 in men with premature
ejaculation.
To characterize the dose/exposure response relationship using PK/PD modeling, as
data permit.

Approximately 75 men will participate in this study. The research is conducted
in America, the Netherlands and possibly later in other countries. In the
Netherlands there will be approximately 30 healthy male subjects who
participate in the trial. The examination includes a medical examination and
three visits and one telephone follow-up. Between each visit is a period of 4
weeks. The total study lasts 12 weeks.

50 or 150 mg of GSK557296 or placebo during 8 weeks.

The risks associated with this investigation are linked together with the
possible side effects of the investigational product. The burden on the
volunteer will continue to work with the recording periods, venapunctions and
the introduction of the cannula. All volunteers are closely monitored and
supervised by experienced doctors and studystaff for possible side effects.
The following tests will be performed during this trial: physical examination,
measuring bloodpressure and hart rate, blood- and urine tests, drugscreen,
alcohol tests, ECGs, restrictions in living habits, standardized meals during
admission, use of a stopwatch during intercourse, use the electronic diary to
complete the subject diary questions and fill out questionnaires.

Al volunteers will be closely monitored by experienced physicians and staff.