The purpose of this study is to determine if the administration of GSK958108 can delay ejaculation in patients with primary premature ejaculation as measured by the ejaculatory latency time (ELT) using the masturbation model and sexual visual stimulation, and to evaluate the safety and tolerability of GSK958108 in healthy men with PE

Inclusion Criteria:

• Heterosexual male subject with self-reported moderate or severe primary Premature ejaculation with ejaculation occurring on or before penetration, or shortly there after with minimal stimulation
• Baseline Ejaculation Latency time < 3 minutes
• Subjects must agree to use a contraception methods as per protocol
• Body weight > or = 50 kg and Body Mass Index within the range 19.0-29.9 Kg/m2
• Subject with normal visual acuity (with appropriate correction if needed)
• Subject able to cooperate in all study procedure including the eye examination with use of mydriatics

Exclusion Criteria:

• Erectile dysfunction
• History of migraine
• Current clinically relevant abnormality
• History of psychiatric illness or suicidal attempts or behaviours
• History of any eye disorder or colour blind, excluding myopia and presbyopia
• Cardiac conduction disorder or other clinically significant cardiac disease
• Positive at pre-study drug/alcohol screen and to Hepatitis or HIV tests
• Regular consumption of alcohol
• History of sensitivity or intolerance to drugs
• Consumption of red wine, seville oranges, grapefruit or grapefruit juice [and/or pummelos, exotic citrus fruits, grapefruit hybrids] from 7 days prior to the first dose of study medication
• Subject has received or is continuing to receive any treatment for premature ejaculation in the four weeks prior to the study start
• Use of prescription or non-prescription drugs, including vitamins, herbal and dietary supplements prior to the first dose of study medication
• Participation in another clinical trial in the previous month
• Exposure to more than four new experimental drugs within the previous 12 months
• Where participation in the study would result in donation of blood or blood products in excess of 500 mL within a 56 day period.
• Unwillingness or inability to follow the procedures outlined in the protocol.

Patient-level data for this study will be made available through www.clinicalstudydatarequest.com following the timelines and process described on this site.