This Study Will Investigate the Effect of Single Oral Doses of Retosiban on Cardiac Repolarization, With Moxifloxacin as a Positive Control in Healthy Volunteers.

Inclusion Criteria:

- - Male or female between 18 and 45 years of age inclusive, at the time of signing the
informed consent

- A female subject is eligible to participate if she is of: child-bearing potential and
agrees to use the contraception methods from time of consent until until 48 hours
post last dose; Non-childbearing potential defined as pre-menopausal females with a
documented tubal ligation or hysterectomy; or postmenopausal defined as 12 months of
spontaneous amenorrhea. Females on hormone replacement therapy (HRT) and whose
menopausal status is in doubt will be required to use the contraception methods if
they wish to continue their HRT during the study. Otherwise, they must discontinue
HRT to allow confirmation of post-menopausal status prior to study enrollment. For
most forms of HRT, at least 2 to 4 weeks should elapse between the cessation of
therapy and the blood draw; this interval depends on the type and dosage of HRT.
Following confirmation of their post-menopausal status, they can resume use of HRT
during the study without use of a contraceptive method.

- Healthy as determined by a responsible and experienced physician, based on a medical
evaluation including medical history, physical examination, laboratory tests and
cardiac monitoring. A subject with a clinical abnormality or laboratory parameters
outside the reference range for the population being studied may be included only if
the Investigator and the GlaxoSmithKline (GSK) Medical Monitor agree that the finding
is unlikely to introduce additional risk factors and will not interfere with the
study procedures.

- Body weight (greater than or equal to) >=50 kg and body mass index (BMI) within the
range 19 to 29.9 kg/m^2

- Capable of giving written informed consent, which includes compliance with the
requirements and restrictions listed in the consent form

- No significant abnormality on 12-lead ECG at screening, including the following
specific requirements: ventricular rate >=40 beats per minute, PR interval less than
or equal to (<=) 210 miliseconds (msec), Q waves less than (<)30 msec, QRS interval
to be >=60 msec and <120 msec; the waveforms must enable the QT interval to be
clearly defined; QTcB or QTcF interval must be <450 msec

- ALT, alkaline phosphatase and bilirubin <=1.5xULN (isolated bilirubin greater than
(>) 1.5x upper limit of normal (ULN) is acceptable if bilirubin is fractionated and
direct bilirubin <35%)

Exclusion Criteria:

- A positive pre-study Hepatitis B surface antigen or positive Hepatitis C antibody
result within 3 months of screening.

- A supine blood pressure that is persistently higher than 140/90 millimeters of
mercury (mmHg).

- A supine mean heart rate outside the range 40 to 90 beats per minute (bpm).

- Current or chronic history of liver disease, or known hepatic or biliary
abnormalities (with the exception of Gilbert's syndrome or asymptomatic gallstones).

- A positive pre-study drug/alcohol screen.

- A positive test for Human Immunodeficiency Virus (HIV) antibody.

- History of regular alcohol consumption within 6 months of the study defined as: an
average weekly intake of >14 drinks for males or >7 drinks for females. One drink is
equivalent to 12 g of alcohol: 12 ounces (360 ml [milliliters]) of beer, 5 ounces
(150 ml) of wine or 1.5 ounces (45 ml) of 80 proof distilled spirits.

- The subject has participated in a clinical trial and has received an investigational
product within the following time period prior to the first dosing day in the current
study: 30 days, 5 half-lives or twice the duration of the biological effect of the
investigational product (whichever is longer).

- Exposure to more than four new chemical entities within 12 months prior to the first
dosing day.

- History of sensitivity to any of the study medications, or components thereof or a
history of drug or other allergy that, in the opinion of the investigator or GSK
Medical Monitor, contraindicates their participation.

- Where participation in the study would result in donation of blood or blood products
in excess of 500 ml within a 56 day period.

- Pregnant females as determined by positive serum human chorionic gonadotropin (hCG)
test at screening or prior to dosing. Lactating females.

- Unwillingness or inability to follow the procedures outlined in the protocol.

- Urinary cotinine levels indicative of smoking or history or regular use of tobacco-
or nicotine-containing products within 6 months prior to screening.

- Unable to refrain from consumption of red wine, seville oranges, grapefruit or
grapefruit juice and/or pummelos, exotic citrus fruits, grapefruit hybrids or fruit
juices from 7 days prior to the first dose of study medication.

- History or presence of any medically significant disease, or any disorder that would
introduce additional risk or interfere with the study procedures or outcome. In
particular, a family history of QT prolongation, of early or sudden cardiac death or
of early cardiovascular disease.

- Use of prescription or non-prescription drugs, including vitamins, herbal and dietary
supplements from 14 days before screening until the follow-up visit unless in the
opinion of the Investigator and sponsor the medication will not interfere with the
study or compromise subject safety.

- Serum calcium, magnesium or potassium levels outside the reference range

- History of sensitivity to quinolone antibiotics or components thereof or a history of
drug or other allergy that, in the opinion of the investigator or GSK Medical
Monitor, contraindicates their participation.