Effect of Single Doses of 10 mg NRL001 Applied as a Suppository to the Anal Canal or Rectum

Inclusion Criteria: * No previous history of ano-rectal conditions/ diseases * No history of cardiovascular disease * 18 to 75 years of age * Males and females (pre-menopausal females of child-bearing potential must be using adequate contraceptive methods and have a negative pregnancy test before the start of the study) Exclusion Criteria: * Use of medication in the last 30 days with a vasodilatory activity * Use of monoamine oxidase inhibitors (MAOI) presently or within the last two weeks before study participation * Use of any medication in the last 30 days applied to the anus and/or via the rectum (exception: participation in NRL001-01/2006 (SUPP) for previous dosing into the anal canal) * Application of any unlicensed medication within the previous 3 months (exception: participation in NRL001-01/2006 (SUPP)) * Regular intake of more than 21 units of alcohol per week * History or any evidence of cardiovascular disease including ischaemic heart disease and hypertension (defined on examination: systolic blood pressure greater than 160mmHg or diastolic blood pressure greater than 90mmHg; based on at least two separate readings), peripheral vascular disease or Raynaud's syndrome * Presence of diabetes mellitus * History or symptoms of thyroid diseases, including hypo- or hyperthyroidism * Pregnant females * Breast feeding mothers * Presence of concomitant gastrointestinal diseases or disorders, such as significant abdominal symptoms and haemorrhoids but also any significant organ (e.g. renal, hepatic or cardiac) dysfunction * Volunteers whom the investigator feels would not be compliant with the requirements of the trial