Study to Investigate Safety and Response to 1 or 2 g Rectal Suppositories Containing 5 or 10 mg NRL001.

Inclusion criteria

• No previous history of ano-rectal conditions or diseases
• No history of cardiovascular disease
• 18 to 60 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, or use of any medication currently or within the last 30 days which the Investigator believes may affect the study participation or results
• Use of monoamine oxidase inhibitors presently or within the last 2 weeks before study participation
• Use of any medication in the last 30 days applied to the anus and/or via the rectum
• Application of any unlicensed medication within the previous 3 months or participation in any other research study in the last three months which involved being paid a disturbance allowance; having an invasive procedure (e.g. venepuncture >50ml, endoscopy) or exposure to ionising radiation.
• 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 160 mmHg or diastolic blood pressure greater than 90 mmHg; 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 or lactating females
• History of any clinically relevant allergy
• 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 comply with the requirements of the trial
• Volunteers who have been exposed to more than 5 mSv of ionising radiation in the last 12 months.