Sodium Picosulphate vs. Placebo in Functional Constipation

Inclusion Criteria: 1. Male and female patients, aged 18 and above 2. Suffering from functional constipation, according to their medical history, as defined by the Rome III diagnostic criteria Criteria fulfilled for the last 3 months with symptom onset at least 6 months prior to diagnosis. 1. Must include 2 or more of the following: * straining during at least 25% of the defecations * lumpy or hard stools in at least 25% of the defecations * sensation of incomplete evacuation for at least 25% of the defecations * sensation of anorectal obstruction/blockade for at least 25% of the defecations * manual manoeuvres to facilitate at least 25% of the defecations (e.g. digital evacuation, support of the pelvic floor) * fewer than 3 defecations per week 2. Loose stools are rarely present without the use of laxatives 3. There are insufficient criteria for irritable bowel syndrome (IBS) (i.e. recurrent abdominal pain or discomfort is not the predominant symptom associated with defecation or a change in bowel habit, and with features of disordered defecation) 3. Able and willing to complete a daily e-diary 4. Able and willing to use the trial rescue medication (i.e. 10 mg bisacodyl suppositories) 5. Signed and dated written informed consent prior to enrolment into the study in accordance with GCP and local legislation Exclusion Criteria: 1. Eating disorders such as anorexia nervosa and bulimia, as a cause of excessive use of laxatives 2. Patients whose constipation is caused by primary organic disease of the colon or pelvic floor 3. Patients with metabolic disorders, neurological disorders, severe or psychiatric disorders, or any other significant disease or intercurrent illness (e.g. abdominal/gastrointestinal surgery) that, in the Investigators opinion, would interfere with participation in the trial 4. Patients with restricted mobility (e.g. wheelchair bound, or bed-ridden) that, in the Investigators opinion, would interfere with participation in the trial 5. Patients with a known hypersensitivity to sodium picosulphate, bisacodyl or any other ingredient in the study medication (sodium picosulphate and matching placebo drops, bisacodyl suppositories) 6. Patients with ileus, intestinal obstruction, acute surgical abdominal conditions (such as acute appendicitis and acute inflammatory bowel diseases), or severe dehydration 7. Patients with anal fissures or ulcerative proctitis with mucosal damage 8. Patients with known clinically significant abnormal electrolyte values 9. Patients whose concomitant therapy includes an opioid medication (e.g. morphine, codeine) 10. Constipation which, in the Investigators opinion, is caused by medication (e.g. anticholinergics) 11. Patients who are not willing to discontinue the use of prohibited concomitant therapy (see Section 4.2.2) 12. Pre-menopausal women (last menstruation £ 1 year prior to signing informed consent) who:are nursing (breast-feeding) or who are pregnant OR who are of child-bearing potential and are not practicing an acceptable method of birth control, or do not plan to continue using this method throughout the study. 13. Participating in another trial with an investigational product with 1 month of enrolment into this study 14. Drug or alcohol abuse 15. Concomitant use of antibiotics