| E.1 Medical condition or disease under investigation | 
| E.1.1 | Medical condition(s) being investigated  | 
| Crohn's disease & Colitis Ulcerosa | 
 
| ziekte van Crohn & Colitis Ulcerosa | 
 
 
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| E.1.1.1 | Medical condition in easily understood language  | 
| inflammatory bowel diseases | 
 
| inflammatoire darmziekten, ontstoken darmziekte | 
 
 
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| E.1.1.2 | Therapeutic area  | Diseases [C] - Digestive System Diseases [C06] | 
| MedDRA Classification | 
| E.1.3 | Condition being studied is a rare disease  |  No  | 
| E.2 Objective of the trial | 
| E.2.1 | Main objective of the trial  | 
| Investigating whether 50 mg allopurinol is non-inferior to 100 mg in combination with azathioprine or mercaptopurine by measuring  and comparing thiopurine metabolites  | 
 
| •	Non-inferioriteit van 50 mg allopurinol ten opzichte van 100 mg op basis van 6-TGN en 6-MMP concentraties, te bepalen vóór en na de interventie  | 
 
 
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| E.2.2 | Secondary objectives of the trial  | 
-Comparing patient tolerability in terms of adverse events -comparing allopurinol concentrations -comparing enzyme activity for XO, TPMT and HRPT -comparing disease activity scores (CDAI and MAYO)  | 
 
•	Aantonen van eventuele verschillen in verdraagbaarheid o.b.v. bijwerkingenprofiel voor en na de interventie •	Bepalen en vergelijken van allopurinol spiegels voor en na de interventie •	Het bepalen en vergelijken van de enzymactiviteit van XO, TPMT en HPRT voor en na de interventie •	Aantonen mogelijk verschil in ziekteactiviteit o.b.v. CDAI-scores bij Crohn patiënten en Mayo scores bij Colitis Ulcerosa patiënten 
 | 
 
 
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| E.2.3 | Trial contains a sub-study  |  No  | 
| E.3 | Principal inclusion criteria  | 
-Crohn's disease or Colitis Ulcerosa -At least one month perior usage of 100 mg allopurinol daily with azathioprine or mercaptopurine -at least 18 years old | 
 
•	Ziekte van Crohn of Colitis Ulcerosa  •	Ten minste één maand gebruiker van combinatie azathioprine of mercaptopurine met 100 mg allopurinol per dag •	Leeftijd >18 jaar 
 | 
 
 
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| E.4 | Principal exclusion criteria | 
| -Age below 18 years old | 
 
| -Leeftijd <18 jaar | 
 
 
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| E.5 End points | 
| E.5.1 | Primary end point(s) | 
| 6-TGN and 6-MMP concentrations | 
 
| 6-TGN en 6-MMP concentraties | 
 
 
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| E.5.1.1 | Timepoint(s) of evaluation of this end point | 
| Right before and one month after the intervention | 
 
| Vlak vóór en één maand na de interventie | 
 
 
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| E.5.2 | Secondary end point(s) | 
-Frequency and incidence adverse events -Allopurinol concentrations -Enzyme activity XO, TPMT and HPRT -Disease activity scores (CDAI for Crohn's and Mayo for Colitis Ulcerosa) | 
 
-Frequentie en incidentie bijwerkingen -Allopurinol concentraties -Enzymactiviteit XO, TPMT en HPRT -Ziekteactiviteitsscores (CDAI en Mayo bij respectievelijk Crohn's en Colitis Ulcerosa patiënten) | 
 
 
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| E.5.2.1 | Timepoint(s) of evaluation of this end point | 
| Right before and one month after the intervention | 
 
| Vlak vóór en één maand na de interventie | 
 
 
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| E.6 and E.7 Scope of the trial | 
| E.6 | Scope of the trial | 
| E.6.1 | Diagnosis |  No  | 
| E.6.2 | Prophylaxis |  No  | 
| E.6.3 | Therapy |  Yes  | 
| E.6.4 | Safety |  Yes  | 
| E.6.5 | Efficacy |  Yes  | 
| E.6.6 | Pharmacokinetic |  Yes  | 
| E.6.7 | Pharmacodynamic |  No  | 
| E.6.8 | Bioequivalence |  Yes  | 
| E.6.9 | Dose response |  Yes  | 
| E.6.10 | Pharmacogenetic |  No  | 
| E.6.11 | Pharmacogenomic |  No  | 
| E.6.12 | Pharmacoeconomic |  No  | 
| E.6.13 | Others |  No  | 
| E.7 | Trial type and phase | 
| E.7.1 | Human pharmacology (Phase I) |  No  | 
| E.7.1.1 | First administration to humans |  No  | 
| E.7.1.2 | Bioequivalence study |  No  | 
| E.7.1.3 | Other |  No  | 
| E.7.1.3.1 | Other trial type description |  | 
| E.7.2 | Therapeutic exploratory (Phase II) |  No  | 
| E.7.3 | Therapeutic confirmatory (Phase III) |  No  | 
| E.7.4 | Therapeutic use (Phase IV) |  Yes  | 
| E.8 Design of the trial | 
| E.8.1 | Controlled |  Yes  | 
| E.8.1.1 | Randomised |  No  | 
| E.8.1.2 | Open |  Yes  | 
| E.8.1.3 | Single blind |  No  | 
| E.8.1.4 | Double blind  |  No  | 
| E.8.1.5 | Parallel group |  No  | 
| E.8.1.6 | Cross over  |  Yes  | 
| E.8.1.7 | Other |  No  | 
| E.8.2 |  Comparator of controlled trial | 
| E.8.2.1 | Other medicinal product(s) |  Yes  | 
| E.8.2.2 | Placebo  |  No  | 
| E.8.2.3 | Other |  No  | 
| E.8.2.4 | Number of treatment arms in the trial | 1 | 
| E.8.3 | 
                                The trial involves single site in the Member State concerned
                             |  Yes  | 
| E.8.4 |  The trial involves multiple sites in the Member State concerned  |  No  | 
| E.8.5 | The trial involves multiple Member States |  No  | 
| E.8.6 Trial involving sites outside the EEA | 
| E.8.6.1 | Trial being conducted both within and outside the EEA |  No  | 
| E.8.6.2 | Trial being conducted completely outside of the EEA |  No  | 
| E.8.7 | Trial has a data monitoring committee |  No  | 
| E.8.8 | 
                        Definition of the end of the trial and justification where it is not the last
                        visit of the last subject undergoing the trial
                     | 
| LVLS | 
 
| laatste bezoek laatste deelnemer | 
 
 
 | 
| E.8.9 Initial estimate of the duration of the trial | 
| E.8.9.1 | In the Member State concerned years | 1 | 
| E.8.9.1 | In the Member State concerned months |  | 
| E.8.9.1 | In the Member State concerned days |  |