Is thiopurine therapy in ulcerative colitis as effective as in Crohn's disease?

Population pharmacokinetics of azathioprine active metabolite in patients with inflammatory bowel disease and dosage regimens optimisation

Azathioprine is a first-line drug used to maintain the remission of inflammatory bowel disease (IBD). As a prodrug, azathioprine is metabolised to produce active 6-thioguanine nucleotides (6-TGN). There are large individual variations in the pharmacokinetics/pharmacodynamics of 6-TGN in patients with IBD. Here, we aimed to develop a model to quantitatively investigate factors that affect 6-TGN pharmacokinetics to formulate a dosage guideline for azathioprine. Data were collected prospectively from 100 adult patients with IBD who were receiving azathioprine. Patients were genotyped for two single-nucleotide polymorphisms (TPMT*3C c.719A > G and NUDT15 c.415C > T). Using high-performance liquid chromatography, we measured 156 steady-state trough concentrations of 6-TGN within the range 0.09 to 1.16 mg/L (ie 133-1733 pmol per 8 × 10⁸ RBC). The covariates analysed included sex, age, body-weight, laboratory tests and concomitant medications. A population pharmacokinetic model was established using "non-linear mixed-effects modelling" software and the "first-order conditional estimation method with interaction." Body-weight, TPMT*3C polymorphisms and co-therapy with mesalazine were found to be important factors influencing the clearance of 6-TGN. A dosage guideline for azathioprine was developed based on the PPK model that enables individualised azathioprine dosing in adult patients with different body-weights, TPMT*3C genotypes and co-administration with mesalazine.

Pharmacological- and non-pharmacological therapeutic approaches in inflammatory bowel disease in adults

Inflammatory bowel diseases (IBDs) are a group of chronic inflammatory conditions mainly of the colon and small intestine. Crohn's disease (CD) and ulcerative colitis (UC) are the most frequent types of IBD. IBD is a complex disease which arises as a result of the interaction of environmental, genetic and immunological factors. It is increasingly thought that alterations of immunological reactions of the patients to their own enterable bacteria (microfilm) may contribute to inflammation. It is characterized by mucosal and sub mucosal inflammation, perpetuated by infiltration of activated leukocytes. CD may affect the whole gastrointestinal tract while UC only attacks the large intestine. The therapeutic goal is to achieve a steroid-free long lasting remission in both entities. UC has the possibility to be cured by a total colectomy, while CD never can be cured by any operation. A lifelong intake of drugs is mostly necessary and essential. Medical treatment of IBD has to be individualized to each patient and usually starts with anti-inflammatory drugs. The choice what kind of drugs and what route administered (oral, rectal, intravenous) depends on factors including the type, the localization, and severity of the patient's disease. IBD may require immune-suppression to control symptoms such as prednisolone, thiopurines, calcineurin or sometimes folic acid inhibitors or biologics like TNF-α inhibitors or anti-integrin antibodies. For both types of disease (CD, UC) the same drugs are available but they differ in their preference in efficacy between CD and UC as 5-aminosalicylic acid for UC or budesonide for ileocecal CD. As therapeutic alternative the main mediators of the disease, namely the activated pro-inflammatory cytokine producing leukocytes can be selectively removed via two apheresis systems (Adacolumn and Cellsorba) in steroid-refractory or dependent cases. Extracorporeal photopheresis results in an increase of regulatory B cells, regulatory CD8(+) T cells and T-regs Type 1. Both types of apheresis were able to induce clinical remission and mucosal healing accompanied by tapering of steroids.

Usefulness of salicylate and thiopurine coprescription in steroid-dependent ulcerative colitis and withdrawal strategies

5-aminosalicylic acid (5-ASA) and thiopurines (azathioprine and mercaptopurine) are the most common drugs used as a maintenance treatment for ulcerative colitis. A considerable proportion of these patients develop corticosteroid dependency, and thiopurines are the standard treatment in this scenario. Dual prescriptions of both thiopurines and 5-ASA are common practice in steroid-dependent ulcerative colitis, in an attempt to optimize the efficacy of therapy. On the one hand, the potential protective role of 5-ASA against colorectal cancer argues in favour of prescription of both medications. The possible synergism between the two drugs, because of the inhibition of thiopurine methyltransferase (TPMT) enzyme activity by 5-ASA, has been postulated as another justification for dual prescription. However, existing evidence does not support that this combined strategy is superior to monotherapy with thiopurines. On the other hand, in patients showing prolonged disease remission, the possibility of discontinuing maintenance treatment can be considered on an individualized basis. The high frequency of relapses after thiopurine withdrawal should always be taken into account, but the potential adverse effects of the medication also need to be considered. A properly indicated treatment with thiopurines may need to be continued for life in many patients.

Common misconceptions about 5-aminosalicylates and thiopurines in inflammatory bowel disease

Misconceptions are common in the care of patients with inflammatory bowel disease (IBD). In this paper, we state the most commonly found misconceptions in clinical practice and deal with the use of 5-aminosalicylates and thiopurines, to review the related scientific evidence, and make appropriate recommendations. Prevention of errors needs knowledge to avoid making such errors through ignorance. However, the amount of knowledge is increasing so quickly that one new danger is an overabundance of information. IBD is a model of a very complex disease and our goal with this review is to summarize the key evidence for the most common daily clinical problems. With regard to the use of 5-aminosalicylates, the best practice may to be consider abandoning the use of these drugs in patients with small bowel Crohn’ s disease. The combined approach with oral plus topical 5-aminosalicylates should be the first-line therapy in patients with active ulcerative colitis; once-daily treatment should be offered as a first choice regimen due to its better compliance and higher efficacy. With regard to thiopurines, they seem to be as effective in ulcerative colitis as in Crohn’ s disease. Underdosing of thiopurines is a form of undertreatment. Thiopurines should probably be continued indefinitely because their withdrawal is associated with a high risk of relapse. Mercaptopurine is a safe alternative in patients with digestive intolerance or hepatotoxicity due to azathioprine. Finally, thiopurine methyltransferase (TPMT) screening cannot substitute for regular monitoring because the majority of cases of myelotoxicity are not TPMT-related.

Azathioprine maintains long-term steroid-free remission through 3 years in patients with steroid-dependent ulcerative colitis

BACKGROUND

Studies assessing the efficacy of azathioprine (AZA) in steroid-dependent ulcerative colitis (SD-UC) are scarce. The purpose of this trial was to explore the efficacy of AZA in maintaining steroid-free remission in SD-UC patients and the factors associated with sustained response.

METHODS

In this observational cohort study, 42 subjects with SD-UC were recruited for AZA therapy during a 3-year period. AZA was adjusted for a target dose of 2-3 mg/kg/day. Steroid therapy was tapered off following a standardized regimen. The primary endpoint was the annual rate of steroid-free response to AZA. Secondary endpoints included clinical recurrence, yearly steroid dose, and safety of treatment.

RESULTS

On an intention-to-treat basis, the proportion of patients remaining in steroid-free remission at 12, 24, and 36 months was 0.55, 0.52, and 0.45, respectively. A significant decrease in the flare-ups rate and in requirement for steroids were observed during 3 years on AZA compared with the previous year (P = 0.000 for both). Patients with and without sustained response were comparable according to demographics, extent of disease, dose of AZA, steroids, and 5-aminosalicylate (5-ASA) use. Only disease duration <36 months was associated with off-steroids remission (P = 0.02, odds ratio [OR] 3.12, 95% confidence interval [CI] 1.89-7.64). The AZA benefit-risk profile was favorable.

CONCLUSIONS

In this open-label observational trial AZA showed sustained efficacy for maintenance of clinical remission off steroids and steroid sparing through 3 years of therapy in SD-UC. Patients with earlier UC are those who most probably will have sustained steroid-free remission at the end of 12 months while on AZA.

Ulcerative colitis practice guidelines in adults: American College Of Gastroenterology, Practice Parameters Committee

Guidelines for clinical practice are aimed to indicate preferred approaches to medical problems as established by scientifically valid research. Double-blind placebo controlled studies are preferable, but compassionate-use reports and expert review articles are used in a thorough review of the literature conducted through Medline with the National Library of Medicine. When only data that will not withstand objective scrutiny are available, a recommendation is identified as a consensus of experts. Guidelines are applicable to all physicians who address the subject regardless of specialty training or interests and are aimed to indicate the preferable but not necessarily the only acceptable approach to a specific problem. Guidelines are intended to be flexible and must be distinguished from standards of care, which are inflexible and rarely violated. Given the wide range of specifics in any health-care problem, the physician must always choose the course best suited to the individual patient and the variables in existence at the moment of decision. Guidelines are developed under the auspices of the American College of Gastroenterology and its Practice Parameters Committee and approved by the board of trustees. Each has been intensely reviewed and revised by the Committee, other experts in the field, physicians who will use them, and specialists in the science of decision analysis. The recommendations of each guideline are therefore considered valid at the time of composition based on the data available. New developments in medical research and practice pertinent to each guideline will be reviewed at a time established and indicated at publication to assure continued validity. The recommendations made are based on the level of evidence found. Grade A recommendations imply that there is consistent level 1 evidence (randomized controlled trials), grade B indicates that the evidence would be level 2 or 3, which are cohort studies or case-control studies. Grade C recommendations are based on level 4 studies, meaning case series or poor-quality cohort studies, and grade D recommendations are based on level 5 evidence, meaning expert opinion.

Meta-analysis: the efficacy of azathioprine and mercaptopurine in ulcerative colitis

BACKGROUND

Debate exists regarding to whether thiopurine therapy is as effective in ulcerative colitis (UC) as it is in Crohn's disease.

AIM

To review systematically the efficacy of azathioprine (AZA) and mercaptopurine (MP) in UC, and to conduct a meta-analysis of randomized clinical trials evaluating the efficacy of AZA/MP for the induction or maintenance of UC clinical remission.

SELECTION OF STUDIES

Evaluating AZA/MP for induction and/or maintenance of clinical remission of UC. Randomized-controlled-trials comparing AZA/MP with placebo/5-aminosalicylates were included in the meta-analysis.

SEARCH STRATEGY

Electronic and manual. Study quality: Independently assessed by two reviewers.

DATA SYNTHESIS

By 'intention-to-treat'.

RESULTS

Thirty noncontrolled studies (1632 patients) were included in the systematic review. Mean efficacy of AZA/MP was 65% for induction and 76% for maintenance of the remission. Seven controlled studies were included in the meta-analysis. (i) Induction of remission: four studies (89 AZA/MP-treated patients) showed mean efficacy of 73% vs. 64% in controls (OR = 1.59; 95% CI = 0.59-4.29). (ii) Maintenance of remission: six studies (124 AZA/MP-treated patients) showed mean efficacy of 60% vs. 37% in controls (OR = 2.56; 95% CI = 1.51-4.34). When only studies comparing AZA/MP vs. placebo were considered, OR was 2.59 (95% CI = 1.26-5.3), absolute risk reduction was 23% and number-needed-to-treat (NNT) to prevent one recurrence was 5.

CONCLUSION

Thiopurine drugs (AZA/MP) are more effective than placebo for the prevention of relapse in UC, with an NNT of 5 and an absolute risk reduction of 23%.

Experience of maintenance infliximab therapy for refractory ulcerative colitis from six centres in England

BACKGROUND

Infliximab is used for treatment of Crohn's disease and, following the Active Ulcerative Colitis Trials (ACT) 1 and 2, it has been used as rescue and maintenance therapy in moderate and severe ulcerative colitis (UC).

AIM

To report on English experience with maintenance infliximab in terms of response and colectomy rates and side-effect profile in UC.

METHODS

A retrospective audit conducted by using a web-based questionnaire filled in by 12 gastroenterologists from six English centres.

RESULTS

Of the 38 patients receiving induction with infliximab, 28 (73.6%) maintained an ongoing response (8-weekly infusions 5 mg/kg) for a mean duration of 16.8 months (range 4-59), with 21 (55.3%) being in remission. Three of 38 patients (7.9%) who also responded had a secondary loss of response after an average of 10 months (range 8-13); seven of 38 patients (18.4%) showed no response. The colectomy rate was seven of 38 (18.4%, five non-responders and two with secondary loss of response). Adverse effects occurred in five patients (13.2%). Two discontinued infliximab (alopecia, invasive breast cancer). The three less-severe adverse effects were acute and delayed-type hypersensitivity reactions and one persistent otitis media.

CONCLUSION

Our experience suggests acceptable response rates, colectomy rates and side-effect profile of maintenance therapy with infliximab in moderate and severe UC.

Review article: treatment algorithms to maximize remission and minimize corticosteroid dependence in patients with inflammatory bowel disease

BACKGROUND

Crohn's disease (CD) and ulcerative colitis (UC) are chronic inflammatory diseases of the intestine, which frequently require surgery for complications or failure of medical therapy.

AIM

To seek evidence and provide direction for clinicians on optimal strategies to enable steroid free remission in inflammatory bowel disease.

METHODS

Scientific literature was reviewed using MEDLINIE with a specific focus on medical therapies for inducing and maintaining remission of CD and UC. The results were discussed at a roundtable meeting to reach a consensus on key issues.

RESULTS

Several therapies have demonstrated efficacy for the treatment of active, moderate-to-severe CD and UC. These include agents, which induce remission [corticosteroids, infliximab and adalimumab (CD only)] or maintain remission and spare corticosteroids [azathioprine, mercaptopurine, methotrexate (CD only), infliximab and adalimumab (CD only)]. Wide variability exists in the use of these agents.

CONCLUSION

Treatment strategy algorithms are developed for use of these therapies that maximize remission and minimize corticosteroid dependence in patients with moderate-to-severe CD and UC.

Review article: the management of steroid dependency in ulcerative colitis

BACKGROUND

Approximately 20% of patients with ulcerative colitis have a chronic active disease often requiring several courses of systemic steroids in order to achieve remission, but followed by relapse of symptoms during steroid tapering or soon after their discontinuation. Although short term control of symptoms can be achieved with steroid treatment, this pattern of drug response, known as steroid-dependency, leads to important complications of the treatment, while a significant proportion of patients requires colectomy.

AIM

To review the studies currently available specifically evaluating the management of steroid-dependent ulcerative colitis.

RESULTS

The clinical and biological mechanisms of steroid-dependency are not well understood compared with those determining steroid-refractoriness. Very few evidence-based data are available concerning the management of patients with steroid-dependent ulcerative colitis. The therapeutic role of aminosalicylates, thiopurines, methotrexate, infliximab, leukocyte apheresis and other drugs in the treatment of steroid-dependent ulcerative colitis are evaluated.

CONCLUSIONS

Outcomes of studies in steroid-refractory patients may not be applicable to steroid-dependency. Trials are needed to define the correct approaches and new strategies to ameliorate the therapy of steroid-dependent ulcerative colitis.

Systematic review: sphincter of Oddi dysfunction--non-invasive diagnostic methods and long-term outcome after endoscopic sphincterotomy

BACKGROUND

Sphincter of Oddi dysfunction is a benign, functional gastrointestinal disorder for which invasive endoscopic therapy with potential complications is often recommended.

AIMS

To review the available evidence regarding the diagnostic accuracy of non-invasive methods that have been used to establish the diagnosis and to estimate the long-term outcome after endoscopic sphincterotomy.

METHODS

A systematic review of English language articles and abstracts containing relevant terms was performed.

RESULTS

Non-invasive diagnostic methods are limited by their low sensitivity and specificity, especially in patients with Type III sphincter of Oddi dysfunction. Secretin-stimulated magnetic resonance cholangiopancreatography appears to be useful in excluding other potential causes of symptoms, and morphine-provocated hepatobiliary scintigraphy also warrants further study. Approximately 85%, 69% and 37%, of patients with biliary Types I, II and III sphincter of Oddi dysfunction, respectively, experience sustained benefit after endoscopic sphincterotomy. In pancreatic sphincter of Oddi dysfunction, approximately 75% of patients report symptomatic improvement after pancreatic sphincterotomy, but the studies have been non-controlled and heterogeneous.

CONCLUSIONS

Patients with suspected sphincter of Oddi dysfunction, particularly those with biliary Type III, should be carefully evaluated before considering sphincter of Oddi manometry and endoscopic sphincterotomy. Further controlled trials are needed to justify the invasive management of patients with biliary Type III and pancreatic sphincter of Oddi dysfunction.