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DRUG TREATMENT OF INFLAMMATORY BOWEL DISEASE. Objectives. Describe the mechanism of action, pharmacokinetics and adverse effects of drugs in IBD. INFLAMMATORY BOWEL DISEASE. Ulcerative Colitis Crohn ’ s disease. Inflammatory bowel disease.
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Objectives • Describe the mechanism of action, pharmacokinetics and adverse effects of drugs in IBD
INFLAMMATORY BOWEL DISEASE • Ulcerative Colitis • Crohn’s disease
Inflammatory bowel disease • Inappropriate inflammatory response to intestinal microbes in a genetically susceptible host
Ulcerative colitis - diffuse mucosal inflammation - limited to colon - defined by location (eg proctitis;pancolitis)
Crohn’s disease - patchy transmural inflammation - fistulae, strictures - any part of GI tract
AIMS OF THERAPY • Suppress inflammatory response • Suppress the immune reaction
Aminosalicylates corticosteroids • Acute maintenance acute
Aminosalicylates • precise MOA unknown • act on epithelial cells • anti-inflammatory • modulate release of cytokines and reactive oxygen species
Aminosalicylates • Local effect on mucosa in reducing inflammation
Aminosalicylates Sulfasalazine Mesalamine Olsalazine
Aminosalicylates Sulfasalazine Mesalamine Olsalazine
Sulphasalazine • Broken down by gut bacterial azoreductase to 5-aminosalicylate & sulphapyridine
SULFASALAZINE Bacterial Flora (Colon) Bacterial azoreductase Sulfapyridine 5-aminosalicylic Acid Acts through the lumen Absorbed Anti-inflammatory Effect Systemic Adverse Effect
Aminosalicylates • 5-ASA absorbed in small intestine • Acetylated by N- acetyltransferase-1 • Excreted in urine
Indications • Maintaining remission in UC • Reduce risk of colorectal cancer by 75% (long term Rx for extensive disease) • Less effective for maintenance in CD • Inducing remission in mild UC/CD (higher doses)
Contraindications/cautions • 5-ASA - Salicylate hypersensitivity • Sulfapyridine - G6PD deficiency (haemolysis) - Slow acetylator status ( risk of hepatic and blood disorders)
Adverse effects • Dose-related • Idiosyncratic (rare) - blood disorders - skin reactions – lupus like syndrome; Stevens-Johnson syndrome; alopecia
Blood disorders • Agranulocytosis; aplastic anaemia; leucopenia; neutropenia; thrombocytopenia; methaemoglobinemia • Patients should advised to report any unexplained bleeding; bruising; purpura; sore throat; fever or malaise
Steven’s Johnson syndrome • immune-complex–mediated hypersensitivity • erythema multiforme • target lesions, mucosal involvement
Newer formulations • Mesalazine (5-ASA) • Balsalazide (a prodrug of 5-ASA) • Olsalazine (5-ASA dimer)
Mesalazine • Available as • Enteric-coated tablets (for ileal Crohn’s disease) • Slow release tablets (for proximal bowel Crohn’s) • Enemas, suppositories (for distal colonic disease) • Used when sulphasalazine can not be tolerated
Aminosalicylates Sulfasalazine • Oral use Mesalamine (5-aminosalicylic acid). • Oral delayed release capsules • Enema Olsalazine. • 5-ASA-n=n-5-ASA • Bacterial flora breaks it into 5-ASA
Anti-inflammatory &Immunosuppressive Drugs • Corticosteroids • Prednisolone • Hydrocortisone
Corticosteroids USES • Remission Induction • Route of Administration Oral Intravenous Topical (Enema)
Indications Indications • Moderate to severe relapse UC & CD • No role in maintenance therapy • Combination oral and rectal
Immunomodulators • Azathioprine • Cyclosporine • Infliximab (Anti-TNF-)
Thiopurines Azathioprine • MOA: inhibit ribonucleotide synthesis; induce T cell apoptosis by modulating cell (Rac1) signalling
Indications • Steroid sparing agents • Active disease CD/UC • Maintenance of remission CD/UC • Generally continue treatment x 3-4years
Ciclosporin • MOA:inhibitor of calcineurin preventing clonal expansion of T cells • Indicated in Severe UC • No value in CD
Methotrexate • MOA: inhibitor of dihyrofolate reductase; anti-inflammatory • Inducing remission/preventing relapse in CD • Refractory to or intolerant of Azathioprine
Infliximab • Indicated active and fistulating CD - in severe CD refractory or intolerant of steroids & immunosupressants - for whom surgery is inappropriate • MOA: anti-TNF monoclonal antibody • Potent anti-inflammatory
Antibiotics • Metronidazole • Ciprofloxacin • Clarithromycin • “Probiotics” (administration of “healthy” bacteria)
Drugs for IBD • Aminosalicylates • Glucocorticoids • Immunosuppressives • Cytokine modulators • Antibiotics
Management of UC to induce remission • oral +- topical 5-ASA • +- oral corticosteroids • Azathioprine • iv steroids/Colectomy/ ciclosporin (severe)
Maintaining remission • oral +- topical 5-ASA • +- Azathioprine (frequent relapses)
Management of CD to induce remission • oral high dose of 5-ASA • +- oral corticosteroids reducing over 8/52 • Azathioprine • iv steroids/ metronidazole/elemental diet/surgery/infliximab
Maintaining remission +- Azathioprine (frequent relapses) Methotrexate (intolerant of azathioprine) Infliximab infusions (8 weekly)