25. Lower GI Pharmacology Flashcards
What drugs are used in the treatment of inflammatory bowel disease?
Aminosalicylates Corticosteroids Immunosuppressive agents Antimicrobials TNFa inhibitors
When are aminosalicylates indicated?
Reduce symptoms of mild disease
Given for 4-6 weeks in UC to prevent relapse
How do aminosalicylates work?
Block leucotriene and prostaglandin formation, therefore blocking transcription of inflammatory cytokines
Name an aminosalicylate
Sulfasalazine
What are the side effects of aminosalicylates?
GIT disturbance
Hypersensitivity
Thrombocytopaenia
How do corticosteroids work?
Inhibit CK production
Name a corticosteroid
Prednisolone
Name a side effect of corticosteriods
Osteoporosis
Can cause dependency
When are immunosuppressive agents indicated?
Long term maintenance if disease does not respond to aminosalicylates or steroids
How do the immunosuppressive agents used in IBD work?
Purine analogues which inhibit nucleic acid synthesis
Name 3 immunosuppressive agents given in IBD
Azathioprine
Mercaptopurine
Methotrexate
What are the contraindications for mercaptopurine?
Not given in pregnancy
Cause bone marrow suppression
What are antimicrobials used for in IBD?
Only for secondary complications
What are biological treatments for IBD?
TNFa inhibitors: monoclonal antibodies against TNF
Name an anti-TNF
Infliximab
What 3 methods are used by laxatives?
Retain water and electrolytes in lumen
Reduce mucosal absorption
Increase intestinal motility
What are the side effects of bulk forming agents?
Reduce drug absorption
Can cause intestinal and oesophageal obstruction if patient is not taking in enough water
How do osmotic laxatives work?
Hold water in lumen by increasing the osmotic pressure of stool
Give some examples of osmotic laxatives
Magnesium sulphate or hydroxide
Sodium (bis) phosphate
Lactulose
Which patient groups should you take care in prescribing osmotic laxatives to?
Children
Renal impairment
How do contact/stimulating laxatives work?
Stimulate myenteric plexus and mucosa to change muscle tone
This decreases the permeability of the mucosa
Name 2 contact laxatives
Senna
Bisacodyl
What form is Bisacodyl given in?
Suppository
Useful in those with difficulty swallowing
Give 2 types of constipating agents
Absorbent compounds
Opiates
Name 2 absorbent compounds
Pectin
Aluminium hydroxide
How do opiates act as constipating agents?
Increase muscle tone and decrease propulsive movements
Name an opiate constipating agent
Imodium
