Chapter 1: Gastro-Intestinal system- medications Flashcards
MOA of aminosalicylates and examples
Balsalazide (pro-drug of 5-ASA)
Mesalazine (5-ASA)
Olsalazine (dimer of 5-ASA, cleaves lower in bowel)
Sulfasalzine (5-ASA and sulfapyridine carrier)
MOA not fully understood but thought to reduce cytokine and free radical formation and inhibit prostaglandin synthesis.
MOA of corticosteroids and examples
Beclometasone Budesonide Hydrocortisone Methylprednisolone Oral prednisolone
MOA of antimetabolites and examples
Azathiopurine
Mercaptopurine
Methotrexate
Side effects of aminosalicylates
Blood dyscrasias due to bone marrow suppression (pt counselling) : report unexplained bleeding, sore throat and fever
Nephrotoxity
Salicylate hypersensitivity e.g itching, hives
Yellow/orange bodily fluids with sulfasazine. May colour contact lenses
Counselling points for aminosalicylates
sulfasazine may colour bodily fluids yellow/orange
Blood dycrasias: fever, sore throat, unexplained bleeding, bruising
Monitoring requrements of aminosalicylates
Causes nephrotoxity so renal function should be measured before starting, 3 months in then annually.
Monitoring requirements for sulfasazine
Causes nephrotoxity so renal function should be measured before starting, 3 months in then annually.
LFTs monthly for the first 3 months
Close monitoring of full blood counts (including differential white cell count and platelet count) is necessary initially, and at monthly intervals during the first 3 months.
MOA, onset and examples of bulk forming laxatives
Swells in the gut to increase faecal mass to stimulate peristalsis
takes within 24 hours but takes 2 to 3 days for full effect
ispaghula husk, methylcellulose and sterculia.
side effect of bulk forming laxatives
bloating
flactulence
gut obstruction
Counselling points for bulk forming laxatives
avoid in faecal impaction
maintain fluid intake to avoid gut obstruction
swallow with lots of water and not immediately before bed
MOA, onset and examples of osmotic laxatives
Increase amount of fluid in large bowel to allow easier passage of stool
Onset of action = 2-3 days with exception of enemas which have an onset of action of 15-30 minsLactulose
Macrogols
Phosphate and sodium citrate enemas
Side effects of osmotic laxatives
Bloating, cramping, abdominal pain, diarrhoea, nausea, flatulence, increased thirst
Cautions associated with osmotic laxatives
Avoid lactulose in lactose intolerant pts
movicol has high sodium content
MOA, Onset and examples of stimulant laxatives
•Senna
•Bisacodyl
•Sodium picosulfate
•Docusate - weakest stimulating potential, stool softener properties.
Trigger rhythmic contractions of intestinal muscles to eliminate stool
Onset of action = 6-12 hours
glycerol suppository works in 15-30 minutes
Side effects of stimulant laxatives
Bloating, cramping, abdominal pain, diarrhoea, nausea, flatulence, increased thirst
senna colours urine yellow/brown
excessive use results in hypokaeleamia, diarrhoea, lazy bowel
Counselling pts for stimulant laxatives
For short term use - 1 week
Take at night to pass stool in the morning
Moisten suppository in water before use
MOA, Example of prokinetic laxative
Prucalopride-Only used in women
Selective, high-affinity, serotonin (5HT4) receptor agonist, which stimulates intestinal motility
Onset of action = unknown
Side effect of prokinetic laxative
Headache, nausea, diarrhoea, abdominal pain
When are prokinetic laxatives cautioned
Caution in ischaemic heart disease or arrhythmias. Considered when treatment with other laxatives has failed.
MOA, Onset and examples of stool/ faecal softners
•Docusate and glycerol suppositories •Arachis oil enema •Liquid paraffin methylcellulose Add moisture to stool to allow strain-free bowel movements Onset of action = 15-30 minutes
Side effects of stool softeners
Electrolyte imbalance with prolonged use- malabsorption of vitamin A,D,E,K
Anal seepage, lipid pneumonia, granulomatous disease of the GI tract
Side effects associated with stimulant laxatives used in palliative care
Co-danthramer Co-danthrusate Dantron is genetoxic and carcinogenic Results in red urine local irritation/ excoriation- avoid prolonged contact time
Counselling advise it a pt ha to switch brand of mesalazine
report any changes in symptoms
What is the MHRA alert associated wirh stimulant laxatives
pts should use lifestyle and diet first line
then bulk forming then osmotic then stimulant. this is due to its misuse and abuse.
not licensed otc for under 12 year olds
only enough supply for two courses
Loperamide Indication and moa
Antipropulsive
prolongs the duration of intestinal transit time by binding to opiod receptors in the GI tract
Standard treatment of diarrhoea for rapid control of symptoms in over 12 year olds
What is the adult dose for loperamide
Initially 4mg, the 2mg for up to 5 days, take a dose after each loose stool.
Max 16mg a day (2mg x8 a day)
Repeated treatment may be indicated