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
What is the MHRA alert associated with Loperamide
Serious cardiovascular events (such as QT prolongation, torsades de pointes, and cardiac arrest), including fatalities, have been reported in association with large overdoses of loperamide.
Healthcare professionals are reminded that if symptoms of overdose occur, naloxone can be given as an antidote. The duration of action of loperamide is longer than that of naloxone (1–3 hours), so repeated treatment with naloxone might be indicated; patients should be monitored closely for at least 48 hours to detect possible CNS depression.
Pharmacists should remind patients not to take more than the recommended dose on the label.
Side effects associated with lopermide
dizziness, flatulence, headache and nausea
Contra indications associated with loperamide
Active ulcerative colitis; antibiotic-associated colitis; bacterial enterocolitis; conditions where abdominal distension develops; conditions where inhibition of peristalsis should be avoided
Licensed age for lopermide capsules
8 years old
Licensed age for loperamide syrup
4 years old
When should lopermide be avoided
When the pt is experiencing bloody diarrhoea or inflammatory diarrhoea (fever, severe abdo pain)
What is the MOA of alginates and examples
Gaviscon sodium chloride sodium bicarbonate and calcium carbonate
Gaviscon advance (with potassium) both of which cotain sodium chloride and potassium bicarbonate
works by forming a viscous gel raft on top of stomach to prevent reflux
MOA and examples of antacids
Neutralises stomach acid providing immediate symptom relief in 15-30 mins
aluminium hydroxide - constipating and long acting
calcium salt induce rebound acid secretion and prolonged high doses also cause hypercalcaemia and alkalosis, and can precipitate the milk-alkali syndrome.
magnesium salt which is laxating and long acting e.g magnesium trisilicate, magnesium carbonate, co-magadrox
potassium salt
sodium salt
Simeticone with Hydrotalcite
Which are the low NA+ preparations of antacids
maalox and mucogel (co-magadrox) Altacite Plus (Simeticone with Hydrotalcite)
why is simeticone used in palliative care
acts as an anti-foaming agent reducing flactulence so can reduce hiccups in palliative care because they are uncomfortable for the pt
When should antacids be taken and which formulation is best
after each main meal or at bedtime when required
liquid is best
what are the antacids interactions
Impaired absorption of drugs- leave a 2 hour gap
e.g tetracyclines, quinolones, bispohosphonates
damages drugs that have enteric coating by increasing the intestinal pH
high sodium content resulting in fluid retention so avoid in hypertension, heart liver and kidney disease
MOA of PPI and examples
Inhibits gastric acid secretion by blocking hydrogen- potassium ATPase (proton pump) of the gastric parietal cell. It is the most effective anti-secretory drug
Omeprazole safe in pregnancy
Lansoprazole- 30 to 60 minutes before food
Esomeprazole
Pantoprazole
Raberprazole
What are the labelling requirements for PPI
Swallow this medicine whole. Do not crush or chew
do not take indigestion remedies 2 hours before or after taking the medicine
Cautions for PPI
Masks symptoms of gastric cancer
Increased risk of fractures and osteoporosis
increased risk of GI infcetions- c. diff due to reducd acidity
side effects associated with PPI
GI upset: abdo pain, diarrhoea, constipation, nausea, dizziness, dry mouth, insomnia, skin reactions
If PPI is being used long term what should be monitored
can cause hypomagesaemia especially when pt is taking digoxin so it should be measured before and during treatment
fractures
rebound acid secretion, protacted dyspepsia after stopping
What drug interactions are associated with omeprazole
Clopidogrel- reduced antiplatelet effect
Methotrexate-decreased clearance of methotrexate
What is the mHRA advice given for PPI’S
Proton pump inhibitors (PPIs): very low risk of subacute cutaneous lupus erythematosus (September 2015)
Very infrequent cases of subacute cutaneous lupus erythematosus (SCLE) have been reported in patients taking PPIs. Drug-induced SCLE can occur weeks, months or even years after exposure to the drug.
If a patient treated with a PPI develops lesions—especially in sun-exposed areas of the skin—and it is accompanied by arthralgia:
advise them to avoid exposing the skin to sunlight;
consider SCLE as a possible diagnosis;
consider discontinuing PPI treatment unless it is imperative for a serious acid-related condition; a patient who develops SCLE with a particular PPI may be at risk of the same reaction with another;
in most cases, symptoms resolve on PPI withdrawal; topical or systemic steroids might be necessary for treatment of SCLE only if there are no signs of remission after a few weeks or months.
MOA and examples of H2 antagonists
Reduceds gastric acid secretion by blocking H2 receptors in the gastric parietal cells. It is an antisecretory drug. cimetidine- enzyme inhibitors famotidine nizatidine ranitidine- safe in pregnancy
side effects associated with h2 antagonists
headaches, rashes, dizziness, diarrhoea
Psychiatric symptoms: confusion, depression, hallucinations in elderly or very ill pts
cautions
masks symptoms of gastric cancer
MOA and examples of antimuscarinics
reduces intestinal motility by blocking muscarinic receptors which would normal stimulate parasympathetic responses such as rest and digest Atropine Dicycloverine Hyoscine Butylbromide (buscopan) Hyoscine hydrobromide (kwells) Propantheline bromide
what are the side effect associated with antimuscarinics
" can't see, can't pee, can't poo, can't spit" blurred vision urinary retention constipation dry mouth Tachycardia, palpitations and arrthymias pupil dilation reduced bronchial secretions angle closed glaucoma (raises intra-ocular pressure) confusion in the elderly drowsiness impairs driving
Cautions associated with antimuscarinics
Susceptibility to angle-closure glaucoma
Conditions causing tachycardia e.g hyperthyroidism
CVD E.G arrthymias, congestive heart failure
Contra-indications for antimuscarinics
prostatic enlargement, urinary retention,
paralytic ileus, GI obstruction, toxic megacolon
myasthenia gravis- characterised by muscle weakness
narrow angle glaucoma
what is the maxiumum single dose and max dose for ranitidine
75mg single dose
300mg daily dose
what is the MHRA alert for hyoscine butylbromide injection
The MHRA advises that hyoscine butylbromide injection can cause serious adverse effects including tachycardia, hypotension, and anaphylaxis; several reports have noted that anaphylaxis is more likely to be fatal in patients with underlying coronary heart disease. Hyoscine butylbromide injection is contra-indicated in patients with tachycardia and should be used with caution in patients with cardiac disease; the MHRA recommends that these patients are monitored and that resuscitation equipment and trained personnel are readily available.
MOA and examples of antipasmodics
direct relaxants of intestinal smooth muscle
Mebeverine
alverine
peppermint oil
Contraindications for antipasmodics
mebererine and alverine and contraindicated in paralytic ileus
pt counselling for peppermint oil
swallow whole so avoid local irritation in mouth/oesophageus
can cause heartburn
what is used as treatment for food induced anaphylaxis and how does it work
what is the dose
adrenaline epipen
Acts on both alpha and beta receptors and increases both heart rate and contractility (beta1 effects); it can cause peripheral vasodilation (a beta2 effect) or vasoconstriction (an alpha effect)
500 micrograms, using adrenaline 1 in 1000 (1 mg/mL) injection, repeat dose after 5 minutes if no response; if life-threatening features persist, further doses can be given every 5 minutes until specialist critical care available, to be injected preferably into the anterolateral aspect of the middle third of the thigh.
drugs used for management of symptoms in food allergy (not adrenaline)
Sodium cromoglicate is licensed as an adjunct to dietary avoidance in patients with food allergy. Chlorphenamine maleate is licensed for the symptomatic control of food allergy.
what is the mOA of pancreatin
Supplements to compensate for reduced or absent pancreatic enzyme secretion. They assit with the digestion of starch, fat and protein.
how should pts take pancreatin
with meals/snacks- immediately before or after
Use PPI to suppress acid which inactivates it if necessary
Do not mix with hot food or drinks- it is inactivated by heat
If mixed with foods or drink do not keep for over an hour
enteric coated preps deliver higher doses of pancreatin
side effects of pancreatin
GI effects
buccal mucosa and perioral irritation
excessive doses casuse hyperuricaemia, hyperuricosuria
can cause skin irritation or hypersensitivity when handling
cautions for pancreatin
fibrosing colonpathy in cystic fibrosis with high dose pancreatin
risk factors: male children, more severe cystic fibrosis and laxative use.
If new or changing abdo symptoms- exclude colonic damage
Contra-indications for pancreatin
Pancrease HL® and Nutrizym 22® gastro-resistant capsules should not be used in children aged 15 years or less with cystic fibrosis
its associated with colonic strictures
pt counselling associated with pancreatin
ensure adequate hydration at all times
