Flashcards in Gastrointestinal Chapter ONE Deck (27)
Name the NINE areas covered by the BNF in the GI chapter
1. Dispepsia and GORD 2. Antipasmodics and motility drugs 3. Ulcers 4. Diarrhoea 5. Chronic disease 6. Laxatives 7. Local preparations and anal disorders 8. Stoma care 9. Drugs affecting intestinal secretions
Define Indigestion, dyspepsia, GORD and peptic ulcer
1. Indigestion = lack of adequate digestions
2. dyspepsia = collective of symptoms including pain, fullness, bloating, N&V
3. GORD - Acid regurgitation into the oesophagus aka heart burn
4. Peptic ulcer - wounds in the stomach or duodenum
Name FOUR common antacids and their side effects
1. aluminium hydroxide (maalox) - constipation
2. Magnesium carbonate - laxative effect (also belching)
3. Bismuth - neurotoxic and encephalopathy and constipation.
4. Calcium antacids - cause rebound secretions
Explain the following counselling points for anacids - best time to take them, mode of action, use with other drugs, patients with hypertention.
best taken when symptoms occur, between or after meals and at bedtime. Dont take with other drugs as can impair absorption. Can also damage enteric coatings. The words "low na+" indication sodium content, directed at those with hypertention.
What is simeticone and what is it used for?
and antifoaming agent added to antacids to reduce flatulence
What are alganated with antacids used for?
They form a raft of foam on stoma of the stomach contents to prevent GORD. combined with antacids they also reduce the viscosity of the stomach and its ph
Name Three antimuscarinic drugs used for GI disorders like IBS (which are characterised by smooth muscle spasms) and explain all the side effects
Atropine - Dicycloverine and hyoscine. Constipation due to blocked sweat gland receptors. Bradycardia, blocked m3 receptors in AV and SA nodes. Reduced bronchial secretions (blocked secretry glands) dilation of pupils (relaxation of cilliary muscle), photophobia (dilated eyes). Dry mouth (blocked salavary gland receptors. flushing (dialation of capillaries). Dry skin (block lacrimal glands)
Explain why antimuscarinics are contraindicated in myasthenia gravis, paralytic ileus, pyloric stenosis and prostatic enlargment. name one major side effect of antimuscarinics in general
Myastheis gravis - weakening of muscle cells - blocked Ach receptors from neurons telling muscle to contract.
Paralytic ileus (arrest of movement of food through the ileum - antimuscarinics slow down bowel movement. Pyloric stenosis - (blocked pyloric sphincter). Prostate enlargement (antimuscarinics exacerbate obstructive symptoms in both these conditions. a major side effect of antimuscarinics is slowed motility of intestines
name TWO anstispamodics and explain any cautions they have aswel as the general mechanism of action
Indication is same as antimuscarinics - but have no serious side effects. Direct relaxants of smooth muscle probably through sodium ion channels. Do not break or crush peppermint oil capsules as they can irritate mouth/oesophagus
Name two motility stimulants and explain their mode of action
Metoclopramide and Comperidone - Dopamine receptor antagonists that stimulate gastric emptying and instestinal transit. They also enhance the strength of the oesophageal sphincter
Name two main causes of H.pylori and outline the treatment of both
Helicobacter pylori infection - needs to be confirmed before starting treatment - seven day course of 1. PPI BD, + clarithromycin and (amaxicillin or metronidazole).
Second cause is NSAID induced ulcers - PPI can be given prophylactically
What the NICE guidelines for treating a patient presenting with dyspepsia
1. uninvestigated dyspepsia is treated with PPI for FOUR weeks. if no response test for H.pylori
2. If positive H.pylori treat with eradication therapy
3. If no response treat with PPI or H2 blocker for 4 weeks
How is GORD managed
1. Antacids and alginated
2. H2 receptor antagonists and PPI
Name two H2 blockers used in the management of ulcers, list their side effects including reasons and explain they limitation in OTC use
1. TWO antacids cimetidine and Ranitidine
2. side effects include GI disturbances (diarrhoea or constipation) due to stomach irritation and responce to drug
- Headaches, dizziness, by partially binding to H1 receptors on blood vessels causing them to dialate
- CNS disorders are experienced with cimetidine as it can cross the blood brain barrier (1st gen antihistamine)
- skin and rash side effects can occur due to stimulation of peripheral nerve ending that contain H1 receptors
3. They can be sold OTC to patients over 16 for not more than TWO weeks use
Give an overview of what prostaglandin analogues are and explain which one can be used in GI disorders. Also, explain any warning and side effects
Prostaglandins are fatty acids with hormon like effects. They bind to specific receptors to produce varying responces. Misoprostol can be used to reduce stomach acid as it binds to the E1 prostaglandin analogue. It can also be used to induce labour and is therefore not recommended for women of child bearing age as it causes expulsion of urinary contents (there is an E1 receptor in the uterus).
Name four PPI's and explain the class side effects. Also explain which can be sold OTC and any restriction it may have
Esomeprazole, Lansoprazole, Omeprazole, Pantoprazole.
PPI's can cause stomach disturbances as they increase gastrin level, which is a result of accumulation of H+ ions in the cell.
Symptoms of headache, fatigue rarely irritation and anxiety can be a result of vitamin defficiency, in particular B12, which normally result from long term use. Stomach acid help break down this nutirents but lack of stomach acid can cause them to go unabsorbed
Explain the physiology of emesis
1. The brain has two structure located outside the BBB, tthe vomiting center and the chemoreceptor trigger zone.
2. The vomiting center has muscarinic receptor that when activated causes neuronal messages to the stomach to initate emesis.
3. The chemoreceptor has 2 receptors the 5HT (aka serotonin) and dopamin receptors that when activated send signals to trigger the vomiting muscarinic receptors.
4. vomiting center can also be stimulated by higher brain centers
5. the stomach also has enterochromaffin cells that release serotinin in responce to toxic agents which then trigger the vomiting center.
explain the physiology of motion sickness
1. The inner ear has a structure called the vistibule located in the labrynth which is involved in regulating balance - disturbances with the vistibule sends signals to the vistibula nuclei located next to the chemorecptor trigger zone - it containes Histamine 1 receptors. when activated it trigger the chemo zone and then the chemo zone trigger the vomiting center
Explain the different classes of anti-emetics in relation to areas in the brain they work
1. H1 blockers that act in the vestibula zone include antihistamines promethazine and cyclizine.
2. Serotonin blockers which end in setron act on the 5HT receptor of the brain include ondasetron.
3. Dopamin receptor in the chemoreceptor zones are blocked by antipsychotic drugs like chlopromazine and prochloperazine and also metoclopromide. One more D2 antagonist to droperidol which is similar to haloperidol
4. Antimuscarinic receptors include hyoscine which acts directly on the vomiting center.
Explain when each antiemetic type is useful and the associated side effects
1. H1 blockers in the vistibule zone are good for morning sickness and motion sickness as that is where they are triggered but can cause sedation and dowsiness.
2. 5HT antagonists in the chemo zone are good for chemo induced sickness side effects include headache and GI side effects and 5ht receptors are present in the stomach.
3. D2 receptors work in the chemo zone and are therefore also useful for chemo induces sickness. However side effects are more serious including hypotention (blocked muscarinic receptors) and EPS.
4. metoclopramide is also a D2 blocker but also works locally in the stomach to increase motility - can cause fatigue (mal absorption) and EPS's.
5. antimuscarinic - hyoscine work on the vomiting center are good for prophylaxis and motion sickness (antimuscarininc side effects)
How is acute diarrhoea treated and what are the side effects of the medication. Also what are the restrictions for over the counter use
Loperamide is an antimotility drug can be sold OTC to patients over 12 years. Main side effects of loperamide is cramps and dizziness
Define THREE chronic bowel conditions
1. Ulcerative colitis - inflamation of the colon causing pain and diarrhoea
2. Crohn's disease - when section of the digestive tract become inflamed and ulcerated - also causes diarrhoea and pain
3. Diverticular disease - condition in which there is sac or pouch formed at weak parts of the colon. It is treated with bulk-forming drugs and high fibre diet.
Aminosalicylates are drugs commonly used in UC (ulcerative colitis) and CD (crohn's disease) - name two such drugs and explain their side effects. Additionally, describe one important consulting point with aminosalicylates
1. Mesalazine and Sulfasalazine
Side effects include - diarrhoea, N&V abdominal pain - (generic GI disturbances) - Sulfasalazine can turn uring orange. Becuase of its antiinflamatory action, patients should look out for signs of infection and blood disorderes.
Name four groups of laxatives and give examples
1, Bulk forming (fybogel and methylcellulose)
2. Stimulant (bisacodyle, docustate, senna, picosulfate, glycerol, dantron) - can cause hypokalaemia due to usage of ions for contraction
3. Stool softners (liquid parafin) -
4. osmotic (lactulose) - take up to 48hrs to act
Explain how haemorroids are treated locally and give counselling points for local anaesthetics
Haemorrhoids are locally treated with ointments and suppositories - local anaesthetic ointments can be absorbed through the sckin and therefore should be avoided in infants and children.
2. Preperations should be used for no more than 7 days as the skin can become sensitised to the local anaesthetic
3. Local anaesthetics can be combined with steroids
name 2 uses of bile acid sequestrants and describe one important counselling point
colestyramine is an insoluble resin that binds cholestral in hypercholesterolemia. It can also releive diarrhoea by acting like a bulk forming laxative. It can interfere with other drugs so it should be taken an hour before or 3 to 4 hours after normal medication