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Thick Stuff > BASIC - GASTROINTESTINAL & HAEMATOLOGY > Flashcards

BASIC - GASTROINTESTINAL & HAEMATOLOGY Flashcards

1
Q

Names of bulk-forming laxatives?

A

Ispaghula husk, methylcellulose, sterculia

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2
Q

Indications of bulk-forming laxatives?

A
  • Constipation (patients who can’t increase dietary fibre)

- Mild chronic diarrhoea

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3
Q

Mechanism of bulk-forming laxatives?

A
  • Hydrophilic substance (polysaccharide or cellulose), not absorbed or broken down in gut
  • Attracts water into stool and increases its mass
  • Increased stool bulk stimulates peristalsis to help relieve constipation
  • Need adequate fluid intake
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4
Q

Side effects of bulk-forming laxatives?

A
  • Mild abdominal distension and flatulence

- Rarely, faecal impaction and GI obstruction

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5
Q

Contraindications of bulk-forming laxatives?

A
  • Colonic Atony
  • Intestinal obstruction
  • Faecal impaction
  • Undiagnosed rectal bleeding
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6
Q

Prescription of bulk-forming laxatives?

A
  • Oral granules, powder to be dissolved in water or tablets (methylcellulose)
  • Dose to be taken with at least 150ml liquid
  • Preferably after meals, morning and evening – e.g. 1 sachet BDS
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7
Q

Names of stimulant laxatives?

A

Senna, Bisacodyl, glycerol suppositories

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8
Q

Indications of stimulant laxatives?

A

Constipation

As suppositories for faecal impaction

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9
Q

Mechanism of stimulant laxatives?

A
  • Stimulant laxatives increase water and electrolyte secretion from the colonic mucosa
  • Increasing volume of colonic content and stimulating peristalsis
  • Direct pro-peristaltic action, although the exact mechanism differs between agents
    o Bacterial metabolism of Senna in intestine produces metabolites that have a direct action on the enteric nervous system, stimulating peristalsis
    o Rectal administration of glycerol suppositories, provokes a similar but more localised effect and can be useful to treat faecal impaction
    o Docusate sodium has both stimulant and faecal softening actions
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10
Q

Side effects of stimulant laxatives?

A
  • Abdominal pain/cramps
  • Diarrhoea
  • Prolonged use
    o Melanosis coli (reversible pigmentation of intestinal wall)
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11
Q

Contraindications of stimulant laxatives?

A
  • Contraindications for Senna
    o Intestinal Obstruction
    o Atony
    o Undiagnosed abdominal pain
  • Contraindications for glycerol suppositories
    o Avoid in haemorrhoids or anal fissures
  • Avoid during pregnancy
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12
Q

Prescription of stimulant laxatives?

A
  • Regular oral administration, usually BDS

- When rectal, PRN or once only

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13
Q

Prescription in palliative care?

A

Prescribe a softener and stimulant (Movicol, co-danthrosate)

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14
Q

Names of osmotic laxatives?

A

Lactulose, Macrogol (Movicol), phosphate enema

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15
Q

Indications of osmotic laxatives?

A

Constipation and faecal impaction – 1st line Movicol in paediatrics
Bowel preparation prior to surgery or endoscopy
Hepatic encephalopathy – lactulose

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16
Q

Mechanism of osmotic laxatives?

A
  • Osmotically active substances (sugars/alcohol) that remain in gut lumen
  • Hold water in stool
  • Maintain volume and stimulate peristalsis
  • Lactulose
    o Reduces ammonia absorption by increasing gut transit rate and acidifying stool
    o Inhibits proliferation of ammonia-producing bacteria
    o Useful in hepatic encephalopathy
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17
Q

Side effects of osmotic laxatives?

A
  • Flatulence
  • Abdominal cramps
  • Nausea
  • Diarrhoea
  • Phosphate enema
    o Local irritation, electrolyte disturbances
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18
Q

Interactions of osmotic laxatives?

A
  • Effects of warfarin may be slightly increased
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19
Q

Contraindications of osmotic laxatives?

A
  • Contraindications
    o Intestinal obstruction (risk of perforation)
    o Severe IBD
    o Toxic Megacolon
  • Contraindications for lactulose
    o Galactosaemia
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20
Q

Caution of phosphate enema?

A

o Heart failure, ascites, electrolyte disturbances

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21
Q

Prescription of osmotic laxatives?

A
  • Orally used prescribed regularly
  • May take a few days for an effect to be seen, as need to pass through GI tract
  • Phosphate enema PRN or once only
  • Taken with or without food
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22
Q

Name of antimotility drugs?

A

Loperamide

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23
Q

Indications of loperamide?

A
  • Symptomatic treatment of diarrhoea
  • Chronic diarrhoea
  • Faecal incontinence
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24
Q

Mechanism of loperamide?

A
  • Opioid similar to pethidine however does not penetrate CNS
  • Agonist of opioid u-receptors in GI tract
  • Reduces peristaltic contractions of gut smooth muscle
  • Transit of bowel contents is slowed and anal sphincter tone is increased
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25
Side effects of loperamide?
- Constipation - Abdominal cramping - Flatulence
26
Cautions of loperamide?
- Acute ulcerative colitis – risk of perforation and megacolon - C.diff colitis - Acute bloody dysentery - Children <12 years old
27
Prescription of loperamide?
- Purchased OTC – 4mg followed by 2mg following each loose stool to maximum of 8mg per day - Usually tablets or capsules
28
Names of antacids?
Gaviscon, Peptac
29
Indications of antacids?
- Mild GORD | - Dyspepsia
30
Mechanisms of antacids?
- Usually an alginate with one or more antacids (sodium bicarbonate, calcium carbonate, magnesium or aluminium salts) - Antacids – buffer stomach acids - Alginates – increase viscosity of stomach contents, reducing reflux - Form a floating raft, separating gastric contents from GOJ
31
Side effects of antacids?
- Diarrhoea (magnesium), constipation (aluminium)
32
Interactions of antacids?
- Divalent cations bind to other drugs and reduce absorption o ACEi, cephalosporins, ciprofloxacin, tetracyclines, bisphosphonates, digoxin, levothyroxine, PPIs - Increase alkalinity of urine – increase excretion of aspirin and lithium
33
Contraindications of antacids?
- Caution in fluid overload or hyperkalaemia (sodium or potassium containing preparations)
34
Prescription of antacids?
- Oral suspensions or chewable tablets | - Take following meals, before bedtime and/or symptomatically
35
Communications to have in antacids?
- Discuss lifestyle measures to reduce GORD o Smaller meals, avoiding food and drink triggers, stop smoking, raising head of bed - Leave a gap of >2 hours when taking medications that interact - Come back if symptoms of bleeding, vomiting, dysphagia and weight loss
36
Names of H2RA?
Ranitidine
37
Indications of ranitidine?
- Peptic ulcer disease (2nd line) - GORD - Dyspepsia - Gastric acid reduction in obstetrics
38
Mechanism of ranitidine?
- H2 receptor antagonists reduce gastric acid secretion - Acid usually produced by proton pump of gastric parietal cell - Proton pump can be stimulated by other things than histamine so cannot completely suppress gastric acid production
39
Side effects of ranitidine?
- Diarrhoea, Constipation - Headache - Dizziness
40
Caution of ranitidine?
- Can mask symptoms of gastric cancer
41
Dose change in renal impairment in ranitidine?
- Reduce dose if eGFR<50 – excreted by kidneys
42
Prescription of ranitidine?
- Can be purchased short-term OTC | - Typical dose 150mg BDS
43
Names of PPIs?
Lanzoprazole, Omeprazole, esomeprazole, pantoprazole
44
Indications of PPIs?
- H.pylori eradication - Peptic Ulcer - GORD - Dyspepsia
45
Mechanism of PPIs?
- Irreversibly inhibit H/K/ATPase in gastric parietal cells | - Suppress gastric acid secretion completely
46
Side effects of PPIs?
- GI upset - Headache - High doses can increase risk of fractures - Prolonged – hypomagnesaemia – tetany or ventricular arrhythmias
47
Interactions of PPIs?
- Omeprazole inhibits CYP450 enzymes
48
Caution of PPIs?
- Mask symptoms of gastric cancer - Increased risk of fractures – adequate intake of Vit D and Ca - Risk of GI infections
49
Max dose in hepatic impairment in PPIs?
- Max dose 20mg
50
Prescription of PPIs?
- Oral usually – best taken in morning - 20mg OD omeprazole - Lowest dose for shortest period possible
51
Monitoring of PPIs?
- Before – check serum magnesium | - Prolonged use (>1 year) – check serum magnesium
52
Name of antispasmodic?
Hyoscine butylbromide (Buscopan)
53
Indications of hyoscine?
- IBS - Colicky pain in cancer - Palliative care - Reduce copious respiratory secretions (death rattle)
54
Mechanism of hyoscine?
- Competitive inhibitor of Ach - Blocks the parasympathetic ‘rest and digest’ effects so: o Increase HR and conduction o Reduces smooth muscle tone o Reduces peristaltic contraction o Relax pupillary constrictor and ciliary muscles preventing accommodation
55
Side effects of hyoscine?
- Tachycardia - Dry mouth - Constipation - Urinary retention - Blurred vision
56
Caution of hyoscine?
- Angle-closure glaucoma
57
Contraindications of hyoscine?
- GI obstruction - Myasthenia gravis - Paralytic ileus - Prostatic enlargement - Urinary retention - Arrhythmias
58
Interactions of hyoscine?
- Adverse effects enhanced with other antimuscarinics e.g. TCAs
59
Prescription of hyoscine?
- Buscopan 10mg 8-hourly – available without prescription
60
Names of dopamine receptor antagonists antiemetics?
Metoclopramide, domperidone
61
Indications of dopamine receptor antagonists antiemetics?
- Prophylaxis and treatment of nausea and vomiting in reduced gut motility - N&V associated with migraine - Radiotherapy and chemotherapy induced N&V - Prevention of PONV - Palliative care – Nausea and vomiting due to gastric stasis and irritation, hiccups
62
Mechanism of dopamine receptor antagonists antiemetics?
- D2 receptor is main receptor in chemoreceptor trigger zone (CTZ) - Dopamine promotes relaxation of stomach and LOS and inhibits gastroduodenal coordination - Blocking D2 has prokinetic effect
63
Side effects of dopamine receptor antagonists antiemetics?
- Diarrhoea, drowsiness, hypotension, menstrual irregularities - Metoclopramide o Extrapyramidal syndromes – acute dystonic reaction (facial and skeletal muscle spasms) o Galactorrhoea, gynaecomastia - Domperidone does not cross BBB o Dry mouth
64
Contraindications of dopamine receptor antagonists antiemetics?
- Phaeocytochroma - Gastrointestinal obstruction/perforation, 3-4 days after GI surgery - Cardiac disease – domperidone
65
Caution of dopamine receptor antagonists antiemetics?
- Young adults - Asthma - Bradycardia - Parkinson’s (Metoclopramide)
66
Dose changes in renal/hepatic impairment of dopamine receptor antagonists antiemetics?
Hepatic Impairment - Caution in severe - Dose reduction of 50% in severe Renal Impairment - Avoid in renal impairment
67
Interactions of dopamine receptor antagonists antiemetics?
- Risk of EPSE increased with antipsychotics | - Do not combine with dopaminergic agents for Parkinson’s - antagonise
68
Prescription of metoclopramide?
o Short term use – 5 days o Dose 10mg up to TDS o Metoclopramide available IV/IM and orally
69
Name of iron supplements?
Ferrous Fumarate, Ferrous Sulphate
70
Indications of iron?
- Treatment of iron deficiency anaemia - Prophylaxis of iron deficiency anaemia in patients with risk factors: o Poor diet, malabsorption, menorrhagia, gastrectomy, haemodialysis
71
Mechanism of iron?
- Replenish iron stores o Iron needed for erythropoiesis – synthesise haem component of haemoglobin - Iron best absorbed in Fe2+ state – in duodenum and jejunum - Absorption increased by stomach acid and ascorbic acid (Vit C) - Once in blood, iron bound by transferrin for either bone marrow for erythropoiesis or stored as ferritin in liver, bone marrow, spleen and skeletal muscle
72
Side effects of iron?
- Nausea, epigastric pain - Constipation, diarrhoea - Bowel motions turn black - IV iron – irritation and hypersensitivity reactions
73
Contraindications of iron?
- May exacerbate bowel symptoms in intestinal disease (IBD, diverticular disease, strictures)
74
Interactions of iron?
- Reduce absorption of other drugs o Levothyroxine, bisphosphonates o Take at least 2 hours before oral iron
75
Prescription of iron?
- Ferrous fumerate – 210mg tablets 1-2 times a day | - Once Fe returned to normal, continue for 3 months to replenish iron stores
76
Communication to patients of iron?
- Taking with food helps reduce GI side effects - May turn stools black - Iron treatment stopped 7 days before colonoscopy
77
Monitoring of iron?
- FBC until haemoglobin returned to normal | - Should rise by 20g/L per month
78
Name if vitamin B12 supplement?
Hydroxocobalamin
79
Indications of hydroxocobalamin?
- Treatment of macrocytic anaemias and subacute combined demyelination of cord in B12 deficiency - Pernicious anaemia
80
Mechanism of hydroxocobalamin?
- Addition vitamin B12 replenishes stores
81
Side effects of hydroxocobalamin?
- Diarrhoea, headache, nausea
82
Contraindications of hydroxocobalamin?
- If both Vitamin B12 and folic acid deficiency: | o Replace both simultaneously
83
Prescription of hydroxocobalamin?
- Hydroxocobalamin given by IM injection o If prophylaxis of macrocytic anaemia – 1mg every 2-3 months o If macrocytic anaemia without neurological complications – 1mg three times a week for 2 weeks and then 1mg every 2-3 months o If macrocytic anaemia with neurological involvement – 1mg OD on alternate days until no improvement then 1mg every 2 months
84
Monitoring of hydroxocobalamin?
- FBC before and during treatment
85
Indications of folic acid?
- Folate-deficient megaloblastic anaemia - Prevention of neural tube defects - Methotrexate treatments
86
Mechanism of folic acid?
- Synthetic form of Vitamin B9 or folate - Replaces stores - Reduces risk of neural tube defects
87
Side effects of folic acid?
- Abdominal distention - Decreased appetite - Flatulence - Nausea
88
Contraindications of folic acid?
- If both Vitamin B12 and folic acid deficiency: | o Replace both simultaneously
89
Prescription of folic acid?
- Folate-deficiency – 5mg OD for 4 months - Prevention of neural tube defects o Low risk - 400 micrograms OD, before conception to 12 weeks o High risk – 5mg OD, before conception to 12 weeks o Sickle Cell – 5mg OD throughout pregnancy - Methotrexate treatment – 5mg once weekly to be take on different day to methotrexate dose
90
Monitoring of folic acid?
- FBC before and during treatment
91
Name of vitamin K replacement?
Phytomenadione
92
Indications for vitamin K?
- All newborn babies to prevent vitamin K deficiency bleeding - Reverse anticoagulant effect of warfarin
93
Mechanism of vitamin K?
- Reverses warfarin by providing fresh supply of Vitamin K for synthesis of Vitamin-K dependent clotting factors (Factor 2, 7, 9, 10) - Effect apparent 12-24 hours after administration
94
Cautions of vitamin K?
- Give IV injections very slowly – risk of vascular collapse
95
Interactions of vitamin K?
- May alter warfarin dosing requirements after treatment
96
Prescription of vitamin K?
- Neonates – 1mg IM as single dose at birth - To treat high INR – low dose (1mg oral or IV) given - Major bleeding – 10mg IV

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