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Clinical Pharmacology > Gastroenterology > Flashcards

Gastroenterology Flashcards

1
Q

Dyspepsia: Management

What are treatment steps and investigation steps for isolated dyspepsia?

A

Uninvestigated Dyspepsia: if unnecessary to investigate; trial of management. Proceed up ladder if no resolution of symptoms

First Line: Medication Review and Lifestyle Advice

  1. Medication Review: precipitants include NSAIDs, bisphosphonates, corticosteroids, calcium antagonists, SSRIs
  2. Lifestyle Advice: healthy eating, weight reduction and smoking cessation. Avoid precipitants inc. smoking, alcohol, chocolate and coffee. Have main meal well before going to bed.
  3. Self treatment: antacids

Second Line: Emperical Full Dose PPI for 1 month

  1. Omeprazole: 40mg OD. More effective than antacids and H2RA

Third Line: H. Pylori - Test and Treat

Diagnosed by H. Pylori serology (may also use breath test, or stool antigen): if positive 7-day PAC500

Forth Line: H2RA or Pro-Kinetic Therapy

Considered if there is inadequate response to PPI. e.g. ranitidine. Generally less effective.

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2
Q

Gastro-Oesophageal Reflux Disease​

What are the symptoms of GORD, and when is endoscopy indicated?

A
  1. Heartburn (retrosternal pain, worse on bending or lying down), acid regurcitation, and occasionally dysphagia.
  2. Odynophagia to hot liquids suggests oesophagitis.
  3. Endoscopy if treatment refractory or complications (dysphagia suspected).
  4. Risk of progression from Barrett’s to malignancy ~0.2% per year
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3
Q

Gastro-Oesophageal Reflux Disease: Treatment

What are treatment strategies for GORD?

A
  1. Lifestyle: avoid excess alcohol, aggravating foods (fats) reduce weight, stop smoking, raise head of bed
  2. Medical management:
    1. Mild: trial of antacids or alginates, but PPI more effective. H2RA are generally ineffective
    2. Severe (symptoms, or proven pathology): PPI (omeprazole 40mg, 4 – 8 weeks, reduce to 20-40mg maintenance)
    3. Prokinetics (e.g. metoclopramide) may accelerate gastric emptying and reduce reflux
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4
Q

Proton Pump Inhibitors

What are the mechanisms, indications, adverse effects and interactions of PPIs?

A
  1. Mechanism: block H/K/ATPase (proton pump) system in parietal cells; inhibit gastric acid secretion
  2. Indications:
    1. Short term for gastric / duodenal ulcer
    2. H. pylori triple therapy
    3. Reduces risk of rebleed following endoscopic treatment of bleeding PU (intravenous, high dose). Note indicated urgently in haematemesis / malena
    4. Short term for GORD and NUD
    5. Prevent / treat NSAID ulcers
  3. Adverse effects: commonly diarrhea, headache, abdominal pain. Rare: interstitial nephritis and osteoporosis
  4. Interactions: possible clopidogrel. May increase c. difficile risk in patients on antibiotics
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5
Q

Histamine H2 receptor antagonists

What is the mechanism, indications, adverse effects and interactions of H2 receptor antagonists (e.g. ranitidine)

A
  1. Mechanism: block H2 receptors stimulating acid secretion from parietal cells in the stomach
  2. Indications: as PPI, which are generally more effective (heal gastric and duodenal ulcer, relieve symptoms of GORD, NUD and NSAID ulcers)
  3. Adverse effects: as PPI; diarrhea, GI disturbance, altered LFT, headache, dizziness.
  4. Interactions: Cimetidine inhibits cP450, therefore avoid on patients on warfarin, phenytoin and theophylline. Other H2RAs do not have this property
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6
Q

Decompensated Liver Disease

What are the signs and precipitants of decompensated liver disease? What assessment and monitoring is required?

A
  1. Signs: mental slowness, confusion, drowsiness and liver flap
  2. Precipitants:
    1. Sepsis: culture blood and urine, tap ascites if present (WCC, protein, culture), CXR
    2. Bleeding
    3. Renal Failure: electrolyte abnormalities
    4. Constipation
    5. Medication (sedatives or over diuresis)
  3. Assessment:
    1. Bloods: FBC, coagulation, U&E, LFTs, glucose
    2. USS abdomen
    3. Assess for alcohol withdrawal
    4. Dietary assessment
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7
Q

Decompensated Liver Disease: Ascites​

If ascites are present, a diagnostic tap may be performed. This requires ~50ml fluid to be drawn off. What investigations are required?

A
  1. Microbiology: WCC and culture in blood culture bottles (anaerobic and aerobic)
  2. Biochemistry: total protein and albumin
  3. Cytology
  4. USS: unless ascites recurrent​
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8
Q

Decompensated Liver Disease: Encephalopathy

What is the management for encephalopathy associated with decompensated liver disease?

A
  1. Assess: for precipitating factors
  2. Stop sedatives
  3. Lactulose: 20ml oral, TDS, titrating until three soft motions / day. Binds gut ammonia, reducing severity of encephalopathy
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9
Q

Irritable Bowel Syndrome: Diagnosis

What are the symptoms of IBS, and what criteria are used to make the diagnosis?

A
  1. Presentation: commonly includes pain, bloating, alternating constipation and diarrhea, and a sense of incomplete evacuation and fatigue.
  2. Diagnosis: made by Rome III criteria. Investigations are necessary only to exclude other causes:
    1. Pain relieved by bowel movement
    2. Onset of pain relates to change in stool frequency
    3. Onset of pain related to change in stool appearance
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10
Q

Irritable Bowel Syndrome: Management

What are the main management options for IBS

A
  1. Bowel symptoms:
    1. Constipation predominant: use a laxative (soluble fibre or osmotic agent (macrogol)
    2. Diarrhoea predominant: antimotility agent (loperamide)
  2. Pain: antispasmodics such as mebeverine, alverine citrate or hyoscine relieve pain. Few side-effects, with the exception of antimuscarinic hyoscine (associated antimuscarinic s/e)
  3. TCA: low dose has peripheral effect on enteric nerves
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11
Q

Inflammatory Bowel Disease: Acute Severe Colitis

What are the diagnostic criteria of acute severe colitis, and what investigations should be carried out?

A
  1. Diagnosis: Bloody diarrhea > 6/ day with:
    1. Tachycardia > 90 OR
    2. Temperature > 37.8 OR
    3. Anaemia < 10.5g/dL OR
    4. ESR > 30mm/hr
  2. Require admission and intensive treatment, as colectomy rate is 30%. Investigations:
    1. Monitoring:
      1. Pulse and T 4 times per day
      2. FBC, U&E, CRP daily
      3. Stool Chart
    2. Imaging: AXR; colorectal surgeons if colonic diameter >5.5cm (toxic megacolon)
    3. Stool sample: C. difficile assay (no antibiotics unless positive)
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12
Q

Inflammatory Bowel Disease: Acute Severe Colitis

What is the management for acute severe colitis?

A
  1. I.V Fluids: 3L/day (2:1 normal saline / 5% dextrose), with 60-80 mmol KCl/day
  2. Steroid:
    1. IV hydrocortisone (100mg four times a day)
    2. Rectal hydrocortisone 100mg in 100ml N/saline twice daily
  3. Transfer to specialist care
  4. Poor responders: identified at Day 3 with frequency >8/day, CRP > 45mg/L require ciclosporin or infliximab. Specialist decision, and involves consultation with colorectal surgeons

Note: in setting of uncertainty, it is better to assume severe UC and start hydrocortisone, than assume infection and hold off. Acute severe UC will get worse untreated, whereas infective colitis will usually get better with steroids.

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13
Q

IBD: Treatment Options

What are the options for induction and maintenance therapies in UC and Crohns?

A
  1. Induction:
    1. Corticosteroid (oral prednisolone, I.V hydrocortisone) first line for UC and chrons. If failing to control and add on therapy required:
    2. Aminosalicylates: useful in UC, not CD
    3. Azathioprine / Mercaptopurine used in CD in which treatment cannot be tapered, or > exacerbation in 2 months
  2. Maintenance: note: corticosteroids should never be used as a maintenance treatment; they do not work. Best options are
    1. Azathiorprine
    2. Mercaptopurine
    3. Methotrexate
  3. Biologics: choices are infliximab (UC and Crohn’s) and adalimumab (Crohn’s). Specialist decision, both work better if used at an early stage.
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14
Q

Aminosalicylates

What are the components of sulfasalazine, what are adverse effects and contraindications?

A
  1. Components: Combination of 5-ASA (mesalazine; the active moiety) and sulfapyridine; the carrier of 5-ASA to the colon and the commonest cause of side effects.
  2. Adverse effects:
    1. Common (about 5%) diarrhea, nausea, headache, rash
    2. Rare: agranulocytosis, aplastic anaemia, leucopenia and thrombocytopenia (monitor blood count)
  3. Contra-indications: avoid in patients with aspirin sensitive asthma (contain salicylate)
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15
Q

Diarrhoea

What options are available for the treatment of diarrhea?

A
  1. Loperamide: well tolerated, may be associated with abdominal cramps, dizziness and drowsiness. Can be used for chronic diarrhoea (e.g. IBS)
  2. Codeine phosphate
  3. Co-phenotrope

**Note: **anti-motility agents may precipitate **toxic megacolon **in UC and are avoided.

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16
Q

Constipation: Laxative Choices

What are the main classes of laxatives, examples of each, and situations in which they may be used.

Note: in the setting of uncertainty; **lactulose and senna **is a safe and effective combination, and a good default.

A
  1. Bulk Forming: e.g. Fybogel
    1. Mechanism: stimulate perisalsis by increasing fecal mass. Take time to work; not suitable for acute relief.
    2. Indications: small, hard stools (e.g. constipation IBS, diverticulosis)
  2. Osmotic: e.g. lactulose, macrogol (↑ cost)
    1. Mechanism: draw water into large bowel, or retain fluid they were administered with. Increase frequency.
  3. Stimulants: senna, bisacodyl, dantron (terminally ill)
    1. Mechanism: stimulate bowel. Fastest onset. Taken at bedtime to induce morning effect.
    2. **Indications: **drug-induced constipation.
  4. Feacal softeners: docusate
    1. Indications: normal frequency but hard stool; painful conditions (fissure, haemorrhoids)
17
Q

Anti-emetics: Ondansetron

For ondansetron, what is the:

  1. Class
  2. Mechanism
  3. Indications
  4. Adverse effects
A
  1. Class: 5HT3 receptor antagonist
  2. **Mechanism: **blocks 5HT3 receptors in the gut, and possibly centrally in the chemoreceptor trigger zone
  3. **Indications: **Post-op nausea or vomiting, chemotherapy and radiotherapy.
  4. **Adverse effects: **usually well tolerated; may cause headache and constipation with prolonged use.
18
Q

Anti-emetics: Prochloperazine, Chlorpromazine

For prochloperazine and chlorpromazine, what is the:

  1. Class
  2. Mechanism
  3. Indications
  4. Adverse effects
A
  1. Class: phenothiazines
  2. **Mechanism: **blocks dopamine receptors in the chemoreceptor trigger zone
  3. Indications: Post-operative nausea or vomiting, drug induced vomiting
  4. **Adverse effects: **may cause EPSPs and anticholinergic effects. Chlorpromazine is more sedating that prochlorperazine
19
Q

Anti-emetics: Haloperidol

For haloperidol, what is the:

  1. Class
  2. Mechanism
  3. Indications
  4. Adverse effects
A
  1. Class: Butyrophenone
  2. Mechanism: blocks dopamine receptors in chemoreceptor trigger zone (like prochloperazine and chlorpromazine)
  3. Indications: Post-operative nausea and vomiting, useful in palliative care for renal failure and hypercalcaemia
  4. **Adverse effects: **sedative, anticholinergic, EPSPs. Contraindicated in PD. Can cause apathy and withdrawal, particularly if used at high doses for > 1 - 2 weeks
20
Q

Anti-emetics: Metoclopramide

For metoclopramide, what is the:

  1. Class
  2. Mechanism
  3. Indications
  4. Adverse effects
A
  1. Class: dopamine recepto antagonist; similar to phenothiazines (prochloperazine and chlorpromazine)
  2. **Mechanism: **weak dopamine inhibition in chemoreceptor trigger zone (unless large doses used); prokinetic
  3. **Indications: **useful in **functional bowel obstruction **(e.g. opiate induced, GORD etc.) Less useful in PONV, chemotherapy or radiotherapy
  4. **Adverse effects: **Agitation, EPSP (avoid in Parkinsons; Domperidone is an alternative that does not cross BBB) mechanical bowel obstruction
21
Q

Anti-emetics: Cyclizine

For cyclizine, what is the:

  1. Class
  2. Mechanism
  3. Indications
  4. Adverse effects
A
  1. **Class: **antihistamine, antimuscarinic
  2. **Mechanism: **inhibits histamine receptors in vomiting centre, slows peristalsis in GI tract
  3. **Indications: **PONV, drug induced motion sickness (prochloperazine also appropriate), mechanical bowel obstruction. Less useful for chemotherapy or radiotherapy.
  4. Adverse effects: drowsiness, dry mouth, urinary retention
22
Q

​Anti-emetics: Dexamethasone

For dexamethasone, what is the:

  1. Class
  2. Mechanism
  3. Indications
  4. Adverse effects
A
  1. Class: Corticosteroid
  2. Mechanism: not fully understood; reduces cerebral oedema (relieves ↑ICP) , may affect prostaglndins in the brain
  3. Indications: raised ICP, liver metastases, PONV, chemotherapy
  4. **Adverse effects: **usual corticosteroid
23
Q

Antiemetics: specific clinical scenarios

Which would be the most appropriate anti-emetic in the following scenarios:

  1. Post-op Nausea and Vomiting
  2. Motion sickness, labyrinthine disorders
  3. Functional Bowel Obstruction / Gastric Statsis
  4. Mechanical Bowel Obstruction
  5. Drug induced vomiting
  6. Vomiting associated with hypercalaemia and renal failure
A

Clinical Pharmacology (11 decks)

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