Week 9: Gastrointestinal - Dyspepsia, Nausea, Diarrhea, Constipation Flashcards
Definition of constipation
Defecation <3 times per week; often with straining and passage of hard, uncomfortable stool
Frequency or consistency outside normal for patient
Symptoms of constipation
- Decreased frequency of bowel motion
- Change nature of stool
- Straining
- Incomplete sense of evacuation
- Bloated
- Cramp/discomfort
Causes of constipation
Lifestyle
- Inadequate fluid intake
- Low fibre diet
- Lack exercise
Other causes
- Some medications
- Conditions including MS, Parkinson’s, diabetes, depression and hypothyroidism
- Obstruction of bowel
- Pregnancy
- Advancing age
Complications of constipation
- Anorexia and nausea often experienced with constipation
- Continued fluid absorption from bowel lead to fecal impaction leading to overflow diarrhea or bowel obstruction
- Hemorrhoids and anal fissures from straining
- Fecal impaction can lead to urinary retention and overflow incontinence
- Elderly can also experience confusion and delirium
Non pharmacological interventions for constipation
The four F’s
- Fibre = increase gradually to avoid bloating and flatulence (adequate fluid)
- Fluid
- Fitness
- Feet - positioning on toilet
Treatment of constipation
- When to use laxative
- Factors influencing laxative choice
Use laxative if
- Lifestyle and dietary changes are ineffective
- Fecal impaction develops
- Taking or starting opioid analgesic
Factors affecting laxative choice
- Symptoms
- Rate of onset
- Age
- Preference of patient
- Adverse effects
- Effectiveness of previous treatment
- Cost
Bulk forming laxatives
- MOA
- Examples
- Indication
- Practice point
MOA
- Increase volume of intestinal contents, stimulating peristalsis or intestinal motility
Examples
- Psyllium
Indications
- Mild constipation - can take 3 days to see full effect
Practice points
- Adequate hydration is required
- Gradual increase in fibre will decrease likelihood of adverse effects such as bloating, impaction, flatulence
Osmotic laxatives
- MOA
- Examples
- Indication
- Practice points
MOA
- Draw fluid into feces or retain fluid in colon by osmotic effect to increase volume of stool therefore stimulating peristalsis
Examples
- Lactulose
- Glycerine
- Macrogol
- Sorbitol, saline
Indications
- Lactulose can take 2-3 days to work (chronic constipation)
- Low dose of mactrogol useful in chronic constipation
- Glycerine suppositories and large doses of macrogol can be used hen rapid relief is required (within 2 hrs effect)
Practice points
- Take with fluid to augment osmotic effect
- Affect fluid balance in body so be careful in CVD patients
Stimulant laxatives
- MOA
- Examples
- Indications
- Practice points
MOA
- Direct stimulation of nerve endings in colonic mucosa, which increases intestinal motility
- Cause accumulation of water and electrolytes in colon
Examples
- Bisacodyl
- Senna
Indications
- Reserved or opioid induced constipation or severe constipation unresponsive to bulking or osmotic laxatives
Practice points
- Take effect within 6-12 hrs
- Should not be used long term as it can be difficult to establish normal bowel movements one ceased (rebound constipation)
Stool softening laxatives
- MOA
- Examples
- Indications
- Practice points
MOA
- ease passage via assisting absorption of water into stool
Examples
- Docusate
- Liquid paraffin (children)
Indications
- Usually in combination with another laxative (stimulant)
Practice points
- No evidence that use alone are effective laxatives
- Onset of action is 1-3 days
Suppositories and Enemas
- MOA
- Indications
- Examples
MOA
- Used locally when rapid effect is required or patient cannot take medication orally
- Inserted rectally
- Suppositories are semi-solid (melt when hit warmth of rectum)
- Enemas are liquid based
Indications
- Treat fecal impaction
Examples
- Glycerine suppositories
- Osmotic enemas
Laxative - special populations (pregnancy)
- Avoid stimulant laxatives
- Suggest management advice (4 f’s)
- If have to use laxative suggest bulk forming or stool softener
- Docusate, lactulose or sorbitol are category A
Laxatives - special populations (elderly)
Following factors can contribute to development of constipation
- Changed environment
- Decrease mobility
- Drugs
- Diminished intake of fiber and fluid
- Painful anorectal disorders
- Co-morbidities which cause loss of muscle power
Bulking agents effective if mobile
Osmotic and stimulant useful if bed bound and on opioids
Fecal impaction
- Definition
- Presentation
- Management
Definition
- Contents of colon build up to point where cannot physically pass
- Presents as fecal incontinence or overflow diarrhea
Management
- High dose oral macrogol
- Suppositories and enemas
- Manual disimpaction
Prevention and treatment of opioid induced constipation
- Constipating effect is mediated through mu receptor in GIT
> Peristalsis is decreased, pancreatic and biliary secretions are decreased (necessary for proper stool formation and passing) - Constipating effect is dose related and tolerance rarely develops
Agents of choice
- Stool softener + stimulant or osmotic laxative
Definition of diarrhea
Classification of diarrhea
Definition
- Increase in fecal discharge, in terms of volume, fluid quantity and/or frequency relative to usual bowel habits
Classification
- Acute (<7 days)
- Persistent (>14 days)
- Chronic (>28 days)
Clinical features of diarrhea
- Rapid onset
- N&V may be present prior to or during acute diarrhea
- Abdominal cramping and tenderness
- If due to rotavirus - might experience symptoms of cough and cold
- Acute infection diarrhea is usually watery with no blood present
- Complete resolution of symptoms 2-4 days
Causes of acute diarrhea
- Some infectious agents
> Virus (rotavirus, norovirus)
> Bacterial (e.coli, campylobacter, vibrio cholerae, salmonella, clostridium difficile)
> Parasite (Giardia) - Contaminated food and water (travelers diarrhea)
- Drugs
Causes of chronic diarrhea
- Coeliac disease - disorder of small bowel caused by immune response to ingested wheat or wheat related products
- Irritable bowel syndrome - cause thought to include altered bowel motility, hypersensitivity and psycho social factors
- Inflammatory bowel disease (ulcerative colitis and Crohn’s disease) - chronic, relapsing condition characterized by chronic inflammation
- Lactose intolerance - deficiency of lactase in small bowel mucosa resulting in lactose malabsorption
- Diverticular disease - herniations of colonic mucosa through the muscle layer in large bowel
- Fecal impaction - constipation with overflow
- Gastrointestinal cancer - persistent diarrhea
Substances commonly causing diarrhea
- Acarbose and Metformin
- Alcohol
- Antibiotics
- Cytotoxic agents
- Food and drug addititves (sorbitol, mannitol, fructose)
- Laxative
- Magnesium containing antacids
- NSAIDS
Management of acute diarrhea
- ORS
- Short term dietary adjustment
- Treatment options
Most cases are self limiting and do not require drug therapy
- Oral rehydration solutions (ORS) prevent dehydration and correct electrolyte disturbances (IV rehydration may be required in severe cases)
- Short term dietary adjustments
> Limit consumption of fatty, sweet or spicy food
> Increase consumption of starchy food
> Avoid alcohol and caffeine
> Increase probiotics
> Limit fruit juice in children (sugar makes it worse)
> May get lactose intolerance for period of time
Treatment options - Fluid in adults - ORS - OTC anti-motility medicines > Loperamide > Diphenoxylate
Symptoms of moderate to severe dehydration (most dangerous complication of diarrhea)
- Weight loss
- Lethargy
- Dry lips, eyes, tongue
- Increase thirst
- Sunken eyes
- Sunken fontanelle (babies)
- Loss of skin rigidity
- Decrease urine output
- Rapid pulse
- Dark urine
Antidiarrheas/Antimotility agents
- MOA
- Indications
- Contraindications
MOA
- Slow gut motility and allow more toxins to be absorbed (slow resolution of diarrhea)
Indication
- Short term use for control of symptoms during periods of social inconvenience as just prevents inevitable
Contraindications
- Patients where possibility of invasive organism
- Should not be used in children
Opioid anti-diarrheas
- MOA
- Indications
- Contraindications
- Side effects
MOA
- Activate opioid receptors in gut wall to reduce bowel motility and increase fluid absorption back into body
Indication
- Short term treatment of acute diarrhea
Contraindications
- Intestinal obstruction, chronic diarrhea, children
- Avoid long term use due to potential addictive effect
Side effects
- Abdominal pain
- Bloating
- N&V
- Constipation
Other diarrhea treatment options
- Antibiotics
- Anti-cholinergics
Antibiotics (metronidazole, tinidazole, norfloxacin)
- Severe bacterial/protozoal infections or if there is an outbreak requiring prophylactic therapy
Anti-cholinergics (Hyoscine, atropine, hyoscamine)
- Slow gut by blocking cholinergic receptors
- Doses of OTC products too low to work
- Increased dose can have adverse effects due to action in CNS as well as GIT
Definition of gastro-oesophageal reflux disease (GORD)
Condition that develops when reflux of stomach contents causes troublesome symptoms and/or complications and significantly effects person’s wellbeing
- Reflux symptoms > 2 times a week or significant impact of QALY
Pathophysiology of GORD
Key factors
- Spontaneous or transient or sustained relaxation of lower esophageal sphincter
- Low resting pressure of LOS
- Increased intra abdominal pressure
- Reduced esophageal clearance
- Impaired mucosal defences
Risk factors of GORD
Comorbidities of GORD
Factors increasing the likelihood of reflux
Risk factors
- Genetic
- Demographic (age, gender, pregnant)
- Lifestyle (diet, coffee consumption, alcohol, dietary habits, body mass index, physical exercise, smoking)
- Environmental (hiatus hernia, stress, medication use)
Comorbidities
- Abdominal pain/dyspepsia
- Dysphagia
- Asthma
- Chest pain
- ENT infection
- URT infection
- Anxiety/mood disorders
- Cough and/or laryngitis
Likelihood of reflux increases when
- Gastric pressure increases (obesity, pregnancy, tight clothing)
- Gastric volume increase after meals
- Gastric contents near LOS (laying down or bending over)
- Gastric emptying delayed (fatty food)
Complications of GORD
Not adequately treated can develop complications from long term acid exposure
- Oesophagitis
- Oesophageal strictures
- Oesophageal cancer
GORD lifestyle modifications
- Raise head of bed at night
- Smaller more frequent meals
- Weight loss
- Smoking cessation
- Decrease alcohol intake
- Avoid bending or stooping after eating
- Avoid eating or drinking 2-3 hrs before bed
- Decrease intake of fatty food, spicy food or chocolate
- Decrease caffeine intake
Pharmacological treatment of GORD
- Treatment options
> MOA
> Prefix/suffix (examples)
Antacids
- Neutralize hydrochloric acid secreted by gastric parietal cells
Alginate-antacids
- Form relatively pH neutral barrier to decrease exposure to esophageal to acidic gastric content
- Examples (alginic acid, sodium alginate)
H2RAs
- Competitively block histamine 2 receptor on parietal cells, reducing gastric acid secretion
- Examples (-tidine)
PPIs
- Inactivate the hydrogen/potassium ATPase enzyme system (proton pump) suppressing both stimulated and basal acid secretion
- Examples (-prazole)
Mild/Moderate GORD 1st line therapy - Antacids
- Practice points
Antacids
- Short term relief of symptoms (fast onset and short duration)
- Take between meals or at bed when expect symptoms to occur
- Optimal effect 1-3 hrs after meals
- Tablet should be chewed or sucked before swallowing and take with glass of water
- May need 2nd line if required more that twice a week
GODR - H2 receptor antagonists (H2RAs)
- Practice points
- Onset about 30-45 min
- Duration about 10 min
- Some available OTC
- Generally well tolerated
GORD - Proton pump inhibitors (PPI)
- Practice points
- Drug interactions with PPIs
- Most effective if taken 30-60 min before food
- Onset 1 hr but can take 2-3 days to see full effect
- Duration 12 hrs
- Take for 4 weeks then review
Drug interactions
- Clinically important interactions are rare
- All acid suppressing drugs potentially decrease absorption of some drugs by increasing gastric pH
> separate by 2 hrs
- PPI mainly metabolized by CYP2C19 and CYP3A4 enzymes
GORD maintenance therapy
Aim
- Control symptoms
- Reduce risk of complications
- Minimize cost
Peptic ulcer disease (PUD)
- Definition
- Common forms
- Types of ulcers
Definition
- Breakthrough entire thickness of gastric or duodenal mucosa as result of acid and pepsin in gastric juice
Common forms
- Associated with H. Pylori
- Associated with aspirin and NSAIDS
Types of ulcers
- Duodenal
- Gastric
Causes of PUD
- H. pylori
- NSAID use
- Smoking
- Chronic alcohol consumption
- Chemotherapy and radiotherapy
- Stress related mucosal damage
Clinical presentation of PUD
- Mild pain (burning, gnawing or aching)
- Abdominal pain (burning or feeling discomfort)
- Nocturnal pain
- Severity of pain fluctuates
- Pain often occurs 1-3 hrs after meal
- Patients may complain of heartburn, belching, bloating, nausea or vomiting
- Bleeding indicated by coffee ground vomit or black, tarry stools
Complications of PUD
- Mild to severe hemorrhage (hematemesis, weakness, fainting, blood in stool, thirst and sweating)
- Stomach or duodenal wall perforation (causes intense, persistent abdominal pain)
- Gastric outlets obstruction (caused by scarring, spasm or inflammation from ulcer)
Goals of therapy in PUD
- Eradicate H. pylori
- Resolve symptoms
- Reduce acid secretion
- Promote epithelial healing
- Prevent ulcer related complications
- Prevent ulcer recurrance
Lifestyle modifications of PUD
- Avoid exposure to factors known to worsen disease and exacerbate symptoms
- Reduce psychological stress
- Avoid smoking
- Avoid alcohol consumption
- Avoid food or beverages that exacerbate ulcer symptoms (spicy, fatty, acidic)
- Avoid NSAIDS or aspirin use
Eradication of H.pylori
1st line
- Esomeprazole (PPI)
+ clarithromycin + amoxicillin with triple therapy having 85-90% success rate as H.pylori is resistant to either on own
NSAID related PUD
- Most are gastric
- Stop NSAID if possible and use PPI for 4-8 weeks
- Several factors increase risk of developing GI complications
> Age
> History of PUD or ulcer bleeding
> High NSAID dosage
> Prolonged use
> Concomitant drug therapy
Low dose aspirin and PUD
- Increase risk of PUD with low dose aspirin
- Effect is dose dependent and not reduced by enteric coated or buffered aspirin
Pathophysiology of nausea and vomiting
See diagram
- Nausea and vomiting caused by stimulation of salvation and respiratory centers, pharyngeal, GI and abdominal muscle contraction which is stimulated by the central vomiting center in medulla.
- The Central vomiting center is stimulated by chemoreceptor trigger zone, vestibular system, cerebral cortex and gastrointestinal visceral afferents
Causes of acute N&V
- Medications/toxins
- Physical stress
- Emotional stress
- Motion/vestibular activity
- Most common cause is viral gastrointestinal and bacterial food poisoning
- Mechanical GI obstruction
- Pregnancy
- Neurological
Causes of chronic N&V
- Drugs
- GI conditions
- General medical conditions
- Neurological conditions
- Psychiatric/psychological
What drugs cause N&V
- Chemotherapy
- Opiates
- NSAIDS
- Digoxin
- Antiarrhythmia
- T2DM
- Antibiotics
- Nicotine
- Anticonvulsants
- High dose vitamins
Non pharmacological treatment for N&V
- Gradually drink larger amounts of clear liquids
- Avoid solid food
- Eat light, bland food
- Avoid fried, greasy or sweet food
- Eat slower and smaller, more frequent meals
- Do not mix hot and cold foods
- Drink beverages slowly
- Avoid activity after eating
- Rest
- Temporarily discontinue oral medication if they irritate stomach if it is safe
Management of N&V
- Identify underlying cause
- Ensure adequate hydration ORS
- Antiemetic drugs
> Dopamine antagonist, sedating antihistamines, anticholinergics, 5HT3 antagonists
N&V - Dopamine antagonists
- MOA
- Examples
- Practice point
MOA
- Block dopamine receptor in chemoreceptor trigger zone
Examples
- Domperidone
- Metoclopramide
- Prochlorperazine
Practice points
- All except doperidone work elsewhere in CNS and may cause EPSE under 20 yrs
- Drowsiness due to CNS activity
N&V - Sedating antihistamines
- MOA
- Examples
- Practice points
MOA
- Act on H1 and dopamine receptors in CTZ
Example
- Pheniramine
- Promethazine
Practice points
- Used to prevent motion sickness and other vestibular disorders
- Cause sedation
- Do not use under 2 yrs
N&V - anticholinergics
- MOA
- Examples
- Practice points
MOA
- Block muscarinic receptor in vestibular system
Examples
- Hyoscine
Practice points
- Used only for motion sickness
- Avoid in children <2 yrs
- Lots of ADR
N&V - 5HT3 antagonist
- MOA
- Examples
- Practice points
MOA
- Activation stimulates visceral nerve fibers in GIT and stimulates CTZ, antagonist blocks activation of these receptors
Examples
- Ondansetron
Practice points
- Associated with cancer chemotherapy and radiotherapy
- Post operative
- Used where conventional antiemetics not tolerated
- Common for morning sickness
N&V complementary therapies that are clinically proven
Ginger
- High dose
- Recommended for morning sickness
- Prevention of travel sickness
Vitamin B6
- Preventing and treating morning sickness
- Avoid large dose due to peripheral neuropathy
