Lecture 4 And 5 Constipation Flashcards
Incidence of constipation in female > male (__ fold)
2.5
Definition of constipation
Unsatisfactory defacation - infrequent stools, difficulty passing stools or both
Diagnostic criteria for chronic constipation
Prescence of greater than or equal to 2 of the following for last 3 months
- straining
- lumpy hard stool
-incomplete evacuation - sensation of anorectal obstruction
-manual help to defacation - <3 spontaneous bowel movement per week
- loose stools not present
Causes of constipation
No identifiable underlying cause
Bloating or straining, difficulty with defecation, linked with bad diet
3 types:
Normal transit constipation
Days-synergic
Slow transit constipation
Drugs commonly associated with constipation
OTC: calcium supplements, antacids, aluminum containing iron supplements, antihistamines, anti diarrheal agents, Dimenhydrinate
Rx medication: opioids, anticholinergic, CCB, tricyclic antidepressants, diuretics, antispasmodics, antipsychotics, antiseizure meds
Complications of constipation
Hemorrhoids
Fissures
Fecal impaction
Megacolon
Malnutrition
Rare : pelvi organ prolapse in women
Very rare - intestinal perforation
Red flags for constipation
GI bleeding
Unexplained iron deficiency anemia
Unintentional weight loss
Palpable abdominal mass
Family hx
Sudden acute onset
Symptom onset >50 yrs of age
Abdominal pain
Non pharmacological treatment approaches to constipation (diet)
- High fibre diet ( 28-38gm per day). Ex. Lentils, chickpeas, kidney beans, prunes, plumes, raspberries
- fluid intake 2-3L
- fruit in diet
High sorbitol foods - Priunes, prune juice
Non pharmacological treatment approaches to constipation (lifestyle)
Regular excercise
Regular scheduled time for toilet use
Avoid suppressing urge to defecate
Weight loss
Increase calories if on low cal diet
Four general classes of Laxatives sold as OTC
Bulk forming laxatives
Osmotic laxatives
Stimulant laxatives
Emollient/stool softener
Bulk forming laxatives
Soluble / insoluble fibers
Preferred : Psyllium ( eg. Metamucil) - natural fiber from husks of plant seeds, another name is isaghula
Alternates: calcium polycarbophil (fibrecon), methyl cellulose (citrucel)
Others: all natural
Guar gum
Sterculia gum
Inulin
Bulk forming laxatives
MOA
Onset
Adverse affects
Drug interaction
MOA: increase stool weight and constituency, decreases GI transit time
Onset : 12-72 hours ( usually 1-3 days)
** Often first line treatment except constipation from poor GI motility or opioids **
Adverse affects: bloating, flatulence, diarrhea
Drug interactions: avoid use within 2 hours of administration of medication
What are the types of osmotic laxatives and their MOA
MOA : poorly absorbed solutes or ions act by exerting an osmotic gradient and retain water in lumen
Types: saline laxatives, hyperosmotic
Osmotic laxatives : Saline
Onset
Caution
0.5-3hrs
Caution: in chronic constipation due to risk of electrolyte disturbances, avoid in renal impairment (can cause Hypermagnesemia)
Osmotic laxatives : Hyperosmotic ( glycerin suppository)
Onset
Adverse effects
Use in children
Instructions
Quick (15-30 mins)
Well tolerated but can cause local irritant effect
2-6 yrs - 1 supp daily prn
<2 yr- limited data, use 1 ever 3 days prn
Moisten in lukewarm water, then insert and retain for about 15 mins if possible
Osmotic laxatives: Hyperosmotic (PEG)
Onset
Adverse effects
Drug interactions
Dose
48-96 hours
Adverse effects: bloating, flatulence, diarrhea
Avoid use within 2 hours of administration
Dose: add 17g powder to 250ml water, juice, coffee or tea and stir until dissolved
Use in acute or chronic constipation
PEG + electrolyte solution
Colyte, golytely
Complete bowel evacuation before surgery or diagnostic procedures or for refractory constipation
LARGE volume
Osmotic laxatives : Hyperosmotic (Lactulose)
Onset
Acute or chronic
Adverse effects
Non absorbable disaccharide (fructose, galactose)
Onset: 24-48 hours
Acute or chronic
Adverse effects: flatulence, bloating, nausea, diarrhea
Lactulose downsides and drug interactions
Downsides: sweet taste, can be masked by diluting in water, juice, or milk, less effective than PEG 3350
Drug interactions: avoid use within 2 hours of administration
Stimulant Laxatives ( Anthranoid laxatives)
Sennosides ( anthraquinones, ie senokot, ex-lax)
Cascara
Onset 8-10ths
Bisacodyl.diphenylmethane (Dulcolax)
Oral 6-8h, supp 0.5-1hr
Large interpatient variability with dose
Stimulant laxatives adverse effects
Abdominal cramps, diarrhea ; others: hypokalemia ; suppositories irritation
Senna discolour urine
Bisacodyl oral are enteric coated - caution with use of PPI or H2blockers
Usually short term
Emollient/ stool softeners (docusate)
Onset
Effectiveness
12-72 hours
Not been found effective for constipation
Enemas
Stretches colon to produce urge to defecate
Faster onset
Examples:
- mineral oil retention enemas
- phosphate enemas
- Tap water enemas
Administering enema
Lubricate nozzle
Lie on left side with knees bent
Insert nozzle in rectum
Gently squeeze container
Retain the solution until cramping is felt
