Chapter 82: Laxatives Flashcards
laxative are used to
ease or stimulate defication
- soften the stool
- increase stoole volume
- hasten fecal passage through the intestine
- facilitate evacuation from the rectum
- misuse comes from misconceptions of what constitutes normal bowel function
laxative effect
- production of soft, formed stool over 1 or more days
- relativelty mild
Catharsis
- prompt, fluid evaculation of bowel
- fast and intense
what is the function of the colon
- absorbs water and electrolytes
delayed transport through colon causes
excessive fluid absorption and hear stool
what is normal bowel elimination
varies widely (2-3 times per day to 2 times per week)
proper bowel movement is dependent on
dietary fibre
benefits of fibre
- absorbs water (softens feces and increases size)
- can be digested by colonic bacteria whose growth can increase fecal mass
what is the frequent cause of constipation
low fibre diet
what is potimal fibre intake per day
20-60 g
constipation can be cuased by
variety of disease or drugs, poor diet, dysfunction of pelvic floor and anal sphincter or slow intestinal transit
what are the factors that can cause intestinal slowdown
- dehydration
- inadequate amounts of fibre
- ignoreing urge to deficate
- lack of physical activity
- irritable bowel syndrome
- changes in lifestyle or outine, includinf pregnancy, aging and travel
- illness
- frequent use or misuse of laxiatives
- specific diseases, such as stroke, diabetes, thryroid disease, and parkinson disease
constipation
type 1-2
normal
type 3-4
diarrhea
type 5-7
contradictions to laxative use
- abdominal pain, nausea, cramps, symptoms of appenndicitis, regional enteritis, diverticulitis, or ulcerative colitis
- acute surgical abdomen
- fecal impaction or bowel obstruction
- habitual use/abuse
laxatives should be used with caution is
pregnancy and lactation
Classification of Laxatives
- Bulk-forming laxatives (psyllium [metamucil] _
- surfactant laxatives (docusate sodium [Colace] )
- stimulant laxatives (Bisacodyl [dulcolax])
- osmotic laxatives (polyethylene Glycol [restoralax])
Group I
act rapidly (2-6 hours) and give stool a watery consistency; useful for preparing bowel for diagnostic procedures or surgery
Group II
intermediate latency (6-12 hours)
- produce semifluid stool
Group III
act slowly (1-3 days) to produce a soft, formed stool; uses include treating chronic constipation and preventing straining at stool
Bulk Forming Laxatives include
psyllium [metamucil]
- mehtylcellulose [entroce; solution]
- polycarbophil [Prodiem]
- inulin [Benefibre]
Bulk Forming Laxatives MOA
swell with water to form a gel that softens and increases fecal mass
Bulk forming laxatives is often used in the treatment of
diverticulosis and IBS
Bulk forming laxatives adverse effects
minimal
- esophageal obstruction if swallowed without sufficent fluids; intestinal obstruction
Surfactant Laxatives are also called
stool softeners
Surfactant Laxatives MOA
lowers surface tension, which facilitates penetration of water into feces.
Act on intestinal wall to
- inhibit fluid absorption
- stimulate secretion of water and electrolytes into intestinal lumen
surfactant laxatives promote
more water and fat in the stools
Surfactant laxatives examples
Docusate salts [sodium and calcium] (colace)
how long does it take for Docusate salts [sodium and calcium] (colace) to produce a soft stool
several days
surfactant laxative require
adequate fluids
Stimulant laxative is used for
treatment of medication related constipation and slow intestinal transit constipation
Stimulant laxatives MOA
stimulate intestinal motility and increase amounts of water and electrolytes in intestinal lumen
stimulant laxatives include
Bisacodyl (Dulcolax)
- senna/sennosides (senokot preperations; Ex-Lax)
- cascara sagrada
osmotic laxatives low doeses work in
6-12 hours
high doses of osmotic doses see results in
2-6 hours
Polyethylene glycol (PEG) [Restoralax]
- non absorbing compound that retains water in the intestinal lumen causing fecal mass to soften and swell
Glycerin suppository onset
15-60 mins
Polyethylene glycol (PEG) [Restoralax] onset
48-96 hours
Polyethylene glycol (PEG) [Restoralax] can also be used for
catharsis
Lactulose onset
24-48 hours
osmotic laxatives examples
- Polyethylene glycol (PEG) [restoralax]
- glycerin suppository
- lactulose
- magnesium hydroxide [milk of magnesium]
osmotic laxatives adverse effects
- dehydration
- acute renal failure
- sodium retention: exacerbated heart failure, hypertension, edema
Glycerin suppository
softens and lubricates hardened impacted feces and may also stimulate rectal contration
Glycerin suppository onset
occurs about 30 mins after insertion
Mineral oil use
- especially useful when administered by enema to treat fecal impaction
mineral oil adverse effects
- lipid pneumonia
- anal leakage
mineral oil is available in
oral liquid, enema, oral jelly
precalopride [resotran] MOA
- binds with serotonin receptors in the colon and activities the release of Ach
- increases tone and motility
precalopride [resotran] is used for
chronic constipation in females who have other therapies
precalopride [resotran] side effects
headache, nausea and vomiting
Linaclotide [Constella] indication
- chronic idiopathic constipation and IBS-C in adults
Linaclotide [Constella] adverse effects
diarhea and abdominal pain
Laxatives should be administered
30 minutes before the first meal of the day
Methylnaltexone [relistor] is indicated for
opiod induced constipation in palliative care in patients who have other therapies
Methylnaltexone [relistor] side effects
abdominal pain. diarrhea, flatulence, nausea, dizziness
Methylnaltexone [relistor] negatives
expensive, protect from light
Methylnaltexone [relistor] onset
30mins-4houra
what are the types of bowel cleansing products for colonoscopy
- sodium phosphate (oral fleet or fleet enema)
- polyethylene glycol (PEG)
sodium phosphate (oral fleet or fleet enema)
- hypertonic with body fluid
- can cause dehydration and electrolyte disturbances
- possibility or renal damage
Polyethylene Glycol - Electrolyte solutions adminstration
typically 4L
- must ingest 250-500ml every 10 mins for 2-3 hours.
- 2L evening before; 2L day or colonoscopy
hwo do you know if a patient is fully cleansed
BM becomes clear yellow liquid
Polyethylene Glycol - Electrolyte solutions onset
commences within 1 hour
Polyethylene Glycol - Electrolyte solutions most common adverse effect
nausea, bloating, and abdominal discomfort
Polyethylene Glycol - Electrolyte solutions tips
- drink through straw, rinse with mouthwash, non red candy, dimenhydrinate if nausea, chew gum, refrigerate solution
laxative abuse causes
- bowel movements occur daily
- weight loss
Polyethylene Glycol - Electrolyte solutions consequences
- diminished defectory reflexes, leading to further reliance on laxatives
- electrolyte imbalance, dehydration, colitis
bulk forming use
- acute and chronic constipation
- IBS
- diverticulosis
Surfactant use
- acute and chronic constipation
- softening of fecal impaction; movements in anorectal
- facilitation of bowel condition s
osmotic laxative use
- chronic constipation
- diagnostic and surgical preps
stimulant laxative use
- acute constipation
- diagnostic and surgical bowel preps
adverse effects of bulk forming laxatives
- impaction
- fluid overload
- electrolyte imbalances
- esophageal blcokage
surfactant laxatives adverse effects
- skin rashes
- decreased absorption of vitamins
- electrolyte imbalances
osmotic laxatives adverse effects
- abdominal bloating
- electrolyte imbalances
- rectal irritation
stimulant laxatives adverse effects
- nutrient malabsorption
- skin rashes
- rectal irritation
- electrolyte imbalances
- gastric irritation
- rectal irritation
laxative drug interaction
bulk forming laxative concurrently with other medications
