laxatives

laxatives

1. CONSTIPATION

2. CONSTIPATION
•Constipation is a condition where there is
infrequent bowel movement, usually less than 3
stools per week.
•As the food moves down through the large
intestine, the colon absorbs water while forming
waste products or stool. Muscle contraction in
the colon push the stool towards rectum. By the
time the stool reaches rectum it is solid because
most of the water has been absorbed. The colon
muscle contraction are slow or sluggish causing
stool move through colon too slowly.

3. CAUSES:
Diet (Lack of fibers & liquids)
 Lack of exercise
 Age
 Irregular bowel habits
 Drug induced
 Disease States/Conditions
Spasm of sigmoid colon
Dysfunction of myenteric plexus

4. SYMPTOMS OF CONSTIPATION
Infrequent defecation
Nausea
Vomiting
Anorexia
Feeling full quickly
Stools that are small, hard, and/or difficult to evacuate
Rectal bleeding
Weight loss (in chronic constipation)

5. Management of constipation
Beginning with advice on lifestyle (including
exercise and adequate hydration)
Dietary modification.
Consumption of plenty of fresh vegetables, fruits,
milk, and water.
Establishing regular bowel, eating and exercises
habits.
Where lifestyle changes and dietary modification
are insufficient, a laxative may be considered.

6. LAXATIVES
Drugs that promote evacuation of bowels.
Based on intensity of action

7. MECHANISM OF ACTION
All laxatives increase the water content of the faeces
by:
a) A hydrophilic or osmotic action, retaining water
and electrolytes in the intestinal
lumen—increase volume of colonic content and
make it easily propelled.
(b) Acting on intestinal mucosa, decrease net
absorption of water and electrolyte; intestinal transit
is enhanced indirectly by the fluid bulk.
(c) Increasing propulsive activity as primary action
—allowing less time for absorption of salt and water
as a secondary effect.

8. Laxatives modify the fluid dynamics of the mucosal cell
and may cause fluid accumulation in gut lumen by one or
more of following mechanisms:
(a)Inhibiting Na+K+ATPase of villous cells—impairing
electrolyte and water absorption.
(b)Stimulating adenylyl cyclase in crypt cells—increasing
water and electrolyte secretion.
(c)Enhancing PG synthesis in mucosa which increases
secretion.
(d)Increasing NO synthesis which enhances secretion and
inhibits non-propulsive contrations in colon.
(e) Structural injury to the absorbing intestinal mucosal
cells.

9. CLASSIFICATION OF LAXATIVES
1. Bulk forming
Dietary fibre:Bran, Psyllium (Plantago), Ispaghula,
Methylcellulose
2. Stool softener
Docusates (DOSS), Liquid paraffin
3. Stimulant purgatives
(a) Diphenylmethanes:Phenolphthalein, Bisacodyl, Sodium
picosulfate
(b) Anthraquinones (Emodins): Senna, Cascara sagrada
(c) 5-HT4 agonist: Tegaserod
(d) Fixed oil: Castor oil
4. Osmotic purgatives
Saline laxatives, Lactulose, Sorbitol, PEG, Magnesium
oxide

10. Bulk-forming laxatives
 Bulk-forming laxatives are indigestible,
hydrophilic colloids that absorb water, forming a
bulky, emollient gel that distends the colon and
promotes peristalsis.
Common preparations include
Bran
Ispaghula
Methylcellulose and related compounds,
psyllium, or sterculia.
Bulk laxatives are of particular value in those with
small hard stools.

11. Bulk Forming Laxatives
Improve stool consistency and frequency with regular use
Ensure good fluid intake to prevent fecal impaction
Onset of action 2-3 days
Side Effects may include bloating, flatulence, distension

12. STOOL SOFTENERS
Docusates (Dioctyl sodium sulfosuccinate:DOSS)
It is an anionic detergent, softens the stools by net water
accumulation in the lumen by an action on the intestinal
mucosa. Dose: 100–400 mg/day; acts in 1–3 days.
Liquid paraffin
It is a viscous liquid mixture of petroleum hydrocarbons
that is pharmacologically inert.
Taken for 2–3 days, it softens stools and is said to lubricate
hard scybali by coating them.
Dose: 15–30 ml/day—oil as such or in emulsified form.

13. Stool Softeners
May be useful with anal fissures of haemorrhoids
Liquid paraffin is not recommended for treatment of
constipation
-risk of aspiration and lipid pneumonia
-long term use may result in depletion of Vit A, D, E, K

14. Stimulant laxatives
Stimulant laxatives (cathartics) induce bowel
movements through a number of mechanisms.
These include direct stimulation of the enteric
nervous system and colonic electrolyte and fluid
secretion.
Stimulant laxatives in current use include
Phenolphthalein 60–130 mg: LAXIL 130 mg tab.
To be taken at bedtime (tab. not to be chewed).
Bisacodyl 5–15 mg: DULCOLAX 5 mg tab; 10 mg
Senna
Castor oil

15. Stimulant Laxatives
 Increase intestinal motility by stimulating colonic nerves
 Useful with opioids
 Onset of action 8-12 hours
 Development of tolerance is reported to be uncommon
 Generally considered 2
nd
line therapy in elderly due to risk
of electrolyte disturbances
 Other adverse effects include cramping, diarrhoea,
dehydration

16. Osmotic laxatives
Osmotic laxatives are soluble but non absorbable
compounds that result in increased stool liquidity due to
increase in fecal fluid.
saline laxatives such as magnesium hydroxide and
magnesium sulfate
poorly absorbed sugars such as lactulose or sorbitol,
and macrogols (PEG).
Non absorbable Sugars or Salts may be used for the
treatment of acute constipation or the prevention of
chronic constipation.
Magnesium oxide (milk of magnesia) is a commonly
used osmotic laxative. It should not be used for
prolonged periods in patients with renal insufficiency due
to risk of hypermagnesemia.

17. Osmotic Laxatives
Increase fecal water content
bowel distention
increased peristalsis
evacuation
Improving stool frequency
Onset of action – up to 48 hours
Metabolized by bacteria ® flatulence

18. Lactulose It is a semisynthetic disaccharide of fructose
and lactose which is neither digested nor absorbed in the small
intestine—retains water.
Further, it is broken down in the colon by bacteria to osmotically
more active products.
In a dose of 10 g BD taken with plenty of water, it produces soft
formed stools in 1–3 days. Flatulence and flatus is common,
cramps occur in few. Some patients feel nauseated by its peculiar
sweet taste.
Onset of action: 48hrs
Dose: 15-30ml 8 hrly (10g/15ml)
Indication
Hepatic encephalopathy
Distal ulcerative colitis

19. Uses:
1.Functional constipation
2. Bedridden patients
3. To avoid straining at stools (hernia, cardiovascular
disease, eye surgery) and in perianal afflictions
(piles, fissure, anal surgery)
4. Preparation of bowel for surgery, colonoscopy,
abdominal X-ray
5. After certain anthelmintics
6. Food/Drug Poisoning

20. Adverse Effects:
1. Flairing of intestinal pathology, rupture of inflamed
appendix.
2. Fluid and electrolyte imbalance, especially
hypokalaemia.
3. Steatorrhoea, malabsorption syndrome.
4. Protein losing enteropathy.
5. Spastic colitis.
Contraindications:
1. A patient of undiagnosed abdominal pain, colic or
vomiting.
2. Organic (secondary) constipation due to stricture or
obstruction in bowel, hypothyroidism, hypercalcaemia,
malignancies and certain drugs.