It contains various drugs used for constipation. and its mechanism of actions.

1. DRUGS USED FOR
CONSTIPATION
PRESENTED BY
E.POOVARASAN
M.PHARM FIRST YEAR
DEPARTMENT OF PHARMACOLOGY
PSG COLLEGE OF PHARMACY
DRUGS USED FOR CONSTIPATION 1

2. CONTENTS
• INTRODUCTION
• CAUSES OF CONSTIPATION
• DRUGS USED FOR CONSTIPATION
• MECHANSIM OF ACTION OF PURGATIVES AND LAXATIVES
• REFERENCES
DRUGS USED FOR CONSTIPATION 2

3. GIT TRACT
DRUGS USED FOR CONSTIPATION 3
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MY.CLEVELANDCLINIC.ORG

4. CONSTIPATION:
• Constipation means delayed passage of faeces through the intestine
but the defaecation process remains normal.
• Constipation occurs when bowel movements become less frequent
and stools become difficult to pass.
• It happens most often due to changes in diet or routine, or due to
inadequate intake of fibre.
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5. DRUGS USED FOR CONSTIPATION 5

6. DRUGS USED FOR CONSTIPATION 6

7. DYSCHEZIA
• Dyschezia means derangement of defaecation process which may
result due to
• Pain arising from haemorroids or fissure
• Presence of hard dehydrated faecal matter in the rectum
• Sudden cessation of a habitual use of a purgative
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8. DRUGS USED FOR CONSTIPATION:
LAXATIVES:
( Aperients, Purgatives, cathartics)
These are drugs that promote evacuation of bowels. A distinction is
made according to the intensity of action.
a) Laxative or aperients:
Milder action, elimination of soft but formed stools.
b) Purgative or Cathartic:
Stronger action resulting in more fluid and forceful evacuation.
Many drugs in low doses acts as laxative and in larger doses as
purgative.
Aperient(to get rid off) < Laxative ( to loosen) < Emolient( to smooth
and soften < Evacuant ( to empty) < Purgative ( to clean) < cathartic ( to
utterly clean)
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9. LAXATIVES:
Laxatives are used
1. To treat constipation
2. To avoid undue straining at defaecation cases having hernia,
haemorrhoids or cardiovascular disease
3. Before or after surgery of any anorectal disease
4. In bedridden patients
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10. LAXATIVES (Purgatives, Cathartics)
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11. MECHANISM OF ACTION OF LAXATIVES:
All purgatives increase the water content of faeces by
a) A hydrophilic or osmotic action, retaining water and electrolytes in
the intestinal lumen- increase volume of colonic 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.
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12. • However, certain purgatives do increase motility through action on
the myenteric plexuses.
• 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+ ATPas of villous cells – impairing electrolyte and
water absorption.
b) Stimulating adenylyl cyclase inn crypt cells – increasing water and
electrolyte secretion.
c) Enhancing PG synthesis in mucosa which increase secretion.
d) Increasing NO synthesis which enhances secretion and inhibits non-
propulsive contractions in colon.
e) Structural injury to the absorbing intestinal mucosal cells
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13. MECHANISM OF ACTION OF LAXATIVES:
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14. BULK FORMING LAXATIVES:
Examples:
Wheat bran, Psyllium husk, semisynthetic cellulose- Methyl cellulose,
Carboxy-methyl cellulose and polycarbophils.
Site and mode of action:
They are hydrophilic , indigestible vegetable fibres.
They stimulate local peristalsis and defaecation reflexes by increasing
foecal bulk due to their water absorbing and retaining capacity.
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15. Dosage and Latency period:
Adequate amount of water must be taken with all bulk forming
laxatives. Effect withing 10-12 hrs. Latency period is 1 to 3 days.
Side effects:
Bacterial digestion of vegetable fibres within the colon may lead to
bloating and flatus causing abdominal discomfort.
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16. STOOL SOFTENER:
LUBRICANT LAXATIVES:
Example: Liquid Paraffin
Site and mode of action: It is a luminally active agent . It is pharmacologically inert
mineral oil.
It is foecal lubricant and stool softener as it retards water absorption from the
stool.
Dosage :
It is given as 15-30 ml per day at bed time.
Side effects:
• It is not palatable but can be given in emulsified form or with juices.
• Frequent use leads to the deficiency of fat soluble vitamins as they are carried
away with stool in emulsified form.
• It also delays the healing of enteric fistula.
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17. SURFACTANT LAXATIVES:
Example; Dioctyl sodium sulfosuccinate( Docusate), Glycerine suppositories.
Site and mode of action:
• It is an anionic detergent which softens the stool by decreasing the surface
tension of the fluids in the bowel.
• It also acts as wetting agent for the bowel, because by emulsifying colonic
contents if facilitates the penetration of water into faeces.
Dosage
• 100-400 mg orally per day.
• de effects:
• It is bitter in taste, it can cause nausea.
• Cramps and abdominal pain may occur.
• Hepatotoxicity may occur after prolonged use.
• It increases the absorption of liquid paraffin, hence should not be given
together.
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18. PURGATIVES:
• Purgatives are used complete colonic cleansing prior to
gastrointestinal endoscopic procedures.
• These may also be needed for postoperative or post MI bed-ridden
patients and to flush out worms after the use of an anthelmintic drug.
• These are also used to prepare the bowel before surgery or
abdominal X-ray and may be needed for neurologically impaired
patients.
• In low doses these can be used as laxative also .
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19. OSMOTIC PURGATIVES:
Examples:
A) Saline Purgatives: Magnesium sulfate, Magnesium hydroxide (Milk
of magnesia) and sodium sulfate and sodium phosphate.
B) Polyethylene glycol ( PEG):
Electrolyte osmotic purgative.
Site and Mode of action:
All of them act on small as well as large intestine.
Saline Purgatives:
• Saline purgatives are soluble inorganic salts which increase the faecal
bulk by retaining water by osmotic effect, thus increasing peristalsis
indirectly.
• Magnesium salts also release CCK which further helps in increasing
intestinal secretions and peristalsis.
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20. Polyethylene glycol( PEG)
• Electrolyte osmotic purgative contains a nonabsorbable polyethylene
glycol (PEG) which is a sugar that retains water by virtue of its high
osmotic nature.
• It is used in a form of a balanced isotonic solution prepared by adding
sodium chloride.
Side Effects :
• These hyper osmolar agents may lead to intravascular fluid depletion
and electrolyte disturbances.
• These should never be used on long-term basis.
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21. IRRITANT PURGATIVES/ STIMULANT
PURGATIVES:
Examples;
a) Anthraquinone laxatives: Senna, cascara, aloe
b) Organic irritants: Phenolphthalein, Bisacodyl , Sodium picosulfate
c) Oils: caster oil
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22. Site and mode of action:
• All of them stimulate peristalsis by irritant action on intestinal
mucosa.
• They also stimulate colonic electrolyte and fluid secretion by altering
the absorptive and secretory activity of the mucosal cells.
Anthraquinone laxatives:
• Aloe, senna and cascara occur naturally in plants. Senna is most
commonly used.
• These plant purgatives contains anthraquinone glycosides.
• On reaching colon, the bacteria degrades them to active principles-
‘anthrol’ – which either acts locally or is absorbed into circulation.
After being excreted through bile it then stimulates small intestine.
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23. Bisacodyl
• Site of action of organic irritants is in the colon.
• Bisacodyl is activated in the intestine by deacetylation.
• Its deacetylated metabolite is therefore active. It irritates colonic
mucosa to increase fluid secretion, as well as stimulate enteric
neurons to promote peristaltic movements.
sodium picosulfate
• In the colon sodium picosulfate converted to the active metabolite
bis( P- hydroxyphenyl) pyridyl-2-methane which stimulates
peristalsis and promotes water and electrolyte accumulation.
Castor oil
• . It is hydrolysed in intestine by pancreatic lipase to ricinolic acid
which increases the intestinal motility.
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24. Side effects
• Senna glycosides are secreted through milk, hence should be avoided
in lactating mothers.
• These glycosides turn urine colour to yellowish – brown (acidic urine)
or to red ( alkaline urine).
• All anthraquinones can produce abdominal cramps and nausea.
• Phenolphthalein turns urine reddish pink if alkaline and cause
carcinogenicity.
• Bisacodyl, is however, quite safe, except for occasional abdominal
cramps and skin rashes. Higher doses can cause mucosal damage.
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25. • Prolonged use or overdosage of sodium picosulfate can cause colonic
atony and hypokalaemia.
Castor oil
• unpalatability , frequent cramping , after – constipation and risk for
damaging intestinal mucosa
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26. Others:
5HT4 RECEPTOR AGONISTS:- PRUCALOPRIDE
• It activates prejunctional 5-HT4 receptors on enteric neurons,
increase release of Ach , promoting propulsive contractions in ileum
• It is approved for use of chronic constipation and predominant IBS.
Opioid Antagonists :
Methylnaltrexone, alvimopan
Chloride channel activator:- Lubiprostone
• They are PG analogue and act through EP4 receptor and to stimulates
guanyl cyclase C and there is activation Cl- channels increase Cl-
rich intestinal fluid and accelerates colonic transit.
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27. CHOICE AND USE OF PURGATIVES:
Functional constipation:
• Infrequent production of hard straining stools
• Spastic constipation ( irritable bowel – ispaghula or other fibre)
• Atonic constipation( sluggish bowel) - initial measures fluid, intake ,
exercise. Then go for bulk forming agent or osmotic laxatives( lactulose or
Mag.hydroxide)
Bedridden patients:
Prevention: bulk forming agents, doscusates, lactulose and liquid paraffin.
Treatment : Enema ( soap-water/ glycerine); bisacodyl or senna may be used
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28. Straining at stools :
• Essential to keep faeces soft. Use adequate dose of bulk forming
agent, lactulose or docusates
Preparation of bowel for surgery colonoscopy, abdominal X-ray;
• Needs of emptied contents – saline purgative, bisacodyl or senna
After certain anthelminitics; ( tape worm)
• Saline purgative or senna – flush out the worm with drug.
Food / drug poisoning:
• Saline purgatives.
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29. LAXATIVE ABUSE:
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30. REFERENCES
• ESSENTIALS OF MEDICAL PHARMACOLOGY – 8TH EDITION BY K.D
TRIPATHI.
• MEDICAL PHARMACOLOGY BY PADMAJA UDAYAKUMAR
• SHARMA AND SHARMA’S PRINCIPLES OF PHARMACOLOGY
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