This document discusses various types of saline cathartics (laxatives) including their definitions, mechanisms of action, preparations, and uses. The main types discussed are bulk forming laxatives, osmotic laxatives, lubricant laxatives, surfactant laxatives, and purgatives. Specific saline cathartics described in detail include magnesium hydroxide, magnesium sulfate (Epsom salt), and magnesium carbonate. Their preparations, assays, uses as laxatives or other purposes, and dosages are provided.

1. Saline cathartics

2. Definition
• Drugs that relieve constipation and promote
defecation.
• It is otherwise called as laxatives or purgatives.
• Constipation is delayed passage of faeces
• Presence of hard dehydrated fecal matter in
the rectum.
• Habitual use of purgatives.
• Presence of haemorrhoids and fissures

3. • Constipation is relieved by non
therapeutic measures like increasing the
fibre content of daily diet intake or
increase daily fluid intake.
• If it fails the laxatives and purgatives are
used.
• The intensity of their action depends on
dose.
• Laxatives eliminates soft semisolid stool
and the purgative lead to watery
evacuation.

4. The order of effectiveness is described
as follows
• Aperients – to smooth and soft
• Evacuant – to empty
• Purgative – to clean
• Catharatic – to completely
clean

5. Types of laxative
•Bulk forming laxatives
•Osmotic laxatives
•Lubricants laxatives
•Surfactant laxatives

6. Bulk forming laxatives
• It acts on intestinal luminal
• Hydrophilic
• Indigestible vegetable fibres which
stimulate peristalsis .
• Peristalsis produce defecation reflexes
by increasing the fecal bulk due to their
water absorbing and retaining capacity.

7. Bulk forming laxatives
• Eg wheat bran. Isphagula , carboxy
methyl cellulose
• Administered with plenty of water.
• Side effect :
• Bacterial digestion of vegetable
fibres within the colon may leads to
abdominal discomfort.

8. Osmotic diuretic
• Non absorbable
• Indigestible disaccharide.
• Osmotic action
• Eg Sorbitol and lactulose.
• Dose: 10 g twice daily with plenty of water.
• Side effect:
• Lead to flatulence, nausea and cramps.

9. Lubricant laxatives
• Pharmacologically inert mineral oils.
• It acts on intestinal lumen.
• It is fecal lubricants and stool softener by
decreasing the water absorption from the
stools.
• Eg liquid paraffin
• 15-30ml / day at bed time
• Leads to deficiency of fat soluble vitamin.

10. Surfactant laxatives
• Luminally active laxative.
• An anionic surfactant which softens the stools
by decreasing the surface tension of fluids in
the bowel.
• Sometimes it act as wetting agent for the
bowel by emulsifying the colonic contents
which facilitates the mixing of water in to fatty
substance of feces
• Eg docusate sodium

11. PURGATIVE

12. • It provides semi fluid stool or leads to watery
evacuation.
• These are used for complete cleaning of bowel
prior to gastrointestinal endoscopic
procedures.
• To flush out the worms of post bed ridden or
post operative patients after the use of
anthelmintic drugs

13. • Cleaning the bowel before surgery or taking
abdominal x-ray
• Classification
• Osmotic purgatives
• Irritant purgatives

14. Osmotic purgative
• Electrolyte osmotic purgative
• Saline purgatives

15. Electrolyte osmotic purgative
• It contains non absorbable PEG
• It retains water due to its high osmotic nature.
• It is given along with a balanced isotonic
solution which contain sodium chloride,
Sodium bi carbonate, sodium sulphate and
potassium chloride.
• It is safer to all patient.

16. Saline purgatives
• It is soluble inorganic salts which acts by
increasing the fecal bulk by retaining water
due to its osmotic effect thus increases the
peristalsis indirectly.
• Magnesium salts also releases cholecytokinin
which is used to increases the intestinal
secretions and peristalsis

17. Common side effect
• It is given along with plenty of water because
being irritant it may induce vomiting.
• High osmolar property leads to intravascular
fluid depletion and electrolyte disturbances.
• Long term usage should be avoided for
hypertensive and cardiac failure patient.
• Long term use of magnesium for renal failure
patient leads to risk of hyper magnesemia.

18. Irritant Purgatives
• Anthraquinone derivatives – senna,
cascara and aloe
• Oils – Castor oil
• Organic irritants- Phenolphthalein,
bisacodyl
• All the above stimulate intestinal
peristalsis due to their irritant action

19. Common side effect
• Senna glycoside leads to
melanosis coli on long term use.
• Long term of castor oil use leads
to damaging the intestinal
mucosa.
• Bisacodyl leads to hypokalemia.

20. MAGNESIUM HYDROXIDE

21. Preparation
• It is an aqueous suspension of hydrated
magnesium oxide.
• Light magnesium oxide is mixed with sodium
hydroxide solution to get a cream.
• It is diluted with water; the suspension is
poured in thin stream into a solution of
magnesium sulphate with constant stirring.
• The precipitate is allowed to settle .

22. • The clear liquid is decanted off.
• The residue is transferred into a
calico filter washed thoroughly with
water until it is free from sulphate
ions and finally mixed with the
required quantity of purified water.

23. • In this reaction sodium hydroxide reacts with
magnesium sulphate and gives masnesium
hydroxide.
• In the above formula pharmacopoeia permits
the use of the following pharmaceutical aid.
• 0.1% citric acid which is used to minimize the
reaction between glass containers and milk of
magnesia during storage.
• Otherwise it imparts bitter taste.

24. • 0.5 ml / 1000 ml of volatile oil as a flavouring
agent.
• 0.2% of sodium benzoate
• 0.125% of methyl paraben as preservative

25. Assay-complexometric
• Weigh accuratley about 0.1 g
dissolve in 20 ml of 2M HCl and
dilute to 100 ml with water . To 50ml
of this solution add 5 ml of strong
ammonia – ammonium chloride
buffer and titrate with 0.05M
disodium edetate, using 50 mg of
mordant black II mixture as indicator.

26. uses
• Antacid and laxative.
• Alkaline mouth wash
• It is used to liberate alkaloids from solution.
• Dose
• As Antacid 5-10 ml
• As laxative 15-30 ml
• It should not be refrigerated
• Shake well before use.

27. MAGNESIUM SULPHATE
EPSOM SALT

28. Preparation
• Laboratory
• Neutralising of magnesium carbonate with
hot sulphuric acid. Filter the solution and
concentrate the filtrate to get crystals

29. From Magnesite / Calcined Dolomite
• The reaction of sulphuric acid
with magnesite / calcined
dolomite.

30. From brine solution
• Brine is treated with milk of lime gives
magnesium hydroxide. The sulphur di
oxide and air is passed through this
suspension. Magnesium sulphate
crystallised out.

31. Mechanism of action
It does not get absorbed from
intestine, so it retains sufficient
water within the lumen which
leads to increase in the hydrostatic
pressure of the lumen to promote
peristalsis of bowel.

32. Assay - complexometric
Weigh accurately about 0.3 g dissolve
in 50 ml of water, add 10 ml of strong
ammonia – ammonium chloride
solution and titrate with 0.05 M
disodium edetate using mordant black
II as indicator, untill a blue colour is
obtained.

33. Use
• Osmotic laxative
• Electrolyte replenishers.
• It is also used in renal impaired
patients as laxative.

34. MAGNESIUM CARBONATE

35. Preparation of Heavy magnesium
carbonate
• It is preapared by double decomposition
of magnesium sulphate and sodium
carbonate.
• 125 parts of magnesium sulphate and
150 parts of sodium carbonate.
• Dissolved in boiling water separatley.
• Two solutions are mixed , filtered,
washed, evaporated and dried

37. Preparation of light magnesium
carbonate
125 parts of magnesium sulphate
solution is mixed with 150 parts of
sodium carbonate in cold water ,
heated for 5 minutes then precipitate
is collected, washed untill gives a slight
reaction for sulphate and dried in an
oven.

38. uses
• Antacid
• Osmotic laxative
• Pharmaceutical aid
• Slow acting antacid. [ during
pregnancy and lactation]
• Cathartic

39. Dose
• Antacid
• 300-600 mg
• Laxative
• 2-4 g