SALINE CATHARTICS
Cathartics are drugs used to relieve constipation. The term
laxative is used for mild cathartics whereas purgatives is used for strong
cathartics. They are also given for the expulsion of intestinal parasite and
also for clearing the bowels before surgery if necessary.
Constipation can be because of following reasons like
weakness of intestinal, intestinal spasm, emotional tension improper diet, lack
of physical exercise or work, side effect of the drugs etc. In constipation
fecal material becomes hard and dry, use of laxative and purgative provides relief
from constipation by elimination of bowel contents.
Cathartics or
laxatives can be considered under the following class:
1. Mild laxatives:
are those drugs, which promote evacuation of bowel with minimum adverse
effects. Drugs included in this group are:
• Bulk producing
drugs: Which promote evacuation of bowel by increasing the stools bulk
volume and water contents. Eg; Isapgol, agar- agar methyl cellulose etc.
• Stool softeners
(Emollient): Which penetrate and
soften the stool. Eg: D-soctyl sodium sulphosuccinate, liquid
paraffin, etc.
2. Strong purgatives:
Cause complete evacuation of the bowel and bowel become in active and also
given to remove the solid particles from intestine before certain x-ray
examination or surgery. There are two kinds of strong purgatives.
• Irritant or
stimulant: These are drugs or chemicals, which act by local irritation or
intestinal tract and bring about stimulation of peristaltic activity. Eg
Phenolphthalein, senna, etc.
• Saline cathartics:
These act by increasing the osmotic load of intestine by absorbing large
quantity of water and they’re by stimulating peristalsis.Eg: magnesium
compounds.
Magnesium sulphate
Synonym: Epsom
Salt
Chemical formula:
MgSO4 .7H 2O
Method of
Preparation:
Laboratory: In laboratory it is prepared by treating a
solution of magnesium carbonate with dilute sulphuric acid. The mixture is
stirred well and carbon di oxide is removed, then the solution is evaporated to
get the crystals of magnesium sulphate.
Chemical reactions:
MgCO3 + H2SO4→MgSO4+
CO2+ H2O
Commercially:
Dolomite
It is prepared by reacting Sulphuric acid with dolomite.
Dolomite is a mixture of magnesium and calcium carbonate. The magnesium
sulphate being water soluble remains in the solution while the impurities such
as calcium carbonate undergo precipitation, thus the solution id filtrated and
filtrate is subjected to evaporation to get the crystals of magnesium sulphate.
Chemical reactions:
MgCO3.CaCO3 + 2 H2SO4
→MgSO4 + CaSO4+ 2CO2+2 H2O
Description:
Colourless crystals or a white, crystalline powder with bitter and saline in
tatse, soluble in boiling water and practically in soluble in alcohol
Storage: Store
protected from moisture
Medicinal uses:
• Saline cathartic
as osmotic laxative
• Electrolyte
replacement
Sodium Ortho Phosphate
Synonyms:
Disodium Hydrogen Phosphate,Sodium ortho phosphate
Chemical formula:
Na2HPO4 nH2O (n=12, 10, 8, 7, 5, 2 or 0)
Description:
Colourless, transparent crystals; very efflorescent, Soluble in water and
practically in soluble in alcohol
Method of
preparation: It is prepared by treating sodium carbonate with a hot
solution of phosphoric acid. The solution is neutralised, concentrated and
crystals are separated, centrifuged, washed and dried
Chemical reactions:
H3PO4 + Na2CO3→
Na2HPO4 + H2O+ CO2
Storage: Store
protected from moisture
Medicinal uses:
• Saline cathartic
• Electrolyte
replacement
• Standard buffer
solution
• Softening hard
water
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