Methods of preparation of Syrups
1. Solution with the aid of heat;
•The usual method for preparing syrup,
used for
•Volatile
substance (flavored substances).
•Substance injured by heat.
•Rapid preparation of syrup.
•Sucrose is added to the purified water and heat is applied until the solution is effected. Then, add the heat stable components to the hot syrup, the mixture is allowed to cool and its volume is adjusted to the required volume. If heat liable substance (volatile flavoring oils) are required to be added, they are added to the syrup after the solution rapidly cooled to the room temperature.
•Excessive heat must be avoided, because sucrose (disaccharide) may be hydrolyzed into monosaccharide, dextrose (glucose) and fructose (levulose). This hydrolytic reaction known as inversion and the produced sugars known as inverted sugars.
•Invert sugar properties:
•Substance injured by heat.
•Rapid preparation of syrup.
•Sucrose is added to the purified water and heat is applied until the solution is effected. Then, add the heat stable components to the hot syrup, the mixture is allowed to cool and its volume is adjusted to the required volume. If heat liable substance (volatile flavoring oils) are required to be added, they are added to the syrup after the solution rapidly cooled to the room temperature.
•Excessive heat must be avoided, because sucrose (disaccharide) may be hydrolyzed into monosaccharide, dextrose (glucose) and fructose (levulose). This hydrolytic reaction known as inversion and the produced sugars known as inverted sugars.
•Invert sugar properties:
•More susceptible for fermentation and microbial growth.
•Tend
to darken in color.
•But decrease oxidation of other drugs (levulose formed is reducing sugar)
•Levulose formed is sweeter than sucrose.
•The rate of inversion process is enhanced by the medium acidity.
•Overheating cause caramelizaltion of sucrose (amber color)
•Syrups cannot be sterilized by autoclaving without caramelization (amber color).
•But decrease oxidation of other drugs (levulose formed is reducing sugar)
•Levulose formed is sweeter than sucrose.
•The rate of inversion process is enhanced by the medium acidity.
•Overheating cause caramelizaltion of sucrose (amber color)
•Syrups cannot be sterilized by autoclaving without caramelization (amber color).
2. Solution by agitation without the aid of heat;
•To
avoid heat-induced inversion of sucrose.
•This process is used in those cases where heat would cause loss of valuable volatile constituents.
•The syrup is prepared by adding sucrose to the aqueous solution in a vessel of greater capacity than of syrup to be prepared. This permits active agitation and rapid solution.
•This process is time consuming than that using heat but result in a product has maximum stability.
•When solid agent are to be added to a syrup, it is best to dissolve the solid in a minimum amount of purified water and then incorporated in the syrup. When solid substances are added directly to the syrup, they dissolve slowly due to the viscosity of syrup and the limited amount of water available in the syrup.
•This method is used for preparation of
•This process is used in those cases where heat would cause loss of valuable volatile constituents.
•The syrup is prepared by adding sucrose to the aqueous solution in a vessel of greater capacity than of syrup to be prepared. This permits active agitation and rapid solution.
•This process is time consuming than that using heat but result in a product has maximum stability.
•When solid agent are to be added to a syrup, it is best to dissolve the solid in a minimum amount of purified water and then incorporated in the syrup. When solid substances are added directly to the syrup, they dissolve slowly due to the viscosity of syrup and the limited amount of water available in the syrup.
•This method is used for preparation of
•Cough syrups e.g.,
Codeine Phosphate Syrup.
R /
Codeine phosphate 5 g
Purified water 15 ml
Chloroform spirit 25 ml
Sufficient syrup to make 1000 ml.
nIn case of diabetic patients, sorbitol
solution can be used in the preparation instead of syrup. It has about half the
sweetening power of syrup.
3. Addition of sucrose to a medicated liquid or to a flavored liquid
•Occasionally,
a medicate liquid (tincture or fluid extract) is the source of medication in
the preparation of the syrup.
•Tinctures and fluid extracts contain alcohols soluble ingredients.
•Addition of tincture or extracts to syrup may cause precipitation of the alcohol soluble components.
nIf the alcoholic components are not desired or unnecessaryfor the corresponding syrup, they are generally
removed by mixing the tincture or extract with water, allowing the mixture to stand until separation of the water insoluble agent is completed., and filtering them from the mixture. The filtrate then is the medicated liquid to which the sucrose is added in preparation of syrup.
nIf the alcohol soluble components are requiredto be medicinal part of the syrup, some means of rendering them water soluble is employed.
•In some cases, tinctures or extracts is miscible with the aqueous preparation, it may be added directly to simple syrup to medicate it.
•Tinctures and fluid extracts contain alcohols soluble ingredients.
•Addition of tincture or extracts to syrup may cause precipitation of the alcohol soluble components.
nIf the alcoholic components are not desired or unnecessaryfor the corresponding syrup, they are generally
removed by mixing the tincture or extract with water, allowing the mixture to stand until separation of the water insoluble agent is completed., and filtering them from the mixture. The filtrate then is the medicated liquid to which the sucrose is added in preparation of syrup.
nIf the alcohol soluble components are requiredto be medicinal part of the syrup, some means of rendering them water soluble is employed.
•In some cases, tinctures or extracts is miscible with the aqueous preparation, it may be added directly to simple syrup to medicate it.
4. Percolation
•In this procedure, purified water or an aqueous solution is
permitted to pass slowly through a bed of crystalline sucrose packed in a
percolator, thus dissolving it and forming syrup.
•A piece of cotton is placed in the neck of the percolator to prevent the passage of un-dissolved sucrose.
•To be successful in this process:
nThe percolator should be cylindrical with a short conical base.
nCoarse crystalline sucrose must be used to avoid formation of compact mass through which the liquid can not pass.
nThe cotton must not be pressed too tight (slow flow) or too loose (fast flow).
•Syrup USP is an example of Syrup prepared by percolation.
Preservation of syrup
•A piece of cotton is placed in the neck of the percolator to prevent the passage of un-dissolved sucrose.
•To be successful in this process:
nThe percolator should be cylindrical with a short conical base.
nCoarse crystalline sucrose must be used to avoid formation of compact mass through which the liquid can not pass.
nThe cotton must not be pressed too tight (slow flow) or too loose (fast flow).
•Syrup USP is an example of Syrup prepared by percolation.
Preservation of syrup
•Syrup can be preserved by
•Storage at low temperature not above
25°C.
•Adding a preservative such as glycerin, benzoic acid, sodium benzoate, methyl paraben or alcohol in the formulation.
•By maintaining of a high concentration of sucrose as a part of the formulation.
•Adding a preservative such as glycerin, benzoic acid, sodium benzoate, methyl paraben or alcohol in the formulation.
•By maintaining of a high concentration of sucrose as a part of the formulation.
