Table of Contents
The syrup is a saturated or concentrated, viscous aqueous solution of sucrose/sugar substitute with or without flavor/medicinal substances in purified water.
Simple syrup contain 85% w/v (65% w/w); specific gravity 1.313 (USP) or 66.7% w/w as per Indian Pharmacopeia/BP.
Composition of Syrup
Most syrups contain the following components in addition to the purified water and drug(s):
- (a) Sugar, usually sucrose or other sugar substitutes are used to provide sweetness and viscosity, (Sugar-free alternative- Sorbitol, Saccharine, Aspartame)
- (b) Antimicrobial preservatives,
- (c) flavorants & colorants,
- (d) Syrups may also contain solubilizing agents, thickeners, or stabilizers.
Syrup may contain preservatives. Glycerin, methylparaben, benzoic acid, and sodium benzoate may be used to prevent bacterial and mold growth. Glycine, benzoic acid (0.1%–0.2%), sodium benzoate (0.1%– 0.2%), and various combinations of methylparaben, propylparaben, and butylparaben or alcohol are commonly used as antimicrobial preservatives.
Types of Syrup
1. Simple Syrup
When Purified Water alone is used in making the solution of sucrose, the preparation is known as “syrup,” or “simple syrup
2. Medicated syrup
When Syrup contains medicinal substance is know as medicated syrup – cough syrup
3. Flavoured Syrup
Syrups containing flavoring agents but not medicinal substances are called flavored vehicles; Containing Aromatic/ Flavoured – Flavoured syrup (Cherry & Raspberry syrup)
Advantages of Syrup
- Retard oxidation because it partly hydrolyzed into dextrose & levulose (reducing sugary ) – So prevent decomposition of many substances – No preservative needed.
- Exert high osmotic pressure – prevents the growth of MOs (Bacteria, Fungi, molds etc)
- Palatable sweet – a vehicle for bitter / Nouseous substances.
Preparation of Syrups
Syrups are prepared using one of four techniques: solution with heat, solution by agitation, the addition of sucrose to a liquid medication or flavored liquid, and percolation.
- Solution with Heat
- This method is a suitable preparation method, if the constituents are not volatile or degraded by heat. Purified water is heated to 80–85°C, and then removed from its heat source. Sucrose is added with vigorous agitation. Then, other required heat-stable components are added to the hot syrup, the mixture is allowed to cool, and its volume is adjusted to the proper level by the addition of purified water. In instances in which heat-labile agents or volatile substances, such as flavors and alcohol, are added, they are incorporated into the syrup after cooling to room temperature.
- Invert sugar: When heat is used in the preparation of syrups, inversion of a slight portion of the sucrose (a disaccharide) into monosaccharides, dextrose (glucose), and fructose (levulose) by hydrolyzation process. This hydrolytic reaction is referred to as “inversion,” and the combination of the two monosaccharide products is “invert sugar.” Sucrose solutions are dextrorotary, but, as hydrolysis proceeds, the optical rotation decreases and becomes negative when the reaction is complete. The rate of inversion is increased greatly by the presence of acids; the hydrogen ion acts as a catalyst in this hydrolytic reaction. Fructose is responsible for the darkening of syrup. Invert sugar is more readily fermentable than sucrose and tends to be darker in color. But, its two reducing sugars prevent the oxidation of other substances.
- Agitation without Heat
- This method is used for substances that degradation on heating or volatilize formulation constituents.
- Addition of Sucrose to a Liquid Medication or Flavored Liquid:-
- This method is often used with fluidextracts or tinctures. Example
- In the percolation method, either purified water or the source of the medicinal component is passed slowly through a bed of crystalline sucrose, thus, dissolving it and forming a syrup. Example Ipecac syrup
- Syrup on Storage subject to Crystallisation which causes locking of Cap of the container. Glycerine, Sorbital & Propylene glycol is added in small quantity to the syrup to prevent crystallization of sucrose.
- Storage: completely filled & well-stoppered bottle and stored in a cool place (not exceeding 25-degree centigrade)
- Syrup may be dark color due to the fermentation of sugar.
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