Syrup Lecture 3 - Middle Technical University

Middle Technical University Institute of Medical Technology/Al.mansour Pharmaceutics/ Syrups Lecture 3 Pharmacy Department/First Grade  syrups Syrups are a nearly saturated aqueous solutions of sugar, with or without medicinal or flavoring ingre...

Middle Technical University Institute of Medical Technology/Al.mansour Pharmaceutics/ Syrups Lecture 3 Pharmacy Department/First Grade  syrups Syrups are a nearly saturated aqueous solutions of sugar, with or without medicinal or flavoring ingredients. They are characterized by a sweet test and relatively high viscosity. Medicinally, syrups can be classified into: 1-Non-medicated syrups: are used as a vehicle for several preparations. 2-Medicated syrups: contain substances (active pharmaceutical ingredients, (APIs)). They have therapeutic effects such as antihistamine (Allermine®), cough syrup (Sedilar®), etc.  Pharmaceutically, syrups are classified into: 1-Sugar-based syrups: which are concentrated solutions of sugar (e.g. sucrose and dextrose). 2-Sugar-free syrups: are formulated with artificial sweetening agents and viscosity builders (e.g. saccharin sodium, sorbitol, sodium cyclamate). They are used for patients regulating their diet (e.g. diabetic patients). These syrups are not viscous in nature and therefore, we must add viscosity builder such as glycerine, methyl cellulose (MC), hydroxyethyl cellulose (HEC), etc. :Sugar-based syrups 1-Sucrose-based syrups 2-Dextrose-based syrups 1. Sucrose – based syrups Sucrose: Is one of the purest commercially available substance and it is the preferred carbohydrate for syrups because: 1. Purity. 2. Degree of sweetness (100%). 3. Lack of colour. 4. Ease of handling. 5. Inertness. 6. Availability.  Stability of sucrose-based syrups (disadvantages) Sucrose is subjected to two degenerative pathways in aqueous solution: fermentation and hydrolysis. 1-Fermentation: As a carbohydrate, sucrose in dilute aqueous solution provides a nutrient medium for the growth of moulds and yeasts. The consequences of this growth are: a-Turbidity (change in color) b-Change in odor. c-Change in taste.  The ability of these organisms to grow is reduced as the concentration of sucrose is increased. Therefore, syrups should contain enough sucrose to approach saturation.  Nearly saturated solutions of sucrose (if stored in good storage conditions) are self- preservatives because they don’t contain free water for microorganisms to grow in.  Few syrups contain 0.1 – 0.2% w/v preservatives such as benzoic acid, sodium benzoate, etc.  2-Hydrolysis: Sucrose is a disaccharide compound. It undergoes hydrolysis to give fructose (levulose) and glucose (dextrose). C H O +H O 12 22 11 C H O +C H O 2 6 12 6 6 12 6 (Sucrose) (Glucose) (Fructose)  The reaction takes place in the presence of strong acid and heat.. It is also called “inversion reaction” because the solution of sucrose rotates polarized light to the right while it rotates the polarized light to left after hydrolysis. This is because levulose has greater rotating capacity than dextrose. The inverted sugar has specific properties: *Solutions of inverted sugar are subjected to fermentation at higher degrees than solutions of sucrose. *After inversion, the solution becomes sweeter because sucrose is rated with a sweetness of 100% while dextrose is rated 74% and levulose with 173%. *The formed laevulose by inversion seems to be responsible for the brown discoloration that develops in some of the colorless syrups. This change in colour is called “caramelisation” and it occurs in syrups containing strong acids. To eliminate this discoloration, dextrose might be used instead of sucrose (i.e. dextrose-based syrups).  2-Dextrose-based syrups Dextrose may be used as a substitute for sucrose in syrups containing strong acids in order to eliminate the discolouration associated with caramelization and the problem related to sucrose hydrolysis.  The formulas in which dextrose was used instead of sucrose include syrup of hypophosphates and compound syrup of hypophosphates. Hydroiodic acid (HI) syrup was the only official syrup using dextrose. Ferrous iodide syrup containing dextrose has been formulated as well The differences between sucrose and dextrose are 1. Dextrose forms a saturated solution in water at 70% w/v which is less viscous than simple syrup. 2. Dextrose dissolves more slowly than sucrose. 3. Dextrose has less sweetness than sucrose (74%). 4. The saturated solution of dextrose readily supports the growth of microorganisms. Consequently, it is more easily fermented (the saturated solution of sucrose is self- preservative).  Preservatives are usually required for dextrose-based syrups. Glycerine may be used in a concentration of 30 – 45% v/v to act as preservative. In addition, this concentration of glycerine improves the viscosity and gives additional sweetness to the preparation. Sugar-free syrups (non-nutritive syrups) Sucrose is the sugar most frequently employed in syrups. However, several formulas have been developed which contain no sugar. These are intended for patients suffering from diabetes.mellitus (hyperglycemic) Some early formulas included glycerin in order to take the advantage of its viscosity and sweetness. However, glycerin as well as propylene glycol are glycogenic substances (i.e. converted to glucose in the body). Therefore, substances to be used as sugar substituents should be non-glycogenic (e.g. methylcellulose or General formula for sugar-free syrup 1. Sweetening agent. 2. Viscosity builder. 3. Preservative. 4. Purified water