US Pharm. 2014;39(5):57-58.
Method of Preparation: Calculate the quantity of each ingredient for the amount to be prepared. Accurately weigh or measure each ingredient. Mix the hydroxyzine pamoate, xanthan gum, and sorbic acid with the propylene glycol (PG) to form a smooth paste. Incorporate the sorbitol solution; flavor and mix well. Add sufficient syrup to final volume and mix well. Package and label.
Use: This preparation has been used to manage pruritus that is due to allergic conditions such as chronic urticaria and atopic and contact dermatoses, and for histamine-mediated pruritus.
Packaging: Package in tight, light-resistant, childproof containers.
Labeling: Keep out of reach of children. Shake well before taking. Discard after ____ [time period].
Stability: A beyond-use date of 14 days when stored in a refrigerator may be used for this preparation.1
Quality Control: Quality-control assessment can include weight/volume, pH, specific gravity, active drug assay, color, rheologic properties/pourability, physical observation, and physical stability (discoloration, foreign materials, gas formation, mold growth).2
Discussion: In addition to its other uses, hydroxyzine is often used in the management of pruritus caused by allergic conditions such as chronic urticaria and atopic and contact dermatoses, and for histamine-mediated pruritus.
Hydroxyzine pamoate (Vistaril, C21H27ClN2O2.C23H16O6, MW 763.27) occurs as a light yellow, practically odorless powder that is practically insoluble in water. About 1.7 mg of pamoate is equivalent to 1 mg of hydroxyzine HCl.1
Xanthan gum (corn sugar gum) is a high-molecular-weight polysaccharide gum with a molecular weight of approximately 2 × 106. Xanthan gum occurs as a cream or white-colored, odorless, free-flowing, fine powder. It is soluble in cold or warm water, but is practically insoluble in ethanol and ether. Xanthan gum is used as a stabilizing agent, as well as a viscosity-increasing agent in suspensions. It is nontoxic and compatible with most other excipients, and it has good stability (in the presence of enzymes, salts, acids, and bases) and viscosity properties over a wide range (pH 3-12). Xanthan gum solutions can tolerate up to about 60% water-miscible organic solvents, such as ethanol.3
PG (C3H8O2) occurs as a clear, colorless, viscous, practically odorless liquid with a sweet taste, somewhat resembling glycerin. It has a specific gravity of 1.038 g/mL and is miscible with acetone, chloroform, 95% ethanol, glycerin, and water. PG is not miscible with fixed oils or light mineral oil; it will, however, dissolve some essential oils. PG is actually a better solvent than glycerin. It is similar to ethanol as an antiseptic and is used in cosmetics and in the food industry as a vehicle for flavors and emulsifiers. PG is stable and can be mixed with numerous other solvents.4
Sorbic acid (C6H8O2, MW 112.13) occurs as a white, free-flowing, crystalline powder with a characteristic odor. It is slightly soluble in water, soluble in alcohol, and soluble 1 g in 19 mL of PG. Sorbic acid has a melting range of 132°C to 135°C. It should be preserved in tight containers and protected from light; exposure to excessive heat should be avoided.1,5
Sorbitol (D-glucitol, C6H14O6, MW 182.17) is a hexahydric alcohol related to mannose, and it is isomeric with mannitol. It occurs as a white or almost colorless, odorless, crystalline, highly hygroscopic powder and should be stored in tight containers. Sorbitol has a pleasant, cooling, sweet taste and is approximately 50% to 60% as sweet as sucrose. The pH of a 10% w/v aqueous solution ranges from 4.5 to 7.0. Sorbitol is relatively chemically inert, is compatible with most pharmaceutical excipients, and melts at about 110°C to 112°C. It is available as a 70% solution.6
Syrup (simple syrup) is a clear, sweet vehicle used as a sweetening agent and as the base for many flavored and medicated syrups. It contains 85% w/v sucrose in water and has a specific gravity of not less than 1.30. Syrup is generally self-preserving as long as the sucrose concentration is maintained sufficiently high. It is best to prepare syrup without the use of heat, but boiling water may be used. Syrup should be stored in tight containers, preferably in a cool place.7
1. U.S. Pharmacopeia 36/National Formulary 31. Rockville, MD: U.S. Pharmacopeial Convention, Inc; 2013:335-398,1265,2262,2397.
2. Allen LV Jr. Standard operating procedure for performing physical quality assessment of oral and topical liquids. IJPC. 1999;3:146-147.
3. Shah HC, Singh KK. Xanthan gum. In: Rowe RC, Sheskey PJ, Quinn ME, eds. Handbook of Pharmaceutical Excipients. 6th ed. Washington, DC: American Pharmaceutical Association; 2009:782-785.
4. Weller PJ. Propylene glycol. In: Rowe RC, Sheskey PJ, Quinn ME, eds. Handbook of Pharmaceutical Excipients. 6th ed. Washington, DC: American Pharmaceutical Association; 2009:592-594.
5. Reynolds JE, ed. Martindale: The Extra Pharmacopoeia. 30th ed. London, England: Pharmaceutical Press; 1993:1138.
6. Shur J. Sorbitol. In: Rowe RC, Sheskey PJ, Cook WG, Quinn ME, eds. Handbook of Pharmaceutical Excipients. 7th ed. Washington, DC: American Pharmaceutical Association; 2012:776-779.
7. U.S. Pharmacopeia 36/National Formulary 31. Rockville, MD: U.S. Pharmacopeial Convention, Inc; 2013:2262.
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