Syrups usually contain 85%–86% w/v of sucrose. They resist bacterial growth by virtue of their exosmotic effect on microorganisms. For syrups containing less than 85% w/v sucrose, sufficient concentration of polyols such as sorbitol, glycerin, propylene glycol or polyethylene glycol should be added to have the required osmotic pressure.
The sources of contamination in pharmaceuticals arises from raw materials, processing containers, equipment, manufacturing environment, working personnel and packaging materials. These contaminants allow the growth of various microorganisms such as Salmonella species, Escherichia coli, Enterobacter species, Pseudomonas aeruginosa, Clostridium and Candida albicans which are undesirable in oral liquid preparations. The presence of a preservative will hinder the growth of microbes, thereby extending the…
To enhance the appeal and for easy identification of different products, a coloring agent is used. The coloring agent should match well with the flavor in the preparation, for example, green with mint and brown with chocolate flavor. The colorant used should be generally water soluble, nonreactive with other components, stable at the pH range…
Solutions come into immediate contact with the taste buds on the tongue. Drugs and other adjuvants are generally not palatable. To enhance the palatability and to mask the undesired taste of the drugs, sweeteners are used. Examples of sweeteners are sucrose, saccharin, aspartame, sucralose and liquid glucose.
These are compounds or mixtures of compounds that resist changes in the final pH upon addition of small quantities of acid or base. Hence, buffering agents are used in the liquid preparation to prevent changes in the pH upon dilution or addition of an acid or alkali. They dissolve weakly acidic or basic drug in…
The solvents usually used in the oral liquid preparations are purified water, alcohol, glycerin and propylene glycol. Purified water: Naturally occurring water exerts its solvent effect on most of the drug substances. In oral preparations, demineralized water or purified water is used. Alcohol: This is the most useful primary solvent for many organic compounds. It acts as…
This enhances the solubility of poorly water-soluble drugs by modifying them into their water-soluble derivatives. For example, the solubility of disodium phosphate ester of betamethasone in water is 1000 times greater than its parent compound.
The term “hydrotropy” has been used to designate the increase in solubility in water of certain substances due to the presence of large amounts of additives. This phenomenon is more closely related to complexation involving a weak interaction between the hydrotrophic agent and the solute. This phenomenon is also due to the change in the…
The solubility of a compound may be increased by complexing it with a complexing agent. When an insoluble compound forms a complex that is more soluble in a solvent, the total solubility is equal to the inherent solubility of the uncomplexed drug and the concentration of the drug complex in solution. When a drug is…
Solubilization increases the solubility of poorly water-soluble solute molecules in an aqueous solution of surface active agents or surfactants due to which a thermodynamically stable solution is formed. When surfactants are added to water at low concentrations, they tend to orient at the air–liquid interface. As additional surfactant is added, the interface becomes fully occupied…