Liquid Dosage Forms in Pharmaceutics

A mixture where one substance (solute) is dissolved evenly in another substance (solvent). The solvent is typically present in a larger amount, but exceptions exist like syrup.

Water is the most common solvent used in pharmaceutical solutions due to its compatibility with the body and ability to dissolve many substances. It has a high dielectric constant, which helps dissolve ionizable materials, and lacks selectivity, meaning it can dissolve a wide range of substances.

Purified water is a type of water used in pharmaceutical preparations. It undergoes a process to remove salts, making it suitable for many applications.

This type of water is specifically prepared for injections. It is sterilized, free of pyrogens (fever-causing substances), and free of salts. It undergoes a specific purification process and is often packaged in airtight containers.

Specialized types of Water for Injection are used for specific drug formulations. For example, CO2-free water is used for aminophylline and phenobarbitone sodium, while O2-free water is used for apomorphine and ergotamine maleate.

Liquid dosage forms, like solutions, are easy to swallow, especially for children and older adults. The drug dissolves quickly, making it available for absorption. They can be used for drugs that irritate the stomach, as they are diluted by the stomach contents upon ingestion.

Liquid dosage forms can be bulky and inconvenient to transport and store. They can also be prone to spoilage due to instability of the drug or ingredients. Microorganisms can grow in these formulations, and accurate dosage administration can be challenging. Certain drugs can have an unpleasant taste.

Aqueous solutions are liquid preparations where water is the primary solvent. These solutions are widely used in pharmaceuticals due to water's ability to dissolve many substances.

An example of a non-aqueous solvent used in liquid formulations. It is a thick and viscous liquid that is commonly used in syrup preparations. Syrup BP, for instance, contains a large proportion of sucrose as the solute dissolved in a smaller amount of water.

A type of liquid dosage form where the drug is suspended in a liquid medium. The drug particles are not dissolved but dispersed evenly throughout the liquid. This allows for uniform distribution of the drug.