Liquid Dosage Forms in Pharmaceutics

Study Notes

Solutions, the solvent is generally present in a greater amount
Exceptions exist, like Syrup BP, which contains 66.7% w/w sucrose (solute) in 33.3% w/w water (solvent).

Easier to swallow (for pediatric and geriatric patients)
Drugs are immediately absorbed (even if the drug is a precipitate, acid, and sufficiently wetted/finely divided.)
Uniform distribution (e.g. suspensions and emulsions)
Irritable drugs (e.g. aspirin, potassium chloride) are better as solutions because they are immediately diluted by gastric contents minimizing damage.

Water is the most widely used solvent due to its physiological compatibility and lack of toxicity
Water has a high dielectric constant, which aids in the dissolution of ionizable materials.
Water lacks selectivity as a solvent.

Purified Water BP: This water is freshly boiled and cooled immediately before use. It contains no salts and can be produced by distillation or deionization.
Water for Injection: Used in parenteral (non-oral) solutions. Required to be sterile, pyrogen-free, and salt-free.
- Special types include (but are not limited to):
  - CO2-free water for solutions containing phenobarbitone sodium or aminophylline
  - O2-free water for solutions containing apomorphine and ergotamine maleate
- Apyrogenic distilled water is prepared by boiling, cooling, and sealing the water in containers while excluding air before sterilizing via autoclaving.