What is a liquid medicine?
Pharmaceutically produced liquid medicines can either be called liquids, solutions, syrups or mixtures. Liquid medicines are largely designed for patients who are unable to swallow tablets or capsules and are prescribed mainly for children and the elderly and are designed to ensure that the drug is dispersed evenly throughout, the taste of the drug is masked by sweeteners and flavourings and a usual dose is 5mL – a sensible amount to swallow. The consistency is considered by manufacturers as gloopy liquids are easier to manage and are less likely to be aspirated.
Figure 1 Diagrammatic representation of a liquid.
Water is the most commonly used solvent. Due to drug instability in water, some liquid medicines contain stabilisers. Occasionally alternative liquid solvents such as glycerol or alcohol are used. Where the drug does not dissolve in the liquid solvent, manufacturers use suspending agents to ensure homogenous drug distribution. The figure above provides a diagrammatic representation of what may be found in a liquid medicine. It can be seen that these are not simple formulations and considerably more complex than a crushed tablet in water.