Often, I hear questions surrounding what are liquid dosage formulations. I thought I might take the opportunity to provide a short introduction to liquid dosage formulations. Liquid dosage formulations may be in the form of suspensions or syrups, metered dosed inhalers (MDIs), or creams or lotions. All of these systems would typically have particles present or droplets present in their formulations. There could also be parentals, such as injections or intravenous infusions, which may be particle free.
Some concerns related to liquid formulations may be the stability or the shelf-life of the product. The systems cannot necessarily separate, or at least if they do separate they must be able to be shaken or brought back to their original suspended state. The appropriate Active Pharmaceutical Ingredient (API) must be present and there could be potential for polymorph concerns there. A consistent dosage uniformity must also be present whether it is the particle distribution consistency or the API concentration. It must be consistent to maintain consistent therapeutic performance. Or general look and feel of the product. If the system is agglomerated or if water and oil separates, it may look unnatural or undesirable. These changes in a particle system could potentially impact the metabolism or the digestive system and they certainly could affect the bio-availability. Ultimately, the choice of liquid formulations is often related to the patient demographics – who will be administering the product and who will be consuming it.
If you are interested in learning more about liquid dosage formulations, I invite you to view the on-demand webinar: Gain Control of Liquid Formulations with Inline Particle and Droplet Measurements.