Liquid Dosage Forms

Approximately 22% of dosage forms are liquids, comprising solutions, syrups, elixirs, suspensions, emulsions, liposomes, and lotions. The number of liquid dosage forms is on the rise due to the approval of biotherapeutics, such as monoclonal antibodies, drug-antibody conjugates, and vaccines. Liquid dosage forms are designed to overcome challenges arising from physicochemical and biopharmaceutical parameters. In addition, liquids are tailored for administration through various routes to achieve a therapeutic milieu. Liquid formulations incorporate different classes of inactive ingredients to improve the shelf-life of drug compounds. Liquids require unique processing conditions and facilities to prevent microbial contamination. In particular, liquid formulations administered through injectable, ophthalmic, inhalation, and nasal routes must meet sterile compendial requirements. Because of unique formulation and administration requirements, liquid dosage forms require specialized primary packaging containers to facilitate ease of administration. Quality control and quality assurance programs are instituted to evaluate the process and product specifications of dosage forms. Compliance with good manufacturing practices and quality control specifications ensures safe and efficacious dosage forms. In this chapter, we discuss different aspects of liquid dosage forms, including formulation considerations, manufacturing and testing procedures, and packaging and labeling requirements.