Liquid Dosage Forms Overview

Liquid Dosage Forms

• Solutions: Solvent is typically present in greater amount.
• Exceptions: Syrup BP has 66.7% w/w sucrose (solute) in 33.3% w/w water (solvent).

Advantages of Liquid Dosage Forms

• Easier to swallow (especially for children and the elderly).
• Drugs are immediately available for absorption (even if finely divided or acidic).
• Uniform distribution of drug (like in suspensions or emulsions).
• Irritable drugs (like aspirin or potassium chloride) are better absorbed as solutions, leading to less gastric irritation.

Disadvantages of Liquid Dosage Forms

• Liquid dosage forms can be bulky, taking up more space for transport and storage.
• Containers may be damaged to the point of needing replacement
• Stability of drug and excipients might be affected.
• These forms are conducive to microbial growth.
• Dosage administration can sometimes be inaccurate.
• Drug taste can be an issue.

Choice of Solvent - Aqueous Solutions

• Water is the most common solvent due to physiological compatibility and lack of toxicity.
• Water has a high dielectric constant, which aids in dissolving ionic materials.
• Water does not have a high degree of selectivity.

Types of Pharmaceutical Water

• Purified Water BP: Freshly boiled and immediately cooled before use, no salts. Distillation or deionization is employed for purification.

• Water for Injection: Used in parenteral solutions. It must be sterile, pyrogen-free, and salt-free.

• Special types of Water for Injection include CO2-free (e.g., phenobarbital sodium, aminophylline) and O2-free (e.g., apomorphine, ergotamine maleate). Apyrogenic distilled water is also boiled for 10 minutes, cooled, sealed, and autoclaved to sterilize.

This quiz explores the various aspects of liquid dosage forms, focusing on solutions, their advantages, and disadvantages. It highlights the importance of solvent choice, particularly aqueous solutions, and examines the implications for drug absorption and storage. Test your knowledge on the characteristics and considerations of liquid medications.