Unit 2: Calculations, Powders & Liquid Dosage Forms

February 13, 2026

Semester 1
BP103T

Introduction to Calculations, Powders & Liquid Dosage Forms

Unit 2 deals with the mathematics of pharmacy and the formulation of solid (Powders) and liquid dosage forms. You will learn how to calculate precise quantities for syrups and injections using Isotonicity and Alligation methods. The unit also covers the formulation of various powders, including special types like Eutectic mixtures and Effervescent granules, and the basics of Liquid Dosage Forms.

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Syllabus & Topics

  • 1Pharmaceutical Calculations: Imperial & Metric system
  • 2Calculations: Percentage solutions, Alligation, Proof spirit
  • 3Isotonic Solutions: Freezing point & Molecular weight method
  • 4Powders: Definition, Classification, Advantages/Disadvantages
  • 5Types of Powders: Simple, Compound, Dusting, Effervescent, Efflorescent, Hygroscopic
  • 6Eutectic Mixtures and Geometric Dilutions
  • 7Liquid Dosage Forms: Advantages, Disadvantages, Excipients, Solubility enhancement

Learning Objectives

Perform calculations for preparing Isotonic solutions.
Solve problems based on Alligation method and Proof spirit.
Describe the method of Geometric Dilution for potent drugs.
Classify powders and explain Eutectic mixtures with examples.
List excipients used in Liquid Dosage Forms.

Frequently Asked Questions (FAQs)

Q1. What is Alligation Method?

Alligation is a calculation method used to determine the proportions in which two solutions of different concentrations must be mixed to obtain a solution of a desired intermediate concentration.

Q2. What are Eutectic Mixtures?

Eutectic mixtures are combinations of two or more substances (such as camphor and menthol) that liquefy on mixing at room temperature because their melting point is lowered below room temperature.

Q3. What is the difference between Effervescent and Efflorescent powders?

  • Effervescent powders release CO₂ gas when mixed with water (e.g., citric acid + sodium bicarbonate).

  • Efflorescent powders lose their water of crystallization on exposure to air and become powdery (e.g., atropine sulfate).

Q4. What are Geometric Dilutions?

Geometric dilution is a method used to mix a small quantity of a potent drug with a large amount of diluent. The drug is first mixed with an equal amount of diluent, and this mixture is then repeatedly mixed with equal portions of diluent to ensure uniform distribution.

Q5. What is Proof Spirit?

Proof spirit is a standard used to express the alcohol content of alcoholic preparations. In India, 100% proof spirit = 57.1% v/v ethyl alcohol.