4. IMPURITIES

These free B.Pharm notes on impurities in pharmaceuticals cover chapter 4 of Pharmaceutical Inorganic and Analytical Chemistry (BP106T), a first-semester subject. Read the key points below, then study the complete chapter PDF. You can browse every chapter in the Pharmaceutical Inorganic and Analytical Chemistry category.

Overview of impurities in pharmaceuticals

These notes explain the effects of impurities on a product and the ICH guidelines for impurity profiling. They then cover the main sources of impurities, from synthesis, formulation and storage to particulate matter, by-products, microbes and heavy metals. The notes end with tests for specific impurities, the contents of an official monograph, limit tests and the regulatory importance of impurities.

Key points on impurities in pharmaceuticals

• Impurities may cause incompatibility, decreased shelf life, instability, reduced therapeutic effect, changes in appearance and toxic effects.
• ICH guidelines ask for identification and characterisation of every impurity present at 0.1% or more in an Active Pharmaceutical Ingredient.
• Water is the main source of heavy metals such as As, Cd, Cr and Mn, and distilled or demineralised water avoids them.
• Limit tests are quantitative or semi-quantitative tests that identify and control small quantities of impurity using a selective reaction with the trace impurity.
• Regulators such as the FDA, EMA and ICH worry most about genotoxic or carcinogenic impurities, so manufacturers must do complete impurity profiling.

Relevance to pharmacy practice

The quality and safety of a medicine depend mainly on its impurities, which can reduce its effect or cause toxic and allergic reactions even at low levels. Knowing where impurities come from helps a pharmacist control them and meet the rules required for market approval.

Every chapter in this subject builds on the one before it, so do not skip topics that look simple. Definitions, principles, procedures and examples are the parts that examiners return to most often, and a clear understanding here will also make later subjects easier to follow in the coming semesters.

Quick revision checklist

Use this self-test after reading the chapter on impurities in pharmaceuticals. If you can do all of the following without looking at your notes, you are ready for the exam.

• I can explain: the effects of impurities on a product
• I can explain: the main ICH guidelines on impurities
• I can explain: the seven sources of impurities
• I can explain: what an official monograph contains
• I can explain: why regulators control genotoxic impurities

Study and exam tips

Start by reading the chapter once for the overall idea, then revise impurities in pharmaceuticals using headings, definitions, principles, reactions and examples. Short-answer questions in the university exam usually ask for definitions, principles, procedures, reactions and uses, so write these in your own words and practise the equations, tables and flow charts that the chapter has.

For wider reading, standard books and open resources such as the NCBI Bookshelf help you confirm terms and see more examples. Revise impurities in pharmaceuticals again a day later and again a week later, because spaced revision improves long-term memory.

This page is part of the Pharmaceutical Inorganic and Analytical Chemistry series for first-semester B.Pharm students on B.Pharm Guru, where every chapter has a short summary and a full PDF. Bookmark this page and share it with classmates who are preparing for the same exam.

Related notes: 6. HEAVY METALS AND MODIFIED LIMIT TESTS FOR CHLORIDE AND SULPHATE, 7. ACID-BASE CHEMISTRY AND BUFFER SYSTEMS IN PHARMACY.

Next: 5. LIMIT TESTS: CHLORIDE, SULPHATE, IRON, ARSENIC AND LEAD. Back to the Pharmaceutical Inorganic and Analytical Chemistry category.