These free B.Pharm notes on poison and antidote cover chapter 19 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.
Table of Contents
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Overview of poison and antidote
These notes define poisons, antidotes and toxicology, and cover the routes of poisoning, general treatment and first aid. They then explain gas poisoning, snake venom and anti-snake venom, and heavy metal poisoning by arsenic, lead and mercury, followed by the classification of antidotes and the properties, assay and uses of sodium thiosulphate, activated charcoal and sodium nitrite.
Key points on poison and antidote
- An antidote cancels the effect of a poison by neutralising it chemically, by an opposite pharmacological action, or by changing it into a less toxic form.
- Vomiting may be induced for a non-corrosive poison, but must not be induced for corrosive poisons, alkalies or kerosene.
- Anti-snake venom is prepared by immunising horses with venom, and polyvalent ASV has antibodies against Cobra, Russell’s viper, Common krait and Saw-scaled viper.
- Arsenic, lead and mercury bind sulfhydryl groups of enzymes, and chelating agents such as dimercaprol and calcium disodium edetate remove these metals from the body.
- In cyanide poisoning, sodium nitrite forms methaemoglobin that binds cyanide, and sodium thiosulphate then converts cyanide to thiocyanate, which is passed out in urine.
Relevance to pharmacy practice
Pharmacists are often the first contact in cases of poisoning, so they must know first aid and which antidote suits which poison. The iodometric and permanganate assays of sodium thiosulphate and sodium nitrite are also important methods in pharmaceutical analysis.
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.
Frequently asked questions on poison and antidote
How are antidotes classified?
Physical antidotes stop absorption, such as activated charcoal; chemical antidotes react with the poison, such as dimercaprol for metals; and physiological antidotes give an opposite effect, such as atropine for organophosphates.
How does sodium thiosulphate act as an antidote for cyanide?
Sodium thiosulphate converts cyanide to thiocyanate, which is safely passed out in urine. The enzyme rhodanese carries out this change in the body.
Why is activated charcoal used in poisoning?
Activated charcoal is very porous and strongly adsorptive, so it is an emergency antidote for certain toxins, alkaloids, amines, gases and heavy metal salts. It must be given immediately after the poison is swallowed.
Quick revision checklist
Use this self-test after reading the chapter on poison and antidote. If you can do all of the following without looking at your notes, you are ready for the exam.
- I can explain: the general treatment of chemical poisoning
- I can explain: the four groups of poisonous snakes
- I can explain: the effects and treatment of heavy metal poisoning
- I can explain: the classification of antidotes with examples
- I can explain: how nitrite and thiosulphate treat cyanide poisoning
Study and exam tips
Start by reading the chapter once for the overall idea, then revise poison and antidote 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 poison and antidote 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: 2. ERRORS IN ANALYSIS: SOURCES, TYPES AND MINIMIZATION, 3. ACCURACY, PRECISION AND SIGNIFICANT FIGURES.
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