[Chemistry Class Notes] on Bismuth Subsalicylate Pdf for Exam

What is Bismuth Subsalicylate?

Bismuth Subsalicylate is a generic medicine which is an ‘over the counter’ drug (sold without the need of prescription). It is commonly used to treat upset stomach and discomforts due to indigestion like heartburn, diarrhoea, etc. It is derived from salicylic acid and known for its anti-inflammatory response. Because of this, bismuth subsalicylate is sold as an antacid under the common brand name – Pepto Bismol and Pink Bismuth.

Salicylic Acid

When salicylic acid reacts with bismuth hydroxide, we get bismuth subsalicylate. Salicylic acid is obtained from plants and is well known for its antibacterial and anti-inflammatory properties. Bismuth subsalicylate is a bismuth salt of Salicylic acid.  

The empirical formula for salicylic CH₆O₃ or HOC₆H₄COOH. It is a benzoic acid with a hydroxy group at its ortho position. This hydroxyl group is hydrolysed to obtain bismuth subsalicylate.

Structure of Bismuth Subsalicylate

C₇H₅BiO₄ is the empirical formula for bismuth subsalicylate. On hydrolysing Bismuth salicylate ( empirical Formula – Bi(C₆H₄(OH)CO₂)₃), we obtain bismuth subsalicylate.

The molecular weight of bismuth subsalicylate is 363.1g/mol. Bismuth subsalicylate has some chemical and physical characteristics that make it useful. The properties are as follows:

Chemical and Physical Properties

• Appearance –  bismuth subsalicylate is like a white solid or white crystalline powder which is fluffy in nature.

• Colour- It is white in colour

• Odour-  Bismuth subsalicylate gives no smell. It is odourless.

• Taste- It has no taste.

• Solubility- Bismuth subsalicylate is insoluble in water, ether and alcohol. However, it is soluble in acids, alkalies and oil.

• Shelf life- It is a stable compound in air. However, bismuth subsalicylate does react with light and is thus advised to be kept in the dark and dry place.

Below are the Numerical Values for the Compound Bismuth Subsalicylate:

• Density – 0.43 g/cm³

• Melting Point – 350⁰C

• Molar mass – 362 g/mol

What is Bismuth Subsalicylate Used for?

Bismuth subsalicylate is commonly used to treat diarrhoea and upset stomach. It also works as a weak antacid. It is known to treat traveller’s diarrhoea. It helps against the growth of diarrhoea-causing bacteria because of its antibacterial properties. It reduces the flow of electrolytes and other fluids into the intestines. It also has anti-inflammatory properties and therefore is commonly sold under the generic brand names such as Pepto Bismol. Bismuth subsalicylate  is prescribed in the following conditions:

Advisable Precautions and Dosage

Bismuth subsalicylate is advised to be taken with a doctor’s recommendation. Bismuth subsalicylate is said to interfere when taken in combination with other medicines. So if you are currently on any sort of medication, it is advised to let your doctor or pharmacist know about it. It is also not recommended to be used in the last 3 months of pregnancy as it affects the baby’s health and can interfere in normal delivery.

If you are taking a tablet in a chewable form, chew it well before swallowing. If you are prescribed a liquid form, shake the bottle well before use. In case of a missed dose, don’t double dose in order to make up for it. Store the medicine at a dark and a dry place away from children. Children just recovering from chicken-pox and influenza should not take this medicine.

The adverse effects of this medicine are only experienced when taken inappropriately or overdose or if taken for an extended period of time. This is due to salicylate toxicity. The overall effect of the salicylate in treating inflammation of stomach lining is yet to be understood completely but it does inhibit the secretion of pepsin which makes bismuth subsalicylate the only salicylate colloid to be sold over the counter medicine.

What Medicines Contain Bismuth?

Bismuth subsalicylate is commonly sold under Pepto Bismol, which is used to treat mild diarrhoea and stomach discomfort. These are sold as over the counter medication. Also, it is used in combination with other medicines in the treatment of syphilis. Some common Bismuth subsalicylate medicines are sold under different brand names such as: