What’s in a medicine?
If you look at boxes of medicines you are unlikely to find a complete list of ingredients as you would for a food product. The label of a medicine box will tell you what the active ingredient (the "drug") is but not all of the inactive components which are present. In a tablet for example, these other components are there for a number of good reasons including:
- giving it bulk because many drugs are so potent (very strong) that you sometimes only need one crystal or less, which would be a bit difficult to take;
- to add colour to help identify one medicine from another;
- as a type of "glue" to hold the components together after they are compressed into a tablet;
- to help break the tablet up if you take it in water.
These extra ingredients are sometimes referred to as excipients. These extra ingredients are sometimes referred to as excipients. Information on the active ingredients and excipients in a medicine can be found on the Electronic Medicines Compendium.
Examples of excipients in medicines:
Imigran tablets contain the following excipients:
Lactose, microcrystalline cellulose, croscarmellose sodium, magnesium stearate, methylhydroxypropylcellulose and opaspray white
Tamiflu oral suspension contains:
Saccharin sodium (E954), sodium benzoate (E211), sodium dihydrogen citrate (E331(a)), sorbitol (E420), titanium dioxide (E171), tutti frutti flavour (arabic gum (E414), maltodextrins, natural flavouring substances, propylene glycol), xanthan gum (E415)
Ritalin tablets contain:
Calcium phosphate tribasic special, gelatine, lactose, magnesium stearate, methylphenidate hydrochloride, talc, wheat starch
Glivec tablets contain:
Cellulose microcrystalline, crospondone, hypromellose, iron oxide yellow (E172), macrogol, magnesium stearate, red iron oxide (E172), silica colloidal anhydrous, talc
Augmentin oral suspension contains:
Xantham gum, aspartame, colloidal silica, silicon dioxide, hydroxypropyl methylcellulose, succinic acid, raspberry, orange and golden syrup flavours
Try to find out how many drugs are present in Augmentin tablets?
Zantac tablets contain:
Microcrystalline cellulose NF, magnesium stearate EP, methylhydroxypropyl cellulose (E464) EP, film coat, titanium dioxide (E171) EP, triacetin NF
However Zantac effervescent tablets contain different excipients:
Monosodium citrate anhydrous, sodium bicarbonate, aspartame, povidone, sodium benzoate, orange flavour (IFF No. 6), grapefruit flavour (IFF 18C 222)
These Zantac tablets are effervescent (fizzy) tablets - what makes them fizz when you put them into water?
Each ZANTAC 150 Tablet for oral administration contains 168 mg of ranitidine HCl (hydrochloride) equivalent to 150 mg of ranitidine.
What does this mean?
(Hint - ranitidine is a base and can form a salt. The relative molecular mass (molecular weight) of ranitidine is 314.4)
Imigran, Zantac and Augmentin are all trademarks of GlaxoSmithKline plc, its subsidiaries or associated companies. Ritalin and Glivec are trade marks of Novartis Pharmaceuticals. Tamiflu is a trade mark of Roche Products Limited.
More information on what goes into a medicine can be found, for example, at the GlaxoSmithKline web site www.gsk.com under "products" and then "prescription medicines".
Investigate a number of examples in the UK Trademark column and identify the "active ingredients" and the other components. Try and work out why these components have been added.
