Bitter After Taste- Reason and its Masking- Syrup

Bitter after taste     Written by: Mudasir Abbas

Many drugs and sweeteners show bitter after taste. Bitter taste is shown by those ingredients which have both hydrophobic and hydrophilic group. Taste receptors have such type of confirmation that binding of these ingredients from hydrophilic and hydrophobic part results in strong binding of ingredient with taste receptors. If you will take sucrose it will show sweetness for few seconds but if you will take ingredients which shows bitter after taste then you will  feel it's taste for longer time that is due to their strong binding with taste receptors. This bitter after taste can be masked if these ingredients are prevented to strongly bind with taste buds

Along with drugs, there are two types of excipients which binds to the taste buds that are sweeteners and flavors. Whenever you are going to mask the bitter after taste of certain drug, then you should study it's structure thoroughly and also structure of flavors because there is large variety of flavors which have wide range of structures. There are many flavors which resembles in structure to many drugs, so when flavor will have similar structure to the drug then this flavor will compete with the drug to bind with taste buds. As a result of which drug will not strongly bind to the receptors and will pass from oral cavity.

Menthol has bitter after taste and thymol also has a bitter after taste but when you combine them together in equal quantity then they will not show bitter after taste and taste will be masked. Similarly camphor also has similar structure to menthol and thymol. So if you are using 50 gram of camphor and 50gm thymol then 100 gram of menthol will mask the bitter after taste of both ingredients and these both ingredients will mask bitter after taste of menthol. But if you will add more menthol to it then menthol will again start to show it's bitter after taste. Similarly if you will add grapefruit flavor, orange flavor or lemon flavor with menthol, thymol or camphor then flavor will also mask the bitter taste of these ingredients.

Saccharine sodium which is used as sweetener shows bitter after taste and sodium cyclamate also shows bitter after taste because both have hydrophobic and hydrophilic groups in their structure and hence strong binding but both have similar structure so they compete to bind with taste receptors and will pass through oral cavity. Similarly vanilla flavor has resemblance in structure to paracetamol so it will mask it's taste. You can study the structures of many drugs and flavors to mask the bitter after taste of drugs in this way.

Another technique to mask the bitter after taste of drugs is use of sodium salts. Because atom of sodium resembles to NH group (responsible for binding with receptor and hence bitterness) both in case of size of atom and charge so it competes with NH group present in most of the bitter drugs as a result it may cause masking of bitter taste of drugs. But sodium salts have problem that they makes the syrup salty. So to solve this problem you should use the sodium salt with fatty chain as the size of fatty chain will increase then it's salty effect will reduce but masking effect will be retained like sodium glutamate also known as China salt is best to be used for this purpose.

Another technique to mask the bitter taste of drugs is to use Kyron T314. Kyron has property that it exchanges it's ions with the drug. So when you will sufficiently wet granulate Kyron with the drug then entire drug will be adsorbed over the Kyron. All of the NH groups of drug which are responsible for bitterness will be adsorbed over Kyron and in this way bitter after taste of drugs will be masked. These interactions between Kyron and drugs are weak due to which they are separated from each other in stomach.

Kyron is also regarded as super disintegrant. It is the only disintegrant which shows disintegration through quadruple mechanism.

1. It swells with water
2. It exchanges the ions with drugs and water
3. It wicks the water within its structure hence withdraw high quantity of water and water through its hydrostatic pressure breaks the tablet 
4. And it's fourth mechanism is plastic deformation it is deformed during compression after removal of compression force but this molecule will when absorb water then it will come to its original position in DT and hence will break the tablet to make its space.

 Written by: Mudasir Abbas