When Pharmaceutical company discover new molecules that are going to become a drug, there is an obvious step where they manufacture the API – Active Pharmaceutical Ingredient, but beyond that, they also need to make sure that the drug is packaged right as a tablet or capsule, is bio-available and there is a big branch of making it ready called formulation. Formulation of the drug is especially important for drugs that are taken orally since it makes the difference between a working and bio-available drug and a non-available drug or drug that is destroyed by stomach acid or in worse cases, causes a strange reaction on consumption.
One component in the formulation process is Coating. This is the process by which the API is covered with a safe polymer.
The reasons to coat are many:
- Oral delivery for controlled, enteric, sustained or delayed release.
- Mask the taste or odor of the API
- Block oxidation of the API or block water vapor access to the API
- Time release ion resin suspension technology
- Cosmetic coatings
- Differentiate between dosage forms
- Blinding samples in clinical trials
- Providing gastric acid resistance
The common way of doing this is first form slurry or solution of the API in a binder solution like PVP – Polyvinylpyrrolidone and sprayed onto a substrate. A coating is applied at that stage.
There are many coating solutions each with different characteristics. So for example Poly(butyl methacrylate-co-(2-dimethylaminoethyl) methacrylate-co-methyl methacrylate) is Cationic and soluble at pH less than 5.0.
Thus, finding the target is one step and the development of a compound that affects the target is another followed by an extensive clinical trial but significant steps are required during development that would make the difference in the activity and usability of the drug.