Moisture and heat sensitive material is very common in pharmaceutical formulation. So there should be consider few points like- do not use excipients with high content of water such as corn starch. For moisture sensitive product you need to use excipients with low moisture content and avoid those like starch where moisture content always exceeds 10%. Also avoid using wet granulation technique as the exposure to moisture could affect your material and also the residual moisture after drying could also have an effect. Finally protect your product by either coating with a moisture barrier film coat that mostly contains PVA or pack them in a packaging material that offer high protection against moisture and have little permeability like Alu-Alu, triplex -alu, ...etc. And the relative humidity (RH) of room condition should be NMT 50%.
Following point will be helpful for pharmaceutical formulation-
- Mannitol can choose as the suitable filler. Mannitol is not hygroscopic and will avoid degradation by water absorption. Anhydrous calcium phosphate (Emcompress) is another option.
- Colloidal silicon dioxide (Aerosil 200) can mixed with the active. Aerosil will adsorb water avoiding contact with the sensitive API.
- Anhydrous lactose as a filler could help to formulate moisture sensitive products (spray dried lactose contains 5% hydrated water, anhydrous lactose contains less than 0.1%).
- A coating of the solid dosage form by a non-containing water procedure could help to avoid the contact of the API with the environment.
- Most of the disintegrant has about 5% of water (croscarmellose, crospovidone) but sodium starch glycolate has more water and must be avoided.
- For heat sensitive products, you need to avoid wet granulation that is always followed by drying or to perform wet granulation to a part of excipients without inclusion of the API, followed by mixing of the API and any remainders of excipients. Finally, you have to label your product "keep at temperature not exceeding 25◦C".
- Desiccant may use with packaging.
Water content/Moisture content of few commonly used pharma excipients:
- Calcium Phosphate, Dibasic Anhydrous = 0.1 to 0.2%
- Lactose Anhydrous = ≤1.0%
- Lactose Monohydrate = 4.5 to 5.5%
- Microcrystalline Cellulose = 0.5 - 8.0%
- Mannitol = 0.1-1.0% Starch = > 10%
- Hypromellose = 2-5%
- Crospovidone = 2-5%
- Croscarmellose Sodium = 2-10%
- Sodium Starch Glycolate = 2-10%
- Magnesium Stearate = 0.5 - 6%
- Colloidal Anhydrous Silica = 0.5 - 5.0%
