Povidone is one of the most common and widely used excipients in pharmaceutical formulations.It is usually used as a favourite binder in tablet and capsule manufacturing because of its ability to dissolve in water as well as in IPA.
Povidone is also known as
Grades of Povidone
According to USP,32 Povidone is a synthetic polymer having a different degree of polymerization with different molecular weight. Different degrees of polymerization with viscosity grades are expressed as k value and k value ranges from 10-120.
Following are different k values or grades of povidone
from top to bottom molecular weight and viscosity is increased.
Uses of Povidone
Following are the main uses of Povidone
- Binder 0.5-5%
- Suspending Agent up to 5%
- Dissolution Enhancer or dispersing agent up to 5%
- Coating Agent 0.5-5%
- Tablet Diluent 0.5-5%
- In Eye Drops 2-10%
- Carrier for drugs 10-25%
Povidone As Binder
- Povidone is commonly used as a binder in manufacturing of tablets, capsules and granules used for dry suspensions.
- Povidone is an example of synthetic binders used in pharmaceuticals formulations.
- It is used in wet granulation as a solution in water or IPA.
- It is rapidly soluble in both Water and IPA so it does not affect the dissolution or disintegration profile of the drugs due to its rapid water solubility.
- Granules produced by Povidone are hard and give good tablet hardness without any negative effect on disintegration and dissolution when it is used in optimum quantity.
- Povidone can also be used as a dry binder which can be activated later on by the addition of water or IPA.
- It is also used as a dry binder in direct compression.
- Commonly used grades of Povidobe as a binder in wet granulation are as follow
- Povidone k 25 (2-5%)
- Povidone k 30 ( 2-5)
- Povidone k 90 (1-3)
Dissolution of povidone decreases as the molecular weight or k value of the polymer is increased but the binding property and viscosity are increased.
That’s why Povidone k90 is used in low concentration as compared to povidone k25 and k 90.
How to prepare Binder Solution
- Povidone should be added in solvent in small portions with fast stirring to disperse and dissolve the polymer without forming foam or lumps.
- Povidone k 90 dissolves slowly because it has large molecular weight and high viscosity.
Povidone As Dissolution enhancer
- Povidone is used as a solubilizer in oral solid dosage forms and parenteral formulations.
- It is used to enhance the dissolution of drugs that have poor solubility in oral dosage form.
- Povidone enhances the dissolution by forming a water soluble complex with many drug products.
- Povidone is used as a suspending agent in oral and topical suspensions or solutions.
Povidone is also used to coat the tablets.
Povidone forms a molecular adduct in solution with following
- Salicylic acid
- Sodium salicylate
The efficacy of some preservatives like thimerosal is decreased due to the formation of complex.
Before use, the water content of solid povidone should be checked to calculate the quantity for use in different formulations.
On heating at 150 °C it becomes dark and its aqueous solubility is reduced.
Aqueous solutions are susceptible to mould growth so suitable preservatives should be used.
Povidone is hygroscopic so should be stored in airtight containers.
- Hand Book of pharmaceutical Preparation.
- Polyvinylpyrrolidone Excipients for Pharmaceuticals (V Buhler)
- Practical Experience and Observations
- Role Of Kollidon Cl
- Classification of Excipients.
- Role of diluents in tablet granulation.
- Role of mannitol in pharmaceutical products.