DRUG EXCIPIENT INTERACTION
Pharmaceutical excipient is a pharmacologically inactive substance formulated alongside the API {active pharmaceutical ingredient} of a medicine to impart specific qualities to them.
ROLE OF EXCIPIENT
- Improve bioavailability of drug.
- Enhance stability of formulation
- Provide bulk to the formulation
Drug substances when contact with excipient they can undergo physical and chemical interaction under favorable conditions leads to instability.
MECHANISM OF DRUG EXCIPIENT INTERACTION
They can be classified as :
1. Physical interaction
These are very common in dosage form and also difficult to detect these are involve change in dosage uniformity, color, odor, dissolution and sedimentation rate. These interactions are beneficial and detrimental to the product performance.
2. Chemical interaction :
Chemical interaction involves chemical reaction between drugs and excipients or drugs and impurities or residues in excipients. These interactions are always detrimental to the product because thy produce degradation products.
They are as follows
- chemical interaction between drug and excipients { Maillard reaction} example : chlorpheniramine and dextrose interaction.
primary amines+ reducing sugar form amine which are break into AMADORI compounds
- Interaction of drug with excipient residues : excipients are not exquisitely pure They have some residues which affect drug action.
3.Biopharmaceutical Interaction :
These are the interactions which are observed after administration of medicine. The interaction is between the medicine and the body fluids and have the tendency to influence the absorption of the drug. Which includes
- Premature breakdown of enteric coat.
- Increase in gastrointestinal motility
IMPORTANCE OF THESE STUDIES
These studies are the part of PREFORMULATION study and this study data is essential for IND submission. Helps to avoid surprise problem during formulation process. Maximizes the stability of API. To find out how compatible an excipient is with API. Determine the list of excipient tat can be used in final dosage form.