| Popis: |
The rate and extent to which an unchanged drug reaches the systemic c irculation is called as bioavailability (BA). Bioavailabili ty, a subcategory of absorption is one of the principal pharmacokinetic parameter determined for an active substance form a pharmaceutical product. It also indicates the fractional extent to which a dose of drug reaches its site of action or biological fluid from which the drug has access to its site of action. Physical properties of drug, drug formulation, route of administration, gastric emptying rate etc. are several factors affect the bioavailab ility of drug from its drug product. Poor solubility, enzymatic and transporters barrier, drug stability and short retention of the drug in stomach due to peristaltic movement are several factors decrease t he bioavailability of the drug. This review deals with the bioavailability improvements techniques from poor permeation, lesser stability and short retention of the drug in stomach. Lipid based formulations; ion pairing and use of permeation enhancer are different methods to enhance the bioavailability th rough increase in permeation. Enteric coating, complexation and metabolism inhibitors lead to increase in drug stability. Bioadhesive polymers in formulation improve the gastro retention time serve as improved bioavailable product. |
