Powder handling: Powder Mixing – Powder mixing is an operation that serves to make two or more components uniformly distributed in the powder bed. Mechanisms – There are three main mechanisms involved in the mixing process, related to the different […]
Preservatives: If these materials prevent the initiation and growth of microorganisms in products, they are known as bactericidal preservatives. Some preservatives, either by concentration or activity, may only maintain the bacteria level in the product at the time of manufacture […]
When powders are poured into a pile, segregation occurs. Particles with small size (fine particles) will stay in the center of the pile, and coarser particles tend to concentrate at the periphery. Size segregation is unavoidable, during powder transportation, storage, […]
The term “powder” has more than one connotation in pharmacy. It may be used to describe the physical form of a material, that is, a dry substance composed of finely divided particles. Or, it may be used to describe a […]
Diffusion During Swelling of Matrix – When water-soluble drugs are entrapped in glassy hydrogels, the release of the drugs engages simultaneously the absorption of water and desorption of drug while the hydrogels swell slowly. Drug release kinetics is governed by […]
DRUG RELEASE FROM POLYMER MATRICES: When the conventional dosage forms (i.e. tablets, capsules, ointment or creams) are administered orally or topically, the active drug in the dosage form is immediately released and absorbed into the systemic circulation. The release of […]
APPLICATIONS OF DIFFUSION PRINCIPLES: Drug Absorption by Passive Diffusion – Passive diffusion is the major trans-membrane transport process for most drugs. The driving force for passive diffusion is the difference in drug concentrations on either side of the cell membrane. […]
IN VITRO–IN VIVO CORRELATION: IVIVC refers to a relationship between a physicochemical characteristic of the dosage form, as determined by in vitro dissolution and biological property and as determined by in vivo pharmacokinetics. The objectives of IVIVC are to use […]