Sterile powders: Dry sterile powder is aseptically added to a sterile vial. The dry drug powder is reconstituted with a sterile vehicle before use. Powders for injections are solid substances, distributed in their final containers and which, when shaken with […]
Suspensions: The physical chemist defines the word “suspension” as a two phase system consisting of an undissolved or immiscible material dispersed in a vehicle (i.e., solid, liquid, or gas). The particles of the dispersed phase vary widely in size, from […]
Methods For Formulation of Suspension: 1-Precipitation method: Three precipitation methods are used: Organic solvent precipitation: Water insoluble drugs can be precipitated by dissolving them in water- miscible organic solvent and then adding organic phase to distilled water under standard conditions. […]
Equipment for Suspensions: 1-Mortar and pestle: It consists of a glass or porcelain mortar and a pestle. Advantages: Small quantity suspenisons can be prepared in the laboratory. Low cost. Simplest operation among all other instruments. Disadvantages: Generally, the final particle size […]
Evaluation of Suspensions: Sedimentation method Rheological method Electro kinetic method 1.Sedimentation method : Two parameters are studied for determination of sedimentation: Sedimentation volume Degree of flocculation Sedimentation volume – The suspension formulation(50mL)was poured separately into100mL measuring cylinders and sedimentation volume […]
SETTLING IN SUSPENSIONS : One aspect of physical stability in pharmaceutical suspensions is concerned with keeping the particles uniformly distributed throughout the dispersion. It possible to prevent settling completely over a prolonged period of time, it is necessary to consider the […]
SEDIMENTATION OF FLOCCULATED PARTICLES: When sedimentation is studied in flocculated systems, it is observed that the flocs tend to fall together, producing a distinct boundary between the sediment and the supernatant liquid. The liquid above the sediment is clear because even […]
WETTING OF PARTICLES: The initial dispersion of an insoluble powder in a vehicle is an important step in the manufacturing process and requires further consideration. owders sometimes are added to the vehicle, particularly in large-scale operations, by dusting on the […]
Electric double layer: Particles dispersed in a liquid medium may become charged in one of two main ways. Ionic species present in a solution may be adsorbed at the surface or, alternatively, charges on the surface may arise due to […]