Chapter 14-Suspensions.pdf - UNIT 4 LIQUID DOSAGE FORMS CHAPTER 14 DISPERSE SYSTEMS Suspension Is a two-phase system consisting of a finely divided

Chapter 14-Suspensions.pdf - UNIT 4 LIQUID DOSAGE FORMS...

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Page 1 of 12 UNIT 4: LIQUID DOSAGE FORMS CHAPTER 14: DISPERSE SYSTEM S Suspension Is a two-phase system consisting of a finely divided solid dispersed in a liquid vehicle. The finely divided particles are also referred to as Suspensoids . In these preparations, the substance distributed is referred to as dispersed phase and the vehicle is termed the dispersing phase or dispersion medium . Together, they produce a dispersed system. Dispersions containing coarse particles, usually 10 to 50 um in size, are referred to as coarse dispersion. Dispersions containing particles of smaller size are termed fine dispersions (0.5 to 10 um) In general sense, Suspension may include: 1. Gels 2. Lotions 3. Magmas & Milk 4. Mixtures Characteristics of Oral Suspension Particles should be small uniform sizes that do not settle rapidly The particles that do settle to the bottom of the container should not pack in to a hard cake & should be re-dispersed completely and evenly with a minimum amount of agitation Characteristics of Suspension Should not be too viscous to pour freely from the mouth of the bottle Should have an agreeable odor, color and taste & must not decomposed or support mold growth during storage Must have therapeutic efficacy Suspensions for injections must contain particles size such that they can pass freely through the syringe needle called syringeability . Ophthalmic suspension should be formulated such that the particles do not exceed 10 microns . Below this size, the patient experiences no pain when instilled into the eyes. For Topical use, fine particles are desired to avoid grittiness when applied to the skin. The smaller the size, the greater the covering and protective power of the preparation Reasons for Suspension Certain drugs are chemically unstable when in solution but stable when suspended. Suspension insures chemical stability while permitting liquid therapy. Many patients prefer liquid form than solid forms for swallowing. Convenience in administration of usually large doses Safety and convenience of liquid doses for infants and children. Disagreeable taste of certain drugs when given in solution is negligible when the drug is administered as undissolved particles of a suspension, e.g chloramphenicol Features Desired in a Pharmaceutical Suspensions 1. A properly prepared suspension should settle slowly & should be readily redispersed upon gentle shaking of the container. 2. The characteristics of the suspension should be such that the particles size of the suspensoid remains fairly constant throughout long periods of undisturbed standing. 3. The suspension should pour readily & evenly from its container - Good pharmaceutical suspensions, the particle diameter is between 1 to 50.
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