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Pharmaceutical suspensions: Introductory overview

A pharmaceutical suspension would be considered stable if, after agitation (shaking), the drug particles are homogeneously dispersed


Pharmaceutical suspensions are commonly referred to as dispersion in which the therapeutic agent is dispersed in the external phase (the vehicle). According to this definition the solubility of the therapeutic agent in the vehicle is low. The diameter of the disperse phase may range from circa 0.5 to 100 lm. Systems in which the particle size diameter falls below the above range are termed colloidal.
In pharmaceutical dispersion (suspensions) the internal (drug) phase will separate upon storage; however, the main aim of the formulation scientist is to control the process of separation and, in so doing, optimize the stability of the formulation. A pharmaceutical suspension would be considered stable if, after agitation (shaking), the drug particles are homogeneously dispersed for a sufficient time to ensure that an accurate dose is removed for administration to the patient.

The characteristics of an acceptable pharmaceutical suspension include the following:

·        a low rate of sedimentation
·        the disperse phase must be easily re-dispersed with gentle shaking
·        the flow properties of the suspension should enable the formulation to be easily removed from the container (e.g.bottle, injection vial)
·        Aesthetically pleasing.



Advantages and disadvantages

Advantages of pharmaceutical suspensions
·        Pharmaceutical suspensions are a useful drug deliverysystem for therapeutic agents that have a low solubility.Although low-solubility therapeutic agents may besolubilised and therefore administered as a solution, thevolume of the solvent required to perform this may be large.In addition, formulations in which the drug has beensolubilised using a co-solvent may exhibit precipitationissues upon storage.
·        Pharmaceutical suspensions may be formulated to mask the taste of therapeutic agents.
·        Pharmaceutical suspensions may be employed to administerdrugs to patients who have difficulty swallowing solid-dosageforms.
·        Pharmaceutical suspensions may be formulated to provide controlled drug delivery, e.g. as intramuscular injections

Disadvantages of pharmaceutical suspensions

·        Pharmaceutical suspensions are fundamentally unstable andtherefore require formulation skill to ensure that the physicalstability of the formulation is retained over the period of theshelf-life. The formulation of aesthetic suspension formulations is difficult. Suspension formulations may be bulky and therefore difficult for a patient to carry.
Pharmaceutical suspensions: Introductory overview Pharmaceutical suspensions: Introductory overview Reviewed by gafacom on November 03, 2019 Rating: 5

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