Excipients criteria

Often these design criteria involve competitive requirements. What is best for meeting one criterion may be counterproductive in meeting another. For example, certain excipients such as the hydrophobic stearate lubricants are important for efficient manufacture, yet they have the potential to retard the release of drug from an immediate-release formulation. The design of a dosage form thus frequently requires the optimization of formulation and process variables in a way that best meets all design criteria. 

Parenterais The most important criterion for parenterals is that they have to be sterile for injection or infusion administration. Excipients are added to make parenterals isotonic with blood, improve solubility, and control pH of the solution. The solvent vehicles include water-for-injection, sterile sodium chloride, potassium chloride, or calcium chloride solution, and nonaqueous solvents such as alcohol, glycol, and glycerin. Preservatives, antioxidants, and stabilizers are normally added to enhance the properties of the drug product. 

The replacement of chlorofluorocarbon (CFC) propellants with the non-ozone-depleting hydrofluorocarbons (HFCs) merit mention for two reasons. First, it illustrates how environmental impact can be an important selection criterion at a time when green issues are high profile. Second, HFCs were developed and evaluated for safety and delivery capability by a consortium of pharmaceutical companies, with costs shared and evaluation programs defined by prior agreement between end-users and propellant manufacturers. Such collaboration could be employed usefully in the future to develop novel excipients for delivery or targeting. The benefits would undoubtedly accrue to all. 

Density requirements may also be set by the mentioned Pharmacopoeias, for the relative density of a liquid or solution. For alcoholic solutions such a requirement may be useful to determine whether the correct quality and the correct volume of ethanol have been used in the preparation process. The same is true for other preparations of which the density deviates strongly from water, for example because of the presence of dissolved substances. Preparations that, for example, contain a high percentage of sorbitol or glycerol are well characterised by their density and a determination of the density actually becomes an important identity criterion. The requirements for the relative density are not strictly defined, because the nature and amotmts of the excipients may have a significant impact oti the density of a product. As guidance a precision of maximally three decimal places may be appropriate, with limits of 0.020 unless there is practical information available that requires wider or stricter limits. 

This is a measure of the angle of rotation of plane polarised fight and is often used as an identity criterion for certain materials, especially sugars. When these substances are present in a significant proportion in the final product and when few other excipients are present, the optical rotation can be used as a characteristic that gives quantitative information to the product concentration. 

The interference criterion was an error of not more than 3 0 % in the absorbance. To test the efficiency and selectivity of the proposed analytical methods (A-C) to pharmaceutical formulations, we carried out a systematic study of additives and excipients (e.g. lactose, glucose, dextrose, talc, calcium hydrogen phosphate, magnesium stearate and starch) that usually present in dosage forms. Experiments showed that there was no interference from additives or excipients for methods A-C (Table 3). 

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