1. Difference between prospective validation, retrospective validation and revalidation.
* Carried out during the development stage by means of a risk analysis of the production process, which is broken down into individual steps
* These are then evaluated on the basis of past experience to determine whether they might lead to critical situations
* Where possible critical situations are identified, the risk is evaluated, the potential causes are investigated and assessed for probability and extent, the trial plans are drawn up, and the priorities set.
* The trials are then performed and evaluated, and an overall assessment is made
* If, at the end, the results are acceptable, the process is satisfactory. Unsatisfactory processes must be modified and improved until a validation exercise proves to be satisfactory.
* This form of validation is essential in order to limit the risk of erors occurring on the production scale, eg. In the preparation of injectable products.
* Retrospective Validation involves the examination of past experience of production on the assumption that composition, procedures, and equipment remain unchanged
* Such experience and the results of in-process and final control tests are then evaluated
* Recorded difficulties and failures in production are analyzed to determine the limits of process parameters.
* Retrospective Validation is obviously not a quality assurance measure in itself, and should never be applied to new processes or products. It may be considered in special circumstances only, eg. When validation requirements are first introduced in a company.
* Retrospective Validatoin may then be useful in establishing the priorities for the validation programme. If the results of a retrospective validation are positive, this indicates that the process is not in need of immediate attention and may be validated in accordance with the normal schedule....