Design Controls

Design controls are a system of checks and balances for systematic assessment of the design during all phases of development. It consists of an interrelated set of practices and procedures that are incorporated into the process of design and development. As a result, discrepancies between user requirements, design and the product can be avoided to create a design that will translate into a successful device. The application of design controls to a design process can be depicted in the figure below.

* Design Input - It consists of physical and performance requirements that are the basis of device design. The design input requirements are unambiguous, self-consistent and expressed with quantitative limits of tolerance. The device use environment is also properly characterized and all requirements are thoroughly reviewed.

* Design Output - It consists of the results of each design phase and the total design effort. The finished design output is usually the device master record. Design output includes production specifications as well as a description of the materials which define and characterize the design. The total finished design output is the device with its packaging, labeling and the device master record.

* Design Review - It consists of a documented, comprehensive, systematic examination of a design to evaluate the adequacy of the design requirements, to evaluate the capability of the design to meet these requirements, and to identify problems. Formal design reviews can be designed to detect problems early in the development process. As the design nears completion, the flexibility of implementing optimal solution decreases and the cost to correct design errors increases.

* Design Verification - It is the confirmation by examination and provision of objective evidence to show that the device meets the manufacturer's requirements. It follows a three-pronged approach employing tests, inspections and analyses and is to be documented systematically.

* Design Validation - It is the process of establishing that the device specifications conforms with user needs and intended use. It usually follows design verification and it provides assurance that the design will conform with user needs and intended uses.

All changes made during the design process are documented as the design history file, which is a compilation of records describing the design history of the finished device. Design validation is followed by design transfer where the device design is translated into production specifications. Manufacturing processes are employed to produce a device based on the production specifications. The device is then sterilized, packaged, labelled and marketed, with the FDA approval.