Important as it is to evaluate new products prior to marketing, the marketing authorization process and control of quality, safety and efficacy are compromised if the DRA cannot identify products that are already being marketed without prior approval. It would be inequitable for applicants that have generated scientific documentation and submitted their products to the authorization process to be penalized by delays in reaching the market, expenditure of resources and payment of any fee that is in place, as compared with manufacturers who have not sought premarket approval.

The market inventory needs to be conducted only once, shortly after the marketing authorization system is established. It is normal to issue a provisional marketing authorization at this point, and to conduct a review (or screening) of provisionally authorized products as soon as possible. All manufacturers and importing agencies must be given reasonable notice through official publications (e.g. gazettes), the trade press and other media of their obligation to notify the authority by a specific date of all medicinal products that they currently distribute within the jurisdiction of the authority and that they intend to continue to supply after a duly appointed date on which licensing requirements become effective (1; see also Annex 1).

Once completed, the inventory consists of a printed text and/or electronic database. The information it should contain and the subsequent review of provisionally authorized products are discussed in Annex 1. Essentially the data set comprises pharmaceutical, clinical and administrative information about the product. The model system for computer-assisted drug registration (2 and 3) includes provision for an inventory.

Knowledge of what is already on the market has a number of benefits for public health, including:

• The ability to produce a list of products manufactured at a site found to be unsuitable by GMP inspectors;

• Ready access to a list of products containing a particular substance(s) when a hazard from that substance(s) has been detected;

• Knowledge of competing products for pricing purposes.

It is a major task to build a complete inventory of a hitherto unregulated market and most countries undertake it in stages. It should be undertaken in parallel with the introduction of premarket evaluations and authorizations; a short delay in commencing the inventory quickly becomes a long delay.

Among the first steps in conducting an inventory is to obtain an estimate of the number of products that may require provisional marketing authorization. It can be difficult to arrive at even a reasonably accurate figure, and the total may be dauntingly large. Experience has shown, however, that with each step taken by the DRA in conducting the inventory and accumulating data for the subsequent review, significant numbers of products are voluntarily withdrawn (4). These are likely to be products of marginal viability which do not warrant expending company resources on preparation of the necessary documentation and generation of data on, for example, stability. Some of the products may not even be marketed, but have simply been kept on file as an option for the future.