The international pharmacopoeia provides internationally acceptable standards for the potency, purity and quality of pharmaceutical products moving in international commerce. These standards are available for adoption by Member States in accordance with Articles 21(d) and 23 of the Constitution of the World Health Organization and resolution WHA3.10 of the Third World Health Assembly.
Many national or regional pharmacopoeias rely increasingly on complex techniques of analysis that require expensive equipment and highly trained personnel. Such methods are inapplicable, however, in countries lacking these resources. For the most part, these methods merely permit analyses to be carried out more rapidly than by classical chemical methods.
Whereas earlier editions of The international pharmacopoeia had relied heavily on material taken from certain national pharmacopoeias, the third edition, of which four volumes have been published so far, aims to accommodate the needs of developing countries by offering sound quality standards for essential drugs on the basis (wherever possible) of classical procedures. Volume 1, published in 1979, describes general methods of analysis. Volumes 2 and 3, published in 1981 and 1988 respectively, contain quality specifications mainly for essential drug substances included in WHO’s Model List of Essential Drugs. Volume 4 (1994) includes monographs on pharmaceutical substances, widely used excipients and dosage forms of essential drugs. Volume 5 (in preparation) will contain several new general requirements and additional test methods for substances and dosage forms, and a revised procedure for high-performance liquid chromatography. The volume will also contain specifications for the determination of more than 35 pharmaceutical substances and some 20 finished preparations in tablet form.
The role and objectives of The international pharmacopoeia are thus to a large extent to provide an alternative to some widely used national and regional pharmacopoeias that include sophisticated testing methods. Of course, if laboratory facilities permit use of advanced analytical methods, it is logical to analyse products according to the modern methods of such pharmacopoeias. Indeed, products may often be labelled as conforming to these pharmacopoeias. But where sophisticated testing is not possible, The international pharmacopoeia still allows verification of the quality of a product.
In its twenty-eighth report, the WHO Expert Committee on Specifications for Pharmaceutical Preparations summarized the functions and characteristics of The international pharmacopoeia and commented: “Inter alia, the production of The international pharmacopoeia helps to advance the setting of pharmacopoeial standards at national level, in that it fosters a valuable exchange of experiences gained in a wide variety of countries”. At its thirty-fifth meeting, the Committee recommended that manufacturers in exporting countries be encouraged to use The international pharmacopoeia and to indicate such use in product information.
The international pharmacopoeia is developed in close collaboration with members of the WHO Expert Advisory Panel on the International Pharmacopoeia and Pharmaceutical Preparations, other specialists from government authorities, industry, the academic world and WHO Collaborating Centres. Chapter 4 contains guidance for those preparing or commenting on monographs for inclusion in The international pharmacopoeia.
Analytical procedures used to control the quality of pharmaceutical substances and dosage forms must be adequately validated. Guidelines on validation, endorsed by the WHO Expert Committee on Specifications for Pharmaceutical Preparations, are included in Chapter 4. Since the extent to which validation is necessary is determined by the purpose of the analysis, judgement on the extent to which the guidelines need to be applied must be made on a case-by-case basis. These guidelines are directed primarily to the examination of chemical and physicochemical attributes, but many of the general principles are also applicable to microbiological and biological procedures.
Whenever necessary, monographs included in The international pharmacopoeia rely on the use of reference materials. These are provided either in the form of International Chemical Reference Substances and Melting-point Reference Substances or as International Infrared Reference Spectra. Chapter 4 provides general guidelines for the establishment, maintenance and distribution of chemical reference substances. These include a section on the need for national and/or regional collections of secondary reference materials that have been calibrated against International Chemical Reference Substances. The chapter also contains recommendations for the preparation and use of infrared spectra in pharmaceutical analysis.
The guidelines on reference substances reproduced in Chapter 4 were published in 1982. These guidelines were revised in 1996 in the light of developments in analytical chemistry and international collaboration and to take into account established practice in the use of chemical reference substances for pharmacopoeial purposes. The revised guidelines are not intended to be specific to International Chemical Reference Substances, but are general guidelines for all bodies issuing chemical reference substances, and give advice on the establishment of both primary and secondary reference substances. The revised text was presented in April 1997 to the WHO Expert Committee on Specifications for Pharmaceutical Preparations and will be included as an annex to the Committee’s report. Copies can be obtained from the Quality Assurance unit, Division of Drug Management and Policies, WHO, 1211 Geneva 27, Switzerland.
Some 180 International Chemical Reference Substances and some 60 International Infrared Reference Spectra have been produced and are listed in Chapter 4. Information is also provided on how to obtain them. The establishment of International Chemical Reference Substances and International Infrared Reference Spectra is continuing and new lists will be annexed to the report of the thirty-fifth meeting of the WHO Expert Committee on Specifications for Pharmaceutical Preparations.
A general list of reference substances for pharmacopoeial analysis is issued by the Quality Assurance unit, Division of Drug Management and Policies, WHO, 1211 Geneva 27, Switzerland, and is updated yearly. It provides current information on the availability and sources of reference substances. Most of these substances are prepared and issued by regional/national pharmacopoeial commissions or regional/national quality control laboratories on behalf of drug regulatory authorities. Each substance is generally established for a specific analytical purpose as defined by the issuing body. Use for any other purpose becomes the responsibility of the user and a suitable caution is included in the accompanying information sheet.