Solid drugs taken orally are mixtures of active pharmaceutical ingredients (hereinafter referred to as “API”); agents such as excipients added as binders or diluents; and lubricants added to enhance flow properties of particles. In general, active pharmaceutical ingredients are solid organic substances. In many cases, a substance of the same chemical formula can occur in several polymorphic forms with different crystal structures, a phenomenon known as crystal polymorphism. Compounds noted by the same chemical formula but having different crystal structures are known to exhibit different characteristics with regard to stability and bioavailability†. Conventional methods for distinguishing these polymorphs have been based on X-ray diffractometers and thermal analyzers.
Pharmaceutical development in recent years has begun to focus increasingly on stability, ease of administration (swallowing), and the efficacy of the final pharmaceutical production, in addition to the stability and bioavailability of the APIs. In response to the needs of an aging population, for example, development is currently underway in Japan on formulations that allow elderly people to swallow medications more easily. Companies have begun developing unique formulations (e.g., oral disintegrants, films, jellies) with added functionality and need methods to confirm not just the stability of the APIs, but also the stability of these functions. Reports indicate that more than 60% of new pharmaceuticals developed in recent years have low solubility, which has driven efforts to select the ideal additive to improve dissolution and/or to develop highly soluble amorphous formulations.
At the same time, the Japanese government has promoted the use of generic drugs to cut medical costs. In certain Western nations, market shares for generic drugs have reached 60–70%; in Japan, this share remains at 22.8% (statistics as of Sept. 2011 by number of products). Several measures including a revised remuneration system for medical care services have been taken to promote the use of generics. With the growing availability of drugs containing the same API from multiple manufacturers and increasing consumer choice, there is growing demand for ways to guarantee safety and quality and to set a product apart from the others.
In response, instruments used for analysis of these compounds have been modified in various ways and new methods of analysis have been developed. This special issue will focus on solid, orally administered formulations and present an overview of Rigaku’s analytical technologies that provide effective solutions to problems encountered from drug R&D to production. This issue also introduces the latest technologies in analysis.