In the pharmaceutical industry, reverse engineering (RE) involves breaking down a drug into its individual components, understanding the proportions and methods of the formulation work, and then using this information to reproduce a similar product. Whilst there are many ways to examine a formulator's work, microscopy is one of the simplest and most effective. Let's show you how!
Reverse engineering yields valuable data on active pharmaceutical ingredients (APIs) and excipients, and may be used for competitive product comparisons, patent infringement investigations, or the development of generic formulations.1 Generic companies often use reverse engineering to decode originator products, demonstrate formulation equivalence and accelerate the development of generic drugs. This can be legally and ethically complex, as it often involves navigating patent laws and regulatory requirements. RE can include a number of techniques to help elucidate the qualitative but more importantly the quantitative composition of the RLD. This can involve anything from analytical chemistry techniques (mass spectrometry, NMR, HMPL or GC) to spectroscopy (IR and UV-VIS), crystallography, particle size analysis, various microscopy techniques, and even PAT and molecular biology techniques in biopharmaceuticals.(2,4) Microscopy plays a crucial role in reverse engineering by providing detailed insights into the physical characteristics and structures of materials. Microscopy techniques such as scanning electron microscopy (SEM) and transmission electron microscopy (TEM), can be used to examine the morphology and crystallinity of drug particles. This is important for understanding the physical characteristics, size, shape, and surface features of active pharmaceutical ingredients and excipients. Looking at the macro scale, tablets can be observed to learn about the tablet matrix, the distribution of active ingredients, and the presence of any coating or layers. When utilising microscopy for reverse engineering, it is essential to combine these observations with other analytical techniques (filtration, solubility studies) to obtain a comprehensive understanding of the drug’s composition and characteristics.(3,4)
Technical challenges and solutions
The IMCD Shanghai Pharmaceutical Technical Centre (PTC) team took on the challenge of reverse engineering Entacapone (Comtan®), using polarised light microscopy (PLM) to answer the following questions:
- What was the manufacturing process?
- Which excipient grades were used?
- How was the superdisintegrant added?
The process proved simple yet effective. After gently scraping the coating, the Entacapone RLD tablet core was lightly ground, with the resulting granules observed under the polarising microscope. The morphology, size, and shape of these granules were found to be identical to granules from placebo tablets manufactured by granulation (Figure 1B), confirming the manufacturing process of the originator.
Usually, MCC, which is an insoluble component, is used in the wet granulator process as a filler and process enabler, which the literature research confirmed. To determine which grade of MCC was used in the RLD, the tablets were left to disintegrate over 24h and the undissolved part was compared with the raw excipient itself. Here you can easily identify microcrystalline cellulose 101 as the excipient grade of choice. (Fig 2A and 2B).
So far, we have identified the manufacturing method and the preferred filler. Qualitative analysis revealed that CCS (croscarmellose sodium) is the superdisintegrant used. We wanted to go one step further and see if it was added intra-or-extra-granularly in the Entacapone tablets. Upon hydrating the granules from the RLD tablet, disintegration of the granules into smaller particles was observed, which indicated that Croscarmellose Sodium (Figure 3A) was added intra-granularly. This was compared with hydrated particles for confirmation (Figure 3B). Figure 1A indicates that there was CCS which had been added extra-granularly in RLD tablet. This was compared to raw material particles for confirmation (Figure 3C). So, the croscarmellose sodium was added intra and extra granularly.
Conclusion
Cost and speed to market are the key to success for a generic pharmaceutical company and thus, a sound reverse engineering strategy may prove to be effective in reducing development time. Next to microscopy, this can be combined with several other analytical techniques such as SEM, Raman spectroscopy, powder X-ray diffraction, and HPLC to get more qualitative and quantitative information on the RLD. The work of the team was admitted as a poster for the prestigious AAPS PharmSci 360 (American Association of Pharmaceutical Scientists) that took place in October last year and demonstrates a simple and universal method to decode the RLD’s qualitative formula and manufacturing process using polarised light microscopy as a powerful tool.
Technical Expertise
At IMCD, we have a network of six dedicated Pharmaceutical Technical Centres across the globe to support our customers and partners at every stage of the product development cycle. Our global pharmaceutical centres deliver a range of trainings, develop projects and concepts, and tackle scientific challenges that have wide application appeal. To learn more about IMCD's pharmaceutical network and technical expertise, please click here.