Stability of drug candidates

Shen M, Xiao Y, Golbraikh A, Gombar VK, Tropsha A. Development and validation of k-nearest-neighbor QSPR models of metabolic stability of drug candidates. J Med Chem 2003 46 3013-20. 

Recent developments in drug discovery and drug development spurred the need for novel analytical techniques and methods. In the last decade, the biopharmaceutical industry set the pace for this demand. The nature of the industry required that novel techniques should be simple, easily applicable, and of high resolution and sensitivity. It was also required that the techniques give information about the composition, structure, purity, and stability of drug candidates. Biopharmaceuticals represent a wide variety of chemically different compounds, including small organic molecules, nucleic acids and their derivatives, and peptides and proteins. 

Among physicochemical properties, the stability of drug candidates is receiving increasing attention. Unfortunately, its evaluation very often requires a lot of experimental time and profiling of many molecules would be nearly impossible without new, computer-aided methods. Any effort useful to facilitate this first part of pharmaceutical investigation is appreciated because it can be converted to a considerable lowering of the research cost. 

Drexler, D.M. et al., An automated high throughput liquid chromatography-mass spectrometry process to assess the metabolic stability of drug candidates, Assay Drug Dev. Technol., 5(2), 247, 2007. 

Development and Validation of -Nearest-Neighbor QSPR Models of Metabolic Stability of Drug Candidates. 

Such a result appears to be of major interest given that neither any classification of compounds, nor any training information was applied to the PCA model. A more detailed inspection of the score plot in Fig. 17.5 indicates that some compounds are misclassified, although experimental evaluation of these compounds revealed problems with their chemical stability or solubility. Thus, it appears that this model can be used to evaluate the false-positive (or false-negative) experiments. Moreover, it can also be used to evaluate the metabolic stability from the 3D structure of drug candidate prior to experimental measurements. 

Figure 7.2 Multidimensional structural data produced by predictive models, featuring integrated methods and parallel processing of drug candidates for metabolic (Rourick et al., 1998) and chemical (Fink et al., 1997) stability.

Conduct preliminary stability study of drug candidate in selected physiologic matrix(ces). 

The model can be used to evaluate the metabolic stability from the 3D structure of drug candidates prior to experimental measurements. Thus, we have used a test set of 1346 compounds from Johnson Johnson [20]. 

Salt formation may be key for the efficient purification of ionizable compounds. Various salts can display different solubilities and tendencies to crystallize and might possess physicochemical differences that can be exploited for convenient processing on scale. Salt forms of drug candidates are selected for desired stability, bioavailability, and formulation characteristics (Chapter 12). A few trends for salt selection are shown in Table 11.4. 

Knowledge about the chemical and physical stabilities of a candidate drug in the solid and liquid states is extremely important in drug development for a number of reasons. In the longer term, the stability of the formulation will dictate the shelf life... 

Due to insufficient drug quantity, a complete degradation profile will probably not be possible during prenomination studies, but it should be possible to assess the stability of the candidate drug at a few pH values (acid, alkali and neutral) to establish the approximate stability of the compound with respect to hydrolysis. To accelerate the reaction, temperature elevation will probably be necessary to generate the data. Although it is difficult to assign a definite temperature for these studies, 50-90°C in the first instance is a reasonable compromise. This... 

Pharmaceutical profiling Screening of drug candidates for physicochemical properties relevant for drug delivery, including solubility, lipophilicity, and stability. Phosphatidate Glycerophospholipid with only a phosphate at the sn-3 hydroxyl on the glycerol backbone. 

At the drug discovery stage, lead compounds are often prepared as DMSO solutions. The intrinsic chemical stability of the drug molecule in solution under different stress conditions is the main focus of the stability profiling of drug candidates. Candidates with poor chemical stability can be easily identified while their physical... 

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