Predicting drug substances autoxidation

PURPOSE

Chemical degradation and stability in formulation is a recurrent issue in pharmaceutical development of drugs. The objective of the present study was to develop an in silico risk assessment of active pharmaceutical ingredients (APIs) stability with respect to autoxidation.

METHODS

The chemical degradation by autoxidation of a diverse series of APIs has been investigated with molecular modelling tools. A set of 45 organic compounds was used to test and validate the various computational settings. Aiming to devise a methodology that could reliably perform a risk assessment for potential sensibility to autoxidation, different types of APIs, known for their autoxidation history were inspected. To define the level of approximation needed, various density functional theory (DFT) functionals and settings were employed and their accuracy and speed were compared.

RESULTS

The Local Density Approximation (LDA) gave the fastest results but with a substantial deviation (systematic over-estimation) to known experimental values. The Perdew-Burke-Ernzerhof (PBE) settings appeared to be a good compromise between speed and accuracy.

CONCLUSIONS

The present methodology can now be confidently deployed in pharmaceutical development for systematic risk assessment of drug stability.

A candidate gene study of antiepileptic drug tolerability and efficacy identifies an association of CYP2C9 variants with phenytoin toxicity

BACKGROUND AND PURPOSE

  It is widely acknowledged that individual response to antiepileptic drugs (AEDs) is influenced by genetic factors. However, most of the underlying genes and genetic variants remain unidentified to date. The purpose of this study is to examine the role of common variants in a number of candidate genes in the response to commonly prescribed AEDs.

METHODS

  We recruited 495 patients with epilepsy. Patients were classified according to their response to several AEDs. We genotyped 104 polymorphisms in 17 candidate genes for AED response. We looked for statistically significant associations between these polymorphisms and well-defined AED response phenotypes.

RESULTS

  We identified significant associations of CYP2C9 variant alleles with presence of phenytoin (PHT) adverse drug reactions (ADRs) and of GSTM1 copy number variation with the presence of carbamazepine ADRs. The latter association could not be confirmed in a replication study.

CONCLUSIONS

  Our study is the first comprehensive candidate gene association study in epilepsy pharmacogenetics. Our results confirm the role of CYP2C9 variants in PHT toxicity. No other definite associations were identified. Large-scale efforts are needed to unravel the genetic determinants of AED response.