Hydroxychloroquine / azithromycin in COVID-19: The association between time to treatment and case fatality rate

Mechanism of DNA Intercalation by Chloroquine Provides Insights into Toxicity

Chloroquine has been used as a potent antimalarial, anticancer drug, and prophylactic. While chloroquine is known to interact with DNA, the details of DNA-ligand interactions have remained unclear. Here we characterize chloroquine-double-stranded DNA binding with four complementary approaches, including optical tweezers, atomic force microscopy, duplex DNA melting measurements, and isothermal titration calorimetry. We show that chloroquine intercalates into double stranded DNA (dsDNA) with a KD ~ 200 µM, and this binding is entropically driven. We propose that chloroquine-induced dsDNA intercalation, which happens in the same concentration range as its observed toxic effects on cells, is responsible for the drug's cytotoxicity.

A study of impurities in the repurposed COVID-19 drug hydroxychloroquine sulfate using ultra-high-performance liquid chromatography-quadrupole/time-of-flight mass spectrometry and liquid chromatography-solid-phase extraction-nuclear magnetic resonance

RATIONALE

Hydroxychloroquine sulfate is effective in the treatment of malaria and autoimmune diseases and as an antiviral drug. However, unreported impurities are often detected in this drug, which pose a health risk. In this study, the structures of hydroxychloroquine and six unknown impurities were analyzed using ultra-high-performance liquid chromatography-quadrupole/time-of-flight-tandem mass spectrometry (UHPLC-Q/TOF/MS/MS), and the structures were characterized using liquid chromatography-solid-phase extraction-nuclear magnetic resonance (LC-SPE-NMR) spectroscopy.

METHODS

An Agilent InfinityLad Poroshell HPH-C18 column (100 × 4.6 mm, 2.7 μm) was used. For the analysis of hydroxychloroquine and six unknown impurities, the mobile phase was 20 mM ammonium formate aqueous solution and methanol/acetonitrile (80:20, v/v) using gradient elution. Full-scan MS and MS² were performed to obtain as much structural information as possible. In addition, six unknown impurities were separated by semi-preparative liquid chromatography and characterized using LC-SPE-NMR.

RESULTS

The MS² fragmentation patterns of the impurities were investigated, leading to more structural information and an understanding of the fragmentation pathways of the impurities. The structures of the unknown impurities were confirmed using NMR. In addition, some possible pathways of the formation of the impurities in the drugs were outlined, and these impurities were found to be process impurities.

CONCLUSIONS

Based on the identification and characterization of these impurities, this study also describes the cause of the production of the impurities and provides insights for companies to improve their production processes and a scientific basis for the improvement of the related pharmacopoeias.

Unresolved COVID Controversies: 'Normal science' and potential non-scientific influences

ABSTRACTThe COVID-19 health crisis has so far involved enormous consequences in human pain, suffering and death. While biomedical science responded early, its response has been marked by several controversies between what appeared to be mainstream perspectives, and diverse alternative views; far from leading to productive debate, controversies often preceded polarisation and, allegedly, exclusion and even censorship of alternative views, followed by the pretense of scientific consensus. This paper describes and discusses the main controversies in the production of COVID biomedical knowledge and derived control measures, to establish if alternative positions are also legitimate from a 'normal science' perspective (rather than comparing them for superiority); explores potential non-scientific explanations of the alleged exclusion of certain views; and analyzes ethical issues implied. The operation of non-scientific factors in scientific and regulatory processes (e.g. various forms of subtle corruption) has been documented in the past; the intervention of such influences in the mishandling of controversies (i.e. on early management, non-pharmacological prevention and vaccination) cannot be ruled out and deserves further investigation. Some of these controversies, increasingly visible in the public domain, also involve ethical challenges that need urgent attention. Polarisation, censorship and dogma are foreign to true science and must be left behind.