Clinical effectiveness and prospects of methylene blue: A systematic review

Methylene blue (MB) is a well-known pharmaceutical ingredient that is thought to have a multi-targeted therapeutic effect as an anti-malarial and neuroprotective agent and has recently been identified as a treatment for coronavirus disease 2019 (COVID-19). In this review, we present an overview of relevant clinical trials, including ongoing trials, on the therapeutic uses of MB. A search for clinical trials on clinicaltrials.gov was performed using the terms "methylene blue" and "methylthionine chloride." This review focuses on clinical trials of MB-based therapies applied to brain diseases, cancer imaging and diagnosis, infectious diseases such as malaria or COVID-19, and cardiovascular diseases. Nanoparticle-based delivery techniques have also been briefly discussed in addition to common delivery methods.