Research interests include a focus on understanding how drugs work against parasites and how parasites become resistant to drugs. In the case of African trypanosomiasis, transport related phenomena have been central and a major research area has been associated with understanding drug resistance. This has led to the discovery of new transporters involved in uptake of melaminophenylarsenical and diamidine drugs and eflornithine. In Leishmania changes in drug uptake have also been identified for paromomycin, pentamidine and amphotericin B in selection of drug resistance.
Prof Barrett chairs the Kinetoplastids Drug efficacy working group at the World Health Organisation. Since many drugs work at the level of interference with metabolism he has also pioneered work into biochemistry of parasites, identifying several drug targets and also founded the Scottish Metabolomics facility which is now able to report on metabolomics data outputs in any system, and is now part of the Glasgow Polyomics Facility which is involved in collecting metabolomics, genomics and proteomics data and analysing the data within an active bioinformatics hub.
Prof Barrett is also interested in developing new screens for drugs, including an in vivo imaging model to determine whether drugs act in stage 2 human African trypanosomiasis, and is Director of New Projects at the Consortium of Parasitic Drug Development. He also is involved in scientific outreach, appearing on radio, television and writing frequently in magazines and newspapers on topics in tropical medicine and application of Omics research.