PPIG and COVID-19: Drugs currently being used to treat COVID-19 patients include Chloroquine, Hydroxychloroquine, Azithromycin, and Remdesivir are all cytochrome P450 (CYP) inhibitors [27], although Remdesivir has only shown this for in vitro activity by Gilead Sciences as described in the Remdesivir (GS-5734) investigator’s brochure, Edition 5, 21 February 2020 and listed in the NIH COVID-19 Treatment Guidelines, Since these drugs downregulate CYP, which has a heme moiety, this decreases the demand for heme production [28].