Inclusion Criteria:  Healthy male and/or female subjects with suitable veins for cannulation or repeated venepuncture. Males must be willing to use appropriate contraception methods. Females must not be lactating and must be of non-childbearing potential, confirmed at Screening. Have a body mass index between 18.5 and 30 kg/m^2 (inclusive) and weigh at least 50 kg and no more than 100 kg (inclusive) at Screening.  Exclusion Criteria:  History of any clinically significant disease or disorder. History or presence of gastrointestinal, hepatic or renal disease, or any other condition known to interfere with absorption, distribution, metabolism, or excretion of drugs. A positive Corona Virus Disease 2019 test at Screening or admission to the Clinical Unit on Day -1. Any clinically significant abnormalities in clinical chemistry, haematology, or urinalysis results. Any clinically significant abnormal findings in vital signs. clinically significant abnormalities on 12-lead electrocardiogram. Any positive result at the Screening Visit for Hepatitis B surface antigen, hepatitis C virus antibody, and human immunodeficiency virus antibody. Known or suspected history of drug abuse in the last 2 years. Current smokers or those who have smoked or used nicotine products within the 3 months prior to the Screening Visit. Known or suspected history of alcohol or drug abuse. Use of any prescribed or non-prescribed medication. Subjects with acute pulmonary insufficiency, marked neuromuscular respiratory weakness, obsessional states, phobic states, sleep apnoea syndrome, or unstable myasthenia gravis. History of severe allergy/hypersensitivity or ongoing allergy/hypersensitivity, as judged by the investigatoror history of hypersensitivity to drugs with a similar chemical structure or class to AZD4831 or midazolam. History or ongoing allergy/hypersensitivity to drugs(including but not limited to rash, angioedema, acute urticaria). Subjects who, in the opinion of the Investigator, have any clinically significant skin condition.