Inorganic Nitrate (NaNO3) Prevention of Contrast-Associated Acute Kidney Injury

Inclusion Criteria: * Planned coronary angiogram or contrast-enhanced CT scan. * High-risk for contrast-associated acute kidney injury (AKI) with creatine/Glomerular filtration rate (GFR) within 90 days as defined as: 1. Undergoing coronary angiogram with GFR \<45 mL/min/1.73m2 OR 2. Undergoing coronary angiogram with GFR \<60 mL/min/1.73m2 and concurrent risk of AKI as defined by Hamilton et al. BMC2 risk prediction model ≥ 7%. OR 3. Undergoing contrast-enhanced CT scan with GFR\<45 mL/min/1.73m2 * If subject is a woman of child-bearing potential, subject agrees to the use of highly effective contraception starting at screening and during study participation. * Ability to take oral medication and be willing to adhere to the study intervention regimen. * Ability to understand and willingness to agree to an informed consent Exclusion Criteria: * Already fulfilling definition of acute kidney injury prior to contrast exposure by kidney disease improving global outcomes (KDIGO) criteria (absolute increase in creatinine from baseline of 0.3mg/dL or more OR relative increase in creatine of 50% or more from baseline). * Primary indication for Percutaneous Coronary Intervention (PCI) including acute ST-segment elevation myocardial infarction * End-stage renal disease actively on dialysis. * Received any intravenous or intraarterial contrast within five days from planned contrast administration. * Cardiac arrest within 14 days of planned contrast administration. * Systolic blood pressure \< 100mmHg or diastolic blood pressure \<60mmHg OR currently receiving inotropes or vasopressors for hemodynamic support. * History of hypersensitivity or known allergy to any of the components of the investigational product or placebo including sodium nitrate, inorganic nitrate, beet root juice, or lactose. This does not include lactose intolerance. * Pregnancy or nursing female * Participation in other investigational trials within the past 30 days prior to enrollment. * Use of tadalafil within 48 hours, sildenafil or vardenafil within 24 hours, and avanafil within 12 hours of initiation of trial medication. If participant is on continuous dosing of tadalafil, sildenafil, vardenafil, or avanafil, they will be excluded from the trial. If participant is on intermittent dosing of tadalafil, sildenafil, vardenafil, or avanafil, patient agrees to withhold use of medication for duration of medication treatment extending 48 hours after the final dose.