Does High-dose Vitamin B3 Supplementation Prevent Major Adverse Kidney Events During Septic Shock?

• Nicotinamide treatment (Drug): Nicotinamide (500 mg) will be mixed in 50 ml of 0.9% saline and administered intravenously every 12 h for a total of 72 h.
• placebo treatment (Drug): For the placebo group, an identical volume of 0.9% saline will be administered in the same manner.

Primary outcomes

• proportion of patients meeting one or more criteria for MAKE30 [3 years after study start]: MAKE30 is : in-hospital mortality, receipt of new RRT, or persistent renal dysfunction defined as a final inpatient serum creatinine value ≥2 time baseline serum creatinine

Sex: All, ages: 18 Years to any

Inclusion Criteria:

* Adult patients with septic shock defined as sepsis with persisting hypotension requiring vasopressors to maintain MAP ≥65 mm Hg and having a serum lactate level >2 mmol/L (18 mg/dL) despite adequate volume resuscitation.
* Written informed consent

Exclusion Criteria:

* Presence of inclusion criteria for more than 24 hours
* Immediate indication to start renal replacement therapy at the time of randomization: Hyperkalemia≥ 6.5 mmol /l, metabolic acidosis with pH <7.15 not controlled by medical treatment, diuretic resistant acute pulmonary edema or accumulation of a toxic requiring dialysis.
* Formal indication of Nicotinamide supplementation according to the attending physician (eg pellagra, undernutrition, severe alcoholism)
* Known severe chronic kidney disease (clearance <30 ml /min) in the last 3 months preceding the setic shock or kidney transplant recipient.
* Moribund patient (estimated survival less than 24 hours)
* Patient who are not expected to survive to day 30 due to terminal-stage disease (terminal respiratory or heart failure, Child C cirrhosis, uncontrolled cancer)
* Resuscitated cardiac arrest
* Pregnant or lactating
* Legal tutorship and guardianship
* Lack of social security coverage.