Inclusion Criteria

• Male or female 
• Age ≥ 18
• Able to give informed consent to the study
• Restless legs syndrome symptoms affirming diagnosis
• Must meet IRLS Diagnostic Criteria
  • An urge (distressing need) to move the legs usually associated with painful or uncomfortable sensations in the legs
  • Urge to move may be present without the uncomfortable sensations
  • Arms or other body parts may be involved in addition to the legs
  • Urge to move or unpleasant sensations are worse or exclusively present at rest or inactivity, such as lying down or sitting
  • Urge to move or unpleasant sensations are partially/temporarily relieved with walking or moving the legs
  • Urge to move or unpleasant sensations are worse in the evening or night than during the day or only occur in the evening or night
  • When symptoms are severe, the worsening at night may not be noticeable but must have been previously present.
• Should be on a stable (FDA approved) RLS treatment for at least 8 weeks prior to screening
• Score ≥ 15 on the IRLS Rating Scale at screening and on day 0 prior to dosing
• If on anti-depressants and sleep medications must be on a stable dose for at least 6 months
• Has regular sleep hours between 9 pm and 9 am
• If at risk for pregnancy
  • Must have a negative pregnancy test at baseline 
  • Have had a hysterectomy, tubal ligation, or otherwise be incapable of pregnancy
  • Have practiced any of the following methods of contraception for at least one month prior to study entry
    • Hormonal contraceptives
    • Spermicide and barrier
    • Intrauterine device
    • Partner sterility

Exclusion Criteria

• RLS secondary to other CNS disease or injury, including peripheral neuropathy and neurodegenerative disorders
• Stage 4 - 5 CKD, on dialysis or anticipated to start dialysis while participating in this study
• Any pain related (e.g., frequent muscle cramps, myalgia, fibromyalgia) or sleep related disorders (e.g. sleep apnea, unless on stable CPAP) which may confound the outcome measures
• History of neuroleptic akathisia
• Parenteral iron use within 6 weeks prior to screening
• History of > 10 blood transfusions in the past 2 years
• Anticipated need for blood transfusion during the study
• Known hypersensitivity reaction to any component of Injectafer® (Ferric Carboxymaltose)
• Previously randomized to Injectafer® (FCM or VIT-45) in a clinical trial
• Current acute or chronic infection other than viral upper respiratory tract infection
• Malignancy other than basal or squamous cell skin cancer, or has been cancer free for ≥ 5 years
• Pregnant or lactating
• Seizure disorder currently being treated with medication
• Baseline ferritin ≥ 300 ng/mL
• Baseline TSAT ≥ 45%
• History of hemochromatosis or hemosiderosis or other iron storage disorders
• AST or ALT greater than 2 times the upper limit of normal
• Hemoglobin greater than the upper limit of normal
• Known positive hepatitis B antigen (HBsAg) or hepatitis C viral antibody (HCV) with evidence of active hepatitis (i.e., AST/ALT greater than the upper limit of normal)
• Known positive HIV-1/HIV-2 antibodies (anti-HIV)
• Received an investigational drug within 30 days before randomization
• Chronic alcohol or drug abuse within the past 6 months
• Any other pre-existing laboratory abnormality, medical condition or disease which in view of the investigator makes participation in this study put the subject at risk
• Unable to comply with the study requirements