Citrate/Lactate Dialysates

Drug Overview

In the highly specialized field of Nephrology and intensive care medicine, Continuous Renal Replacement Therapy (CRRT) is the gold standard for managing critically ill patients with Acute Kidney Injury (AKI) who are hemodynamically unstable. CRRT Solutions containing physiological buffers are critical for maintaining homeostasis. Citrate/Lactate Dialysates and replacement fluids act as a precisely calibrated Targeted Therapy to ensure continuous electrolyte and acid-base balance while safely filtering the blood.

• Drug Category: Nephrology / Critical Care Medicine
• Drug Class: CRRT Solutions (Dialysates and Replacement Fluids / Regional Anticoagulants)
• Generic Names: Regional Citrate Anticoagulant Solutions; Lactate-Buffered Hemodiafiltration Solutions
• US Brand Names: PrismaSol, Phoxillum, Regiocit, Prismocitrate, Duosol
• Route of Administration: Extracorporeal circuit (Intravenous via central venous hemodialysis catheter)
• FDA Approval Status: Fully FDA-approved for use in continuous renal replacement therapies for the treatment of acute renal failure, severe fluid overload, and severe electrolyte/acid-base imbalances.

What Is It and How Does It Work? (Mechanism of Action)

CRRT solutions are sterile, large-volume fluids formulated to mimic human plasma. Because the kidneys are failing, the body cannot excrete metabolic acids or regenerate bicarbonate. Delivering pure bicarbonate in stable, large-volume IV bags is chemically difficult because it precipitates with calcium and magnesium. Therefore, “bicarbonate precursors”—specifically citrate and lactate—are used.

At the molecular and physiological level, these solutions provide dual functions:

1. Lactate-Based Solutions:

L-lactate is absorbed from the dialysate into the patient’s systemic circulation. Within the liver, the enzyme lactate dehydrogenase oxidizes lactate into pyruvate, which then enters the gluconeogenic pathway or the Krebs cycle. The systemic metabolism of one mole of lactate consumes one mole of hydrogen ions and ultimately generates one mole of bicarbonate. This safely and gradually buffers the patient’s metabolic acidosis.

2. Citrate-Based Solutions (Regional Anticoagulation and Buffering):

Citrate acts as a highly advanced Targeted Therapy within the CRRT circuit.

• Regional Anticoagulation: Trisodium citrate is infused pre-filter (before the blood enters the artificial kidney). Citrate tightly chelates ionized calcium in the blood. Because ionized calcium (Factor IV) is an absolute requirement for the coagulation cascade, dropping the circuit effectively paralyzes the clotting process inside the machine, preventing the filter from clotting without thinning the patient’s systemic blood.
• Metabolic Buffering: As the citrate-calcium complex enters the patient’s systemic circulation, the citrate is rapidly metabolized by the liver, skeletal muscle, and renal cortex via the citric acid cycle (Krebs cycle). The complete oxidation of one molecule of citrate yields three molecules of bicarbonate, profoundly correcting metabolic acidosis. To replace the chelated calcium, a separate continuous infusion of calcium chloride or calcium gluconate is administered directly to the patient.

FDA-Approved Clinical Indications

• Primary Indication: To maintain precise electrolyte and acid-base balance during continuous renal replacement therapy (CRRT) in critically ill patients.
• Other Approved Uses:
  • Regional anticoagulation of the extracorporeal CRRT circuit (specifically Citrate) to prolong filter lifespan without systemic bleeding risks.
  • Management of severe, refractory fluid overload in cardiogenic or septic shock.
  • Clearance of dialyzable toxins and drug overdoses in hemodynamically unstable patients.

Dosage and Administration Protocols

The dosing of CRRT solutions is termed “effluent dose” or “clearance rate,” typically calculated based on the patient’s body weight.

Dose Adjustments and Special Populations:

• Hepatic Insufficiency (Liver Failure): Both citrate and lactate require hepatic metabolism to be converted into bicarbonate. In severe liver failure or profound hypoxemic shock, the liver cannot metabolize these precursors. This leads to dangerous accumulation (Type B Lactic Acidosis or “Citrate Lock”). In these populations, citrate/lactate must be avoided or heavily reduced, and pure bicarbonate-based solutions should be utilized instead.
• Severe Hypoxemia / Shock: Metabolism of citrate requires oxygen. In severe tissue hypoxia, citrate metabolism halts, requiring a switch to alternative anticoagulation and buffering strategies.

Clinical Efficacy and Research Results

Current critical care guidelines (KDIGO) and extensive clinical data (2020-2026) heavily favor regional citrate over systemic heparin for CRRT:

• Filter Lifespan: Regional Citrate Anticoagulation (RCA) reliably extends the median operational lifespan of a CRRT hemofilter to 60–72 hours, compared to 24–48 hours for heparin, minimizing interruptions in dialysis and reducing nursing workload.
• Bleeding Risk Reduction: Unlike systemic heparin, citrate provides purely localized anticoagulation. Modern meta-analyses confirm that RCA reduces the risk of systemic bleeding events by 40% to 50% in ICU patients, which is vital for post-surgical or trauma patients requiring dialysis.
• Acid-Base Normalization: Both lactate and citrate solutions demonstrate equal, near 100% efficacy in normalizing systemic pH (maintaining between 7.35 and 7.45) within 24 to 48 hours of continuous therapy initiation in patients without severe hepatic impairment.

Safety Profile and Side Effects

Common Side Effects (>10%):

• Mild Electrolyte Shifts: Hypokalemia, hypophosphatemia, and hypomagnesemia, as continuous filtration rapidly removes these electrolytes from the blood. (Modern solutions are now formulated with added potassium and phosphorus to mitigate this).
• Metabolic Alkalosis: Over-delivery and metabolism of citrate or lactate can lead to an excess generation of systemic bicarbonate, raising the blood pH above 7.45.

Serious Adverse Events:

• “Citrate Lock” (Citrate Toxicity): In liver failure, citrate accumulates systemically. It continues to chelate calcium inside the patient’s body, causing profound, life-threatening systemic hypocalcemia and myocardial depression. This is diagnosed when the Total Calcium to Ionized Calcium ratio exceeds 2.5 
• Lactic Acidosis: Exacerbation of systemic acidosis if the liver fails to clear the administered lactate load.

Management Strategies:

CRRT requires vigilant protocolized nursing care. Serum ionized calcium levels must be drawn from the patient and from the machine circuit every 4 to 6 hours. If “Citrate Lock” is suspected (rising total calcium, falling ionized calcium, dropping systemic pH), the citrate infusion must be halted immediately, IV calcium replaced, and the patient transitioned to systemic heparin or no-anticoagulation CRRT with bicarbonate dialysate.

Research Areas

While CRRT itself is a mechanical and chemical life-support system, maintaining perfect physiological homeostasis creates a hospitable microenvironment required for endogenous renal recovery. Currently, cutting-edge regenerative medicine is investigating the integration of bioartificial kidneys into the CRRT circuit. Researchers are testing cartridges lined with human renal proximal tubule stem cells. By utilizing precisely buffered dialysates like citrate to maintain an optimal pH and prevent circuit clotting, these Targeted Therapy cells can safely process the ultrafiltrate, reabsorbing critical immunomodulatory molecules and secreting cytokines that actively promote the regeneration of the patient’s own native injured kidneys.

Disclaimer: The nephrology research discussed is based on preclinical or early investigational phase studies, including ongoing clinical research in kidney disease, renal protection, and related therapeutic pathways. The mechanisms and potential therapeutic applications described remain under investigation and are not established for routine clinical use. This content is intended for scientific and educational purposes only.

Patient Management and Practical Recommendations

Pre-Treatment Tests to be Performed:

• Comprehensive Metabolic Panel (CMP): Baseline Total Calcium, Ionized Calcium, Magnesium, Phosphorus, and Liver Function Tests (LFTs) to rule out severe hepatic impairment.
• Arterial Blood Gas (ABG): To accurately assess baseline pH and bicarbonate levels.

Precautions During Treatment:

• Strict Monitoring: CRRT is an ICU-only procedure. The clinical team must monitor hemodynamic status continuously.
• Nutritional Assessment: Because CRRT continuously removes water-soluble vitamins, amino acids, and trace elements, specialized ICU nutrition (enteral or parenteral) must be proactively administered.

“Do’s and Don’ts” List (For the Care Team and Patient Advocates):

• DO ensure that the medical team is checking the patient’s ionized calcium levels routinely (often every 4-6 hours) while on citrate.
• DO ask the critical care team if electrolyte replacement protocols (like potassium and phosphorus) are active, as continuous dialysis depletes them quickly.
• DON’T mix or inject any other medications directly into the pre-filter citrate line, as this can disrupt the carefully calculated calcium-chelating mechanics.
• DON’T hesitate to inform the critical care nephrologist of any history of chronic liver disease (cirrhosis), as this fundamentally changes which CRRT solution is safe to use.

Legal Disclaimer

The information provided in this guide is for educational and informational purposes only and does not constitute medical advice. It is not intended to be a substitute for professional medical consultation, diagnosis, or treatment. Always seek the advice of a qualified healthcare provider regarding a medical condition, changes in treatment, or prior to starting or stopping any medication. CRRT is a highly complex, life-sustaining procedure managed exclusively by specialized intensive care teams.