What Is Sodium Chloride Injection?

Sodium Chloride Injection, USP—commonly referred to as normal saline—is a sterile, non-pyrogenic, isotonic solution containing 0.9% sodium chloride (NaCl) in water. Its osmolarity closely approximates that of human plasma, making it suitable for intravenous administration without inducing osmotic imbalances.

This preservative-free solution is typically used in a variety of clinical and procedural settings under the supervision of licensed healthcare professionals.

Common terms for Sodium Chloride Injection include:

• Normal saline
• 0.9% NaCl
• Physiologic saline
• Preservative-free saline

⚠️ Important Note:
Sodium Chloride Injection does not contain any antimicrobial or bacteriostatic agents. It is intended for single-dose use only and must be discarded after opening.

What Is Bacteriostatic Normal Saline (BNS)?

Bacteriostatic Normal Saline (BNS) is a sterile isotonic solution of 0.9% sodium chloride in water combined with a bacteriostatic agent, most commonly benzyl alcohol at 0.9% concentration.

This additive inhibits bacterial growth in multi-use settings, allowing the vial to be accessed multiple times in accordance with sterile handling practices and facility protocols.

Key characteristic:

• Intended for multiple-dose use
• Often used for reconstituting medications or repeated injections across a defined time frame

⚠️ Important Note on Neonatal Use:
Bacteriostatic Normal Saline (BNS) is contraindicated in neonates and infants. The benzyl alcohol preservative has been associated with serious adverse events—including fatal “gasping syndrome”—when used in pediatric or vulnerable populations.

⚠️ Benzyl Alcohol Daily Limit Warning:
Total benzyl alcohol exposure should not exceed 99 mg/kg/day to avoid toxicity (per FDA guidance). This applies to all patient populations and is especially critical in those with reduced metabolic clearance.

Comparing Sodium Chloride Injection and BNS

Both solutions are used in procedural medicine and clinical compounding, but they differ significantly in preservative content and usage guidelines.

          Important Note: Certain drugs are incompatible with benzyl alcohol; verify compatibility using manufacturer data or Trissel’s™ IV-Compatibility.

Benefits of Sodium Chloride Injection Over BNS

1. Preservative-Free Formulation

Sodium Chloride Injection avoids the potential for interaction or hypersensitivity linked to preservatives like benzyl alcohol.

2. Improved Injection Tolerance

Patients may experience less local irritation when preservatives are avoided—particularly benzyl alcohol, the agent used in BNS. According to USP <797> commentary, preservative-free preparations are often preferred for direct injection into sensitive tissues. However, individual responses may vary, and tolerability should be assessed on a case-by-case basis.

3. Greater Safety for At-Risk Populations

Sodium Chloride Injection is generally the preferred option for:

• Neonates and infants
• Pregnant or breastfeeding individuals
• Patients with known preservative sensitivities

Considerations When Using Sodium Chloride Injection

While widely used, Sodium Chloride Injection should be administered with caution in certain clinical contexts.

⚠️ Clinical Monitoring May Be Required:

• Patients with fluid retention or renal impairment, such as those with congestive heart failure or pulmonary edema
• Electrolyte and acid-base balance should be monitored during administration
• May interact with some medications (e.g., corticosteroids, corticotropin)

⚠️ Important Note:
Sodium Chloride Injection must be used once and discarded. It is not intended for storage or multiple withdrawals.

Where BNS Excels: Multi-Dose Clinical Applications

1. Repeated Reconstitution or Injections

BNS is frequently selected in environments where multiple doses are required over a short duration, such as:

• Clinical offices
• Procedural suites
• Ambulatory care settings

2. Preservation Against Contamination

The bacteriostatic agent may delay bacterial growth in multi-use containers; vials must still be discarded 28 days after first puncture in accordance with USP <797>.

⚠️ Important Note on Facility Protocols:

Bacteriostatic does not equal sterile after opening. Adherence to USP <797> and institutional infection control guidelines is essential for safe multi-dose vial use.

Sodium Chloride Injection: Formulation Properties

Standard Sodium Chloride Injection, USP is defined by the following pharmaceutical characteristics:

• Concentration: 0.9% sodium chloride (NaCl)
• pH: Typically 4.5–7.0 (check product labeling for exact value)
• Packaging: Sterile, single-use plastic containers (commonly available in 250 mL, 500 mL, and 1000 mL volumes)
• Additives: None – contains no antimicrobial, bacteriostatic, or buffering agents

⚠️ Important Note:
Sodium Chloride Injection is not intended for multi-dose use. Once opened, any unused portion must be discarded in accordance with sterile practice guidelines.

Administration and Monitoring Protocols

Safe and effective use of Sodium Chloride Injection requires collaboration from an interprofessional medical team, including physicians, nurses, and pharmacists.

Clinical teams are responsible for:

• Selecting an appropriate diluent based on drug compatibility and patient-specific needs

• Monitoring for complications such as:

  • Fluid overload

  • Electrolyte imbalance

  • Acid-base shifts

  • Large or rapid volumes can precipitate hyperchloremic metabolic acidosis; monitor serum chloride and bicarbonate

• Ensuring documentation of administration

• Proper disposal of remaining volume post-use

⚠️ Reminder for Healthcare Settings:
Even with preservative-free solutions, strict aseptic technique and monitoring are required to prevent iatrogenic harm, particularly in high-risk patient populations.

Final Thoughts: When to Choose Sodium Chloride Injection

Sodium Chloride Injection, USP is the preferred solution in the following clinical scenarios:

• A single-use application is required
• A preservative-free diluent is clinically indicated
• The patient is pregnant, breastfeeding, pediatric, or has documented sensitivity to bacteriostatic agents
• The goal is to reduce risk of medication interaction, site irritation, or systemic toxicity

While Bacteriostatic Normal Saline (BNS) provides utility in controlled multi-dose settings, preservative-free sodium chloride offers a broader safety margin for vulnerable populations and is often recommended in hospital, surgical, and neonatal care.

Frequently Asked Questions (FAQs)

1. What is the difference between Sodium Chloride Injection and Bacteriostatic Normal Saline (BNS)?

Sodium Chloride Injection is a preservative-free 0.9% NaCl solution intended for single-use only. BNS contains 0.9% sodium chloride plus benzyl alcohol as a preservative, allowing for multi-dose use. This preservative is the key differentiator.

2. Is BNS safe for infants or neonates?

No. BNS contains benzyl alcohol, which is contraindicated in neonates due to the risk of “gasping syndrome”, a potentially fatal condition. Sodium Chloride Injection (preservative-free) is the safer alternative for this population.

3. Can I use BNS and Sodium Chloride Injection interchangeably?

Not always. While both are 0.9% saline solutions, their preservative content makes them suitable for different use cases. Use Sodium Chloride Injection when a preservative-free, single-use product is required. Reserve BNS for multi-use scenarios with appropriate patient screening.

4. What are common clinical uses for Sodium Chloride Injection?

Sodium Chloride Injection is commonly used for:

• IV flushes
• Diluting or reconstituting medications
• Fluid replacement therapy – when isotonic crystalloid is indicated and the patient’s volume status and electrolytes are actively monitored.

5. Why is BNS used in multi-dose applications?

BNS includes benzyl alcohol, which acts as a bacteriostatic preservative. This allows the vial to be accessed multiple times under sterile conditions, reducing waste in clinical environments requiring repeated drug reconstitution or administration.

6. Are there risks associated with benzyl alcohol in BNS?

Yes. Benzyl alcohol may cause:

• Injection site irritation
• Allergic reactions
• Systemic toxicity in vulnerable populations (especially neonates and pregnant patients)
  Always assess the patient’s health status before using BNS.

7. How should Sodium Chloride Injection be stored and handled?

Store Sodium Chloride Injection at controlled room temperature (25°C). Once opened, any remaining volume must be discarded. It should not be reused or stored for later use.

8. Does FDA approve both Sodium Chloride Injection and BNS?

Yes. Both are FDA-approved products when used as labeled. However, their indications and limitations differ, particularly regarding patient age, dosing frequency, and preservative tolerance.

Official FDA Labeling for Reference

• Sodium Chloride Injection, USP
  View FDA labeling on DailyMed (NDC 0409-4888-10)

  Bacteriostatic 0.9% Sodium Chloride Injection, USP
  View FDA labeling on DailyMed (NDC 0409-4889-10)

Disclaimer: This article is intended for informational and educational purposes only. It is not a substitute for medical judgment, product labeling, or institutional protocols. Healthcare professionals should consult drug references and facility guidelines when selecting and administering injectable solutions.