Sterile Water

What is Sterile Water for Injection?

Sterile water for injection (SWFI) is highly purified water that has undergone sterilization to eliminate all microorganisms. Key characteristics:

Property	Sterile Water	Bacteriostatic Water
Preservative	None	0.9% benzyl alcohol
Multi-use	No - single use only	Yes
Stability after opening	Discard unused portion	28 days
Cost	Lower	Slightly higher

When to Use Sterile Water

Appropriate Uses

Sterile water is preferred in these situations:

• Immediate single-dose use - When reconstituted peptide will be used entirely
• Preservative sensitivity - Allergies to benzyl alcohol
• Pediatric/neonatal use - Benzyl alcohol contraindicated
• IV administration - Large volume infusions
• Specific protocol requirements - Some research protocols specify SWFI

When Bacteriostatic Water is Better

For most peptide research applications, bacteriostatic water is preferred:

Situation	Recommended
Multi-dose vial	Bacteriostatic water
Single immediate use	Either
Neonatal use	Sterile water
Benzyl alcohol allergy	Sterile water
Extended storage needed	Bacteriostatic water

Reconstitution with Sterile Water

The Single-Use Limitation

Without preservative protection, contamination risk increases with each vial access:

First puncture: Sterile Second puncture: Contamination possible Multiple punctures: Increasing bacterial risk

Best practice: Use entire contents at once or discard remainder

Stability After Reconstitution

Diluent	Storage	Typical Stability
Sterile water	Refrigerated	24-72 hours maximum
Bacteriostatic water	Refrigerated	3-4 weeks

Proper Handling Procedures

Storage Requirements

Unopened:

• Room temperature acceptable
• Protect from light
• Check expiration date
• Inspect for particles or cloudiness

After Opening:

• Use immediately
• Do not store opened containers
• Discard any unused portion
• Never reuse

Reconstitution Steps

1. Gather materials - Peptide vial, sterile water, alcohol swabs, syringe
2. Verify sterility - Check seal intact, no particles, not expired
3. Clean surfaces - Wipe vial tops with alcohol, let dry
4. Draw water - Use appropriate volume for desired concentration
5. Add to peptide - Inject slowly along vial wall
6. Dissolve - Gentle swirl, never shake
7. Use promptly - Administer or refrigerate immediately

Quality Standards

USP Requirements

Sterile water for injection must meet United States Pharmacopeia (USP) standards:

Parameter	Requirement
Sterility	No microbial growth
Pyrogen-free	No fever-causing substances
Particulate matter	Meets limits
pH	5.0-7.0
Conductivity	Within limits

Packaging Options

Container	Volume	Best For
Single-dose vial	2-5 mL	Individual reconstitution
Multi-dose container	10-30 mL	DO NOT use multiple times
Ampule	2-10 mL	Guaranteed sterility, single use

Common Mistakes to Avoid

Mistake	Risk	Prevention
Reusing opened vial	Bacterial contamination	Discard after single use
Room temp storage of reconstituted	Rapid degradation	Refrigerate immediately
Using tap/bottled water	Contamination, non-sterile	Only pharmaceutical grade
Ignoring cloudiness	Using contaminated product	Discard if not crystal clear

Frequently Asked Questions

Can I use sterile water if I only have one dose to prepare?

Yes, sterile water is perfectly appropriate for single-dose reconstitution. If you’re preparing one dose and will use it immediately, sterile water works well and may be more cost-effective than bacteriostatic water.

Why can’t I save the unused portion of sterile water?

Without preservatives, bacteria can multiply rapidly in opened sterile water. Even with careful technique, each needle puncture introduces potential contamination. The risk outweighs any cost savings from reusing the vial.

Is sterile water the same as distilled water?

No. While both are purified, distilled water is not sterile and is not suitable for injection. Sterile water has been processed specifically to eliminate all microorganisms and meets pharmaceutical standards for injection use.

How do I know if my sterile water is still good?

Check the expiration date, ensure the seal is intact, and visually inspect the water. It should be crystal clear with no particles, cloudiness, or discoloration. If there’s any doubt, discard it and use a fresh container.