How long can reconstituted alteplase be used after mixing at room temperature and when refrigerated?

Reconstituted Alteplase Stability

Reconstituted alteplase (1 mg/mL) must be used within 8 hours when stored at 2–30°C (36–86°F) according to FDA labeling. 1

Storage Guidelines Based on FDA Label

The official FDA prescribing information for Cathflo® Activase® provides explicit stability parameters:

• After reconstitution to 1 mg/mL concentration: The solution may be used for up to 8 hours when stored at 2–30°C (36–86°F)
• No refrigeration requirement: Room temperature storage is acceptable within this timeframe
• No antibacterial preservatives: The product must be reconstituted immediately before use
• Diluent specification: Use only Sterile Water for Injection, USP (NOT Bacteriostatic Water for Injection for the stroke indication) 1

Extended Stability Data from Research

While the FDA label provides conservative guidance, research studies demonstrate alteplase maintains activity under various conditions:

Room Temperature Storage

• Diluted alteplase (0.01 mg/mL) in normal saline remains biochemically stable and bioactive at ambient temperature for up to 24 hours based on in vitro clot lysis assays 2
• Standard concentration (1 mg/mL) stored at 37°C maintains approximately 90% bioactivity at 7 days when reconstituted in either sterile water or bacteriostatic water 3

Refrigerated Storage

Research supports extended stability under refrigeration:

• Alteplase at concentrations of 0.5,1, and 2 mg/mL retained sufficient fibrinolytic activity when stored for up to 14 days at 2°C (28 days for the 0.5 mg/mL dilution) 4
• Protein concentration, percent monomer, and clot lysis activity remained essentially unchanged over this period 4

Clinical Practice Recommendation

For acute stroke treatment, adhere strictly to the FDA-approved 8-hour window at 2–30°C. This conservative approach prioritizes patient safety and regulatory compliance. The extended stability data from research studies, while scientifically valid, applies primarily to catheter clearance applications at lower concentrations and should not be extrapolated to acute stroke dosing without institutional protocol approval.

Key Caveats

• Visual inspection required: Discard if solution shows discoloration or particulate matter
• Single-use vials: Any unused solution should be discarded after the 8-hour window 1
• No mixing with other medications: Alteplase solutions should not contain any other drugs 1
• Time-critical administration: For stroke patients, every minute matters—reconstitute and administer as rapidly as possible regardless of the stability window

The 8-hour FDA guideline provides adequate flexibility for clinical use while maintaining product integrity and patient safety.