Botulinum Toxin Concentration Calculation
When reconstituting 200 units of botulinum toxin with 6 mL, you will have a concentration of 33.3 units per mL (or 33.3 units per cc).
Calculation Method
- To determine the concentration, divide the total number of units by the total volume:
- 200 units ÷ 6 mL = 33.3 units/mL 1
Clinical Implications of Dilution
- Dilution affects the spread of the toxin in tissues - more dilute solutions (like 33.3 units/mL) will diffuse over a larger area compared to more concentrated solutions 2
- The concentration of 33.3 units/mL is considered a moderate dilution that balances localized effect with appropriate tissue spread 3
Reconstitution Best Practices
- Use preservative-free 0.9% sodium chloride for reconstitution 3
- Use large diameter injection needles for reconstitution to minimize mechanical stress on the botulinum toxin protein 2
- Apply only 2-3 gentle injection-aspiration-injection cycles during reconstitution 2
- Avoid aggressive reconstitution techniques (small needles, excessive agitation) which can reduce potency by up to 42% 2
Storage After Reconstitution
- Reconstituted botulinum toxin should be stored in a refrigerator 3
- FDA labeling recommends discarding reconstituted toxin not used within 4 hours 4
- Significant degradation in potency occurs after 12 hours of refrigerator storage 4
- Freezing reconstituted toxin results in approximately 70% loss of potency over 2 weeks 4
Important Considerations
- Botulinum toxin potency units are specific to each product and cannot be converted between different formulations 1
- The potency of botulinum toxin is measured in mouse units, where one unit corresponds to the calculated median lethal intraperitoneal dose (LD50) in mice 1
- In case of suspected overdose, botulinum antitoxin is available from the Centers for Disease Control and Prevention (CDC) 1