Section 4 Plastic and Reconstructive Problems

HANDL I NG BOTUL I NUM TOX I NS

membrane-spanning domain (Hn) and a 50-KDa C-terminal receptor-binding domain (Hc). After that, they investigated the stability parameters of isolated Lc and the binding domains Hc of BoNT to mild agitation. They found that the recombinant light chains of serotype A (LcA) rapidly lost their secondary structures and that mild stirring denatured Hc domains, but the addition of nonionic detergents completely prevented denaturation. They speculated that BoNT domains underwent surface denaturation due to rapid exposure of hydrophobic residues by mechanical agitation. A recent experimental study evaluated the effect of onabotulinumtoxinA after vigorous agitation (con- tinuous inversion and straightening of the vial, 30 times per minute) for up to 6 weeks. 47 Eight mice were each injected intraperitoneally with 1 U of the agitated onabotulinumtoxinA on days 1, 3, 5, 7, 14, 21, 28, and 42. The main outcome measure was death of the mice, demonstrating toxin efficacy. At the end of the study, half of each group of mice (4/8 mice) died within 48 hours of the injection (range 16–48 hours), and the conclusion was that the effect of onabotulinumtoxinA is maintained even when it is agitated vigorously for up to 6 weeks. 47 In a clinical setting, Almeida and colleagues 48 compared muscle paralysis between the sides in a split-face study in which they injected onabotuli- numtoxinA gently reconstituted without foam for- mation on one side of the face (periocular and glabellar areas) and onabotulinumtoxinA rapidly reconstituted with formation of as many bubbles as possible on the other side. They concluded that the presence of foaming during the reconstitution pro- cess did not affect the potency or the short- or long- term effects of the product. A consensus panel on onabotulinumtoxinA held in 2004 concluded that this report supports clinical experience, suggesting that the fragility of BoNTA is not as problematic as previously reported. 22

They randomly selected seven patients who had half of their forehead injected with onabotulinumtoxinA reconstituted gently and the other half with onabotulinumtoxinA reconstituted vigorously. (The vial was placed on a vortex Touch mixer at maximum speed for 30 seconds.) They concluded that the effect and duration after 6 months was the same on each forehead side. The fact that the associated proteins inside the complex of onabotulinumtoxinA might serve to stabilize the neurotoxin molecule and protect it from degradation may explain the different results found between in vitro 46 and in vivo 47–49 studies. There have been no reports of injection of nonbio- degradable material concomitantly with the injection of BoNT, but there is a report of the presence of rubber particles in a reconstituted onabotulinum- toxinA vial. The authors and the manufacturer recommend visual inspection of the product before its use. 50 RimabotulinumtoxinB must be stored at 2 1 C to 8 1 C, 20 and according to Setler, 51 there is no signif- icant loss of activity for up to 30 months under refrigeration, although at room temperature (25 1 C), it drops to at least 9 months. Some controversy remains on the storage of recon- stituted BoNTA vials. Manufacturers recommend administration within 4 to 24 hours after reconsti- tution, 15–19 storage at 2 1 C to 8 1 C (in the refrigera- tor), and not freezing after reconstitution, but several publications suggest that these recommendations may be excessively strict. Foreign Body Storage

Shelf Life After Reconstitution

A multicenter, double-blind study demonstrated in 88 patients that reconstitution with nonpreserved saline up to 6 weeks before use did not reduce

Kazim and colleagues 49 also studied the duration of onabotulinumtoxinA when reconstituted vigorously.

DERMATOLOG I C SURGERY