Background. It is recommended that botulinum toxin be used immediately or within 2 weeks after its reconstitution because its efficacy might be compromised by prolonged storage.
Objectives. To evaluate the efficacy of botulinum toxin type A (BTX-A) reconstituted over 6 consecutive weeks for the treatment of glabellar frown lines.
Methods. Four vials of BTX-A were reconstituted each of 7 days over a period of 6 weeks, totaling 28 vials, corresponding to seven reconstitution dates. During this period, the BTX-A was stored according to the manufacturer's instructions. On the day after the last reconstitution, all of the reconstituted vials were injected in patients from four dermatologic centers taking part in this study. A total of 88 patients were treated on the same day and were followed every 2 weeks for 4 months. All patients were photographed at all stages. A number of professionals assessed the efficacy of reconstituted BTX-A based on the reduction of the maximum frowning capacity of the treated muscles.
Results. Of the 88 patients who were selected, 3 were excluded. Three forms of evaluation were applied, and no statistically significant differences were found in the results presented.
Conclusion. BTX-A may be applied up to 6 weeks after reconstitution without losing its effectiveness. Other factors, which are probably individual, may influence the response to BTX-A injections.