Botulinum toxin type B: pH change reduces injection pain, retains efficacy

Injection of botulinum toxin Type B (BTX-B) is substantially more painful than injection of botulinum toxin Type A (BTX-A).

A method of reducing pain with BTX-B injection without reducing efficacy. This was evaluated in 2 BTX-A-resistant subjects and another BTX-B-naive subject.

Clinical evaluation and computer analysis of photographs were used to confirm efficacy to different dilutions of Type B toxin and confirm BTX-A resistance. A pilot study of 3 subjects involves BTX-B (usually pH 5.6) that was diluted with sodium bicarbonate to normalize the pH to 7.5 in the syringe immediately before injection. Pain assessment compared the different pH BTX-B solutions.

Two patients with acquired resistance to 3 BTX-As in upper facial muscles responded to BTX-B. Injection pain of BTX-B changed to pH 7.5 was significantly reduced and retained efficacy over 10 weeks.

Botulinum toxin Type A resistance is documented to 3 BTX-A brands in 2 patients. They had received low doses of Type A toxin, they responded to Type B toxin. Injection pain of the acidic solution of BTX-B neurotoxin was reduced and efficacy not compromised by changing pH of BTX-B solution to pH 7.5. This method improved patient tolerance to BTX-B injections.