79 / 86
Prager and colleagues evaluated two different dilu-
tions (25 and 40 U/mL) of incobotulinumtoxinA in
the treatment 40 patients with glabellar lines. They
also found no significant difference in the initial
results or after 4 months of follow up between the
two groups.
76
Blepharospasm
Boyle and colleagues studied the effect of high- and
low-concentration onabotulinumtoxinA for the
treatment of benign essential blepharospasm. They
injected 16 patients with concentrations of 10 and
100 U/mL and followed them for 8 months. No sig-
nificant differences were reported in efficacy or
complications.
77
Non Facial Muscles
Experimental Studies
Shaari and colleagues treated the tibialis anterior
muscle in rats and found that a constant dose of
0.2 U of BoNT resulted in greater paralysis when
injected in larger volumes.
78
Ten years later, Kim and
colleagues injected 16 rabbits with 10 U of on-
abotulinumtoxinA at concentrations of 20 and
100 U/mL and drew the same conclusions.
79
Limb Muscle Dystonias and Spasticity
A group from Korea
80,81
injected a fixed dose of
2.5U of onabotulinumtoxinA into the human
extensor digitorum brevis muscle in two dilutions
(5 and 25 U/mL) and measured the compound muscle
action potential amplitude. They concluded that a
fivefold increase in volume did not enhance the par-
alyzing effect of onabotulinumtoxinA. Francisco and
colleagues treated 13 patients with 60U diluted to
50 or 100U/mL for wrist and finger flexor spasticity
and found no significant differences either.
82
Gracies and colleagues
83
conducted a double-blind
randomized controlled trial with 21 individuals with
spastic elbow flexors using 160 U of onabotulinum-
toxinA in two dilutions (20 and 100 U/mL). They
found that the higher dilution group (20 U/mL)
achieved greater neuromuscular blockade and
spasticity reduction than an endplate-targeted
(injection to areas known to be dense in endplates)
or concentrated solution.
Two studies were conducted in children with cere-
bral palsy and limb spasticity. One used onabotuli-
numtoxinA in 38 children at concentrations of 12.5
(
n
= 19) and 50 U/mL (
n
= 19) in the gastrocnemius
muscles for reducing ankle plantar flexor spasticity.
It was found that, although there were no significant
differences in physical evaluation and gait analysis,
the large-volume group presented side effects more
frequently, making a concentrated solution a better
option.
84
In another randomized controlled trial,
22 spastic diplegic or quadriplegic children with
cerebral palsy received a fixed dose of abobotuli-
numtoxinA. Dilutions of 500 U/5mL and 500 U/
1mL were injected in each gastrocnemius muscle.
85
The more diluted preparation was considered
more effective.
Hyperhidrosis
There is no standardized dilution for BoNT treat-
ment of focal hyperhidrosis. Dilutions reported vary
from 1 to 10mL of saline
86–88
for onabotulinum-
toxinA, with most clinicians using between 2 and
5mL. As for abobotulinumtoxinA, reconstitution
volumes vary between 1.25 and 10mL,
86–89
the use
of 2.5 to 5mL being most frequent. In the only study
with incobotulinumtoxinA for hyperhidrosis, the
dilution used was 10 U/mL.
90
In an open, comparative study, nine volunteers were
injected in the axillary region; 3 U of onabotuli-
numtoxinA was diluted in 1, 2, 3, 4, and 5mL of
saline solution. Patient assessments using the iodine-
starch test showed no difference in anhydrotic ha-
los.
91
Another trial compared the same 5-U dose of
abobotulinumtoxinA in three different dilutions
(0.2, 0.4 and 0.6mL) injected in the backs of three
patients with compensatory hyperhidrosis. Larger
anhydrotic halos were found with the more-diluted
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TR I NDADE DE ALME I DA ET AL