Abstract
Two randomized, placebo-controlled studies evaluated the pulmonary function safety of onabotulinumtoxinA (onabotA) for treatment of upper and/or lower limb spasticity. Patients with stable baseline respiratory status received one or two treatments with placebo, 240 U, or 360 U of onabotA. Pulmonary function tests, adverse events, and efficacy were measured at least every 6 weeks for 18 weeks (Study 1) or 30 weeks (Study 2). Study 1 enrolled 109 patients (n = 36–37/group) and Study 2 enrolled 155 patients (n = 48–54/group). Mean baseline forced vital capacity (FVC) was 76–78% of predicted per group in Study 1 and 71% of predicted per group in Study 2. In Study 1, change from baseline FVC values were significantly (p < 0.05) decreased vs. placebo at weeks 3 (240 U −57 mL vs. placebo +110 mL) and 12 (360 U −6 mL vs. +167 mL placebo). In Study 2, change from baseline FVC values were significantly decreased in the 360 U group vs. placebo at weeks 6 (−78 mL vs. +49 mL placebo), 13 (−60 mL vs. +119 mL placebo), 18 (−128 mL vs. +80 mL placebo), and 24 (−82 mL vs. +149 mL placebo). Individual pulmonary function-related adverse events were not correlated with PFT decreases. The most frequent pulmonary-related adverse events were nasopharyngitis (Study 1) and upper respiratory tract infection (Study 2). Ashworth scores were significantly improved at multiple time points in both studies. Injection of onabotA for spasticity in patients with decreased pulmonary function, at single and repeated doses of up to 360 U, was associated with small but statistically significant decreases in FVC or forced expiratory volume 1 s (FEV1) (>12% and 200 mL) that were subclinical and not correlated with any adverse clinical pulmonary events.
Highlights
OnabotulinumtoxinA is a biological medication that is injected into overactive muscles for the treatment of spasticity
In the 360 U group, changes from baseline forced vital capacity (FVC) ranged from −132 mL at week 18 to +35 mL at week 1; in the 240 U group, changes from baseline FVC ranged from +31 mL at week 18 to +87 mL at week 1; in the placebo group, changes from baseline FVC ranged from −6 mL at week 1 to +186 mL at week 24
The event was medically evaluated as inconsistent with the pharmacology of botulinum toxin. These two Pulmonary function tests (PFTs) studies showed a pharmacodynamic effect of onabotA on pulmonary function tests (FVC and forced expiratory volume 1 s (FEV1)), but the present analysis did not uncover any new pulmonary function adverse events that were deemed related to onabotA
Summary
OnabotulinumtoxinA (onabotA) is a biological medication that is injected into overactive muscles for the treatment of spasticity. Respiratory-related adverse events and respiratory dysfunction have been reported in some patients following injection into the limbs for the treatment of spasticity, these are not always considered treatment related [4,5,6]. These changes may be due to systemic spread of toxin at high doses or from worsening neurologic status from spasticity, cognition, or other unrelated medical illness
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