Abobotulinum Toxin A

INTRODUCTION

Indications

Treatment of cervical dystonia in adults in order to decrease severity of abnormal head position and neck pain Temporary improvement of moderate to severe glabellar (frown) lines in adult patients <65 yr.

Action

Inhibits release of acetylcholine from peripheral cholinergic nerve endings, resulting chemical denervation of treated muscle. Therapeutic Effects: Localized reduction of muscle activity, with decreased spasticity in cervical dystonia. Decreased appearance of glabellar lines.

Adverse Reactions/Side Effects Cervical dystonia

CNS: fatigue, headache. EENT: dysphonia, eye disorder. GI: dry mouth, dysphagia. Local: injection site pain. MS: muscular weakness, neck pain. Misc: SPREAD OF TOXIN EFFECT.

Glabellar lines

CNS: headache. EENT: nasopharyngitis, eyelid edema, eyelid ptosis, sinusitus. Resp: nasopharyngitis, dyspnea. GI: nausea, dysphagia. Local: injection site pain/reaction. Misc: SPREAD OF TOXIN EFFECT.

PHYSICAL THERAPY IMPLICATIONS (when treating cervical dystonia or spasticity)

Examination and Evaluation

• Assess dystonia, spasticity, ROM, and functional ability as the drug begins to take effect. Document whether changes in spasticity and tone are consistent with rehabilitation goals.

• Watch for signs that the effects of abotulinum toxin A spread beyond the site of local injection. Signs include generalized muscle weakness, difficulty breathing, vision disturbances, drooping eyelids (ptosis), urinary incontinence, difficulty swallowing, and problems speaking. These signs can occur hours to weeks after injection. Report these signs to the physician immediately.

• Monitor IM injection site for redness, swelling, and irritation. Report prolonged or excessive skin reactions to the physician.

Interventions

• Implement aggressive therapeutic exercises (neuromuscular re-education, postural stabilization, gait training, other task-specific training) to facilitate voluntary motor function and help patient adjust to reduced spasticity and tone.

• Provide appropriate assistive devices (walker, cane, crutches) while patient adjusts to reduced levels of spasticity. Specifically, make sure patient can ambulate and transfer safely while adjusting to reduced tone in the lower extremities.

• When indicated, incorporate serial casting and similar techniques to capitalize on drug effects and achieve maximal soft tissue lengthening and help reduce contractures.

Patient/Client-related Instruction

• Explain to patient and family/caregivers that treatment effects may only last 2–4 months. Periodic re-injection may be needed to sustain muscle relaxant effects.

• Instruct patient or family/caregivers to report any untoward responses such as severe or prolonged headache, drooping eyelids, vision problems, difficulty speaking, or GI problems (nausea, dry mouth, difficulty swallowing).

Pharmacokinetics

Absorption: Minimal but may be significant in selected populations.

Distribution: Unknown