Dosing in initial and sequential treatment sessions should be tailored to the individual patient based on the patient’s head and neck position, localization of pain, muscle hypertrophy, patient response, and adverse event history. The initial dose for a patie nt without prior use of BOTOX should be at a lower dose, with subsequent dosing adjusted based on individual response. Limiting the total dose injected into the sternocleidomastoid muscle to 100 Units or less may decrease the occurrence of dysphagia [see WARNINGS AND PRECAUTIONS].
Still, Botox's use for depression raises a question that confounds some researchers. In some cases, how Botox works is evident: the toxin can block the signals between nerves and muscles, which is why it can help calm an overactive bladder, say, or a twitching eye, or the facial muscles that make wrinkles more apparent. In other cases, however (with migraines as well as with depression), scientists are flummoxed. They may have noticed that the drug works for a given condition, but they aren't always sure why--in sciencespeak, they don't know what the mechanism is.
In 1986, Scott's micromanufacturer and distributor of Botox was no longer able to supply the drug because of an inability to obtain product liability insurance. Patients became desperate, as supplies of Botox were gradually consumed, forcing him to abandon patients who would have been due for their next injection. For a period of four months, American blepharospasm patients had to arrange to have their injections performed by participating doctors at Canadian eye centers until the liability issues could be resolved.[48]
Spread of toxin effects. The effect of botulinum toxin may affect areas away from the injection site and cause serious symptoms including: loss of strength and all-over muscle weakness, double vision, blurred vision and drooping eyelids, hoarseness or change or loss of voice, trouble saying words clearly, loss of bladder control, trouble breathing, and trouble swallowing.
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