Oral zinc supplementation to enhance effects of botulinum neurotoxin injection: an n of 1 study.
All subjects will complete a baseline BoNT injection cycle followed by one, two or three pairs of study BoNT injection cycles. The first pair of study injection cycles will be done by all subjects. For one of these cycles, the subject will ingest one capsule containing OZS (50 mg zinc acetate) daily for 7 days before the injection. For the other cycle of the first pair, the subject will ingest an identical capsule containing placebo for 7 days before injection. These first pair of injection cycles will occur in randomized double blinded cross-over order. At the end of the first pair of study injection cycles (at study visit #3), the subject will be asked if he has reached study endpoint, i.e. has made the decision that one or other treatment is superior, in which case the patient[Right Quote]s participation will terminate. If the subject is not sure enough of a difference but would like to do another pair of blinded cross-over injection cycles with higher dose OZS, a second pair of randomized cross-over injection cycles will follow. For the second pair of cycles, the subject will take either 1 or 2 capsules daily for 7 days prior to injection, one cycle with zinc and the other placebo. The decision whether to take 1 or 2 capsules per day for this pair of cycles is made by the subject at study visit #3, and the order randomized by coin toss by the research coordinator at that time. At study visit #5, the end of this second pair, the subject will decide if he has reached study endpoint (i.e. in favor of one set of capsules, or seeing no difference). If the subject wishes to continue blinded, another pair of injection cycles is undertaken taking either 1 or 2 capsules (as decided by the subject at study visit #5) for 7 days prior to injection as before. Injection cycles will be at intervals of at least 11 weeks, and will be the same length for any pair of injection cycles. Subjects will receive their usual BoNT injection at the usual dose and injection sites for the baseline and first pair of injection cycles. If subject/patient and PI/treating physician decide to lower the dose or extend the interval for the second and/or third pair of injection cycles, this is permitted.
Eligible subjects are all patients who have received two or three BoNT injection cycles from the PI within the prior 8 months, at stable intervals (i.e. these cycle intervals differed by no more than 2 weeks) and stable doses (i.e. total BoNT units injected to the target region varyied by no more than 15%, and used a single toxin brand).
Due to the nature of the PI's practice, this incorporates adults, age 18 to 80, male and female, who have an FDA-approved indication for BoNT injection: most have dystonias of the neck or eyelids or jaw or limb, the others have hemifacial spasm, migraine or limb spasticity.