title: Distribution of the toxin following medial rectus muscular injection of botulinum toxin gel in rabbits.
abstract: OBJECTIVE
  To determine the distribution of the toxin among individual muscles after intramuscular injection of botulinum toxin gel.
  
  
  METHODS
  One eye of 7 New Zealand white rabbits was randomized into group A, and the contralateral eye was into group B. Eyes in group A received medial rectus intramuscular injection of 2.5 IU of 125I-BTX-A gel in 0.1 ml, and those in group B received equivalent amount of 125I-BTX-A solution by medial rectus intramuscular injection. Four rectus muscles and the levator palpebrae superioris were harvested and the radioactivity of muscles was measured 16 hours after the injection.
  
  
  RESULTS
  In group A, the radioactivity of per gram medial rectus was significantly higher than that of other muscles (P < 0.01), and there was no statistically significant difference in the radioactivity of per gram muscles among other muscles (P > 0.05). In group B, the radioactivity of per gram medial rectus and levator palpebrae superioris was significantly higher than that of other muscles respectively(P < 0.05), and the difference in the radioactivity of per gram muscles between medial rectus and levator palpebrae superioris was not statistically significant (P > 0.05). The radioactivity of per gram medial rectus in group A was higher than that in group B (t=3.731, P-0.01), and there was no significant difference in the radioactivity of per gram muscles among other homonymous muscles (P > 0.05).
  
  
  CONCLUSIONS
  The toxin dispersed principally in the injected muscle and the local concentration of the toxin was much high following intramuscular injection of botulinum toxin gel.
authors.affiliation: Zhongshan Ophthalmic Center, Sun Yat-sen Universtity, Guangzhou 510060, China.
authors.forename: Jingchang
authors.initials: J
authors.lastname: Chen
authors.forename: Guanghuan
authors.initials: G
authors.lastname: Mai
authors.forename: Xinping
authors.initials: X
authors.lastname: Yu
authors.forename: Huanyuan
authors.initials: H
authors.lastname: Yu
authors.forename: Heping
authors.initials: H
authors.lastname: Wu
authors.forename: Xiaoming
authors.initials: X
authors.lastname: Lin
authors.forename: Darning
authors.initials: D
authors.lastname: Deng
authors.forename: Ying
authors.initials: Y
authors.lastname: Kang
mesh_terms: D000818:Animals; D019274:Botulinum Toxins, Type A / Q000493:pharmacokinetics*; D005260:Female; D007273:Injections, Intramuscular; D007457:Iodine Radioisotopes / Q000493:pharmacokinetics; D009465:Neuromuscular Agents / Q000493:pharmacokinetics*; D009801:Oculomotor Muscles / Q000000981:diagnostic imaging / Q000187:drug effects*; D011817:Rabbits; D011877:Radionuclide Imaging
chemical_list: D007457:Iodine Radioisotopes; D009465:Neuromuscular Agents; D019274:Botulinum Toxins, Type A