title: Neutrophil margination as a possible mechanism for verteporfin infusion-associated pain.
abstract: OBJECTIVE
  To investigate the changes in absolute neutrophil counts in patients with and without pain after verteporfin infusion.
  
  
  METHODS
  Experimental study.
  
  
  METHODS
  The absolute neutrophil counts were obtained from the blood samples taken at the beginning of infusion and after the end of verteporfin infusion.
  
  
  RESULTS
  Four patients in whom verteporfin infusion-related pain developed had a decrease in the absolute neutrophil counts from a preinfusion mean of 4,589/mm(3) to a postinfusion mean of 1,688/mm(3) while they had pain, as compared with preinfusion and postinfusion counts of 4,912/mm(3) and 4,111/mm(3), respectively, in five control patients having no pain, a difference in proportion that was significant (P =.027).
  
  
  CONCLUSIONS
  Patients in this study with verteporfin infusion-associated pain developed neutropenia during infusion, most likely from drug-induced neutrophil margination. It is possible that medications preventing the transient neutropenia may help avert verteporfin infusion-associated pain.
authors.affiliation: Vitreous-Retina-Macula Consultants of New York, New York 10021, USA. VRMNY@aol.com
authors.forename: Richard F
authors.initials: RF
authors.lastname: Spaide
authors.forename: Leandro
authors.initials: L
authors.lastname: Maranan
mesh_terms: D006801:Humans; D007262:Infusions, Intravenous; D007958:Leukocyte Count; D009503:Neutropenia / Q000097:blood* / Q000139:chemically induced; D009504:Neutrophils; D010146:Pain / Q000097:blood* / Q000139:chemically induced*; D017319:Photosensitizing Agents / Q000008:administration & dosage / Q000009:adverse effects*; D011166:Porphyrins / Q000008:administration & dosage / Q000009:adverse effects*; D000077362:Verteporfin
chemical_list: D017319:Photosensitizing Agents; D011166:Porphyrins; D000077362:Verteporfin