title: Clinical value of monitoring plasma octreotide levels during chronic octreotide long-acting repeatable therapy in carcinoid patients.
abstract: OBJECTIVE
  Octreotide is used to treat patients with neuroendocrine tumors. Previous reports show that octreotide long-acting repeatable (LAR) dose and patient body weight affect nadir plasma octreotide levels (approximately 1250, 2500, 5000, and 11,000 pg/mL for LAR doses of 10, 20, 30 and 60 mg/mo). However, plasma octreotide levels have decreased over time in patients receiving these doses of LAR.
  
  
  METHODS
  From November 2004 until July 2007, trough plasma octreotide levels were determined in 86 patients on long-term octreotide LAR therapy at doses of 30, 60, and 120 mg/mo. Changes in plasma drug levels were analyzed over time using random effects models.
  
  
  RESULTS
  Current plasma octreotide levels for octreotide LAR doses of 30, 60, and 120 mg/mo are approximately 2200, 5200, and 6500 pg/mL, respectively, representing a decrease of approximately 50% to 70% compared with previously reported plasma octreotide levels. The decreases in octreotide levels over time with the 30- and 60-mg/mo LAR doses are highly statistically significant (P = 0.0067, 0.0149, respectively).
  
  
  CONCLUSIONS
  Current plasma octreotide values are significantly lower than previously reported for 30-, 60-, and 120-mg/mo LAR doses. Serial plasma octreotide value measurements should be used to determine if increasing symptoms or tumor growth are associated with suboptimal octreotide levels.
authors.affiliation: Department of Surgery, Louisiana State University Health Sciences Center, New Orleans, LA, USA. ewolte@lsuhsc.edu
authors.forename: Eugene A
authors.initials: EA
authors.lastname: Woltering
authors.forename: Vergilio A
authors.initials: VA
authors.lastname: Salvo
authors.forename: Thomas M
authors.initials: TM
authors.lastname: O'Dorisio
authors.forename: John
authors.initials: J
authors.lastname: Lyons
authors.forename: Gang
authors.initials: G
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Zhou
authors.forename: Jacky R
authors.initials: JR
authors.lastname: Seward
authors.forename: Vay Liang W
authors.initials: VL
authors.lastname: Go
authors.forename: Arthur I
authors.initials: AI
authors.lastname: Vinik
authors.forename: Paris
authors.initials: P
authors.lastname: Mamikunian
authors.forename: Gregg
authors.initials: G
authors.lastname: Mamikunian
mesh_terms: D018931:Antineoplastic Agents, Hormonal / Q000008:administration & dosage* / Q000097:blood*; D002276:Carcinoid Tumor / Q000188:drug therapy* / Q000378:metabolism; D003692:Delayed-Action Preparations; D016903:Drug Monitoring; D006801:Humans; D007273:Injections, Intramuscular; D018358:Neuroendocrine Tumors / Q000188:drug therapy* / Q000378:metabolism; D015282:Octreotide / Q000008:administration & dosage* / Q000097:blood*; D011446:Prospective Studies; D012189:Retrospective Studies; D013997:Time Factors; D016896:Treatment Outcome; D014481:United States
chemical_list: D018931:Antineoplastic Agents, Hormonal; D003692:Delayed-Action Preparations; D015282:Octreotide