title: Assessment of serum concentrations and sedative effects of fentanyl after transdermal administration at three dosages in healthy llamas.
abstract: OBJECTIVE
  To determine the serum concentrations and sedative effects of fentanyl after transdermal administration at 3 dosages in llamas.
  
  
  METHODS
  9 healthy adult female llamas (mean age, 8 +/- 3 years; mean weight, 150 +/- 18 kg).
  
  
  METHODS
  Llamas were allocated to 1 of 3 groups (3 llamas/group). Fentanyl patches (each providing transdermal delivery of 75 microg of fentanyl/h) were placed on shaved areas of the antebrachium of all llamas. In group 1, llamas were treated with 1 patch (anticipated fentanyl dosage, 75 microg/h). In group 2, llamas were treated with 2 patches (anticipated fentanyl dosage, 150 microg/h). In group 3, llamas were treated with 4 patches (anticipated fentanyl dosage, 300 microg/h). For each llama, the degree of sedation was assessed by use of a subjective scoring system and a blood sample was collected for determination of serum fentanyl concentration at 12, 24, 36, 48, 60, and 72 hours after patch placement.
  
  
  RESULTS
  Following the placement of 4 patches, mean +/- SD serum fentanyl concentration in group 3 llamas reached 0.3 +/- 0.08 ng/mL within 12 hours. This concentration was sustained for 72 hours. In group 2, application of 2 patches provided inconsistent results; in group 1, application of 1 patch rarely provided measurable serum fentanyl concentrations. No llamas became sedated at any time.
  
  
  CONCLUSIONS
  Results suggest that application of four 75 microg/h fentanyl patches provides consistent, sustained serum fentanyl concentrations without sedation in llamas. However, the serum concentration of fentanyl that provides analgesia in llamas is not known.
authors.affiliation: Riverview Animal Clinic, 2002 L Schultheis Rd, Uniontown, WA 99179, USA.
authors.forename: Tamara L
authors.initials: TL
authors.lastname: Grubb
authors.forename: Jenifer R
authors.initials: JR
authors.lastname: Gold
authors.forename: John W
authors.initials: JW
authors.lastname: Schlipf
authors.forename: A Morrie
authors.initials: AM
authors.lastname: Craig
authors.forename: Karen C
authors.initials: KC
authors.lastname: Walker
authors.forename: Thomas W
authors.initials: TW
authors.lastname: Riebold
mesh_terms: D000279:Administration, Cutaneous; D000701:Analgesics, Opioid / Q000008:administration & dosage* / Q000097:blood*; D000818:Animals; D002161:Camelids, New World / Q000097:blood; D004305:Dose-Response Relationship, Drug; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage* / Q000097:blood*; D013997:Time Factors
chemical_list: D000701:Analgesics, Opioid; D005283:Fentanyl