Assessment of serum concentrations and sedative effects of fentanyl after transdermal administration at three dosages in healthy llamas.
ABSTRACT To determine the serum concentrations and sedative effects of fentanyl after transdermal administration at 3 dosages in llamas.
9 healthy adult female llamas (mean age, 8 +/- 3 years; mean weight, 150 +/- 18 kg).
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.
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.
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.
[Show abstract] [Hide abstract]
ABSTRACT: To investigate the pharmacokinetics of fentanyl administered transdermally and IV in sheep. 21 adult female sheep. Fentanyl was administered IV to 6 healthy sheep. Transdermal fentanyl patches (TFPs) were applied to 15 sheep 12 hours prior to general anesthesia and surgery. Seria blood samples were collected for 18 hours after IV injection and 84 hours after TFP application. Fentanyl concentrations were quantified via liquid chromatography-mass spectrometry, and pharmacokinetic values were estimated. All sheep completed the study without complications. Following a dose of 2.5 g/kg administered IV, the half-life was 3.08 hours (range, 2.20 to 3.36 hours), volume of distribution at steady state was 8.86 L/kg (range, 5.55 to 15.04 L/kg), and systemic clearance was 3.62 L/kg/h (range, 2.51 to 5.39 L/kg/h). The TFPs were applied at a mean dose of 2.05 g/kg/h. Time to maximum plasma concentration and maximal concentration were 12 hours (range, 4 to 24 hours) and 1.30 ng/mL (range, 0.62 to 2.73 ng/mL), respectively. Fentanyl concentrations were maintained at >0.5 ng/mL for 40 hours after TFP application. IV administration of fentanyl resulted in a short half-life. Application of a TFP resulted in stable blood fentanyl concentrations in sheep.American Journal of Veterinary Research 10/2010; 71(10):1127-32. DOI:10.2460/ajvr.71.10.1127 · 1.21 Impact Factor
[Show abstract] [Hide abstract]
ABSTRACT: Many disease processes and management procedures of small ruminants have the potential to result in painful or noxious stimuli. There are a variety of medications and interventions that can be used to minimize the long-term consequences of pain in these species. The first portion of this article focuses on the commonly used medications available for pain management of small ruminants and discusses the benefits and side effects to their use. The second portion of the article focuses on the management of pain associated with common diseases or procedures of these species.Veterinary Clinics of North America Food Animal Practice 03/2013; 29(1):185-208. DOI:10.1016/j.cvfa.2012.11.004 · 1.75 Impact Factor