Intranasal absorption of buprenorphine - in vivo bioavailability study in sheep

The bioavailability of buprenorphine, HCl (BPP) in sheep after nasal admini stration of two formulations has been studied. 0.9 mg BPP in 150 mu l was a dministered nasally and compared to 0.6 mg i.v. The test solutions were for mulated with 30% polyethylene glycol 300 (PEG 300) and 5% dextrose, respect ively. The bioavailability for PEG 300 was 70% (S.D. +/- 27%, n = 6), where as the bioavailability for 5% dextrose was 89% (S.D. +/- 23%. n = 6). A two -compartment model with initial and terminal serum half-lives of 10 and 23 min, respectively, may describe the pharmacokinetics. The rate of absorptio n for both nasal formulations was very fast (t(max) = 10 min). The C-max wa s 37 ng/ml (S.D. +/- 17) and 48 (S.D. +/- 10) for PEG 300 and dextrose, res pectively. No significant difference was found between the two formulations , but PEG 300 has advantages in relation to freezing point depression and s olubility, which may be considered if further studies are going to be initi ated. The high nasal bioavailability and short time to maximal plasma conce ntration suggests that it is possible to make a clinically relevant nasal f ormulation of BPP for the treatment of pain. (C) 2000 Elsevier Science B.V. All rights reserved.