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- Espefält Westin, Ulrika, et al.
(author)
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Direct nose-to-brain transfer of morphine after nasal administration to rats
- 2006
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In: Pharmaceutical research. - : Springer Science and Business Media LLC. - 0724-8741 .- 1573-904X. ; 23:3, s. 565-572
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Journal article (peer-reviewed)abstract
- PURPOSE: The aim of this study was to quantify the olfactory transfer of morphine to the brain hemispheres by comparing brain tissue and plasma morphine levels after nasal administration with those after intravenous administration. METHODS: Morphine (1.0 mg/kg body weight) was administered via the right nostril or intravenously as a 15-min constant-rate infusion to male rats. The content of morphine and its metabolite morphine-3-glucuronide in samples of the olfactory bulbs, brain hemispheres, and plasma was assessed using high-performance liquid chromatography, and the areas under the concentration-time curves (AUC) were calculated. RESULTS: At both 5 and 15 min after administration, brain hemisphere morphine concentrations after nasal administration were similar to those after i.v. administration of the same dose, despite lower plasma concentrations after nasal administration. The brain hemispheres/plasma morphine AUC ratios for the 0-5 min period were thus approximately 3 and 0.1 after nasal and i.v. administration, respectively, demonstrating a statistically significant early distribution advantage of morphine to the brain hemispheres via the nasal route. CONCLUSION: Morphine is transferred via olfactory pathways to the brain hemispheres, and drug transfer via this route significantly contributes to the early high brain concentrations after nasal administration to rats.
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- Espefält Westin, Ulrika, 1974-
(author)
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Olfactory Transfer of Analgesic Drugs After Nasal Administration
- 2007
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Doctoral thesis (other academic/artistic)abstract
- Nasal administration of analgesics for achieving rapid pain relief is currently a topic of great interest. The blood-brain barrier (BBB) restricts access to the central nervous system (CNS) for several central-acting drugs, such as morphine and dihydroergotamine, which results in a substantial effect delay. Evidence for the olfactory transfer of drugs from the nasal cavity to the CNS after nasal administration, bypassing the BBB, is available for both animals and humans. The aims of this thesis were to study the olfactory transfer of morphine to the CNS after nasal administration, and to compare the nasal transport of analgesic drugs across nasal respiratory and olfactory mucosa. In vivo studies in rodents demonstrated that morphine is transferred via olfactory pathways to the olfactory bulbs and the longitudinal fissure of the brain after nasal administration. Further, olfactory transfer of morphine significantly contributed to the early high morphine brain hemisphere concentrations seen after nasal administration to rats. Olfactory transfer was tracked by collecting and analysing brain tissue and blood samples after right-sided nasal administration and comparing the results to the situation after i.v. administration. The olfactory transfer was also visualised by brain autoradiography. In vitro studies indicated that the olfactory mucosa should not be a major barrier to the olfactory transfer of dihydroergotamine or morphine, since transport of these drugs was no more restricted across the olfactory mucosa than across the nasal respiratory mucosa. The in vitro studies were performed using the horizontal Ussing chamber method. This method was further developed to enable comparison of drug transport across nasal respiratory and olfactory mucosa which cannot be achieved in vivo. In conclusion, these analgesic drugs showed potential for olfactory transfer, and access to the CNS by this route should be further investigated in humans, especially for the drugs with central effects that are currently under development for nasal administration.
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- Fransén, Nelly, et al.
(author)
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The in vitro transport of dihydroergotamine across porcine nasal respiratory and olfactory mucosa and the effect of a novel powder formulation
- 2007
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In: Journal of Drug Delivery Science and Technology. - 1773-2247. ; 17:4, s. 267-271
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Journal article (peer-reviewed)abstract
- The objective was to investigate the transport of dihydroergotamine (DHE) across porcine nasal respiratory and olfactory mucosa and to evaluate the absorption enhancing effect of a novel dry powder formulation compared with a reference solution with the horizontal Ussing chamber method. The powder formulation was obtained by mixing micronized DHE particles and mucoadhesive carrier particles (sodium starch glycolate) to create an interactive mixture. The horizontal Ussing chamber method was chosen as the in vitro model since it provides the opportunity to apply a dry powder formulation and compare the transport across the two types of nasal mucosa. A histological evaluation confirmed that the mucosa had been correctly isolated. The results showed no significant difference in the absorption from the powder formulation compared with the reference solution, but the transport of DHE was significantly higher across olfactory mucosa than across respiratory mucosa. This may be explained by facilitated transport through paracellular transfer along the olfactory nerve cells.
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