Hanne Wulff Nielsen

Nasal bioavailability of peptide T in rabbits: absorption enhancement by sodium glycocholate and glycofurol

The aim of the present study was to investigate the absolute nasal bioavailability of Peptide T from aqueous formulations containing sodium glycocholate, an absorption enhancer with known effect on epithelial tight junctions, and/or glycofurol in a crossover study in rabbits. Additionally, the reversibility of the absorption enhancing effect of sodium glycocholate was studied by applying enhancer and peptide T with different time intervals and calculating Area Under the Curve of the peptide in plasma. It was shown that the bioavailability of Peptide T was significantly enhanced when glycofurol or sodium glycocholate was added to a nasal formulation. The nasal bioavailability of Peptide T in water (control formulation), 5% glycofurol, 5% glycofurol+1% sodium glycocholate and 1% sodium glycocholate was 5.9, 22, 29 and 59%, respectively. As indicated by the differences in t(max), C(max) and time-concentration profiles different patterns of Peptide T absorption were seen from the vehicles containing glycofurol and sodium glycocholate. In the reversibility study, the enhancing effect of sodium glycocholate on nasal absorption of Peptide T was found to be reversible within 4 h. It was concluded, that nasal absorption of Peptide T in rabbits was effectively enhanced by co-administration of sodium glycocholate, which also provided very fast absorption rates as well as a relatively short lasting effect of the absorption enhancing effect. Co-administration of glycofurol leads to enhanced and prolonged absorption of the peptide. Combining the two enhancers did not lead to increased peptide T absorption compared to 5% glycofurol alone.

Intranasal administration of different liquid formulations of bumetanide to rabbits

The bioavailability of bumetanide in rabbits after intranasal administration of eight formulations intended for use in acute situations has been studied. The vehicles tested were combinations of phosphate buffer, pH 7.4, glycofurol 75. polyethylene glycol 200 and coconut oil. A mixture of 51% glycofurol in polyethylene glycol 200 was administered containing doses of 1 and 8 mg bumetanide respectively. For all other formulations the lower dose level only was studied. The tmax obtained ranged from 3 to 10 min. The vehicles resulting in the highest rate of absorption were 60% glycofurol in coconut oil and pure glycofurol. The observed bioavailability for the different formulations ranged from 16 to 37% for the time period 0-120 min. The bioavailability was also calculated omitting the initial peak seen after i.v. injection, which may be undesirable. Using this method bioavailabilities of 33-82, for the time interval 5-120 min was found. The study also demonstrated that the total amount of bumetanide absorbed increased proportionally to the dose administered. The rate of absorption of bumetanide from all formulations tested may be relevant for the treatment of acute oedematous states. The tmax obtained after intranasal administration was shorter than reported for other non-parenteral routes of administration.

High-performance liquid chromatographic analysis of Peptide T in rabbit plasma with on-line column enrichment.

The present paper describes the development of a simple and sensitive analytical method for quantification of Peptide T (PT) in rabbit plasma, using standard analytical equipment and on-line column enrichment, without prior extraction, clean-up or derivatization. The analytical procedure was found to be accurate, precise and linear. The accuracy was 100% (range 97-103%) and the mean precision was 8% (range 3-14%) for all (n=6) concentrations (0, 15, 50, 100 and 200 ng/ml). The total recovery was found to be approximately 80%, and it was found to be dependent upon the injection rate onto the extraction column. The correlation between added and found concentrations was 0.9982, and the limit of detection was estimated to be around 5 ng/ml. The method is therefore found to be suitable for bioavailability studies, involving Peptide T, in rabbits.

Solubilization and Stability of Bumetanide in Vehicles for Intranasal Administration, a Pilot Study

The solubility of bumetanide in vehicles of various polarities, suitable for intranasal administration in acute situations, has been investigated. The solubility at 4°C in glycofurol and polyethylene glycol 200 was high (167 and 143 mg/mL, respectively), decreasing exponentially with addition of phosphate buffer or coconut oil. Vehicles containing coconut oil and glycofurol did not seem to improve the solubility relative to mixtures between glycofurol and buffer. Adequate solubility (approximately 50 mg/mL) was achieved in vehicles containing about 80% cosolvent. The stability of bumetanide was studied at 5°C and 57°C. No degradation was observed at low temperature. At high temperature, bumetanide decomposes in nonaqueous vehicles with half-lifes ranging from 69 to 400 days, but sufficient stability may be obtained by adjustment of pH to 7.4. It may be concluded that it is possible to prepare a clinically relevant formulation for intranasal delivery of bumetanide.

Reversibility and clinical relevance of morphological changes after nasal application of ephedrine nasal drops 1

Abstract To predict the toxicity of nasal formulations, various in vitro and in vivo techniques have been used. Many of these techniques are very sensitive and it is a general problem to extrapolate the results to the clinical situation. The aim of the present study was to establish a clinically well known nasal formulation, Ephedrine Nasal Drops 1%, DAK 63 (EBE), as a relevant reference for other nasal formulations with respect to histological changes to and reversibility of the nasal mucosa after repeated short-term nasal application to rabbits. This ephedrine formulation also contains the well known local irritants, benzalkonium chloride and EDTA, which is why it is abbreviated to EBE. Seventy five μ1 was applied in one nasal cavity of rabbits ( n = 3) four times per day for 1 week, while the other cavity served as a control. Twelve rabbits were divided into four groups and were sacrificed at 4 h and 1, 7 and 21 days after last nasal application, respectively. The macro- and microscopical changes of the nasal mucosa were recorded. Except for minor greyish exudates seen at 4 h, and a slight congestion of the mucosa seen at 4 and 24 h after application, there were no gross changes of the nasal mucosa. The microscopical examination, however, showed an extended infiltration of the mucosa by eosinophils, a general inflammatory reaction and a pronounced atrophy and disorganisation of the epithelium, which was furthermore void of goblet cells and cilia. These microscopical changes were seen after 4 h and, to a minor extent, 24 h after application. After 7 days, no changes could be found, indicating that they were reversible in less than 1 week. It is concluded that EBE may be a good reference in the predictive testing of local toxicity, with respect to a cost/benefit evaluation of nasal formulations, meant for acute or short-term treatment.