Comments on diethylene glycol concentrations.
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Ethylene Glycols↗
Biomedical subjects
L J Schep
Publications and source records attributed to L J Schep.
Controlled release opportunities for oral peptide delivery in aquaculture.
Over the last decade, fish supplies for human consumption have reached over 100 million tons. Due to overfishing, future increases in demand can only be met from the aquaculture industry. This will require increased research in areas such as the control and manipulation of fish reproduction. There is increasing interest in the oral delivery of peptides that control gamete reproduction. However, compared to mammalian species, little is known about the barriers to peptide delivery and methods to improve such delivery. The three major barriers to peptide delivery are the enzymatic barriers sourced from the host luminal and membrane bound peptidases, the immunological cells present within both the enterocytes and underlying connective tissue and the physical barrier of the epithelial cells. Furthermore, the anatomy and physiology of the gastrointestinal tract of these species are markedly different when compared to higher vertebrates and therefore must be considered when designing appropriate delivery systems. Research to date has focused on the oral delivery and subsequent pharmacodynamic responses to the peptides associated with growth and reproduction. However, minimal work has been undertaken to overcome the identified barriers and therefore any future investigations need to attend to these obstacles before the oral delivery of bioactive peptides can become a commercial reality.
Administration, Oral↗
Improvement of the in vitro dissolution of praziquantel by complexation with alpha-, beta- and gamma-cyclodextrins.
Although praziquantel (PZQ) is the primary drug of choice in the treatment of schistosomiasis, its poor solubility has restricted its delivery via the oral route. In spite of its poor solubility, PZQ is well absorbed across the gastrointestinal tract, but large doses are required to achieve adequate concentrations at the target sites. Improving the solubility would enable the parenteral route to be used, thereby avoiding significant first pass metabolism. The aqueous solubility of PZQ was improved by forming inclusion complexes with alpha-, beta- and gamma-cyclodextrins (CDs). These complexes were assessed and confirmed by solubility analysis, Fourier transform infrared analysis, elemental analysis, differential scanning calorimetry and mass spectrometry. Dissolution of PZQ from the alpha-, beta- and gamma-CD complexes was 2.6-, 5- and 8-fold greater, respectively, than that of the pure drug. However, only the beta-complex had a stability constant in the optimum range for pharmaceutical use, suggesting that the preferred complex for further development would be a water-soluble beta-CD derivative.
Antiplatyhelmintic Agents↗
The effect of cetylpyridinium chloride (CPC) on the cell surface hydrophobicity and adherence of Candida albicans to human buccal epithelial cells in vitro.
PURPOSE: This study examined the effects of cetylpyridinium chloride (CPC) on cell surface hydrophobicity (CSH) and adherence of blastospores of Candida albicans (MEN strain) to human buccal epithelial cells (BEC) in vitro. METHODS: The effect of CPC treatment of either C. albicans blastospores or BEC on their subsequent adherence was determined using 35SO4 labelled blastospores in association with a Percoll gradient. The effects of CPC treatment of blastospores on their CSH was determined using Hydrophobic Interaction Chromatography. RESULTS: Treatment of exponential and stationary phase blastospores with CPC (50 micrograms mL-1) for 0.5-30 minutes, or with CPC (0.5-50 micrograms mL-1) for 15 minutes resulted in significant reductions in both blastospore CSH and adherence to BEC in vitro. No correlation was apparent (r < 0.8) between reduced CSH and reduced blastospore adherence following treatment with CPC (0.5-50 micrograms mL-1). Significantly reduced adherence of C. albicans (stationary or exponential growth phases) to human BEC was also observed following treatment of BEC with CPC (50 micrograms mL-1) for 0.5-30 minutes or with CPC (0.5-50 micrograms mL-1) for 15 minutes. Antiadherence effects were observed at both sub and super-minimum inhibitory concentrations of CPC. CONCLUSIONS: It is suggested that, whilst the ability of CPC to reduce the CSH of C. albicans may contribute to its reduced adherence to human BEC in vitro, reduced CSH is only one of several possible factors that contribute to the observed antiadherence effects.
Cell Adhesion↗
Primary interactions of three quaternary ammonium compounds with blastospores of Candida albicans (MEN strain).
The absorption of three quaternary ammonium compounds (QAC), cetylpyridinium chloride, cetrimide and benzalkonium chloride, onto the surface of blastospores of Candida albicans (MEN strain) was examined at room temperature. Equilibrium uptake occurred in less than 30 seconds for cetylpyridinium chloride and cetrimide whereas 5 min contact time was required for benzalkonium chloride. The adsorption of all three agents may be mathematically described as Langmuirian and hence a concentration-dependent formation of drug-monolayer on the surface of the blastospore occurred. From this the number of molecules adsorbed onto the surface of a single blastospore was calculated to be 1.33 x 10(12), 3.17 x 10(12) and 2.32 x 10(12) for cetylpyridinium chloride, cetrimide and benzalkonium chloride, respectively. These dissimilarities are most likely due to differences in the orientations of both the cationic nitrogen atom and the accompanying lipophilic portions of each QAC at the blastospore surface. Relating these observations to the known antiadherence effects of cetylpyridinium chloride and cetrimide, it can be concluded that monolayer coverage of the blastospore surface with QAC does not account for the observed reduced adherence. This suggests that the anti-adherence effects are due to either direct interaction with, or steric blockade of, adhesions on the blastospore surface.
Adsorption↗