Enhancement of Nasal Delivery of a Renin Inhibitor in the Rat Using Emulsion Formulations

Nasal absorption of O-(N-morpholino-carbonyl-3-L-phenylaspartyl-L-leucinamide of (2S,3R,4S)-2-amino-1-cyclohexyl-3,4-dihydroxy-6-methylheptane (I), a renin inhibitor, was evaluated in two rat nasal models, one involving surgery and the other requiring no surgical intervention. Oleic acid/monoolein emulsion formulations were tested along with a control PEG 400 solution. The percent absolute bioavailability of the compound was enhanced from 3–6% (PEG 400 solution) to 15–27% when the emulsion formulations were used. The different nasal model techniques (with and without surgery) did not produce any statistical difference in the absolute bioavailability values for I. Emulsion formulations did not produce appreciable damage as assessed morphologically. It is suggested that emulsion formulations containing membrane adjuvants such as oleic acid and monoolein can be used to enhance the nasal delivery of low-bioavailable, lipid-soluble drugs.____________________     

The in Vitro Release of Some Antimuscarinic Drugs from Monoolein/ Water Lyotropic Liquid Crystalline Gels

Purpose. To investigate the potential use of a monoolein/water lyotropic liquid crystalline gel for the vaginal delivery of the antimuscarinic drugs, propantheline bromide and oxybutynin hydrochloride to treat urinary incontinence, using Myverol 18-99 as a commercially available grade of monoolein. Methods. The influence of propantheline bromide and oxybutynin hydrochloride on the phase structure of Myverol 18-99/water gels was investigated using polarising microscopy. The in-vitro release of the antimuscarinic drugs from Myverol 18-99/water gels was determined and the release pattern interpreted with the aid of results from swelling studies and partition coefficient determinations. Results. Myverol 18-99 forms gels with lyotropic liquid crystalline structures in the presence of water. The addition of propantheline bromide and oxybutynin hydrochloride promoted the formation of gels with a lamellar phase structure. The gels absorbed water at a rate inversely proportional to their initial water content until they reached an equilibrium water content of ~40% w/w whilst maintaining their physical integrity. The release of the antimuscarinic drugs was sustained over a period of ~18 hours and followed square root of time kinetics indicating that the rate of release was diffusion controlled. Conclusions. The in-vitro release behaviour of Myverol 18-99/water gels suggested that they are suitable carriers to deliver propantheline bromide or oxybutynin hydrochloride. The results of swelling studies indicated that a confined area, such as the vaginal cavity, would be a suitable site of administration.     

立方晶及其在药剂学中的研究进展

立方晶是两亲性脂质和表面活性剂在水中自发形成的立方液晶的纳米分散体系。立方晶属于自稳定体系,是双连续的水相和脂相形成的类似“蜂窝”状的结构,在其中表面活性剂插入脂质双分子层,晶胞在三维方向上以无限循环方式排列,形成极小曲面的紧密结构。立方晶独特的脂水双连续相立方液晶结构,能够同时增溶亲水、亲脂及两亲性分子,具有生物可降解性、高生物黏附性、制备工艺简单等诸多优点使之在药物载体领域展现较大的优势。本文结合近年文献报道,阐述了立方晶的结构、制备、表征和药物载体的研究进展。     

Oral Delivery of a Renin Inhibitor Compound Using Emulsion Formulations

The oral delivery of O-(N-morpholino-carbonyl-3-L-phenylaspartyl-L-leucinamide of (2S,3R,4S)-2-amino-l-cyclohexyl-3,4-dihydroxy-6-methylheptane (I), a new renin inhibitor, was studied in the in vivo rat model using emulsion formulations. The components of the emulsion formulations were chosen based on their proposed effects on membrane structure, membrane fluidity, and solute transport. The percent absolute bioavailability (%AB) of I was increased from 0.3% (water suspension) to 5.1% when long-chain unsaturated fatty acid (oleic acid, linoleic acid, etc.)- and mono- and diglyceride (monolein, dilaurin, etc.)-containing emulsion formulations were used. Considering very high first-pass liver extraction of the compound (80%), it is suggested that emulsion formulations increased the intestinal transport of the compound significantly. The solubility of I in aqueous media with and without bile salt (20 mM) was found to be low (~1 µg/ml). Incubation in 0.01 N HC1 did not affect the particle size of the emulsion. The titration of oleic acid/monoolein emulsion in a pH 6.5 medium with a mixed bile salt system indicated reduction in the particle size of the emulsion. Drug precipitation was observed above 30 mM bile salt concentrations. No drug crystals could be detected in the intestinal contents of the rats when emulsion formulations were ingested. These results suggest that in the intestine of the animals, the particle size of the emulsions is reduced in the presence of bile fluid while the drug resides primarily in the oil phase. The mechanism of enhanced transport of I from the emulsion formulations is discussed along with the possibility of cotransport for the drug and oil. Emulsion formulations can be a potential delivery form for low-bioavailable lipid-soluble drugs.     

甘油单油酸酯液晶载体材料的体外毒性研究

目的：评价立方液晶载体材料甘油单油酸酯（glycerol monoolein,GMO）的细胞毒性。方法：体外培养大鼠皮肤成纤维细胞,以MTT法及琼脂覆盖法评价立方液晶对大鼠皮肤成纤维细胞的细胞毒性分级情况。结果：甘油单油酸酯对大鼠皮肤成纤维细胞的细胞活力无明显影响,毒性分级为0级。结论：甘油单油酸酯无潜在的细胞毒性,是一种生物相容性良好的载体材料。