A new long shelf life formulation of modified Ham's F-10 medium: Biochemical and clinical evaluation

Purpose To evaluate biochemically and clinically a new formulation of modified Ham's F-10 medium made without the inclusion of hypoxanthine. The medium was formulated for long-term storage and use by separately preparing a stable liquid (basal) portion and a freeze-dried supplement containing the labile medium components.Results Following 18 months of storage the basal medium was biochemically analyzed for its amino acid (aa's) and vitamin content. Cysteine and tryptophan were decreased to less than 30% of their starting theoretical concentrations (STCs). Asparagine, serine, tyrosine, histidine and lysine were present at 50% to 70% of their STC. The remaining aa's were all within 90% of their STCs except arginine which was at 77%. All of the vitamins were present at 90% or more of their STCs except inositol, riboflavin and'thiamine which were present at 70% of their STCs. IVF with the new formulation resulted in 13 deliveries from 51 aspirations (25%) as compared with 10/39 (26%) in 1991, when standard medium preparation was used. Oocyte donation resulted in 30 deliveries from 84 cycles (36%) with the new formulation as compared with 21/65 (32%) in 1991.Conclusions (1) The new basal with lyophilized supplement formulation produces similar clinical results in the IVF laboratory as medium prepared in the standard fashion, (2) certain amino acids and vitamins are not stable in the liquid basal medium, and (3) the separate formulation of a liquid basal medium with lyophilized supplement is convenient, viable alternative to modified Ham's F-10 medium prepared in the standard manner (i.e., from powder) and may decrease the need for frequent medium preparation.Modified Ham's F-10 Medium, Irvine Scientific, Santa Ana, California.Presented at the 42nd Annual Meeting of the Pacific Coast Fertility Society, Indian Wells, California, April 20–24, 1994.     

Hydroxypropyl-β-Cyclodextrin Increases the Aqueous Solubility and Stability of Pilocarpine Prodrugs

Purpose. The effects of 2-hydroxypropyl--cyclodextrin (HP--CD) on the aqueous solubility and stability of two lipophilic bispilocarpine prodrugs were investigated at pH 7.4. Methods. The solubility of prodrugs was studied by phase-solubility method (0–72.5 mM HP--CD). The stability of one of the prodrugs was investigated as a function of temperature (40°C–70°C) and HP--CD concentration (0–72.5 mM). The apparent rate constants (k ₁, k ₂) for degradation of prodrug in 1:1 and 1:2 inclusion complexes and apparent stability constants (K _1:1, K _l:2) were calculated by the curve-fitting method. Results. The phase-solubility diagrams were classified as A_p-type and the apparent stability constants (K _l:l, K _l:2) for 1:1- and 1:2-inclusion complexes were calculated to be 143–815 M^–l and 29–825 M^–1, respectively. The stability of prodrug increased as a function of HP--CD concentration over the studied temperature range. The shelf-life (t _90%, calculated by the Arrhenius equation) of the prodrug in 72.5 mM HP--CD solution increased 5.1-fold and 6.1-fold at 25°C and 4°C, respectively. Conclusions. The solubility of the prodrugs was shown to increase markedly in phase-solubility studies. The degradation rate of prodrug in stability studies was shown to be slower in the l:2-complex than in the l:l-complex and the relative amounts of complex species were found to be dependent on CD concentration.     

Multihost, Multiparasite systems: An application of bifurcation theory

Author to whom all correspondence should be addressed (email: j.v.greenman{at}stir.ac.uk). The local analysis of multihost multiparasite models has beenhampered by algebraic intractability. There have been two responsesto this difficulty: extensive numerical investigation, and simplificationto a level where analytical techniques work. In this paper wedescribe another approach, based on bifurcation theory, in whichthe qualitative properties of the model equilibrium structureare realized on an array of maps drawn in parameter space. Thisapproach is described in the context of two models: the basictwo-host shared microparasite S–I model and the single-hosttwo-microparasite S–I (susceptible-infective) model. Theprocedure involved does not require model simplification througha reduction in dimensionality. It can handle intraspecific aswell as parasite-mediated competition and, in the second model,single-host parasite coexistence. The map arrays provide a concisecatalogue of the possible modes of behaviour of a system andan explanation for changes in that behaviour. In particular,the reasons why the conjectures made about the behaviour ofthe first of these models do not hold throughout parameter spaceare immediately clear from the map structure, as are the conditionsfor collusive and competitive behaviour between the two typesof parasite in the second model.     

Degradation Kinetics of BMP 777, an Elastase Inhibitor

Purpose. The objective was to evaluate the degradation profile of the elastase inhibitor DMP 777 and lay the foundation for formulation development. Methods. The pK_a was determined by potentiometric titration in mixed-aqueous solvents. The degradation kinetics were studied as a function of pH, buffer concentration, ionic strength, methanol concentration and temperature using a stability-indicating HPLC assay. The degradation products were identified by LC-MS, NMR, and by comparison with authentic samples. Results. The pK_a for the protonated piperazine nitrogen was estimated to be 7.04. The pH-rate profile is described by specific acid-, water-, and specific base-catalyzed pathways. The pH of maximum stability is in the range of 4 to 4.5 where water is the principal catalyst in the reaction. Buffer catalysis, primary salt effects and medium effects were observed. The proposed mechanism for acid catalyzed degradation is the rarely observed A_AL1 which involves alkyl-nitrogen heterolysis. The driving force for the reaction appears to lie in the stability of the benzylic carbocation. The proposed mechanism for base catalyzed degradation is B_AC2 which involves -lactam ring opening. The -lactam ring of DMP 777, a monolactam, appears to be as reactive as that in benzylpenicillin in the k _OH controlled region where a similar mechanism of hydrolysis should be operative. A contributing factor to this increased reactivity may lie in the reduced basicity of the -lactam nitrogen making it a good leaving group. Conclusions. The degradation profile indicates that development of a solution dosage form of DMP 777 with adequate shelf-life stability at room temperature is feasible.     

Stability of aztreonam in a portable pump reservoir used for home intravenous antibiotic treatment (HIVAT)

The stability of the monocyclic -lactam antibiotic aztreonam in portable pump reservoirs was studied during storage at temperatures of-20°C and +5°C and during drug delivery at 37°C. Three 100-ml drug reservoirs and three glass containers containing 60 mg/ml aztreonam were stored at-20°C and 2-ml samples were analysed in the freshly prepared solution and after thawing at days 7, 21, 28, 70 and after 6 months of storage. A separate triplicate batch of 100-ml prefilled drug reservoirs and glass containers containing a similar aztreonam concentration (60 mg/ml) were refrigerated and tested immediately after preparation and daily for 8 days and after 70 days. Solutions of aztreonam in duplicate freshly prepared reservoirs were tested for stability when the solution was pumped at 37°C over a 24-h period. All solutions were inspected for visual changes and tested for pH. Drug concentration was analysed by high-performance liquid chromatography. No colour changes or pH differences were observed in any of the solutions in the reservoirs or containers. No statistically significant decrease in aztreonam concentration could be detected after 6 months of storage at-20°C. Aztreonam was stable at 5°C for at least 8 days. A 24-h pumping period at 37°C showed a 3.6% decrease in aztreonam concentration. Aztreonam at a concentration of 60 mg/ml in a pump reservoir is sufficiently stable to be used in home intravenous antibiotic treatment programmes.     

Stability of Interleukin 1β (IL-1β) in Aqueous Solution: Analytical Methods,Kinetics, Products,and Solution Formulation Implications

The thermal stability of IL-1 in aqueous solution as a function of temperature (5–60°C), pH (2–9), buffer (acetate, citrate, tris, and phosphate), and cyroprotectants (sugars, HSA) was investigated in this study. The analytical methodologies included RP-HPLC, SEC, ELISA, IEF-PAGE, SDS-PAGE, and bioassay. The degradation and inactivation of IL-1 at or above 39°C were attributed to autoxidation of the two cysteine residues in the denatured protein, followed by hydrophobic/covalent aggregation and precipitation. At or below 30°C, IEF- and SDS-PAGE results suggest a possible deamidation reaction. The difference in mechanism of degradation precludes the prediction of formulation shelf life from accelerated temperature data. Nonetheless, the good stability observed at 5°C suggests that a solution formulation may be feasible for IL-1.     

盐酸乌拉地尔(利喜定)注射液与临床常用5种药物的配伍稳定性考察

目的 :考察盐酸乌拉地尔注射液分别与氯化钾、门冬氨酸钾镁、碳酸氢钠、维生素C、盐酸利多卡因5种注射液的配伍稳定性。方法 :采用紫外分光光度法考察各配伍液在室温条件下 (15℃～25℃ )配伍0h～8h内吸收度、吸收曲线变化 ,测定 pH值 ,同时观察其外观和普通显微镜下的变化。结果 :盐酸乌拉地尔注射液在10 %葡萄糖输液中分别与以上5种注射液混合配伍后 ,pH值、外观、普通显微镜下及紫外吸收光谱各项检查均无变化。结论 :盐酸乌拉地尔注射液分别与以上5种注射液配伍稳定。     

眼镜蛇毒高活性抗补体因子的体外溶血活性研究

目的　了解云南孟加拉眼镜蛇毒高活性抗补体因子的体外溶血活性。方法　采用由豚鼠血清、豚鼠红细胞和该抗补体因子组成的体外溶血体系 ,对其溶血活性、溶血活性稳定性以及多种二价金属离子、EDTA对其溶血活性的影响进行研究。结果　该抗补体因子溶血活性的比活力为 1 391KU·g- 1 ,其溶血活性对温度、酸碱表现出较好的稳定性 ,1、2、5mmol·L- 1 的Ca2 + 、Mg2 + 、Mn2 + 能促进抗补体因子的溶血活性 ,1、2mmol·L- 1 的Zn2 + 、Co2 + 能促进抗补体因子的溶血活性 ,而 5mmol·L- 1 的Zn2 + 、Co2 + 则抑制抗补体因子的溶血活性 ,Cu2 + 在 1、2、5mmol·L- 1 时则强烈抑制抗补体因子的溶血活性 ,EDTA能强烈抑制抗补体因子的溶血活性。结论　云南孟加拉眼镜蛇毒高活性抗补体因子具有一定的溶血活性 ,并且具有较好的温度耐受性及酸碱稳定性。多种二价金属离子及EDTA能促进或抑制这种溶血活性     

蚯蚓纤溶酶的纯化及pH值、温度和胰蛋白酶对其纤溶活性的影响

目的纯化并鉴定蚯蚓纤溶酶 ,研究pH、温度和胰蛋白酶对其纤溶活性的影响。方法以赤子爱胜蚓为材料 ,采用硫酸铵盐析、DEAESepharoseCL 6B离子交换色谱、SephadexG 75凝胶过滤和制备电泳等分离技术纯化蚯蚓纤溶酶 ;利用纤维平板和聚丙烯酰胺凝胶电泳研究pH、温度和胰蛋白酶对蚯蚓纤溶酶纤溶活性的影响。结果分离得到纤溶酶 4种单一组分 :EFE 1、EFE 2、EFE 3、EFE 4 ;分子量分别为 2 70 0 0、2 80 0 0、2 30 0 0、330 0 0 ;4种组分对温度的适应范围较广 ;pH值对其纤溶活性的影响不尽相同 ,但都在pH低于 1.5时纤溶活性完全丧失 ;胰蛋白酶对纤溶酶 4种组分均无降解作用 ,对其纤溶活性无影响。结论纤溶酶口服药制剂宜制成肠溶型     

那格列奈片的稳定性研究

目的:建立那格列奈片的稳定性分析方法,研究那格列奈片的稳定性。方法:采用HPLC法;色谱柱为ZY1104型YWG-C_(18)为(250mm×4.6mm,10μm);流动相:乙腈—[醋酸—醋酸钠缓冲液(pH3.6)]—甲醇(2:2:1);紫外检测波长258nm;流速1.0mL·min~(-1);内标法室温测定。结果:那格列奈在0.1～0.8mg·mL~(-1)范围内线性关系良好(r=0.9999);回收率为(100.05±0.88)％。结论:该稳定性分析方法操作简便,结果准确可靠,可排除分解产物的干扰。本片对湿、热及光均稳定,加速试验3个月其含量基本不变。