Poly(ethylene glycol)-b-poly(1,3-trimethylene carbonate) Amphiphilic Copolymers for Long-Acting Injectables: Synthesis,Non-Acylating Performance and In Vivo Degradation

This article presents the evaluation of diblock and triblock poly(ethylene glycol)-b-poly(1,3-trimethylene carbonate) amphiphilic copolymers (PEG-PTMCs) as excipients for the formulation of long-acting injectables (LAIs). Copolymers were successfully synthesised through bulk ring-opening polymerisation. The concomitant formation of PTMC homopolymer could not be avoided irrespective of the catalyst amount, but the by-product could easily be removed by gel chromatography. Pure PEG-PTMCs undergo faster erosion in vivo than their corresponding homopolymer. Furthermore, these copolymers show outstanding stability compared to their polyester analogues when formulated with amine-containing reactive drugs, which makes them particularly suitable as LAIs for the sustained release of drugs susceptible to acylation.     

Preparation and Evaluation of [18F]AlF-NOTA-NOC for PET Imaging of Neuroendocrine Tumors: Comparison to [68Ga]Ga-DOTA/NOTA-NOC

Background: The somatostatin receptors 1–5 are overexpressed on neuroendocrine neoplasms and, as such, represent a favorable target for molecular imaging. This study investigates the potential of [¹⁸F]AlF-NOTA-[1-Nal³]-Octreotide and compares it in vivo to DOTA- and NOTA-[1-Nal³]-Octreotide radiolabeled with gallium-68. Methods: DOTA- and NOTA-NOC were radiolabeled with gallium-68 and NOTA-NOC with [¹⁸F]AlF. Biodistributions of the three radioligands were evaluated in AR42J xenografted mice at 1 h p.i and for [¹⁸F]AlF at 3 h p.i. Preclinical PET/CT was applied to confirm the general uptake pattern. Results: Gallium-68 was incorporated into DOTA- and NOTA-NOC in yields and radiochemical purities greater than 96.5%. NOTA-NOC was radiolabeled with [¹⁸F]AlF in yields of 38 ± 8% and radiochemical purity above 99% after purification. The biodistribution in tumor-bearing mice showed a high uptake in tumors of 26.4 ± 10.8 %ID/g for [⁶⁸Ga]Ga-DOTA-NOC and 25.7 ± 5.8 %ID/g for [⁶⁸Ga]Ga-NOTA-NOC. Additionally, [¹⁸F]AlF-NOTA-NOC exhibited a tumor uptake of 37.3 ± 10.5 %ID/g for [¹⁸F]AlF-NOTA-NOC, which further increased to 42.1 ± 5.3 %ID/g at 3 h p.i. Conclusions: The high tumor uptake of all radioligands was observed. However, [¹⁸F]AlF-NOTA-NOC surpassed the other clinically well-established radiotracers in vivo, especially at 3 h p.i. The tumor-to-blood and -liver ratios increased significantly over three hours for [¹⁸F]AlF-NOTA-NOC, making it possible to detect liver metastases. Therefore, [¹⁸F]AlF demonstrates promise as a surrogate pseudo-radiometal to gallium-68.     

醋酸奥曲肽治疗肝硬化失代偿期上消化道出血的临床效果观察

目的醋酸奥曲肽治疗肝硬化失代偿期上消化道出血的临床效果。方法按照随机数字表法将60例肝硬化失代偿期上消化道出血患者均分为实验组和对照组,分别采取单纯垂体后叶素和醋酸奥曲肽+垂体后叶素治疗,比较两组患者治疗效果。结果实验组患者治疗总有效率明显高于对照组,差异具有显著性(P0.05);两组患者不良反应总发生率对比,差异无统计学意义(P0.05)。结论醋酸奥曲肽+垂体后叶素治疗能够有效缩短肝硬化失代偿期上消化道出血止血时间,提高治疗效果,不良反应发生率低,临床应用价值较高。     

Quantitative determination and validation of octreotide acetate using 1H‐NMR spectroscopy with internal standard method

Quantitative nuclear magnetic resonance (qNMR) is a well‐established technique in quantitative analysis. We presented a validated ¹H‐qNMR method for assay of octreotide acetate, a kind of cyclic octopeptide. Deuterium oxide was used to remove the undesired exchangeable peaks, which was referred to as proton exchange, in order to make the quantitative signals isolated in the crowded spectrum of the peptide and ensure precise quantitative analysis. Gemcitabine hydrochloride was chosen as the suitable internal standard. Experimental conditions, including relaxation delay time, the numbers of scans, and pulse angle, were optimized first. Then method validation was carried out in terms of selectivity, stability, linearity, precision, and robustness. The assay result was compared with that by means of high performance liquid chromatography, which is provided by Chinese Pharmacopoeia. The statistical F test, Student's t test, and nonparametric test at 95% confidence level indicate that there was no significant difference between these two methods. qNMR is a simple and accurate quantitative tool with no need for specific corresponding reference standards. It has the potential of the quantitative analysis of other peptide drugs and standardization of the corresponding reference standards.     

甲基红共振瑞利散射法测定多肽药物奥曲肽

采用共振瑞利散射(RRS)法测定奥曲肽,建立了测定痕量奥曲肽的方法。在pH=3.78的B-R缓冲溶液中,奥曲肽与甲基红相互作用后,共振瑞利散射显著增强,在280～370nm范围内呈现高的散射强度,且以310nm处的ΔIRRS最强。在优化的测试条件下,奥曲肽浓度在0～0.54mg/L范围内与散射强度有良好的线性关系,对奥曲肽的检出限(3σ)达3.6μg/L。该方法用于合成样品中奥曲肽的测定,回收率为98.3%～100.7%;用于奥曲肽注射液中奥曲肽含量的测定,结果与HPLC法测得的结果相近。     

高效液相色谱法定量分析奥曲肽

建立奥曲肽的高效液相色谱定量分析方法。色谱柱为Eclipse plus C18柱(4.6 mm×250 mm,5 μm),流动相为乙腈-0.25%高氯酸水溶液(体积比为30∶70),流量为1.0 mL/min,检测波长为210 nm,柱温为25℃。奥曲肽的质量浓度在4.38~219 μg/mL范围内与色谱峰面积成良好的线性关系,相关系数为0.9999,检出限为1.1 ng,定量限为2.19 ng。测定结果的相对标准偏差为0.26%~0.46% (n=5),加标回收率为97.41%~100.26%。该方法简便、快速、准确,适用于奥曲肽原料药与制剂的定量分析。     

Functionalized Resins for the Synthesis of Peptide Alcohols

Peptide alcohols are clinically important compounds that are underexplored in structure–activity relationship (SAR) studies in drug discovery. One reason for this underutilization is that current syntheses are laborious and time consuming. Herein, we describe the preparation and utility of Rink, Ramage, and Sieber-chloride resins, which enables the use of a general, easy and practical method for the attachment of fluorenylmethoxycarbonyl (Fmoc)-amino alcohols to a solid support, in the synthesis of peptide alcohols. This method is the first straightforward Fmoc/tBu synthesis of peptide alcohols starting from a pre-loaded resin. The synthesized peptide alcohols can be detached from the linkers through conventional methods. Treatment with trifluoroacetic acid (TFA) (95 %) and scavengers such as triisopropylsilane and water for 2 h is sufficient to obtain a fully deprotected peptide alcohol, while treatment with 20 % hexafluoroisopropanol in dichloromethane renders a fully protected peptide alcohol that can be further modified at the C-terminus. As examples, the new resins were used in straightforward, relatively rapid syntheses of the peptide alcohols octreotide, alamethicin, and a segment of trichogin GA IV, as well as the first synthesis of stapled peptide alcohols.     

Combined derivatization and high‐performance liquid chromatography with fluorescence and ultraviolet detection for simultaneous analysis of octreotide and gabexate mesylate metabolite in human pancreatic juice samples

A simple and sensitive method based on the combination of derivatization and high‐performance liquid chromatography with ultraviolet and fluorimetric detection was developed for the simultaneous determination of octreotide and gabexate mesylate metabolite in human pancreatic juice samples. Parameters of the derivatization procedure affecting extraction efficiency were optimized. The developed method was validated according to the International Conference on Harmonization guidelines. The calibration curves were linear over a range of 0.1–15 µg/mL for octreotide and 0.20‐15 µg/mL for gabexate mesylate metabolite. Derivatized products of octreotide and gabexate mesylate metabolite were separated on a Luna C₁₈ column (4.6 × 250 mm; 5 µm particle size) using a gradient with a run time of 36 min, without further purification. The limits of detection were 0.025 and 0.05, respectively, for octreotide and gabexate mesylate metabolite. This paper reports the validation of a quantitative high performance liquid chromatography–photodiode array–fluorescence (HPLC‐PDA‐FL) method for the simultaneous analysis of octreotide and gabexate mesylate metabolite in pancreatic juice by protein precipitation using zinc sulfate–methanol–acetonitrile containing the derivatizing reagent, 4‐fluoro‐7‐nitro‐[2,1,3]‐benzoxadiazole (NBD‐F). Derivatized products of octreotide and gabexate mesylate metabolite were separated on a Luna C₁₈ column (4.6 × 250 mm; 5 µm particle size) using a gradient with a run time of 36 min, without further purification. The method was validated over the concentration ranges 0.1–15 and 0.2–15 µg/mL for octreotide and gabexate mesylate metabolite, respectively, in human pancreatic juice. Biphalin and methyl‐p‐hydroxybenzoate were used as the internal standards. This method was successfully utilized to support clinical studies in humans. The results from assay validations show that the method is selective, sensitive and robust. The limit of quantification of the method was 0.1 µg/mL for octreotide and 0.2 µg/mL for gabexate mesylate metabolite, and matrix matched standard curves showed a good linearity up to 15 µg/mL. In the entire analytical range the intra‐ and inter‐day precision (RSD%) values were respectively ≤5.9% and ≤3.1% for octreotide and ≤2.0% and ≤3.9% for gabexate mesylate metabolite. For both analytes the intra‐ and inter‐day accuracy (bias) values ranged respectively from ?6.8 to –2.5% and from ?4.6 to ?5.7%. This method utilizes derivatization with NBD‐F and provides adequate sensitivity for both drugs. Copyright © 2014 John Wiley & Sons, Ltd.