A capillary electrophoretic–mass spectrometric method for the assessment of octreotide stability under stress conditions

Utilizing erythrosine B absorption spectrum shifts for quantitative determination of octreotide and bromocriptine in their pure forms and pharmaceutical formulations. Evaluation of the method greenness

In the present study, two drugs for treating acromegaly are investigated which are either synthetic growth hormone inhibiting hormone (GHIH) or dopamine receptor agonist. Octreotide (OCT) and bromocriptine (BCT) were quantified with a quick, simple, and sensitive spectrophotometric approach in their authentic forms and commercial dosage forms. This approach was based upon formation of ion pair complex between erythrosine B and investigated drugs in an aqueous buffered solution. For OCT determination the higher sensitivity was obtained using ΔA at 525 nm. On the other hand, BCT was estimated using the absorbance at 556 nm. Under optimal conditions for the reaction, construction of calibration curves were performed within concentration range of 0.4-4 µg ml-1 for OCT and 1-9 µg ml-1 for BCT with with low detection limits (0.094 and 0.235 µg ml-1) and low quantitation limits (0.29 and 0.71 µg ml-1) for OCT and BCT respectively. The developed approach was assessed for linearity, accuracy, precision, limits of detection, and limits of quantitation in compliance with ICH validation recommendations. The suggested approaches demonstrated good linearity, as evidenced by determination coefficients (r2) of 0.999 with a slope 0.14 for OCT and 0.9989 with a slope 0.06 for BCT. Additionally, the environmental friendliness of the investigated method was assessed with some of the recent green analytical chemistry metrics.

Sol-gel Carbowax 20M-zwitterionic ionic liquid composite sorbent-based capsule phase microextraction device combined with HPLC/post-column derivatization for the determination of lanreotide, a human somatostatin analogue in urine

In this research, a sol-gel Carbowax 20M-zwitterionic ionic liquid composite sorbent-based capsule phase microextraction (CPME) device was developed in combination with liquid chromatography-post column derivatization for the first ever reported determination of a somatostatin analogue - lanreotide in human urine. The sol-gel Carbowax 20M-zwitterionic ionic liquid composite sorbent was encapsulated in the lumen of a polypropylene capillary tube and characterized by FT-IR spectroscopy and SEM with energy dispersive X-ray spectroscopy (EDS). The main steps of the CPME workflow were optimized to obtain high extraction efficiency for the target analyte. After the separation of the analyte on a C8 stationary phase, the peptide was derivatized online with o-phthalaldehyde before the fluorescence detection. The main experimental parameters of CPME and the post-column procedures were systematically investigated and optimized. The method was validated in terms of selectivity, linearity, accuracy, precision, limits of detection (LOD), and limits of quantification (LOQ). The relative bias ranged between 88.8 and 115.6 % for the peptide, while the RSD values for repeatability and intermediate precision were less than 14.3 %. The achieved limit of detection (LOD) was 0.2 μΜ while the limit of quantitation (LOQ) was established as 0.9 μΜ. Finally, the sol-gel Carbowax 20M-zwitterionic ionic liquid composite sorbent-based microextraction capsules were found to be reusable for at least 20 extractions. The developed method presented adequate overall performance, and it could be applied in the analysis of selected peptide in human urine samples.

Capillary electrophoresis in the analysis of therapeutic peptides-A review

Therapeutic peptides are a growing class of innovative drugs with high efficiency and a low risk of adverse effects. These biomolecules fall within the molecular mass range between that of small molecules and proteins. However, their inherent instability and potential for degradation underscore the importance of reliable and effective analytical methods for pharmaceutical quality control, therapeutic drug monitoring, and compliance testing. Liquid chromatography-mass spectrometry (LC-MS) has long time been the "gold standard" conventional method for peptide analysis, but capillary electrophoresis (CE) is increasingly being recognized as a complementary and, in some cases, superior, highly efficient, green, and cost-effective alternative technique. CE can separate peptides composed of different amino acids owing to differences in their net charge and size, determining their migration behavior in an electric field. This review provides a comprehensive overview of therapeutic peptides that have been used in the clinical environment for the last 25 years. It describes the properties, classification, current trends in development, and clinical use of therapeutic peptides. From the analytical point of view, it discusses the challenges associated with the analysis of therapeutic peptides in pharmaceutical and biological matrices, as well as the evaluation of CE as a whole and the comparison with LC methods. The article also highlights the use of microchip electrophoresis, nonaqueous CE, and nonconventional hydrodynamically closed CE systems and their applications. Overall, the article emphasizes the importance of developing new CE-based analytical methods to ensure the high quality, safety, and efficacy of therapeutic peptides in clinical practice.

Facile spectrofluorimetric quantitation of octreotide, a synthetic peptide, in its pure form and pharmaceutical formulation; Evaluation of the method greenness

A new, rapid, highly sensitive, and affordable spectrofluorimetric approach has been constructed and validated for the determination of octreotide in its authentic form and pharmaceutical dosage form. Octreotide is an important synthetic analog of the naturally occurring somatostatin hormone. The developed spectrofluorimetric approach is actually dependent on the measurement of octreotide native fluorescence at emission wavelength of 342 nm after excitation at 218 nm. At optimal reaction circumstances, the calibration curve has been constructed over the concentration range of 200- 2000 ng ml^-1 , with excellent linearity. The limits of detection and quantitation values were found to be 55 and 169 ng ml^-1 , respectively. The developed approach has been effectively used to determine octreotide in its pharmaceutical ampoules, without interference from the excipients in the dosage form. The developed approach is simple, time-saving, and does not require multiple pretreatment steps for samples, costly apparatus, or dangerous materials. As a result, it can be actually used to detect and quantify octreotide acetate in quality control laboratories.

Hydrophilic Interaction Liquid Chromatography Coupled with Fluorescence Detection (HILIC-FL) for the Quantitation of Octreotide in Injection Forms

Octreotide is a synthetic cyclic octapeptide analogue of somatostatin-14. It is mainly administered for the treatment of acromegaly, severe diarrhea, and neuroendocrine neoplasias. In this work, a hydrophilic interaction liquid chromatography (HILIC) method with fluorescence (FL) detection was developed and validated for the quantitation of octreotide in solutions for injection. Chromatographic separation was performed on an XBridge®-HILIC analytical column under isocratic elution with a short chromatographic run time of less than 10 min. The mobile phase consisted of ammonium bicarbonate 8.6 mM (pH 8.1)/acetonitrile 35/65 (v/v). The high sensitivity and selectivity of the fluorescence detection, with the excitation wavelength (λexcitation) set at 280 nm and the emission wavelength set at (λemission) 330 nm, enabled a simple sample preparation procedure that included only dilution steps. The calibration curve showed good linearity with a correlation coefficient greater than 0.998. The method was successfully applied to the analysis of commercially available octreotide injection forms.

Effect of Homochirality of Dipeptide to Polymers’ Degradation

As natural polymer materials, proteins are readily biodegradable, interestingly, the synthetic polyamides (PAs) that are based on the same amide bonds (also called peptide bonds in proteins) are barely degradable. Whether did the chirality and configuration of the amino acids play an important role. By using different configuration of amino acids, 4 types of polyamide-imides (PAIs) containing dipeptides of LL, DL, LD, and DD configurations, respectively, were synthesized. It was found that the PAIs based on natural LL configuration of dipeptide structure are much more readily biodegradable than those based on non-natural LD, DL, and DD configuration of dipeptides. It was confirmed that the natural L-configuration of amino acids play a critical role in degradability of proteins. And it also suggested that different type and amount of peptide fragments can be introduced in polymer to create series of polymer materials that can be biodegraded at controllable speed.

Accelerated Forced Degradation of Therapeutic Peptides in Levitated Microdroplets

PURPOSE

Forced degradation is critical to probe the stabilities and chemical reactivities of therapeutic peptides. Typically performed in bulk followed by LC-UV or LC-MS analysis, this traditional workflow consists of a reaction/analysis sequence and usually requires half a day to several days to form and measure the desired amounts of degradants. A faster method is needed to study peptide degradation in a shorter time in order to speed up the drug development process.

METHODS

In the new rapid method developed in this study, peptide degradation occurs in levitated aqueous microdroplets using the Leidenfrost effect.

RESULTS

This two-minute reaction/analysis workflow allows major degradation pathways of Buserelin, Octreotide, Desmopressin and Leuprorelin to be studied. The reactions include deamidation, disulfide bond cleavage, ether cleavage, peptide bond hydrolysis, and oxidation.

CONCLUSIONS

The accelerated forced degradation method requires a minimal amount of therapeutic peptide per stress condition, and the appropriate extent of degradation can be readily generated in seconds by adjusting the droplet levitation time. Levitated microdroplets should be applicable in pharmaceutical development to rapidly determine the intrinsic stability of therapeutic peptides and to aid formulation development by screening the effects of excipients on the stability of the peptides. Graphical abstract.

Recent developments in capillary and microchip electroseparations of peptides (2015-mid 2017)

The review brings a comprehensive overview of recent developments and applications of high performance capillary and microchip electroseparation methods (zone electrophoresis, isotachophoresis, isoelectric focusing, affinity electrophoresis, electrokinetic chromatography, and electrochromatography) to analysis, microscale isolation, purification, and physicochemical and biochemical characterization of peptides in the years 2015, 2016, and ca. up to the middle of 2017. Advances in the investigation of electromigration properties of peptides and in the methodology of their analysis (sample preseparation, preconcentration and derivatization, adsorption suppression and EOF control, and detection) are described. New developments in particular CE and CEC methods are presented and several types of their applications to peptide analysis are reported: qualitative and quantitative analysis, determination in complex (bio)matrices, monitoring of chemical and enzymatical reactions and physical changes, amino acid, sequence and chiral analysis, and peptide mapping of proteins. Some micropreparative peptide separations are shown and capabilities of CE and CEC methods to provide important physicochemical characteristics of peptides are demonstrated.