Article pubs.acs.org/ac
Use of High Resolution Mass Spectrometry for Analysis of Polymeric Excipients in Drug Delivery Formulations Pilar Perez Hurtado,† Pui Yiu Lam,† David Kilgour,† Anthony Bristow,‡ Eileen McBride,‡ and Peter B. O’Connor*,† †
Department of Chemistry, University of Warwick, Coventry, United Kingdom AstraZeneca, Alderley Edge, United Kingdom
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S Supporting Information *
ABSTRACT: Two polymeric excipients, typically used in enabling drug delivery approaches, are Gelucire 44/14 (a product of Gattefosse s.a, St Priest, France) and polysorbate 80; these are known to improve solubility of poorly water-soluble drugs and, hence, increase their effective bioavailability. In addition to the use of Gelucire 44/14 and polysorbate 80 as excipients in drugs, they are also widely used as cosmetic and food additives. In general, complex structures and compositions of drug excipients impact performance of the formulation in vivo and consequently affect drug absorption. Therefore, a comparison between excipients from different suppliers and batches to batch would provide an indication of the impact on drug product performance and also the study of the effectiveness of the system and any problems associated with the formulation. In this study, high resolution Fourier transform ion cyclotron resonance mass spectrometry (FTICR MS) is used to compare two different batches of Gelucire 44/14 and polysorbate 80. With the high resolving power of FTICR MS, it was possible to differentiate between batches of excipients from differences in the identified components. The improved resolution offered by FTICR MS allowed assignment of four polymeric series differences in the two batches of polysorbate 80 and the presence of one compound and three polymeric series differences in the two batches of Gelucire 44/14. The increase in the number of components assigned in the excipients batch using FTICR-MS, compared to the numbers previously assigned by lower resolution TOF MS, underlines the importance of high resolution techniques in analysis of highly complex mixtures.
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Polysorbate 80 is formed by the reaction of fatty acids (commonly, stearic (C18H36O2), oleic (C18H34O2), or linoleic (C18H32O2) acid) with sorbitol in the presence of an acid catalyst.10 The products of this reaction are a mixture of sorbitan polyethoxylates, polysorbate diesters, polysorbate monoesters, isosorbide polyethoxylates, and free PEG (see Figure 2 for structures). Infrared spectrophotometry (IR), thinlayer chromatography (TLC), gas chromatography (GC), and high performance liquid chromatography (HPLC) have been used for analysis of polysorbate 80.10,11 In the 2000s, components of polysorbate 80 were investigated by MALDITOF MS,12 indicating the presence of polyoxyethylene isosorbide and sorbitan polyethoxylate monolinoleate. However, neither experiment could differentiate sorbitan polyethoxylate (1507.84 m/z), sorbitol polyethoxylate monooleate (1507.93 m/z), and sorbitol polyethoxylate dioleate (1507.02 m/z) because of the proximity in mass (±0.1 Da) (see Figure 2). Furthermore, the heterogeneity of polysorbates makes characterization of these molecules a significant analytical challenge. The use of LC-MS has enhanced the characterization
mproving the bioavailability of poorly water-soluble drugs is one of the most significant challenges for the pharmaceutical industry, and a wide variety of different excipients are used to overcome this issue. Enabling formulations often employ polymeric excipients to enhance solubility and therefore bioavailability, two of which are Gelucire 44/14 and polysorbate 80; these are known to improve solubility of poorly water-soluble drugs and, hence, increase their bioactivities.1−3 In addition to the use of Gelucire 44/14 and polysorbate 80 as excipients in drugs, they are also widely used as cosmetic4 and food additives.5 Gelucire 44/14 and polysorbate 80 can improve solubility of the drug within the formulation and in vivo through association with the drug molecule, for example, by micelle formation in the intestinal environment. Therefore, the excipient composition and variability can be critical to product performance and drug absorption. Gelucire 44/14 is formed by polyglycolysis of hydrogenated palm kernel oil with polyethylene glycol (PEG) 1500. Gelucire 44/14 is a semisolid wax, which is composed of approximately 72% mono- and difatty acid esters of PEG 1500; 20% mono-, di, and triglycerides; and 8% free PEG (see Figure 1 for structures).1,6 Different microscopy, NMR, X-ray diffraction, and HPLC-MS techniques have been used for characterization of Gelucire 44/14.1,7−9 © 2012 American Chemical Society
Received: June 8, 2012 Accepted: September 6, 2012 Published: September 24, 2012 8579
dx.doi.org/10.1021/ac301576h | Anal. Chem. 2012, 84, 8579−8586
Analytical Chemistry
Article
polysorbate 80 and Gelucire 44/14, respectively, using FTICRMS, to provide a better understanding about the potential impact of variability in these complex excipients on drug product performance.
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EXPERIMENTAL SECTION
Materials. Two different batches of Gelucire 44/14 (a product of Gattefosse s.a, St Priest, France), identified as (A) and (B), and polysorbate 80, identified as [Acros (A) and Fisher (B)], were provided by AstraZeneca. Chloroform, HPLC grade methanol, and sodium hydroxide were obtained from Fisher Scientific, Leicestershire, UK. Sample Preparation. Gelucire 44/14 samples were dissolved in 1:9 chloroform/MeOH. Polysorbate 80 samples were dissolved in HPLC grade methanol. All solutions were then further diluted in 1 mM sodium hydroxide down to an approximate final concentration of 1 μM. FTICR-MS. The experiments were carried out on a Bruker Solarix 12 T FTICR-MS (Bruker Daltonics. Bremen, Germany). Solutions of Gelucire 44/14 and polysorbate 80 (described above) were electrosprayed at a flow rate of 300 μL/ h. An average of 400 scans using ESI in positive ion mode were obtained. The mass spectrometer was externally calibrated using a standard mixture (HP mix) within the range of interest. External calibration of mass spectra produced a mass accuracy of ≤5 ppm. Internal calibration was also performed using confidently assigned PEGs as internal calibrants, improving the mass accuracy to values
