Drug-Polymer Interaction Studies of Cytarabine Loaded Chitosan Nanoparticles.
Summary: Assessment of possible incompatibilities between drug and excipients is an important parameter of preformulation stage during the pharmaceutical product development of active pharmaceutical ingredient (API). The potential physical and chemical interaction among the components of a delivery system can affect the chemical nature, bioavailability, stability, and subsequently therapeutic efficacy of drugs. In this study, ATR-FTIR spectroscopy was employed to investigate the possible intermolecular interaction of Cytarabine with deacetylated chitosan and tripolyphosphate in the resulting physical blends and crosslinked nanoparticulate system. Two different strategies, physical blending and ionotropic gelation, were adopted to prepare binary or tertiary mixtures and nanoparticulate formulation, respectively.
The IR spectra of CB showed characteristic peaks at 3438.27 cm-1 (primary amine), 3264.74 cm-1 (hydroxyl group) and 1654.98 cm-1 (C=O stretch in cyclic ring); CS at 3361.47 cm-1 (N-H stretching), 1646.18 cm-1 (C=O of Amide I), 1582.36 cm-1 (C=O of Amide II), and sTPP at 1135.77 cm-1 (P=O). CS-sTPP chemical interaction was confirmed from the shift in the absorption band of carbonyl groups (amide I, II) to 1634.66 cm-1 and 1541.17 cm-1 in blank chitosan nanoparticles, and 1636.87 cm-1, 1543.33 cm-1 in CSNP1 (2:6:1), and at 1646.15 cm-1 and 1557.04 cm-1 in CSNP2 (1:3:1). The characteristic peaks of CB were also present in chitosan formulation with a slight shift in the amino group at 3429.43 cm-1 and 3423.21 cm-1, in the hydroxyl group at 3274.54 cm-1 and 3270.73 cm-1, CSNP1 and CSNP2, respectively.
The findings counseled no significant interaction in IR absorption pattern of cytarabine functional groups after encapsulation in CS-sTPP complex, which projected the potential of chitosan nanoparticulate system to entrap cytarabine.
Keywords: ATR-FTIR spectrometry, Chitosan, Cytarabine, Drug-polymer compatibility, Ionotropic gelation method, Sodium tripolyphosphate
The production of quality medicines is a fundamental challenge for bulk drug and its suitable delivery system. The assessment of excipients for impurities and their chemical compatibility with drug molecules is inevitable to assure the stability and effectiveness of a delivery system .
In the preformulation phase, drug-excipient compatibility study signifies the chemical nature, bioavailability and therapeutic safety of drug by evaluating the potential physical and chemical interaction  Among the various techniques, employed for assessment of possible drug-excipient interactions, such as differential scanning calorimetry (DSC), thermogravimetry (TG), hot-stage microscopy (HSM), X-ray diffractometry (XRD), diffuse reflectance spectroscopy (DRS), self-interactive chromatography (SIC), High Pressure Liquid Chromatography (HPLC), thin layer chromatography (TLC), and liquid chromatography (LC) with ultraviolet detection [3, 4], FT-IR is most commonly employed, fast, robust and less-expensive technique .
Since, the dispersive systems were superseded by the much more powerful FT-IR (Fourier-Transform-Infrared) spectrometers IR-spectroscopy has developed into a widely used routine analytical tool  The versatile and green approach of ATR-FTIR technique has made for direct analysis of possible physicochemical interactions between active moiety and formulation components  Furthermore, FTIR spectroscopy provides reliable evidence of the appearance, modification, or desertion of attribute peaks of various functional groups such as C=O, C-H or N-H of the excipients and drugs among physical mixtures and nanoparticles formulations  This instrument allows measuring all types of samples, whether they are solid, liquid or gaseous 
In the clinical trial phase, the failure of a huge number of medicaments to achieve encouraging therapeutic outcomes is due to the lack of target specificity, the frequent and large doses, and subsequent adverse effects . Furthermore, the drastic physiological condition (gastric pH) and degradation of biologically active agents hinder the distribution of drug to a specific disease site  Therefore, the interesting concept of micro and nanoparticles has developed to overcome these disadvantages as a novel drug delivery system. Primarily, the incorporation of active pharmaceutical ingredients in micro/nano-particulate matrix system is deliberating for their protection from drastic in-vivo environment . Moreover, the controlled and sustained liberation of medicinal substances, and conjugation or surface modification of nanoparticles with targeting moiety also provides the potential of treating site-specific release .
In these nanoparticulate systems, a wide range of natural or synthetic polymers (polysaccharides, polymethacrylates, polyanhydrates, polyesters/ortho esters, poly lactic-co-glycolic acid and polyphosphohazanes), lipids, dendrimers, and surfactants can be employed to integrate drugs by passive absorption and chemical conjugation .
Low molecular weight chitosan (CS), a natural cationic and hydrophilic amino-polysaccharide macromolecule, is being used in the novel delivery systems because of distinctive biological attributes, such as muco-adhesion, biodegradation, haemocompatibility, non-toxicity, and antibacterial property . CS based nano-particles/fibers, hydrogels and membranes have been formulated to embed bioactive moieties (hydrophilic, hydrophobic and macromolecules), due to the specific tissue targeting and, sustained/controlled release  Ionic gelation technique, among multiple preparation methods comprising complex coacervation, ionotropic gelation, self-assembly method through chemical modification, solvent evaporation/diffusion, and emulsion-droplet coalescence, is preferred for its convenience, relative simplicity, and the rid of organic solvents and high temperatures . Chitosan nanoparticles (CSNPs), have been widely developed for the treatment of various conditions.
For example, nanoparticles of 5-fluorouracil, paclitaxel, catechin, doxorubicin, leucovorin, and pravastatin are used in cancer therapy. Nanoparticles of various other therapeutical agents such as, donepezil, rivastigmine, tacrine, ampicillin, chlorhexidine, levofloxacin, and vancomycin are utilized to treat Alzheimer disease. In order to manage Parkinson's disease, bromocriptine, dopamine, pramipexole, and selegiline can be encapsulated in nanoparticulate system. Numerous antiviral agents (saquinavir, stavudine, tenofovir, and zidovudine) are now encapsulated into chitosan nanocarriers in order to combat HIV. Moreover, several antioxidants (ascorbic acid, rutoside, salvia officinalis, and satureja montana) can also be loaded in nanoparticulate system .
We envisioned the present compatibility investigation to determine possible interaction of Cytarabine (CB) with CS nanoparticle formulation components. All individual components as polymers and drug, their physical mixture, and developed Nanoparticulate formulations have been examined by ATR-FTIR spectrometer. Based on this observation, future studies can be planned to evaluate the effects of formulation parameters on the response variables. The 2D-chemical structure of cytarabine, chitosan, and sodium tripolyphosphate was prepared on Chemdraw 8.0 Pro CambridgeSoft Corporation, USA (Fig. 1).
Cytarabine (C9H13N3O5, PubChem CID: 6253) was purchased from Beijing Mesochem Technology Co., LTD (China). Chitosan low molecular weight (C56H103N9O39, PubChem CID: 71853) was purchased from Sigma-Aldrich Chemie GmbH (USA), Sodium tripolyphosphate (Na5P3O10, PubChem CID: 24455) from MSDS ScienceLab.com, Inc. (Texas) and Acetic acid, glacial 100% (C2H4O2, PubChem CID: 176) Merck Millipore (USA).
Preparation of Physical Mixtures
Physical blends were prepared by intimate trituration of equimolar quantities (10 mg) of CB, CS, sTPP in an agate mortar for about 10 minutes to attain a homogenized mixture . The abbreviations and equivalent ratios of resultant samples are described in Table-1.
Table-1: Chemical composition, equivalent ratio, and sample code for ATR-FTIR analysis.
Sr. No###Sample code###Chemical composition###Equivalent ratio
###4###CB-CS###Cytarabine + Chitosan###1:1
###5###CB-sTPP###Cytarabine + Sodium Tripolyphosphate###1:1
###6###CS-sTPP###Chitosan + Sodium Tripolyphosphate###1:1
###7###CB-CS-sTPP###Cytarabine + Chitosan + Sodium Tripolyphosphate###1:1:1
###8###CSNPb###Chitosan Nanoparticles without Cytarabine###-
###9###CSNP1###Chitosan Nanoparticles loaded with Cytarabine###-
10###CSNP2###Chitosan Nanoparticles loaded with Cytarabine###-
Table-2: Chitosan based nanoparticles with and without the loading of cytarabine.
Formulation code###Cytarabine(mg)###Chitosan(mg)###SodiumTripoly-phosphate(mg)###Stirring rate (rpm)###Stirring time (h)
Synthesis of Blank Chitosan Nanoparticles
The ionotropic gelation method was employed to develop CS nanoparticles according to the method reported by Calvo et al.  Briefly, 10 ml sTPP aqueous solution (1mg/ml) added to 20 ml of 1% aqueous acetic acid solution containing CS (3 mg/ml) to produce blank nanoparticles under constant stirring (700 rpm) at ambient temperature (Table-2). The resulted nanoparticle suspension was ultra-centrifuged using Sigma 1-14 (Sigma Laborzentrifugen GmbH, Germany), and washed three times with distilled water to evacuate the unentrapped drug, and lyophilized in the freeze dryer (CHRIST Alpha 1-2 LD plus, UK) for 24h . The interaction (inter- and intramolecular) between the high degree of positively charged amino groups of CS and the anionic groups of sTPP resulted from the formation of CS based NPs . The mechanism of cross-linking described as illustration in Fig. 2 [22, 23].
Preparation of Chitosan Nanoparticles Loaded with Cytarabine
Cytarabine loaded chitosan nanoparticles were fabricated employing ion gelation method reported by Kalam et al.  CB was dissolved into 20 ml of aqueous acetic acidic solution (1%) containing CS before the addition of 10 ml of sTPP (0.1%). Thereafter, the formulation was stirred magnetically at 700 rpm for 2h, at room temperature. Two formulations (CSNP1 and CSNP2) were fabricated as mentioned in Table-2.
Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopic technique was employed to analyze physical/chemical interaction between pure components and developed formulations . Chemical images of pure drug, polymer, cross linker, their physical blends, and nanoparticles (with and without drug) were acquired by the FTIR spectroscopic imaging approach using ATR-FTIR spectrometer (Bruker tensor 27, Germany). All spectral images were collected using OPUS (v6.5) FT-IR data collection software over a spectral range of 4000-400 cm-1 with 16 co-added scans at a resolution of 4 cm-1. The standard sample cell in the FTIR is a Pike Miracle single-bounce attenuated total reflectance (ATR) equipped with a ZnSe single crystal. Prepared samples were placed directly on the small crystal spot, and the arm rotated over and turned down to press the sample down onto the crystal face to get better contact .
Entrapment Efficiency and Drug Release Profile
The entrapment efficiency of CB was determined by centrifugation method. Nanoparticles were separated from aqueous environment of nanoparticulate system by the ultracentrifugation at 14000 rpm for 30 min. The clear superintend was further diluted 100 times with phosphate buffer saline (pH 7.4). The unentrapped drug was measured from diluted solution by UV spectrophotometer at I>>max of CB (272 nm). Furthermore, standard curve was constructed in PBS solution (pH 7.4) by plotting graph between CB concentrations of 1 mg/ml to 15 mg/ml and UV absorbance, to calculate the amount of entrapped drug in nanoparticulate system. The calibration curve equation (y = 0.0414x - 0.0056) at RA2 = 0.9996 was obtained from MS Excel 2010 and regressed as standard for the quantitative analysis .
In-vitro drug release profile of Cytarabine from chitosan nanoparticles was evaluated by dialysis tube method. The weighed amount of nanoparticulate system was filled in dialysis tube and was immersed in 400 ml of PBS at pH 7.4. The temperature of medium was maintained at 37 +- 0.5 AoC and stirred at 100 rpm in the USP paddle assembly attached with PTFC-2/8 Fraction Collector auto-sampler (Pharma Test, Hainburg, Germany). During the 24 h drug release study, subsequent series of 5 ml aliquots were pulled back from dialysis solution at predetermined time intervals (1, 2, 3, 4, 5, 6, 8, 10, 12, 14, 16, 18, 20, 22 and 24 h) and substituted with equal volume of fresh PBS to sustain sink conditions. Samples were adequately diluted, filtered and analyzed by UV-spectrophotometer (IRMACO GmbH, Geesthacht, Germany) at 272 nm. The released amount of CB was calculated from the regression equation and cumulative drug release (%) was calculated.
Results and Discussion
ATR-FTIR is recognized analytical technique for the analysis of functional group, phase separation behavior, and different types of bonding forces in pharmaceutical ingredients. Considering mid-infrared spectral modifications in the molecular band strength and frequency shifts are acknowledged measures for the occurrence and intensity of inter-intramolecular forces . Generally, pharmaceutical entities comprise particular bonds and characteristic functional groups that vibrate independently at their equilibrium position and weekly interact with each other, without the influence of any electromagnetic (EM) radiation effect .
After the application of an infrared (IR) radiation through a sample, the transitions among vibrational and rotational power levels result in the alteration of dipole moment, because of molecular absorption of IR . Moreover, IR absorption is specific to unique molecular vibration frequency, and the resulting spectrum epitomizes the molecular transmission/absorption and generates a precise fingerprint of sample .
Table-3: Functional groups and characteristic peaks of pure ingredients.
Samples###Functional Groups with Characteristic Peaks###References
###N-H (3438.27 cm-1 and 3356.33 cm-1), O-H (3264.74 cm-1), C-H (2935.62 cm-1), C=O (1654.98 cm-1), N-H (1576.07 cm-1), C-N
###CB###[5, 32 33]
###(1473.25 cm-1), C-O-H (1279.18 cm-1), and C-O-C (1109.10 cm-1 and 1069.08 cm-1).
###N-H and O-H (3361.47 cm-1), C-H (2878.38 cm-1), O-H (2362.21 cm-1), C=O (1646.18 cm-1 and 1582.36 cm-1), CH3 (1374.26
###CS###[6, 35, 40]
###cm-1), C-O-C (1149.85 cm-1), C-O (1059.02 cm-1)
STPP###P=O (1135.77 cm-1) and P-O (891.19 cm-1 and 734.44 cm-1###[5, 9]
Therefore, the elucidation of structure- property relations of pure components with their physical blend, and nanoparticle formulations were analyzed by ATR-FTIR spectrometer and interpreted to indicate the possible interactions and incompatibilities.
FT-IR spectra of pure components
The characteristic bands of cytarabine, deacetylated chitosan, and sodium tripolyphosphate are presented in Fig. 3 and the locations of characteristic band values are given in Table-3. FTIR spectra of CB, as described in Fig. 3(a), revealed the characteristic peak of primary amine (N-H) at 3438.27 cm-1 and 3356.27 cm-1 (asymmetric and symmetric stretch, respectively), broad absorption peak at 3264.74 cm-1 disclosed the presence of O-H stretching. The characteristic peak at a wave number of 2935.62 cm-1 showed C-H asymmetrical stretch; the sharp peaks at 1654.98 cm-1 and 1576.07 cm-1 indicated C=O stretching (aromatic) and N-H bending (secondary amide), respectively. C-N stretching, C-O-H bending and C-O-C stretching (ether) were also observed at 1473.25 cm-1, 1279.18 cm-1 and 1109.10 cm-1, 1069.08 cm-1 respectively. Other researchers in their study, indicating the purity and identity of CB, also reported similar characteristic peaks of pure cytarabine [32, 33].
In the FTIR fingerprint of CS, as in Fig. 3(b), the overlapped characteristic peak of N-H and O-H stretching at 3361.47 cm-1, and absorption band at 2878.38cm depicted asymmetrical stretching vibrations of C-H. The further spectral interpretation demonstrated a broad absorption peak of O-H (stretching) overlapped with C-H at the wave number of 2362.21 cm (which occurs in the presence of a carbonyl group). C=O stretching of amide I at 1646.18 cm-1 and amide II at 1582.36 cm-1 confirmed the presence of N-acetylated groups of CS. The wave numbers at 1374.26 cm-1, 1149.85 cm-1 and 1059.02 cm-1 and ensured the presence of CH3 (asymmetrical deformation), C-O-C bridge (asymmetrical stretching) and C-O (stretching), respectively. Others also reported all the absorption bands of functional groups in chitosan [34, 35].
IR spectral analysis of sTPP, as explained in Fig. 3(c), showed strong P=O stretching vibrations at 1135.77 cm-1, and P-O stretching at 891.19 cm-1 and 734.44 cm-1. Similar characteristic peaks were observed in a study presented by Lima et al. .
FT-IR Spectrum of Physical Blends
Any possible interaction in the physical mixtures of Cytarabine and formulation excipients has been examined and depicted in Fig. 4. The binary blend of drug with polymer (CB-CS), as presented in Fig. 4(a), confirmed all the identical peaks with imperceptible shift and indicating the lack of interaction between functional groups. IR spectra of cytarabine with a cross-linker, as shown in Fig. 4(b), depicted no significant shift in characteristic peaks compared to the individual components (Fig. 3) demonstrating the absence of interactions. The incompatibility of chitosan with sodium tripolyphosphate also studied and the absence of linkage between -NH2 and -P-OH was observed in their physical mixture.
Similarly, the IR spectral analysis of drug, polymer, and cross-linker also confirmed the presence of all individual attribute peaks in their physical mixture without any virtual shift, as illustrated in Fig. 4(d). This part of the investigation has confirmed the compatibility of the drug with its formulation components before the development of nanoparticles. Locations of characteristic band values are summarized in Table-4.
FT-IR Spectrum of Chitosan Nanoparticles
The chitosan-sodium tripolyphosphate matrix system is resulted due to interaction of amino group (CS) and phosphate (sTPP) , as explained in Fig. 2. Different chitosan nanoparticulate formulations have been developed by the ionotropic gelation method from different molar ratios of formulation components (Table-2) to scrutinize the possible interaction and compatibility of components in the formulation. ATR based FTIR spectrum of chitosan nanoparticles, as revealed in Fig. 5(a), the individual chitosan spectra, a broad absorption peak of the hydroxyl group (O-H) was observed at 3241.12 cm-1 specifying the enhanced hydrogen bonding. A characteristic peak of O-H stretching (overlay C-H) was perceived with a negligible shift in the wave number from 2362.21 cm-1 to 2358.04 cm-1. The absorption band of C=O of amide I at 1646.18 cm-1 was shifted at 1634.66 cm-1, indicating a possible interaction with sTPP.
Moreover, the bending vibration of amide II at 1582.36 cm-1 (representing deacetylated group) was also shifted to 1541.17 cm-1 after the ionic interaction with sTPP. This conjugation (between ammonium and phosphoric ions) decreases the solubility of chitosan and accountable for the separation of CS nanoparticles from the solution .
Table-4: Functional groups and characteristic peaks of physical blends.
Physical blends###Characteristic bands with functional groups
###3435-3263.85 cm-1 (N-H and O-H), 2886.19 cm-1 (C-H), 2359.57 cm-1 (O-H), 1654.63 cm-1 (C=O), 1576.90 cm-1 (N-H), 1473.25 cm-1 (C-
###N), 1372.79 cm-1 (-CH3), 1279.57 cm-1 (C-O-H), and 1149-1068.94 cm-1 (C-O-C).
###3438.16-3264.58 cm-1 (N-H and O-H), 2937.26 cm-1 (C-H), 1655.20 cm-1 (C=O), 1577.01 cm-1 (N-H), 1474.06 cm-1 (C-N), 1279.57 cm-1
###(C-O-H), 1136.98 cm-1 (P=O), 1109.98-1069.48 cm-1 (C-O-C), and 735.37 cm-1 (P-O).
###3356.32 cm-1 (N-H and O-H), 2871.14 cm-1 (C-H), 2359.91 cm-1 (O-H), 1645.26 cm-1 (C=O), 1583.36 cm-1 (C=O), 1374.81 cm-1 (-CH3),
###1138.38 cm-1 (P=O), 1056.92 cm-1 (C-O) and 734.58 cm-1 (P-O).
###3438-3264.47 cm-1 (N-H and O-H), 2936-2887.69 cm-1 (C-H), 2359.56 cm-1 (O-H), 1654.48 cm-1 (C=O), 1576.32 cm-1 (N-H), 1471.99 cm-
###1(C-N), 1372.43 cm-1 (-CH3), 1279.30 cm-1 (C-O-H), 1137.32 cm-1 (P=O), 1109-1069.18 cm-1 (C-O-C) and 736 cm-1 (P-O).
To compare the possible interaction of drug with polymer-crosslinker complex, two different formulations (CSNP1 and CSNP2) were developed with different molar ratios of CB, CS and sTPP (2:6:1 and 1:3:1). Fig. 5(b) and (c) represents IR spectra of CB nanoparticles, which disclosed the notable attenuation of absorption spectra with a substantial decrease in strength of absorption peaks, signifying the existence of interaction and entrapment of CB in CS-sTPP matrix system .
The characteristic peaks of primary amine (N-H) symmetrical and asymmetrical at 3438.27 cm-1 and 3356.27 cm-1 of CB were shifted to lower wavenumber in both formulations at 3429.43 cm-1 (CSNP1) and 3423.21 cm-1 (CSNP2) with the absence dierences were noticed at the wavenumber 3264.74 cm-1 (-OH stretching) which were shifted to wavenumber 3274.54 cm-1 (CSNP1) and 3270.73 cm-1 (CSNP2), and absorption peak at 2935.62 cm-1 (C-H asymmetrical stretching) which is shifted to 2920.03 cm-1 (CSNP1) and 2886.15 cm-1 (CSNP2). The spectral peaks of interaction between CS and sTPP were also detected in CSNP1 and CSNP2 at 1636.87 cm-1, 1543.33 cm-1 and 1646.15 cm-1, 1557.04 cm-1, respectively. These are the indicators of CS-sTPP conjugation and interaction. The C-O-H (bending) vibration peaks of CB were also observed in the nanoparticle system at 1423.25 cm-1 and 1421.72 cm-1 for CSNP1 and CSNP2 respectively, ensuring the loading of the drug .
Moreover, Cytarabine has three further strong absorption bands at 1279.18 cm-1, 1109.10 cm-1 and 1069.08 cm-1, which were overlapped with chitosan absorption bands (perceived at the same position in CSNP formulations).
Furthermore, CB showed physical interaction with CS in nanoparticles, which may be due to the electrostatic forces, but no additional characteristic peak or shifting of bands was observed in the physical mixtures or nanoparticulate formulations. This analysis ensures the entrapment of Cytarabine in biocompatible polymer (chitosan) matrix and its accessibility to fabricate the drug delivery system for biological actions.
Entrapment Efficiency and Drug Release Profile
Table-6 describes the encapsulation efficiency of nanoparticle formulations at constant drug content. CSNP1 demonstrated high entrapment efficiency of Cytarabine into nanooparticles was 75.24%, while CSNP2 showed low by 64.41 %. Formulation CSNP1 showed more sustained discharge of Cytarabine from nanoparticulate system whereas drug release from formulation CSNP2 was less sustained (Table-6). The values of drug release (%) after 12 hours and 24 hours were 51.65% and 82.84% respectively from CSNP1, and 72.34% and 89.64% from CSNP2 respectively.
Nanoparticulate formulation CSNP1 revealed high EE with sustained liberation of drug from nanoparticles following 24 hour release period (Fig. 6).
Table-5: Characteristic bands and functional groups of chitosan nanoparticulate system.
Formulations###Characteristic bands with functional groups
###3241.12 cm-1 (N-H and O-H), 2358.04 cm-1 (C-H), 1634.66 cm-1, 1541.17 cm-1 and 1375.98 cm-1 (ammonium and phosphoric ion
###3429.43 cm-1 (N-H), 3274.54 cm-1 (O-H), 2920.03 cm-1 (C-H), 2293.28 cm-1 (O-H), 1636.87 cm-1 and 1543.33 cm-1 (ammonium and
###phosphoric ion conjugation) and 1423.25 cm-1 (C-O-H).
###3423.21 cm-1 (N-H), 3270.73 cm-1 (O-H), 2886.15 cm-1 (C-H), 2282.36 cm-1 (O-H), 1646.15 cm-1 (C=O of amide I), 1557.04 cm-1
###(ammonium and phosphoric ion conjugation) and 1421.72 cm-1 (C-O-H)
Table-6: Entrapment efficiency and drug release behaviour of CSNP1 and CSNP2.
###Formulation code###Entrapment Efficiency (%)###Drug release after 12hr (%)###Drug release after 24hr (%)
Chitosan nanoparticle formulations alone and in combination with cytarabine were successfully prepared using the ionic gelation technique. Among the pre- and post-formulations studies, ATR-FTIR has appeared as a fundamental technique to find out interactions among the formulation components and compatibility to be included in a drug delivery system. The findings from this study have revealed the absence of possible chemical interaction or incompatibility between Cytarabine and chitosan-tripolyphosphate matrix system. Physical state of the cytarabine was modified, which corresponds to the drug crystallinity whereas formulation is thrashing its sharpness at its characteristic peaks.
Absence of detectable crystalline domains in cytarabine-loaded nanoparticulate clearly indicates that drug remained intact and dispersed completely in the formulation, thus modifying the nanoparticles to a disordered-crystalline phase. The analysis of various physical mixtures revealed a slight shift in band/peaks of different functional groups and characteristic peaks of cytarabine were observed at the same wavenumber and intensity points. However, ATR-FTIR spectra of the nanoparticulate formulations revealed the successful entrapment of cytarabine in CS nanoparticles. Furthermore, the compatibility investigations of cytarabine with excipients pretended the absence of precarious substances/excipients. Therefore, it is established that cytarabine can be successfully entrapped the CS nanoparticulate formulations and provide guide for future compatibility assessment of CB.
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|Author:||Madni, Asadullah; Kashif, Prince Muhammad; Nazir, Imran; Tahir, Nayab; Rehman, Mubashar; Khan, Muham|
|Publication:||Journal of the Chemical Society of Pakistan|
|Date:||Dec 31, 2017|
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