In Situ Metastable Form: A Route for the ... - ACS Publications

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In Situ Metastable Form: A Route for the Generation of Hydrate and Anhydrous Forms of Ceritinib Ramanaiah Chennuru,†,‡ Ravi Teja Koya,† Pavan Kommavarapu,† Saladi Venkata Narasayya,† Prakash Muthudoss,† Peddy Vishweshwar,† R. Ravi Chandra Babu,*,‡ and Sudarshan Mahapatra*,† †

Centre for Excellence in Polymorphism and Particle Engineering, Integrated Product Development (IPDO), Dr. Reddy’s Laboratories Ltd., Bachupally, Hyderabad, Telangana, India ‡ Department of Chemistry, College of Science, GITAM University, Visakhapatnam, Andhra Pradesh, India S Supporting Information *

ABSTRACT: Ceritinib is an anaplastic lymphoma kinase (ALK) inhibitor used for the treatment of ALK-positive metastatic non-small cell lung cancer (NSCLC). This BCS class IV drug is developed by Novartis and traded under the name Zykadia. To date two forms [Form A (marketed form) and B] of ceritinib are disclosed in international patent application US 2013/0274279 A1. However, the crystal structure and insight into any solid form of this compound are not available in the literature. In order to achieve better physicochemical properties compared to known solid forms of this compound, novel polymorph identification is chosen as one of the challenging paths to address the issue. In our comprehensive polymorph screening, including in silico and experimental investigations, we discovered three novel solid forms of ceritinib. Out of these three solid forms, two are neat (Form 1 and Form 3) and the remaining one is a hydrate (Form 2). All synthesized forms are further characterized by powder X-ray diffraction, differential scanning calorimetry, and Fourier transform infrared spectroscopy. It is interesting to note that the discovery of this hydrate is in sync with the prediction done using COSMO-RS theory (COSMOthermX software). The current article includes the first single crystal structure of ceritinib Form 1. All forms (Form 1, 2, and 3) of ceritinib are subjected to physicochemical property evaluation like solubility in buffers with a pH range of 1−7, dissolution, and stability. In aqueous solutions and pH 4.5 (acetate buffer), the solubility of Form 2 and 3 is high compared to Form 1, whereas in 0.1 N HCl and 0.01 N HCl Form 1 has a higher solubility compared to Forms 2 and 3. A six-month stability study indicates that all forms (Forms 1, 2, and 3) are stable in ICH stability conditions like accelerated (40 °C ± 2 °C, 75% RH ± 5% RH), long-term (25 °C ± 2 °C, 60% RH ± 5% RH), and low temperature (2−8 °C) conditions. A thorough polymorph screening protocol, including in silico prediction, single crystal structure, and physicochemical properties of different forms and structure property correlations for ceritinib are enlightened in the current paper.

1. INTRODUCTION In recent decades both academic groups and pharmaceutical companies have shown considerable interest in the application of crystal engineering principles to control and tune the physicochemical properties of active pharmaceutical ingredients (APIs).1,2 Further, in the literature it is indicated that a majority of drug molecules (>80%) fail at the late stage of drug formulation and preclinical studies due to issues related to low solubility and poor bioavailability.1,2 Salt formation is found to be the most common and well-practiced approach to improve the physicochemical properties like solubility, stability, dissolution rate, melting point, filterability, etc.3−7 In this regard cocrystals can also be considered as an equal competitor to salt. However, salts are sometimes more likely to form hydrates and have an inherent tendency toward hygroscopicity compared to cocrystals.8,9 On the same line polymorphism in APIs is considered as an alternate, and over decades, it has become a major area of drug research. Polymorphs exhibit unique physicochemical properties, such as melting point, © 2017 American Chemical Society

solubility, bioavailability, stability, color, and mechanical properties, correlating to their unique crystal structure and packing.10−12 Improved aqueous solubility is a primary driving force in the development of novel solid form (amorphous, polymorphs, cocrystals, hydrates/solvates, and salts) selection.13−17 Polymorphs and hydrates are often obtained by slow solvent evaporation or cooling crystallization dealing with the saturated solution of the target compound.18,19 Other crystallization approaches involving variation in crystallization temperature,20,21 milling condition,22 solvent polarity,13 humidity,24 etc. can be explored during polymorph screening and crystallization. However, the discovery of polymorph/hydrate has been always a challenging task. In the current study, we have demonstrated how the pH modulation can act as one of the potential approaches to isolate novel solid forms. The Received: July 24, 2017 Revised: October 7, 2017 Published: October 11, 2017 6341

DOI: 10.1021/acs.cgd.7b01027 Cryst. Growth Des. 2017, 17, 6341−6352

Crystal Growth & Design

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Information Figures S2, S5, S8, and S11). This hydrate is named as Form 2. The attempts to grow single crystals of Form 2 by slow solvent evaporation, vapor diffusion, and cooling crystallization resulted in Form 1 (Form 2 converts to Form 1 in above-mentioned conditions). So, single crystal structure has not been solved for Form 2. However, the phase purity is confirmed by indexing the PXRD pattern and described in the following section. 2.2.3. Ceritinib Form 3. Form 2 (3.0 g) was taken in an ATD and maintained at 120 °C for 10 min to generate Form 3. The obtained material was characterized by PXRD, DSC, TGA, and MC and confirmed to be a neat solid form (see Supporting Information Figures S3, S6, S9 and S12). 2.3. Instrumentation. 2.3.1. Differential Scanning Calorimetry (DSC). DSC thermograms of all samples were recorded on a Thermal Advantage (TA) Discovery instrument by heating the samples at a heating rate of 10 °C/min up to 200 °C with the continuous purging of dry nitrogen gas at a flow rate of 50 mL/min. 2.3.2. Thermogravimetry analysis (TGA). TGA thermograms of all samples were recorded on a Thermal Advantage (TA) Q 500 series machine by heating the samples at a rate of 10 °C/min up to 200 °C with the purging of dry nitrogen gas with a flow rate of 40 mL/min to the balance and 60 mL/min to the furnace. 2.3.3. Powder X-ray Diffraction (PXRD). All X-ray powder diffraction data were collected on a PANalytical X’Pert PRO diffractometer (X’cellerator detector, Cu-anode, 45KV, 40 mA, BragBrentano geometry) using the 2θ scan range, step size, and exposure time of 3−40°, 0.03°, and 1200 s/step, respectively. 2.3.4. Single-Crystal X-ray Diffraction. Single crystal data sets for ceritinib Form 1 were collected in open mounting condition on an Oxford-Super Nova diffractometer with a CCD detector. The crystal structure was solved using direct methods on a reasonably good quality data set obtained from a carefully chosen crystal. 2.3.5. Purity by HPLC. All samples purity was analyzed for the purity by using HPLC. The purity of the samples is calculated by % area normalization. Samples were analyzed using the following parameters and chromatographic conditions, column: YMC Pack ODS-A (150 mm × 4.6 mm, 3.0 μm); flow rate: 1.0 mL/min; injection volume: 10.0 μL; column oven temperature: 30 °C; run time: 60 min; detector wavelength: 215 nm. Gradient program-time (min) 0, 43, 53, 54, and 60 with % mobile phase-A 90, 10, 10, 90, and 90, respectively. Sample Preparation. Ceritinib sample (25 mg) was weighed and transferred into a 50 mL volumetric flak followed by the addition of 40 mL of diluent (acetonitrile/water 50:50% v/v) and sonication to dissolve the material. The volume was made up to mark with diluent and mixed well. The samples were filtered through 0.22 μm polyvinylidene fluoride (PVDF) syringe filter, and the solution was collected in HPLC vials before analysis. Procedure. Blank (acetonitrile/water 50:50% v/v) was injected before to test solution into the chromatography system. The purity of the sample was calculated by percentage area normalization. 2.3.6. Water Content by KF Apparatus. All samples were analyzed for water content by using the Karl Fischer titration method (Metrohm). 100.00 mg of sample was weighed into the titration vessel and titrated using Karl Fischer reagent to calculate the percentage of water content. 2.3.7. Solubility Determination. Equilibrium solubility of Form 1 and the prepared novel polymorphs (Form 2 and Form 3) were determined in Ultrapure water (Millipore, USA) and multimedia buffers. The selected buffers in this regard are 0.1 N HCl, 0.01 N HCl, pH 4.5 acetate buffer, and pH 6.8 phosphate buffer. Excess amount of sample was added into selected media (water and buffers), and the samples were shaken for 24 h at 37 °C in a horizontal orbital shaker (n = 3) at 200 rpm speed. After the requisite time the supernatant was filtered through a 0.45 mmμ PVDF syringe filter, and the filtrate was assayed spectrophotometrically by HPLC at 215 nm using YMC Pack ODS-A, 150 mm × 4.6 mm, 3.0 μm column. 2.3.8. The Drug Release Rate Studies. The drug release profile was studied using the USP apparatus II (paddle) method using Lab India dissolution apparatus. Dissolution studies were carried out in 900 mL of 0.01 N HCl (pH 2.0) at 37° ± 0.5 °C with a stirring of 60 rpm. An

challenge of low aqueous solubility offers an ideal situation for the application of crystal engineering,25 a concept to mitigate the issue with solubility, dissolution rate, and bioavailability. We have conducted polymorph screening in ceritinib (BCS-IV) drug with an aim to identify novel, stable, scalable polymorphs with better/similar physicochemical properties like Form A. In the current research paper, we have reported two anhydrous (Form 1 and Form 3) and one hydrate (Form 2) form of ceritinib and a comprehensive study of their physicochemical properties. Ceritinib is an anaplastic lymphoma kinase (ALK) inhibitor used for the treatment of ALK-positive metastatic non-small cell lung cancer (NSCLC). Ceritinib is used for the treatment of NSCLC following treatment with Crizotinib. It is developed by Novartis and traded under the name Zykadia. It was approved by the US FDA on April 7, 2014. Ceritinib is formulated as hard gelatin capsules with 150 mg strength with a maximum daily dose of 750 mg. So far two polymorphs (Forms A and B) of ceritinib are reported in the literature. In our polymorph screening, we have isolated three crystalline forms of ceritinib and named as Forms 1, 2, and 3. The powder X-ray diffraction pattern (PXRD) and differential scanning calorimetry (DSC) thermogram of Form 1 (Neat form) matches Form A, disclosed in international patent application US 2013/ 0274279 A1. Form 2 and Form 3 are found to be a hydrate and neat form, respectively. An in silico technique always has less importance in generic drug development. However, in the current paper we have discussed how it can be utilized effectively to match the pace of solid form screening (polymorph or hydrate) at the earliest. Single crystal structure analysis of marketing solid form (Form 1) and characterization of synthesized solid forms are reported in the paper. Comprehensive physicochemical properties like solubility, powder dissolution performance assessment, and stress/ hygroscopic stability studies for all forms of ceritinib are explained thoroughly in the current paper.

2. EXPERIMENTAL SECTION 2.1. Materials and Methods. Ceritinib API was provided by Dr Reddy’s Laboratories Ltd., and it was further purified by recrystallization from acetone. All other chemicals were analytical or chromatographic grade. Water purified from a deionizer-cum-mixed-bed purification system (Millipore, USA) was used in the experiments. 2.2. Preparation of Ceritinib Anhydrous and Hydrate Forms. 2.2.1. Ceritinib Form 1. Ceritinib input material was dissolved in acetone, and the solution was heated up to 50 °C followed by cooling down to room temperature (∼25 °C) to lead to precipitation. The precipitate was filtered and suck dried under a vacuum. The formation of Form 1 was confirmed by PXRD, DSC, thermogravimetric analysis (TGA), and moisture content (MC) (see Supporting Information Figures S1, S4, S7, and S10). For single crystal analysis, colorless block-shaped single crystals were obtained by the vapor diffusion method in 3−4 days using acetone as solvent and n-heptane as antisolvent. 2.2.2. Ceritinib Form 2. Ceritinib (3.0 g) was taken in a 100 mL Easymax reactor, and 15 mL of acetic acid was added to it at room temperature. The pH of the resulting solution was found to be around 2.5. The clear solution was maintained at room temperature over constant stirring using an overhead stirrer with 350 rotations per minute (RPM). The pH of the reaction was increased to 11−12 by using 1 M NaOH solution, followed by maintenance of reaction mass at room temperature for 24 h leading to precipitation. The precipitate was filtered and suck dried under a vacuum at room temperature. The isolated material was dried in the air tray dryer (ATD) at 40 °C for 2 h. The formation of a new solid hydrated form was confirmed by PXRD, DSC, TGA, and KarlFischer titration for MC (see Supporting 6342



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amount equivalent to 750 mg of ceritinib samples was added to the dissolution medium. A total of 5.0 mL of sample was withdrawn after 5, 10, 15, 20, 30, 45, and 60 min, and an equivalent volume is replaced by10 mL of fresh 0.01 N HCl. The solutions were filtered through a 0.22 mm membrane (μ PVDF syringe) filter, and the concentration of ceritinib was determined spectrophotometrically at 215 nm using YMC Pack ODS-A, 150 mm × 4.6 mm, 3.0 μm column. 2.3.9. pH Study. A pH study was conducted for all solubility samples kept for 24 h time point in different buffers (0.1 N HCl, 0.01 N HCl, pH 4.5 acetate buffer and pH 6.8 phosphate buffer). After 24 h incubation at 200 rpm at 37 °C in different buffers, the samples were withdrawn, and the pH of initial and final were measured using a Metrohm pH meter.

with their corresponding Hex values is tabulated in Table 1 and Table S1 (see Supporting Information). 3.2. Hydrate Screening. Ceritinib molecular structure indicates the presence of eight hydrogen bond acceptors and three hydrogen bond donors. This clearly gives an intuition of strong hydrogen bonds with water. It is noteworthy that to date ceritinib hydrates are not reported in the literature. In this regard hydrate screening for ceritinib was initiated with a background support of COSMORS prediction. There are number of methods reported31 for generation of hydrate forms of API, which includes (i) exposure to different RH,32 (ii) slurry in water32 at different temperature, (iii) temperature cycling of aqueous suspension,33 (iv) slurry in mixed-solvent33 at different temperatures, (v) vapor diffusion, (vi) solvent/ antisolvent mixing at different temperatures, (vii) heating/ cooling crystallization, (viii) solvent exchange at different temperatures, (ix) wet-drying, (x) wet grinding31 at different temperatures, and so on. Most of these crystallization techniques were explored for ceritinib hydrate, but each time they ended up with the known anhydrous solid form, i.e., Form 1. The experimental trials and their results are tabulated in Table S2. 3.3. Discovery of Ceritinib Novel Hydrate via pH Modulation Crystallization Technique. Ceritinib has two strong basic cites, i.e., piperidine N1 with pka −10.07 and pyrimidine N4 with pka −3.059 (Scheme-1). Ceritinib microspecies distribution vs. pH is calculated using Marvin 5.10.1, 2012, ChemAxon.34 This distribution shows that piperidine N1 can be easily protonated at any pH < 5.8, and at the same time it can be easily deprotonated at any pH > 8.6 (Figure 1). This pH-dependent modulation technique for salt making and breaking was selectively used for the discovery of hydrates of the ceritinib free base. Ceritinib (3.0 g) was charged into an RBF, and acetic acid was added slowly to the reactor with constant stirring until all material got dissolved. The pH of the resulting solution was measured to be pH = 2.5. Then excess aqueous sodium hydroxide (1 M NaOH) solution was added into the RBF until a pH of 11.8 is reached. The reaction mass was maintained for 24 h with constant stirring. The reaction mass was filtered and formation of hydrate was confirmed by PXRD, DSC, and moisture analysis (KF titration technique). The discovered hydrated solid form is named as Form 2 (see Supporting Information Figures S2, S5, S8, and S11). Hydrate formation via pH modulation technique is rarely explored in the literature, and we believe this could be one of the additional ways to explore hydrates of active pharmaceutical ingredients. 3.4. Characterization of Ceritinib Forms. 3.4.1. Crystal Structure Analysis. Block morphology crystals of Ceritinib Form 1 were obtained from a saturated solution of acetone at room temperature. The crystal structure was solved and refined in a monoclinic cell with space group P21/n. The overlay of the experimental and simulated PXRD patterns is shown in Figure 2.The asymmetric unit contains only one molecule of ceritinib in the unit cell. The three-dimensional crystal packing in ceritinib Form 1 is supported by intermolecular N5−H5···O3 (2.8395 Å; 128°) hydrogen bonding with a graph set35 of S (6). Ceritinib forms an infinite chain along the b-axis via C17− H17···N1(3.4315 Å; 160°) intermolecular interaction with a graph set35 of C (3) (Figure 3-i). In the three-dimensional packing ceritinib molecules form a ring motif via C26−H26··· N4 (3.3208 Å; 139°) hydrogen bonding for a graph set35 R44 (20) (Figure 3-ii). Crystal structure of Form 1 indicates the

3. RESULTS AND DISCUSSION A literature search (CSD, version-5.36, November 2014) on ceritinib resulted in no hits. As of today, there is no crystal structure available in the literature for ceritinib. Table 1. Excess Enthalpy Calculation for Ceritinib with Different Solvents API

solvent

Hex (kcal/mol)

ceritinib

formic acid acetic acid water n-butylacetate ethylformate anisole iso-propylbenzene pentane n-heptane

−3.4929 −2.4763 −0.844 +0.0078 +0.004159 +0.16481 +0.21824 +0.3914 +0.59

Scheme 1

3.1. COSMOtherm. COSMO-RS (Conductor-like Screening Model for Real Solvents) is a universal theory to predict the thermodynamic equilibrium properties of liquids, which were originally developed by Andreas Klamt.26−29 The propensity to form solvate/cocrystal can be evaluated by calculating the excess enthalpies (Hex). Use of excess enthalpy from the COSMO-RS model is very well-known in the literature.30 On the same line COSMO-RS was used for Ceritinib molecule with the aim to short list the probable solvate/hydrate based on their Hex value. Higher negative excess enthalpies (Hex) for solvent and active pharmaceutical ingredients (API) indicate higher probability of formation of corresponding solvate. It is noteworthy that the excess enthalpy (Hex) for formic acid, acetic acid, and water was found to be −3.49, −2.470, and −0.8, respectively. Ceritinib is a strong base, so considering the pKa difference it is obvious to expect salt formation with formic and acetic acid. However, the negative excess enthalpy of water indicates a higher probability of hydrate formation. Hydrates are pharmaceutically accepted; in this regard screening experiments were conducted on ceritinib with a focus to obtain hydrates. The list of probable solvate/hydrate formation 6343



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Figure 1. Microspecies distribution (%) vs pH.

Figure 2. Experimental powder X-ray diffraction (PXRD) pattern vs. simulated PXRD pattern of Form 1.

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Figure 3. Three-dimensional packing diagram of ceritinib Form 1 showing (i) three-dimensional chains along the b-axis via C−H···N intermolecular interactions, (ii) ring motif for a graph set of R44 (20), (iii) 3D packing diagram along the b-axis.

Table 2. Crystallographic Details of Ceritinib Form 1 SXRD refinement

PXRD refinement

parameters

Ceritinib Form 1

Ceritinib Form 2

CCDC no. chemical formula moiety in asymmetric unit. chemical formula formula weight crystal system space group T [K] a [Å] b [Å] c [Å] α [°] β [°] γ [°] Z V [Å3] Dcalc [g cm−3] M [mm−1] total reflns. unique reflns. observed reflns. R1 [I > 2(I)] wR2 (all) goodness-of-fit instrument

1563222 C28H36ClN5O3S C28H36ClN5O3S 558.13 monoclinic P21/n 293 13.302(5) 8.782(5) 24.896(5) 90 96.785(5) 90 4 2888(2) 1.284 0.242 14058 5874 3913 0.058 0.094 1.018 Bruker Apex diffractometer

NA (C28H36ClN5O3S)·(0.5H2O) (C28H36ClN5O3S)·(0.5H2O) 567.13 triclinic P1 293 19.0875(3) 9.8051(7) 9.0839(1) 80.7260(8) 104.1594(8) 118.9312(1) 2 1777.662(1)

NA C28H36ClN5O3S C28H36ClN5O3S 558.13 triclinic P1 293 18.8831(7) 15.7279(3) 12.4435(6) 115.2045(1) 79.2349(6) 120.5435(2) 4 2894.101(4)

Ceritinib Form 3

0.0554 0.0402

0.0485 0.0926

Bruker D8-Advance

Bruker D8-Advance

Table 3. Hydrogen Bond Metrics in the Crystal Structure of Ceritinib Form 1 interaction

D−H/Å

D−A/Å

H−A/Å

D−H···A [deg]

symmetry

C17−H17···N1 C26−H26···N4 N5−H5···O3 N2−H2···O1 N5−H5···Cl1

0.93 0.93 0.86 0.86 0.86

3.4315 3.3208 2.8395 2.6505 2.9901

Ceritinib Form 1 2.54 2.51 2.23 2.37 2.55

160 139 128 100 113

1/2 + x,1/2 − y, −1/2 + z 1 − x, −y, −z x, y, z x, y, z x, y, z

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Figure 4. Pawley profile fitting of PXRD pattern of Form 2.

Figure 5. Pawley profile fitting of PXRD pattern of Form 3.

Figure 6. Experimental powder X-ray diffraction (PXRD) pattern overlay of ceritinib Forms 1, 2, and 3. Figure 7. DSC thermogram overlay of ceritinib Forms 1, 2, and 3.

presence of three types of graph set leading to ring motif and three-dimensional chains along the b-axis (Figure 3-iii). 3.4.2. Powder Indexing. Powder indexing is used to determine the phase purity of crystalline solid materials.36 In order to determine the phase purity of ceritinib Form 2 and Form 3, powder indexing was performed with the help of Material Studio (Version-8.0). PXRD pattern indexing was carried out using X-cell37/Dicvol38 programs with the option of

automatic space group determination in Material Studio. An empty unit cell was created for the cell having best relative figure of merit (FOM) and weighted profile factor Rwp. The unit cell was further refined by the Pawley method.39 Powder indexing results of Forms 2 and 3 proved them to be unique phase. Powder refinement data of Forms 2 and 3 are shown in 6346



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Table 4. Melting Point Temperature and Enthalpy Values of Ceritinib Forms event

Tonset/peak (°C)

ΔHf (J g‑1)

Form 1

endo endo endo endo exo endo endo endo endo

174.30/176.70 47/74 99.5/101.9 157.4/160.5 161.8/162.8 174.10/176.40 157.8/160.9 161.7/162.9 174.36/175.85

−158.3

Form 1-Melting

Form 2

Form 3

dehydration Form 2 → 3 transition Form 3 melting melt → Form 1 recrystallization Form 1-melting

−9.2 −15.4 +23.1

Form 3 melting melt → Form 1 recrystallization Form 1-melting

3.4.3. Powder X-ray Diffraction (PXRD) Technique. PXRD is a vital and predominant tool for the study of polycrystalline materials and is eminently suited for the routine characterization of polymorphs.40 Polymorphism in Forms 1 and 3 is clearly evident by considering their PXRD pattern (Figure 5). Related to this there are three distinct peaks at 2-θ = 5.42°, 9.37°, and 15.04° in the PXRD of Form 3 found to be absent in Form 1. At the same time two peaks at 2-θ = 12.78° and 15.60° of Form 1 are absent in Form 3 (Figure 6). Comparing the experimental PXRD patterns of Forms 1 and 2, four distinct peaks at 2-θ = 5.05°, 9.61°, 10.09° and 15.11° for Form 2 are absent in Form 1. At the same time three peaks of Form 1 at 2θ 10.63°, 13.25°, and 17.58° are absent in Form 2 (Figure 5). Comparing the experimental PXRD patterns of Form 2 and Form 3, four distinct peaks of Form 2 at 2-θ 5.05°, 9.61°, 10.09°, and 17.11° found to be absent in Form 3. At the same time three peaks of Form 3 at 2-θ 5.43°, 9.36°, and 16.40° are absent in Form 2 (Figure 6). 3.4.4. Thermal Technique. DSC has distinct advantages over other analytical techniques, including the ease, simplicity, and rapidity of the measurements both in terms of identification and characterization. It also provides information on thermodynamic parameters associated with the polymorphic transition.41,42 Polymorphism between different solid forms is well established in the literature by their characteristic melting point and enthalpy of fusion.43 Ceritinib Forms 1, 2, and 3 were

Figure 8. FT-IR spectra of Forms 1, 2, and 3.

Figure 4. Crystallographic information on Forms 2 and 3 are tabulated in Table 2.

Figure 9. FTIR fingerprint plots for ceritinib Forms 1, 2, and 3 (i) wavenumber range from 3700 to 3100 cm−1, (ii) wavenumber range from 3200 to 3020 cm−1, (iii) wavenumber range from 3000 to 2600 cm−1, (iv) wavenumber range from 1700 to 1400 cm−1. 6347



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Table 5. FT-IR Vibrations (Stretching/Bending) in Form 1, 2, and 3a band origin H−OH N−H

wavelength range

Form 1

Form 2

Form 3

description

3616 ∼3450

3440

N−H

1650−1550

1598

CC−H

3130−3070

3118

channel hydrate, OH stretch aromatic 2° amine stretch

3440 3418 1597 1593 (sh) 3118 (vw) 3099 sh

3418 1597 1593 (sh) 3118 (vw)

aromatic 2° amine bend aromatic C−H stretch

3051 3082

3082 3052 3035 1563 (sh) 1571 1508 1313 1142

3035

a

CC−C

1615−1580

1563

CC−C SO SO

1510−1450 1350−1300 1160−1120

1504 1313 1141

1563 (sh) 1571 1508 1314 1139

aromatic ring stretch aromatic ring stretch antisymmetric sulphone stretch symmetric sulphone stretch

Note: Sh - shoulder peak, vw - very weak peak.

Figure 10. Solubility profiles of ceritinib Forms 1, 2, and 3 (a) after 15 min, (b) after 60 min, (c) after 180 min and (d) after 1440 min.

Table 6. Solid Form Stability and Apparent Solubility at Different pH Values initial Form Form Form

form 1 2 3

form after 24 h Form 1 Form 2 Form 3

initial pH pH after 24 h

pH = 1.2

pH = 2.0

pH = 4.5

pH = 6.8

water

1.21 6.48 2.00 1.86

2.01 6.17 6.52 6.73

4.53 5.62 6.80 6.98

6.83 7.22 8.33 8.52

6.87 6.93 6.47 6.90

three kinds of events before the melting endotherm. The first broad endotherm is spreading over 40−80 °C representing the dehydration of Form 2, and the second endotherm of ΔHtrans =

subjected to DSC thermal analysis. The DSC thermogram of Form 1 shows only a melting endotherm, with Tonset/Tpeak at 174.30/176.70 °C. On the other hand, ceritinib Form 2 shows 6348



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Table 8. Hygroscopic Study for Ceritinib Forms 2 and 3 Form 2 Open Condition: Exposed to Air at Room temperature testing intervals

water content (% w/w)

solid phase stability with PXRD

initial 2.59 first day 4.17 third day 4.07 Open Condition: Exposed to Humidity

Form 2 matches with initial matches with initial (90%, ± 10%)

testing intervals



initial first day third day

2.59 8.65 7.47

Form 2 matches with initial matches with initial Form 3

Open Condition: Exposed to Air at Room temperature testing intervals

Table 7. Stress Study Data for Ceritinib Forms 2 and 3

testing intervals

Form 2 stress study and storage conditions initial photo stress (254 nm/ 365 nm)

accelerated stress (40 °C ± 2 °C 75% RH ± 5% RH) thermal stress (60 °C ± 2 °C) compressed stress

stress study and storage conditions initial photo stress (254 nm/ 365 nm)

accelerated stress (40 °C ± 2 °C 75% RH ± 5% RH) thermal stress (60 °C ± 2 °C) compressed stress

water content % w/w

% HPLC purity

initial third day

2.59 3.02

99.77 99.41

10th day third day

2.60 3.84

98.73 98.35

10th day third day

3.15 3.14

99.78 99.63

10th day 2.21 after 1 h of 2.42 compression Form 3

98.94 99.82

testing intervals

water content % w/w

% HPLC purity

initial third day

0.62 1.18

99.77 99.59

10th day third day

1.02 1.44

98.68 99.60

10th day third day

0.89 0.12

99.66 99.57

10th day after 1 h of compression

0.79 1.06

98.65 99.62

testing intervals



initial 0.62 first day 1.41 third day 1.38 Open Condition: Exposed to humidity

Figure 11. In vitro powder dissolution profile of ceritinib Forms 1, 2, and 3.

initial first day third day

PXRD Form 2 matches with initial Form 2

Form 3 matches with initial matches with initial (90%, ± 10%)

water content (% w/w) Solid Phase Stability with PXRD 0.62 2.45 2.13

Form 3 matches with initial matches with initial

shows two independent endothermic events and one exothermic event. The first endotherm and immediate exotherm obtained for Form 3 are related to the melting of Form 3 followed by recrystallization of Form 1 from the melt. The Tonset/Tpeak obtained for these two events match very closely to that obtained for corresponding events in Form 2. The last endotherms of both form Form 2 and 3 overlap with the melting endotherm of Form 1. DSC thermal events for various solid forms of Ceritinib are tabulated in Table 4. 3.4.5. Vibrational Spectroscopy. Vibrational spectroscopy in conjunction with other solid state techniques is considered extremely valuable for a compound existing in multiple polymorphic forms.44−46 Infrared spectra of Form 1, Form 2, and Form 3 of ceritinib are shown in Figures 8 and 9, and detailed peak assignments are tabulated in Table 1. This molecule contains NH, CH3, OSO, C−Cl, and aromatic CC groups, and hence a variety of molecular vibrational modes may be expected. It is obvious to expect a vibrational band around 3600 and 3100 cm−1 for hydrates. The peaks appearing around 3616 cm−1 for Form 2 is attributed to the water present in the crystal lattice. Between anhydrates (Form 1 and Form 3), sharp peaks were observed in the region 3450− 3200 cm−1 attributed to NH stretching vibrations. The weak to medium peaks appearing between 3100 and 3000 cm−1 can be attributed to aromatic H−CC stretching, 1600−1400 cm−1 attributed to aromatic CC−C stretching. Moreover, a series of vibrations between 900 and 650 cm−1 (see Table 5) were found to display pronounced differences between polymorphs which are attributed to the CH out of plane vibrations. This information could potentially point to the fact that the anhydrous forms differ in the stacking as well as H-bonding interactions. Furthermore, the anhydrous Form 3 peak positions resemble Form 2 hydrate that may perhaps indicate Form 3 has a channel anhydrate structure. Fourier transform infrared (FT-IR) spectroscopy along with thermal analysis and PXRD study confirms that ceritinib exists in two anhydrous

PXRD Form 3 matches with initial Form 3

−9.2 J/g with Tonset/Tpeak at 99.5/101.9 °C represents a phase transformation of Form 2 to Form 3. The third endotherm can be assigned to the melting of Form 3 with Tonset/Tpeak at 157.4/ 160.5, and the immediate exotherm can be related to the recrystallization of the melt to Form 1 with Tonset/Tpeak at 161.8/162.8 °C (Figure 7). The DSC thermogram of Form 3 6349



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3.5. Physicochemical Properties Evolution. 3.5.1. Solubility and Powder Dissolution. Solubility. An important goal of drug development protocol is to improve physicochemical properties and enhance the drug efficacy. Solubility remains a major challenging factor for BCS class IV drugs (low solubility, low permeability) because of this poor dissolution leading to limited bioavailability.23 Ceritinib is a BCS class IV drug having an aqueous solubility of 0.001 mg/mL. We have conducted apparent solubility measurement in water at pH 1.2 (0.1 N HCl), pH 2.0 (0.01 N HCl), pH 4.5 (acetate buffer), and pH 6.8 (phosphate buffer). It is interesting to note that Form 2 (0.9 mg mL−1) and Form 3 (0.1 mg mL−1) have a higher aqueous solubility compared to Form 1(0.001 mg mL−1). However, ceritinib Form 1 (107.1 mg mL−1) has the advantage on solubility in acidic pH 1.2 (0.1 N HCl) over Form 2 (3.9 mg mL−1) and Form 3 (0.9 mg mL−1). Also, a similar solubility trend was observed in pH 2.0 (0.01 N HCl) media where Form 1 (10.1 mg mL−1) has advantages over Form 2 (4.4 mg mL−1) and Form 3 (1.5 mg mL−1). Further at pH 4.5 in acetate buffer, Form 2 (84.6 mg mL−1) and Form 3 (82.1 mg mL−1) have a slightly higher solubility as compared with Form 1 (54.1 mg mL−1). As like pH 4.5 in pH 6.8 (phosphate buffer) Form 2 (0.004 mg mL−1) and Form 3 (0.004 mg mL−1) show a slight increase in solubility compared to Form 1(0.02 mg mL−1). Apparent solubility order for different solid form of ceritinib in water at pH 4.5 and 6.8 buffers follows the trend: Form 2 > Form 3 > Form 1 and at pH 2.0, Form 1 > Form 2 > Form 3, after 24 h. Solubility of ceritinib Forms 1, 2, and 3 are pictorially represented in Figure 10. Solubility and different solid form stability at different pH are tabulated in Table 6. Powder Dissolution. In vitro powder dissolution studies were conducted for ceritinib Forms 1, 2, and 3, 2.0 (0.01 N HCl) at 37 °C. In order to get uniform particle sizes during the dissolution study, all ceritinib forms (Form 1, 2, and 3) were sieved under 20 size mesh. The dissolution profiles of Form 2 and Form 3 are comparable to Form 1 (Figure 8). There is a minor difference in the beginning stage of the release profile of Form 1. In the case of Form 2 and Form 3, 90% of the drug gets released in the first 5 min. However, in the case of Form 1 it is only 75%, and it took 20 min to reach a 90% drug release for Form 1. In vitro powder dissolution profiles of Ceritinib Forms 1, 2, and 3 are shown in Figure 11. 3.5.2. ICH Stability Testing. Polymorph Stability. All the forms of ceritinib were stable at ambient conditions of Hyderabad (35 °C and 40% RH) for more than six months. Ceritinib Forms 2 and 3 are subjected to stability testing in accordance with US-FDA stability protocol-Q1A (R2) (stability stating of new drug substance and products).47 Both Forms 2 and Form 3 are subjected to stress [photo stress (254 nm/365 nm), accelerated stress (40 °C ± 2 °C, 75% RH ± 5% RH), thermal stress (60 °C ± 2 °C), and compression stress]; conditions, testing intervals, and observations for stress study are tabulated in Table 7. The results of the stability study indicate that both forms are stable, physically and chemically under above said stress conditions. A hygroscopic study was carried out by exposing the material to a humidity of RH = 90% ± 10% in open conditions at room temperature. Conditions, testing intervals, and observations of relative humidity study are tabulated in Table 8. From the results, it is evident that none of the phases (Forms 2 and 3) show any kind of transformations during the study. Accelerated stability (40 °C ± 2 °C, 75% RH ± 5% RH), long-term stability (25 °C ± 2 °C, 60% RH ± 5% RH), and low

Table 9. Six-Month Stability Data for Ceritinib Forms 2 and 3 Form 2 Storage Condition - 2−8 °C (Low Temperature Stability) period

% water content

% HPLC purity

solid phase stability by PXRD

initial 1.89 99.84 Form 2 first month 1.96 99.89 matches with initial second month 1.91 99.79 third month 1.90 99.78 sixth month 1.61 99.81 Storage Condition - 25 °C ± 2 °C, 60% RH ± 5% RH (Long-Term Stability) period

% water content

HPLC purity


initial 1.89 99.84 Form 2 first month 1.75 99.88 matches with initial second month 1.81 99.79 third month 1.58 99.69 sixth month 1.09 99.87 Storage Condition - 40 °C ± 2 °C, 75% RH ± 5% RH (Accelerated Stability) period

% water content

initial 15th day first month 45th day second month third month sixth month

1.89 1.83 1.78 1.62 1.72 1.13 1.09

% HPLC purity 99.84 99.93 99.81 99.83 99.79 99.58 99.87 Form 3

solid phase stability by PXRD Form 2 matches with initial

Storage Condition - 2−8 °C (Low-Temperature Stability) period initial first month second month third month sixth month Storage Condition period

% water content

% HPLC purity


1.27 99.75 Form 3 1.59 99.83 matches with initial 1.55 99.72 1.18 99.68 1.5 99.88 25 °C ± 2 °C, 60% RH ± 5%RH (Long-Term Stability) % water content

HPLC purity


initial 1.27 99.75 Form 3 first Month 1.79 99.84 matches with initial second month 1.39 99.75 third month 1.31 99.68 sixth month 1.2 99.84 Storage Condition - 40 °C ± 2 °C, 75% RH ± 5% RH (Accelerated Stability) period

% water content

% HPLC purity


initial 15th day first month 45th day second month third month sixth month

1.27 1.55 1.68 1.71 1.56 1.11 1.06

99.75 99.89 99.81 99.78 99.7 99.49 99.87

Form 3 matches with initial

forms along with a hydrate state. FT-IR vibrations both stretching and bending in Forms 1, 2, and 3 are tabulated in Table 5. 6350



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temperature stability (2−8 °C) in packed conditions were conducted for both Form 2 and Form 3. These two forms have shown remarkable stability (physically and chemically) under the above said conditions for six months (Table 9).

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4.0. CONCLUSIONS Two novel forms of ceritinib are identified during the course of polymorph screening. The scientific rationale behind this discovery is clearly nailed down by the integration of experimental and theoretical approaches. The anhydrous and hydrate forms of ceritinib are isolated by following pH modulation crystallization. Both the polymorphs have advantages in terms of stability, solubility, and dissolution rate compared to Form 1. The present discovery has demonstrated a new approach to crystallization with a scientific rationale. We hope the discovered forms may be useful in the downstream of product development by following appropriate formulation strategies.

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ASSOCIATED CONTENT

S Supporting Information *

The Supporting Information is available free of charge on the ACS Publications website at DOI: 10.1021/acs.cgd.7b01027. The crystallographic information files for all crystalline forms can be downloaded from Cambridge structure database with the CCDC No. 1563222, PXRD patterns of Forms 1−3 are given in Figures S1−S3; DSC of Forms 1−3 are given in Figures S4−S8; TGA of Forms 1−3 is given in Figures S7−S9; moisture content (MC) of Forms 1−3 are given in Figures S10−S12; Table S1: Excess enthalpy calculation for ceritinib with different category of solvents; Table S2: The experimental trails and their results for hydrate screening (PDF) Accession Codes

CCDC 1563222 contains the supplementary crystallographic data for this paper. These data can be obtained free of charge via www.ccdc.cam.ac.uk/data_request/cif, or by emailing data_ [email protected], or by contacting The Cambridge Crystallographic Data Centre, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223 336033.

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AUTHOR INFORMATION

Corresponding Authors

*(S.M.) E-mail: [email protected]. Phone: +91-4044346040. Fax: +91-40-4434 6164. *(R.R.C.B.) E-mail: [email protected]. ORCID

Sudarshan Mahapatra: 0000-0001-6369-8811 Notes

The authors declare no competing financial interest.

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ACKNOWLEDGMENTS The authors would like to thank Dr Reddy’s Laboratory for encouraging and providing the facility to do fundamental research. We would also like to thank Prof. T. N. Guru Row for providing the access to the SXRD data collection. The authors would like to thank Mr Dasameswara Rao Kavitapu for extensive anlytical support at Dr Reddy’s.

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REFERENCES

(1) Thayer, A. M. Chem. Eng. News 2010, 88, 13. 6351



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(42) Ford, J. L.; Timmins, P. Pharmaceutical Thermal Analysis: Techniques and Applications; Halsted Press, 1989. (43) Grzesiak, A. L.; Lang, M.; Kim, K.; Matzger, A. J. J. Pharm. Sci. 2003, 92, 2260. (44) Stuart, B. Infrared Spectroscopy; Wiley Online Library, 2005. (45) Smith, E.; Dent, G. Modern Raman Spectroscopy: a Practical Approach; John Wiley & Sons, 2013. (46) Bugay, D. E.; Brittain, H. G.; Cogdill, R. P.; Drennen, J. K.; Brittain, H. Taylor & Francis: New York, 2006. (47) US-FDA Stability Protocol-Q1A (R2) - Industry Guidelines for ICH, 2003, November, 1−22.

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