Development and Characterization of Flurbiprofen-Pyrazinamide Cocrystal Formulation as Potential Combination Therapy for Treating Tuberculosis

Abstract

Purpose: Cocrystallization is emerging as a promising approach in improving physicochemical property of an active pharmaceutical ingredient (API) including solubility, stability, and hygroscopicity [1]. Tuberculosis (TB), the leading cause of death worldwide, is an infectious disease caused by Mycobacterium tuberculosis. The main hurdle in current TB management is the high rate of multi-drug resistance tuberculosis (MDR-TB) and extensively drug-resistance tuberculosis (XDR-TB) due to prolong period of treatment and poor patient adherence [2]. Non-steroidal anti-inflammatory drugs (NSAIDs), as cyclooxygenase inhibitors, have been demonstrated by pre-clinical and clinical trials as adjunctive therapies of TB [3]. Specifically, oral administration of ibuprofen alone showed significant reduction in lung lesions and tissue bacillary load while combination therapy of ibuprofen with the first-line antitubercular drug, pyrazinamide (PZA) has been reported to display positive synergetic effects by reducing colony-forming unit counts [4, 5]. This study aimed to develop a novel fixed-dose drug-drug cocrystal formulation as a safe and efficient fixed-dose combination therapy for TB incorporating PZA and flurbiprofen (FLU), one of the NSAIDs that belongs to Biopharmaceutics Classification System (BCS) class II with poor aqueous solubility and low oral bioavailability. Methods: The cocrystal formulation was prepared by dissolving a total amount of 300 mg of FLU and PZA in a 2:1 molar ratio with ethanol through rapid solvent removal using a rotatory evaporator. The resulting cocrystal products were collected and oven-dried at 60℃, followed by solid-state characterizations including powder X-ray diffraction (PXRD) for crystallinity and phase purity, differential scanning calorimetry (DSC) for melting point and fusion enthalpy, binary Temperature-Composition phase diagram for eutectic points and stoichiometry ratio of cocrystal, Fourier transform infrared spectroscopy (FTIR) for bonding information, and scanning electron microscope (SEM) for particle morphology. Results: The PXRD pattern of the produced FLU-PZA cocrystal products was shown in Fig. 1 with a number of characteristic diffraction peaks at 2θ=12.93°, 17.28°, and 18.41°, revealing formation of a pure crystalline phase. The FLU-PZA 2:1 cocrystal exhibited a sharp melting endotherm at 98℃ in the DSC thermograms as presented in Fig. 2, which was different from FLU (113℃) and PZA (190℃). Additionally, the enthalpy of fusion of the cocrystal (∆Hf=63.7 kJ/mol) was greater than both of FLU and PZA, ∆Hf=28.9 kJ/mol and ∆Hf=30.0 kJ/mol, respectively. On the other hand, two eutectics occurred at 90.7℃ and 93.1℃ corresponding to 0.24 and 0.42 mole fraction of PZA in the phase diagram (Fig. 3), reflecting a 2:1 stoichiometry. In the FTIR spectra, characteristic peak was shifted from 3413 to 3431 cm-1 for the FLU-PZA cocrystal, suggesting a change in the chemical environment of the N-H bond in the amide group of PZA. Other spectral shifts were also observed for other functional groups such as the C=O group. SEM images showed that FLU-PZA cocrystals displayed in irregular large block particles with rough surfaces, which were different from the parent compounds FLU (rectangular with smooth surfaces) and PZA (needle shaped). Conclusion: The FLU-PZA cocrystals in 2:1 molar ratio was successfully synthesized in the present study and confirmed with high degree of phase purity through solid-state characterizations. Therapeutically, the proposed cocrystal formulation may provide an immediate solution as adjunctive therapy, potentially improving TB treatment efficacy, shortening duration of regimen, and mitigating the issue of MDR-TB. Importantly, different drug-drug cocrystal systems with other NSAIDs can be tailored depends on clinical needs as personalized medicine, which can be extended to various respiratory diseases. References: 1.Chow, S.F., et al., Simultaneously improving the mechanical properties, dissolution performance, and hygroscopicity of ibuprofen and flurbiprofen by cocrystallization with nicotinamide. Pharmaceutical research, 2012. 29(7): p. 1854-1865. 2.Pham, D.D., E. Fattal, and N. Tsapis, Pulmonary drug delivery systems for tuberculosis treatment. Int J Pharm, 2015. 478(2): p. 517-29. 3.Kroesen, V.M., et al., Non-Steroidal Anti-inflammatory Drugs As Host-Directed Therapy for Tuberculosis: A Systematic Review. Frontiers in immunology, 2017. 8: p. 772. 4.Vilaplana, C., et al., Ibuprofen therapy resulted in significantly decreased tissue bacillary loads and increased survival in a new murine experimental model of active tuberculosis. J Infect Dis, 2013. 208(2): p. 199-202. 5.Byrne, S.T., S.M. Denkin, and Y. Zhang, Aspirin and ibuprofen enhance pyrazinamide treatment of murine tuberculosis. J Antimicrob Chemother, 2007. 59(2): p. 313-6.