Plasdone K povidones and

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1 Plasdone K povidones and Plasdone S-63 copovidone Properties for Spray-Dried and Melt-Extruded Solid Dispersions Plasdone K povidones and S-63 copovidone polymers used in solid dispersions Plasdone K povidones and Plasdone S-63 copovidone are commonly used polymers for solid-dispersion formulations. Solid dispersions are molecular (thermodynamically stable solid solutions) and/or colloidal (kinetically stable solid suspensions) dispersions of the amorphous active pharmaceutical ingredient (API) dispersed in a polymeric matrix that enhance the solubility of APIs. Amorphous solid dispersions are particularly attractive for many poorly soluble drug candidates due to the fact that they can increase both solubility and dissolution rates of APIs. 1,2 As a result, bioavailability of the poorly soluble APIs can be significantly enhanced. Research in the past decade in soliddispersion formulation and process technologies has established that stable amorphous solid dispersions with high bioavailability can be prepared at commercial scale by spray drying or melt extrusion. For example, studies have indicated that stable solid-dispersion systems with enhanced bioavailability can be prepared with Plasdone K povidone. 3,4 Application Products Benefits Hot-melt Extrusion Spray-dried Dispersions Plasdone K povidone and Plasdone S-63 copovidone Polyplasdone crospovidone Benecel HPMC Klucel HPC Plasdone K povidone and Plasdone S-63 copovidone Benecel HPMC Desirable thermal/rheological properties. Strong hydrogen bond acceptor. Enhances thermodynamic and kinetic stability of solid dispersions. Chemically inert. Non-pH dependent dissolution. Excellent safety profile with clinical precedence. Extrudate is in the form of particles that can be used for direct compaction to simplify tablet preparation. Hydrogen bond acceptor and donator. Superior stabilizer and supersaturation inhibitor. Chemically inert. Non-pH dependent dissolution. Excellent safety profile with clinical precedence. Superior thermal plasticity. Enhances processability and can be used as process aid in hot-melt extrusion. Excellent solubility, stability and low viscosity in a wide range of solvents. Strong hydrogen bond acceptor. Enhances thermodynamic and kinetic stability of solid dispersions. Chemically inert. Non-pH dependent dissolution. Excellent safety profile with clinical precedence. Hydrogen bond acceptor and donator. Superior stabilizer and supersaturation inhibitor. Chemically inert. Non-pH dependent dissolution. Excellent safety profile with clinical precedence. Benefits Solid-dispersion carriers that are suitable for both spray drying and hot melt extrusion processes Excellent solubility and low viscosity in a wide range of solvents allowing flexibility in preparing spray-dried dispersions Plasdone S-63 copovidone offers a wider processing window for melt extrusion based on its thermostability and favorable thermorheological properties Photo courtesy of Leistritz. Long history of use and can be safely used at high use levels With good chemistry great things happen.

2 A range of polymers available for formulation flexibility Plasdone K povidone polymers are homopolymers of polyvinylpyrrolidone (PVP) that differ in molecular weight and glass transition temperature, T g (Table 1). The inhibitory effect of PVP on the crystallization of drugs has been known for a number of years. 5,6 The pyrrolidone ring imparts water solubility and solvent/surfactantlike properties for interfacial activity (Figure 1). For solid-dispersion applications, the 2-pyrrolidone group is capable of accepting hydrogen bonds that are stabilized through pyrrolidone carbonyl groups. Plasdone S-63 copovidone is a 6:4 random copolymer of vinyl pyrrolidone and vinyl acetate. The addition of vinyl acetate groups to the vinyl pyrrolidone polymer chain reduces the copolymer s T g relative to the Plasdone K povidone homopolymers. The vinyl acetate groups in Plasdone S-63 copovidone also add hydrophobicity and reduce hygroscopicity compared to PVP homopolymers. For solid-dispersion applications, both the vinyl acetate and vinyl pyrrolidone monomer units are capable of accepting hydrogen bonds stabilized through acetate and pyrrolidone carbonyl groups. Table 1 Plasdone povidone and copovidone polymer range for formulation of solid dispersions Polymer K-Value Polymer Type Typical Weight Average Molecular Weight Typical Glass Transition Temperature, Tg ( C) Plasdone K Homopolymer 4, 12 Plasdone K Homopolymer 1, 14 Plasdone K Homopolymer 34, 16 Plasdone K-29/ Homopolymer 58, 164 Plasdone S Copolymer 47, 19 Figure 1 Chemical structure of Plasdone K povidone and Plasdone S-63 copovidone polymers n CH 2 CH CH 2 CH n m N O O CH 3 C n:m = 6:4 a. Povidone b. Copovidone Considerations for polymer selection Polymers are critical components of solid dispersions because they act as carriers for the drug and inhibit crystallization in the dosage form and in vivo. 7 In addition to forming a stable system with increased bioavailability, the polymer must have the appropriate safety profile, supporting toxicity data and history of use. It is not unusual for the polymer use level to be 3 to 9 times greater than the API in a finished oral dosage form. Finally, the polymer selected must be amenable to the preferred process technology. When preparing a solid dispersion by spray drying, it is necessary to select a suitable solvent for both polymer and API. Thus, polymers that are soluble in a wide range of solvents allow greater formulation flexibility. In addition, the solution viscosity of the polymer in solvent must also be considered. The solution viscosity of a polymer and solvent combination is important to the feed solution pumping, droplet atomization and droplet drying. In general, it is difficult to produce spray-dried polymer powders from organic solvents with feed solution viscosity above approximately 13 to 18 cp (or mpa s), depending on spray-dryer design, size and nozzle configuration. Solution viscosity is primarily determined by the level of polymer in the solution, polymer molecular weight and the strength of interaction between the polymer and the solvent. In melt-extrusion processing, two important considerations are the T g and the rheological properties of the polymer, API and adjuvant (if any) formulation. The T g of the formulation is important as it defines the lower end of the processing temperature window. Typical practice is to extrude at temperatures 2 C to 4 C above the T g of the system in order to achieve suitable rheological properties for processing. Although high T g polymers are preferred for formulation stability, the lower T g polymers can be melt extruded more easily without additional plasticization beyond that already provided by the API. The rheological properties of the formulation melt determine the energy (motor torque) needed during process start up and steady-state processing. Depending on the power of the extruder motor, melt viscosities below 1, Pa s and preferably below 1, Pa s are desired. Melt viscosity is primarily determined by the difference between the T g of the formulation and the processing temperature, the molecular weight of the polymer and the level of API and adjuvants, which act as low viscosity diluents in the melt. O

3 Safe at high use levels Plasdone povidone and copovidone polymers have a long history of safe use in various pharmaceutical products including oral, topical, ocular and parenteral dosage forms. Plasdone povidone and copovidone polymers have been widely studied and multiple toxicological studies support the safe use of these polymers in pharmaceutical applications. The United States Food and Drug Administration Inactive Ingredients Database (IID) lists the maximum dose levels that have been used in approved New Drug Applications (NDAs). Product Plasdone K povidone Plasdone S-63 copovidone FDA IID approved dose 8 mg* 854 mg * This is the highest level currently listed in IID, but available safety data support use levels similar to Plasdone S-63 copovidone Solution properties of Plasdone povidone and copovidone polymers The solubility of commonly used solid-dispersion polymers in a range of solvents is shown in Table 2. Plasdone S-63 copovidone and Plasdone K povidone polymers are soluble in the widest range of solvents to provide the greatest flexibility compared with other polymers for formulating solid dispersions by spray drying. The solution viscosities of Plasdone S-63 copovidone, Plasdone K-12 povidone and Plasdone K-29/32 povidone polymers with a number of solvents and solvent combinations at increasing polymer concentrations up to 15 wt. % polymer, are shown in Figures 2 to 4. Viscosity was measured using a stress-controlled rheometer equipped with Couette flow setup. The reported viscosity was averaged between shear rates of 1 s -1 and 1 s -1. The results show that Plasdone S-63 copovidone can be spray dried from most solvents up to a polymer concentration of at least 15%, except from dichloromethane (DCM) or DCM:methanol mixtures at the highest concentration (15%). DCM is an exceptionally good solvent for this polymer. When compared with other solvents used at the same (15%) concentration, a higher solution viscosity is achieved. The results for Plasdone K-29/32 povidone are similar to those of Plasdone S-63 copovidone. The viscosities of Plasdone K-29/32 povidone polymer solutions are slightly higher than those of Plasdone S-63 copovidone solutions, due to the higher molecular weight of Plasdone K-29/32 povidone. Finally, the low molecular weight Plasdone K-12 povidone polymer has very low solution viscosity in all solvents, even up to 15% concentration, and is easily spray dried from all solvents at these and even much higher concentrations. Table 2 Plasdone S-63 copovidone and Plasdone K povidone polymers are soluble in a wide range of solvents to provide maximum flexibility for formulating a wide range of APIs Plasdone S-63 copovidone Plasdone K povidone Hypromellose (HPMC) HPMC- Phthalate Hypromellose Acetate Succinate (HPMC-AS) Acrylates Dichloromethane (DCM) S S I I I I Tetrahydrofuran (THF) PS I I S S S Acetone S I PS S S I-S Ethyl Acetate I I I I S I Isopropanol S S I I I I Ethanol S S I I I PS-S Methanol (MeOH) S S I S S S 2:1 DCM:MeOH S S PS S S S 2:1 Acetone:MeOH S S PS S S S 2:1 MeOH:THF S S I S S S S = Soluble (>5 weight %) PS = Partially Soluble (1 5 weight %) I = Insoluble (<1 weight %)

4 Figure 2 Solvent solutions containing up to 15% Plasdone S-63 copovidone are easily spray dried Figure 4 All solutions of Plasdone K-12 povidone are suitable for spray drying Viscosity, mpa.s DCM Methanol Ethanol 2:1 DCM:MeOH 2:1 Acetone:MeOH 2:1 MeOH:THF Acetone Viscosity, mpa.s DCM Methanol Ethanol 2:1 DCM:MeOH 2:1 Acetone:MeOH 2:1 MeOH:THF % Solids % Solids Figure 3 Plasdone K-29/32 povidone produces higher viscosity solutions in various solvents than Plasdone S-63 copovidone at the same concentration Viscosity, mpa.s DCM Methanol Ethanol 2:1 DCM:MeOH 2:1 Acetone:MeOH 2:1 MeOH:THF % Solids Thermal stability of Plasdone povidone and copovidone polymers In preparing a solid dispersion by melt extrusion, the thermal stability of the polymer, as well as that of the API and of any adjuvants, determines the upper processing temperature in the extruder. The thermal decomposition of Plasdone povidone and copovidone polymers has been characterized using thermogravimetric analysis (TGA). TGA measures the amount and rate of change in the mass of a sample as a function of temperature or time in a controlled atmosphere. TGA analysis of Plasdone povidone and copovidone polymers was conducted by increasing the temperature from ambient to 6 C at 1 C/minute and 2 C/minute heating rates under air and nitrogen purge. In separate experiments, the polymer samples were held at a fixed temperature from 14 C to 23 C for 3 minutes. When heated quickly for a short period of time, Plasdone S-63 copovidone was stable, showing no significant weight changes (other than moisture evaporation) up to 3 C (Figure 5). When Plasdone S-63 copovidone was held at 16 C for 3 minutes, minimal weight loss and no color change was observed; however, when a Plasdone S-63 copovidone sample was held at 2 C for 3 minutes, minor weight loss and some yellowing was observed (Figures 6 and 7).

5 Figure 5 Plasdone S-63 copovidone is stable up to 3 C when temperature is increased quickly 4.68% Water loss (.7944 mg) Decomposition begins Figure 6 Plasdone S-63 copovidone showed no degradation at 16 C for 3 minutes All Plasdone povidone and copovidone polymers showed degradation behavior similar to that of Plasdone S-63 copovidone. As temperature increased quickly from ambient to 6 C, degradation was observed between 27 C and 3 C. When the polymer samples were held for 3 minutes at a given temperature, weight and color changes were observed between 19 C and 2 C. On the basis of these results, the recommended maximum extrusion temperature for all Plasdone povidone and copovidone polymers is 18 C. Additional polymer stability data were generated using a parallelplate oscillating rheometer to measure the rheological properties as a function of time at different temperatures. As an example, the rheological properties over time of Plasdone S-63 copovidone at 18 C and 2 C are shown in Figures 8 and 9, respectively. The data show that Plasdone S-63 copolymer experiences no change in rheological properties at 18 C but at 2 C the polymer shows evidence of crosslinking, as indicated by increases in viscosity and the storage modulus (G ). This information further supports the recommendation that the maximum processing temperature for Plasdone povidone and copovidone polymers is 18 C % (.3514mg) Figure 8 Plasdone S-63 copovidone experiences no change in rheological properties over time at 18 C Weight (%) % (.1259mg) Time (min) Universal V4.5A TA Instruments G' (P a) n* (P a.s) 1 G'' (P a) Figure 7 Plasdone S-63 copovidone showed minor degradation at 2 C for 3 minutes time (s) % (.4678mg) Time sweep t=18 C S63 8mm pp-9o, Time sweep step Weight (%) % (.3719mg) Time (min) Universal TA Instruments V4.5A

6 Figure 9 Plasdone S-63 copovidone shows evidence of crosslinking at 2 C G' (P a) n* (P a s) 1 1. G'' (P a) Melt rheology of Plasdone polymers The melt rheology of Plasdone povidone and copovidone polymers has been characterized by first measuring viscosity as a function of shear rate at a constant temperature. In a second experiment, the polymer viscosity at different temperatures and a fixed shear rate was measured. As an example, the viscosity of Plasdone S-63 copovidone as a function of shear rate at 15 C is shown in Figure 11. The data show the shear rate dependency of the material at a specific temperature. The viscosity of Plasdone S-63 copovidone at a range of temperatures from 15 C to 2 C is shown in Figure 12. As expected, the viscosity of Plasdone S-63 copovidone decreases as a function of increasing shear rate and temperature time (s) Figure 11 Plasdone S-63 copovidone shows a decrease in viscosity as a function of increasing angular frequency (shear rate) at 15 C 1.E6 1.E5 1.E6 As the T g of the polymer defines the lower end of the processing temperature window and the thermal degradation defines the upper processing temperature, the recommended processing windows for the neat Plasdone povidone and copovidone polymers are shown in Figure 1. Plasdone S-63 copovidone with its low T g offers the widest processing window compared to Plasdone povidone and copovidone homopolymers. The processing window for all Plasdone polymers will be expanded through plasticization with an API and/or plasticizers. As a result, all of these polymers have been successfully used to prepare solid dispersions via melt extrusion. Figure 1 Plasdone S-63 copovidone alone has the widest processing window for melt extrusion compared with Plasdone homopolymers 2 G ' (P a) 1.E n * (P a s) ang. frequency (rad/s) Figure 12 Plasdone S-63 copovidone melts have workable viscosities over a range of temperatures 1, 1, 1.E5 1 1 G '' (P a) Viscosity, Pa s Shear stress controlled rheometer, angular frequency: = 16 rad/s Temperature C Tmax T g Temperature C Plasdone S-63 copovidone Plasdone S-63 Plasdone K-12 Plasdone K-17 Plasdone K-25 Plasdone K-29/32 copovidone povidone povidone povidone povidone Note: Processing window will be further expanded through plasticization with APIs and/or plasticizers. In summary, the viscosity of the various Plasdone povidone and copovidone polymers over a range of temperatures is shown in Figure 13. Neat Plasdone S-63 copovidone provides workable viscosities at a range of temperatures. Except for Plasdone K-12 povidone, Plasdone K povidone homopolymers cannot be processed neat, as viscosity is not within the workable range below the polymer s recommended maximum extrusion temperature (18 C), but can be and have been extruded successfully through plasticization with the API alone or with additional plasticizers.

7 Figure 13 The melt viscosity of Plasdone povidone and copovidone polymers increases with increasing molecular weight and with increasing T g Viscosity, Pa s 1,, 1,, 1, 1, 1, 1 1 Solid dispersion preparation: Loratadine case study Solid dispersions were prepared by spray drying and hot-melt extrusion methods using loratadine as a model compound and Plasdone S-63 copovidone as the polymeric carrier. The properties of loratadine are summarized in Table 3. Table 3 Properties of loratadine Structure Plasdone S-63 copovidone Plasdone K-12 povidone Plasdone K-17 povidone Plasdone K-25 povidone Plasdone K-29/32 povidone Temperature C Molecular weight Melting point C Glass transition temperature, T g 38 C Degradation temperature 3 C 8 Cl Shear stress controlled rheometer, angular frequency:= 16 rad/s COOCH 2 CH 3 N Figure 14 Hot-melt extruder screw configuration with 4 kneading elements N Hot-melt extrusion process conditions Hot-melt extrusion was performed using a Coperion ZSK-18 extruder in the configuration shown in Figure 14. On the basis of previous research by Chokshi et al., 9 the following temperature profile was selected: Zone Temp. ( C) Higher process temperatures led to visible discoloration of the extrudates, suggesting possible degradation. Samples were prepared under the following conditions Feed rate 2 kg/hr Rotation speed 5 or 7 s -1 Drug:polymer ratio 3:7 or 4:6 Number of kneading elements 2 or 4 Spray drying solvent selection and process conditions Both loratadine and Plasdone S-63 copovidone are soluble in acetone, DCM, methanol and ethanol. In this study, 3:7 and 4:6 drug polymer ratios were spray dried from a 3% total solid solution of DCM:methanol 2:1 (w/w). Spray drying was performed on a GEA SD Micro* spray dryer. The feed material was atomized using a.5 mm two-fluid Schlick nozzle. The samples were spray dried under the same conditions: an inlet temperature of 85 C was maintained for all runs while the peristaltic pump that was delivering the feed solution was adjusted to achieve an outlet temperature of 55 C. The atomization gas was kept at a constant pressure of.5 bar with an atomization flow rate of 1.5 kg/hr, and a process gas flow rate of 25 kg/hr was used for all runs. Once spray drying was completed, the samples were placed into a vacuum oven at 4 C for at least 48 hours to remove residual solvent. Results The amorphous solid dispersions are physically stable after 6 months at ambient temperature and humidity conditions. All extrudates and spray-dried materials were characterized by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD) as amorphous solid dispersions, irrespective of API loading, processing methods and process conditions.

8 Global Headquarters Ashland Inc. 5 East RiverCenter Blvd. P.O. Box 391 Covington, KY U.S.A. Tel: Ashland Specialty Ingredients 8145 Blazer Drive Wilmington, DE 1988 U.S.A. Tel: Regional Centers Europe Switzerland Tel: Fax: India Maharastra Tel: Fax: Asia Pacific Singapore Tel.: Fax: Latin America Mexico Tel.: Fax: pharmaceutical@ashland.com ashland.com Registered trademark, Ashland or its subsidiaries, registered in various countries Trademark, Ashland or its subsidiaries, registered in various countries * Trademark owned by a third party 212, Ashland PC All statements, information and data presented herein are believed to be accurate and reliable, but are not to be taken as a guarantee, an express warranty, or an implied warranty of merchantability or fitness for a particular purpose, or representation, express or implied, for which Ashland Inc. and its subsidiaries assume legal responsibility. Experience with over 1 APIs Ashland scientists have developed spray-dried dispersion formulations for over 1 APIs working with over 5 pharmaceutical and biopharmaceutical companies worldwide. With a fundamental understanding of material and polymer science, as well as pharmaceutical formulation, Ashland can help with the development of your poorly soluble API using solid-dispersion technology. References 1. C. Leuner, J. Dressman, Improving Drug Solubility for Oral Delivery Using Solid Dispersions, Eur. J. Pharm. and Biopharm 5, 47 6 (2). 2. D.Q.M. Craig, The Mechanisms of Drug Release from Solid Dispersions in Water-Soluble Polymers, Int. J. of Pharmaceutics 231, (22). 3. J. Yang, K. Grey, J. Doney, An Improved Kinetics Approach to Describe the Physical Stability of Amorphous Solid Dispersions, Int. J. of Pharmaceutics 384, (21). 4. J. Doney, M. Keshtmand, C. Shores, Amorphous Spray-dried Formulations to Improve Bioavailability of CoQ1, poster presented at 28 AAPS Annual Meeting and Exposition, Atlanta, GA, Nov. 28. This information is available at 5. H. Sekikawa, M. Nakano and T. Arita, Inhibitory Effect of Polyvinylpyrrolidone on the Crystallization of Drugs, Chem. Pharm. Bull. 26 (1), (1978). 6. T. Matsumoto and G. Zografi, Physical Properties of Solid Molecular Dispersions of Indomethacin with Poly(vinylpyrrolidone) and Poly(vinylpyrrolidone-co-vinyl-acetate) in Relation to Indomethacin Crystallization, Pharm. Research 16 (11), (1999). 7. B.E. Padden, J.M. Miller, T. Robbins, P. Zocharski, L. Prasad, J.K. Spence and J. La Fountaine, Amorphous Solid Dispersions as Enabling Formulations for Discovery and Early Development, Am. Pharm. Review (Jan/Feb 211). 8. L. A. Ramos, É.T.G. Cavalheiro, Thermal Behavior of Loratadine, Journal of Thermal Analysis and Calorimetry 87(3), (27). 9. R.J. Chokshi, H.K. Sandhu, R.M. Iyer, N.H. Shah, A.W. Malick, and H. Zia, Characterization of Physico-mechanical properties of Indomethacin and Polymers to Assess their Suitability for Hot-melt Extrusion Processes as a Means to Manufacture Solid Dispersion/Solution, J. Pharm. Sci., 94(11), (25).