NanoCrySP technology for generation of drug nanocrystals: translational aspects and business potential

Catalyzing the Future of Medicinal Chemistry Research in India

The present publication provides a comprehensive look at more than a decade (2010 to midyear of 2023) of medicinal chemistry research in India, focusing on contributions to medicinal chemistry and drug discovery from both Indian academia and industries. The work provides an overview of cutting-edge medicinal chemistry research along with the organic-transformation-based chemical research scenarios in India in the past decade. It also distinguishes areas of research as well as contributions from different federal research institutes, state universities, central universities, and private universities by their geographical locations around India. The paper takes broader stock of the situation by comparing the articles published in the two internationally acclaimed journals in the field, viz. Journal of Medicinal Chemistry and Organic Letters, which highlights the current research trends as well as the thrust needed at the grass-roots level to boost medicinal chemistry and drug discovery research in India. Finally, we believe that this discussion may create a pathway for policymakers and funding agencies to focus their efforts to motivate lesser inclined institutions as well as provide incentives to the institutions primarily involved in medicinal chemistry research, as they already have built capacity for such research.

Preparation and Characterization of Co-Processed Mannitol and Sorbitol Using NanoCrySP Technology

Particle engineering of excipients, at sub-particulate level using co-processing, can provide high functionality excipients. NanoCrySP technology has been recently explored as a novel approach for the generation of nanocrystalline solid dispersion of poorly soluble drugs, using spray drying process. The purpose of the present study was to generate co-processed mannitol and sorbitol (SD-CSM) using NanoCrySP technology having similar composition to commercial co-processed excipient (Compressol® SM, CP). The characterization of excipients was performed to evaluate their various physicomechanical properties. The sub-micron crystallite size of sorbitol in the matrix of mannitol was determined using the Williamson-Hall equation and Halder-Wagner equation. The reduction in crystallite size of sorbitol and mannitol, lower melting point, and lower heat of fusion of SD-CSM could be responsible for excellent compactibility, better tabletability, and comparable compressibility with respect to CP. This was confirmed by the compressibility-tabletability-compactibility (CTC) profile and Heckel plot analysis. Overall, SD-CSM generated using NanoCrySP technology improved functionalities of excipients over CP and would be useful for direct compression application.

Generation of Ophthalmic Nanosuspension of Prednisolone Acetate Using a Novel Technology

PURPOSE

Prednisolone Acetate (PAC) is currently marketed as micronized ophthalmic suspension. The microsuspension has poor dose accuracy and efficacy due to aggregation, slow dissolution rate and limited corneal residence. The ophthalmic nanosuspension of PAC shall show enhanced solubility, dissolution rate and corneal adhesion due to small particle size and increased surface area.

METHODS

In the current work, we prepared ophthalmic formulation of PAC using a novel, spray drying based technology. Firstly, PAC nanocrystalline solid dispersions (NCSD) were prepared using Mannitol (MAN) as the crystallization inducing excipient and two separate stabilizers, Polyvinyl Alcohol (PAC_MAN_PVA) and Vitamin E Tocopheryl Polyethylene Glycol Sulphosuccinate (PAC_MAN_TPGS). The NCSD was dispersed in an aqueous vehicle to obtain an ophthalmic nanosuspension.

RESULTS

The composition, PAC_MAN_PVA (0.3:0.67:0.03%), was pursued due to absence of crystal growth on storage at 40°C/75%RH for 3 months. The resulting nanosuspension showed crystal size, osmolality and viscosity of 590 ± 165 nm, 297 ± 6 mOsm/L and 11 ± 8cP respectively. In 1%w/v SLS media, the nanosuspension showed rapid and complete dissolution of PAC in 120 s. Ex-vivo goat corneal permeation and adhesion study revealed that in comparison to microsuspension, a higher fraction (6.2 times) of nanosuspension adhered to the cornea. Safety studies performed using corneal histopathology and Hen Egg Test- Chorio Allantoic Membrane (HET-CAM) assay showed no physical change in cornea or capillary damage, respectively.

CONCLUSIONS

The NCSD can be explored for generation of ophthalmically acceptable nanosuspensions of poorly soluble drugs.

Comparison of Downstream Processing of Nanocrystalline Solid Dispersion and Nanosuspension of Diclofenac Acid to Develop Solid Oral Dosage Form

The conventional “top-down”, “bottom-up” and “combination” approaches of generating drug nanocrystals produce a “nanosuspension” (NS). It requires significant downstream processing for drying the liquid by suitable means followed by its granulation to develop an oral solid dosage form (OSD). In this paper, we used a novel, spray drying-based NanoCrySP technology for the generation of drug nanocrystals in the form of nanocrystalline solid dispersion (NCSD). We hypothesized that the NCSD would require minimal downstream processing since the nanocrystals are obtained in powder form during spray drying. We further compared downstream processing of NS and NCSD of diclofenac acid (DCF) prepared by wet media milling and NanoCrySP technology, respectively. The NS and NCSD were characterized for crystallinity, crystal size, assay and dissolution. The NCSD was physically mixed with 0.3% Aerosil^® 200, 1.76% croscarmellose sodium (CCS) and 0.4% sodium stearyl fumarate (SSF) and filled into size 0 hard gelatin capsules. The NS was first wet granulated using Pearlitol^® SD 200 (G1 granules) and Celphere^® 203 (G2 granules) in a fluidized bed processor, and the resulting granules were mixed using the same extra granular excipients as NCSD and filled into capsules. A discriminatory dissolution method was developed to monitor changes in dissolution behavior due to crystal growth during processing. Cost analysis and comparison of process efficiency was performed using an innovation radar tool. The NS and NCSD were successfully fabricated with a crystal size of 363 ± 21.87 and 361.61 ± 11.78, respectively. In comparison to NCSD-based capsules (65.13%), the G1 and G2 granules showed crystal growth and decrease in dissolution to 52.68% and 48.37%, respectively, in 120 min. The overall cost for downstream processing of NCSD was up to 80% lower than that of NS. An innovation radar tool also concluded that the one-step NanoCrySP technology was more efficient and required less downstream processing than the two-step wet media milling approach for conversion of nanocrystals to OSD.

Evaluation of Different Techniques for Size Determination of Drug Nanocrystals: A Case Study of Celecoxib Nanocrystalline Solid Dispersion

Celecoxib (CEL) Nanocrystalline Solid Dispersion (CEL_NCSD) was generated by spray drying CEL, mannitol (MAN) and sodium lauryl sulfate (SLS) from a solvent mixture of methanol, acetone and water. The purpose of the work was to determine the size of CEL nanocrystals, investigate agglomeration and inspect dissolution of CEL_NCSD. Size determination was challenging as CEL nanocrystals are embedded in the matrix of MAN. Firstly, neat CEL_NCSD was analyzed using Scherrer equation. Secondly, MAN was dissolved in an aqueous stabilizer medium to selectively measure the size of CEL nanocrystals. Raman Spectra captured in Morphologi G3-ID confirmed the presence of CEL-only particles in the media. This dispersion gave D₉₀ values of 882 ± 170.34 nm in Zetasizer. Discriminatory dissolution studies confirmed total release of 34.61 ± 1.59%, 47.42 ± 0.24%, and 44.61 ± 1.11% at 120 min from a microsuspension (size 3 µm), a nanosuspension (media milled; size 660 nm) and CEL_NCSD, respectively. The dissolution profile of CEL_NCSD was similar to that of a nanosuspension (f2 72.24) instead of a coarse microsuspension. Thus, the present study revealed that optimized sample preparation is critical for the size determination of embedded drug nanocrystals in NCSD. Further, a discriminatory dissolution study substantiated that the size of CEL nanocrystals in CEL_NCSD is well below 1000 nm, thus showing a size-dependent improved dissolution profile.

Permeability Behavior of Nanocrystalline Solid Dispersion of Dipyridamole Generated Using NanoCrySP Technology

Nanocrystals research has been an area of significant interest lately, providing oral bioavailability benefits to solubility- and/or dissolution rate-limited drugs. Drug nanocrystals are generated using top-down or bottom-up technologies. Combination technologies (Nanoedge, Nanopure XP and SmartCrystal) have been recently developed to generate nanocrystals of improved properties. Our lab has also contributed in this field by providing a ‘novel’ platform technology, NanoCrySP, for the generation of nanocrystals. NanoCrySP-generated nanocrystals have improved the oral bioavailability of various molecules. In this study, we aim to assess the permeability behavior of nanocrystals generated by NanoCrySP. Three samples of Dipyridamole (DPM) drug were used in this study: (1) DPM (micron-sized powder), (2) nanocrystals of DPM (NS), generated by media milling (as control) and, (3) nanocrystalline solid dispersion containing DPM (NSD) in the matrix of mannitol (MAN), generated using NanoCrySP technology. In vitro (Caco-2 cell lines) and ex vivo (everted gut sac) studies were conducted in this work. Cellular permeability (P_app) from apical-to-basolateral side in Caco-2 cell monolayer was found to be in the order NS > NSD > DPM, which was the same as their apparent solubility values. Higher P_app from a basolateral-to-apical side suggested a significant contribution of the P-gp efflux transport for DPM, while NS exhibited much higher inhibition of the efflux mechanism than NSD. Both NS and NSD showed higher permeation from the jejunum region in the ex vivo everted gut sac study. Interestingly, P_app of NSD was similar to NS in ex vivo everted gut sac model, however, NSD showed higher mucoadhesion than NS and DPM in this study.