Design and evaluation of celecoxib porous particles using melt sonocrystallization

Ultrasound mechanisms and their effect on solid synthesis and processing: a review

Ultrasound proves to be an effective technique for intensifying a wide range of processes involving solids and, as such, is often used to improve control over both solids formation and post-treatment stages. The intensifying capabilities of ultrasonic processing are best interpreted in the context of the chemical, transport, and mechanical effects that occur during sonication. This review presents an overview of how ultrasound influences the processing and synthesis of solids across various material classes, contextualized within an ultrasound effect framework. By describing the mechanisms underlying the different effects of ultrasound on the solid synthesis and processing, this review aims to facilitate a deeper understanding of the current literature in the field and to promote more effective utilization of ultrasound technology in solid synthesis and processing.

The role of ultrasound in pharmaceutical production: sonocrystallization

Objectives

The main aim of this review was to develop a critical discussion of the key role ultrasound (US) can play on the production of active pharmaceutical ingredients (APIs) by discussing the versatile effect this type of energy produces.

Methods

The different crystallization techniques that can be assisted and improved by US are discussed in the light of the available US devices and the effect pursued by application of US energy. Simple and complex analytical methods to monitor API changes are also discussed.

Key findings

The countless achievements of API US-assisted production are summarized in a table, and outstanding effects such as narrower particle size distribution; decreased particle size, induction time, metastable zone and supersaturation levels; or a solubility increase are critically discussed.

Conclusions

The indisputable advantages of sonocrystallization over other ways of API production have been supported on multiple examples, and pending goals in this field (clarify the effect of US frequency on crystallization, know the mechanism of sonocrystallization, determine potential degradation owing to US energy, avoid calculation of the process yield by determining the concentration of the target drug remaining in the solution, etc.) should be achieved.

Celecoxib confinement within mesoporous silicon for enhanced oral bioavailability

We investigate the physicochemical characteristics of celecoxib (CEL) entrapped within particles of an oxidized porous silicon matrix (pSiox); determine the oral dose response of CEL compared to pure drug and innovator formulation; develop in vivo-in vitro correlation (IVIVC). CEL was loaded into a pSiox matrix by solvent partitioning, with the physical state of the CEL characterized by FTIR, DSC, TGA and XRD, and correlated with in vitro dissolution behavior. Single dose pharmacokinetic parameters of orally dosed CEL were determined in fasted rats for aqueous suspensions of pure CEL, Celebrexr and CEL-pSiox microparticles. Physicochemical testing of CEL-pSiox formulation confirmed the entrapment of CEL within porous nanostructure in an amorphous or non-crystalline form. CEL-pSiox demonstrated superior pharmacokinetics compared with CEL particles or Celebrexr, i.e. increased absolute bioavailability (96.2% vs. 65.2% vs. 88.1%), increased C

Melt sonocrystallized piroxicam for oral delivery: particle characterization, solid state analysis, and pharmacokinetics

OBJECTIVES

The present study investigates the effect of particle engineering technique on powder properties and pharmacokinetics of piroxicam (PXM).

METHODS

PXM was subjected to melt sonocrystallization to obtain product designated as MSCPXM and characterized for various pharmacotechnical parameters, performance characteristics and pharmacokinetic evaluation.

RESULTS

Micromeritic and rheological properties were found to be superior to the original form (OFPXM). On melt sonocrystallization, solubility and intrinsic dissolution rate were enhanced by 76.45% and 33.33%, respectively. Solid state evaluation by DSC and XRPD ruled out possibilities of polymorph formation but confirmed decreased crystallinity index. SEM analysis revealed uniformly shaped smaller drug particles of MSCPXM as compared to PXM. The thermodynamic stability of MSCPXM was monitored by XRPD and the sample was stable even after 3 months of storage at 40 ± 2°C and 75 ± 5% RH. The MSCPXM was formulated as immediate release tablets (F1 - F4) and evaluated with reference tablets of OFPXM (F0). F2 was identified as best formulation with suitable tablet characteristics and in-vitro drug release profile. Pharmacokinetic evaluation of F2 in rats supported the in-vitro data with 2.08-fold increase in bioavailability achieved at 4.8 ± 1.7 h with MSCPXM as compared to OFPXM.

CONCLUSIONS

Conclusively, melt sonocrystallization offered an efficient, solvent-free technique that can be exploited for particle designing of drugs with favorable pharmaceutical properties.

Drug solubility: importance and enhancement techniques

Solubility, the phenomenon of dissolution of solute in solvent to give a homogenous system, is one of the important parameters to achieve desired concentration of drug in systemic circulation for desired (anticipated) pharmacological response. Low aqueous solubility is the major problem encountered with formulation development of new chemical entities as well as for the generic development. More than 40% NCEs (new chemical entities) developed in pharmaceutical industry are practically insoluble in water. Solubility is a major challenge for formulation scientist. Any drug to be absorbed must be present in the form of solution at the site of absorption. Various techniques are used for the enhancement of the solubility of poorly soluble drugs which include physical and chemical modifications of drug and other methods like particle size reduction, crystal engineering, salt formation, solid dispersion, use of surfactant, complexation, and so forth. Selection of solubility improving method depends on drug property, site of absorption, and required dosage form characteristics.

Investigations in the physical mechanism of sonocrystallization

This paper addresses the issue of mechanistic aspects of sonocrystallization with approach of coupling experiments with simulations of bubble dynamics. The major experimental result of our study is that, as compared to a mechanically agitated crystallization system, the dominant crystal size (or median) of the crystal size distribution (CSD) of sonocrystallization systems is smaller, but span of CSD is larger. The CSD is influenced by nucleation rate and growth rate. The nature of convection in the medium is found to be the crucial factor. In a mechanically agitated system, uniform velocity field prevails in crystallization volume, due to which both dominant crystal size and span of CSD reduce. The convection in a sonicated system is of a different kind. This convection has two components, viz. microturbulence (or micro-convection), which is continuous oscillatory motion of liquid induced by radial motion of cavitation bubble, and shock waves, which are discrete, high pressure amplitude waves emitted by the bubble. These components have different impact on crystallization process due to their nature. Shock waves increase the nucleation rate and microtubulence governs growth of the nuclei. However, the effect of shock waves is more marked than microturbulence (or micro-convection). Nucleation rate shows an order of magnitude rise with sonication, while growth rate (and hence the dominant crystal size) reduces with sonication as compared to the mechanically agitated system.

Study of polymorphs of progesterone by novel melt sonocrystallization technique: a technical note

A large number of pharmaceuticals exhibit polymorphism; 23% steroids, 60% sulfonamides, and 70% of barbiturates have shown this property. In this study, we have investigated and compared a new technique termed as melt sonocrystallization (MSC) with melt and sonocrystallization (SC) for induction of polymorphism in progesterone (PRG). Polymorphs were characterized by DSC, XRD, FT-IR, and FT Raman spectroscopy. Melt sonocrystallized progesterone (MSC-PRG) contained both the polymorphs, more soluble form II along with less soluble form I, whereas melt progesterone (M-PRG) and sonocrystallized progesterone (SC-PRG) contained only form I. Improvement in dissolution characteristics of both the polymorphs were compared and form II was found to be more readily soluble than form I in deionized water. Reduction in mean particle size of PRG during SC was also determined using laser diffractometer. During stability testing (40°C/75% RH) for 1 month, metastable form II of MSC-PRG was found to be transformed into its more stable state. MSC technique was thus found as a useful tool for induction of polymorphism.

Particle engineering using sonocrystallization: salbutamol sulphate for pulmonary delivery

The aim of present work was to produce fine elongated crystals of salbutamol sulphate (SS) by sonocrystallization for pulmonary delivery and compare with micronized and spray dried SS (SDSS) for in vitro aerosolization behavior. Application of ultrasound during anti-solvent crystallization resulted in fine elongated crystals (sonocrystallized SS; SCSS) compared to aggregates of large irregular crystals obtained without sonication. Higher sonication amplitude, time, concentration and lower processing temperatures favored formation of smaller crystals with narrow particle size distribution (PSD). SCSS was separated from dispersion by spray drying in the form of loose aggregates (SD-SCSS). The fine particle fraction (FPF) of formulations with coarse lactose carrier in cascade impactor increased from 16.66% for micronized SS to 31.12% for SDSS (obtained by spray drying aqueous SS solution) and 44.21% for SD-SCSS, due to reduced cohesive/adhesive forces and aerodynamic size by virtue of elongated shape of crystals. SD-SCSS was stable without any change in crystallinity and aerodynamic behavior for 3 months at 40 degrees C/75% RH, but amorphous SDSS showed recrystallization with poor aerosolization performance on storage. Sonocrystallization, a rapid and simple technique is reported for production of SS crystals suitable for inhalation delivery.

Ultrasound assisted engineering of lactose crystals

PURPOSE

To engineer lactose crystals of desired size, shape, surface and particle size distribution (PSD) as a carrier for dry powder inhalers (DPI) by ultrasound assisted in-situ seeding.

METHODS

Lactose crystals were obtained from solution by ultrasound assisted in-situ seeding, followed by growth in viscous glycerin solution. The crystals were characterized for physical properties and 63-90 mum size fractions of different batches were mixed with salbutamol sulphate (SS) and compared for in-vitro deposition.

RESULTS

Cooling crystallization with stirring for 10-20 h resulted in crystals with wide PSD and varied shape. Application of ultrasound resulted in rapid and complete crystallization in 5 min with rod-shaped fine crystals (15-30 microm) and narrow PSD. In-situ seeded batches yielded micro-fine rod-shaped seed crystals. Seeding followed by growth in glycerin showed desirable size, high elongation ratio, smooth surface and narrow PSD, while growth under stirring showed high elongation ratio with rough surface. Crystals grown in glycerin showed highest dispersibility and fine particle fraction (FPF) of SS.

CONCLUSIONS

Ultrasound assisted in-situ seeding, followed by ordered growth in glycerin offers rapid technique for separation of nuclei induction from crystal growth yielding desirable characteristics for better dispersion and in-vitro deposition when employed as DPI carrier.

Development of spray-dried co-precipitate of amorphous celecoxib containing storage and compression stabilizers

The purpose of this study was to obtain an amorphous system with minimum unit operations that will prevent recrystallization of amorphous drugs since preparation, during processing (compression) and further storage. Amorphous celecoxib, solid dispersion (SD) of celecoxib with polyvinyl pyrrollidone (PVP) and co-precipitate with PVP and carrageenan (CAR) in different ratios were prepared by the spray drying technique and compressed into tablets. Saturation solubility and dissolution studies were performed to differentiate performance after processing. Differential scanning calorimetry and X-ray powder difraction revealed the amorphous form of celecoxib, whereas infrared spectroscopy revealed hydrogen bonding between celecoxib and PVP. The dissolution profile of the solid dispersion and co-precipitate improved compared to celecoxib and amorphous celecoxib. Amorphous celecoxib was not stable on storage whereas the solid dispersion and co-precipitate powders were stable for 3 months. Tablets of the solid dispersion of celecoxib with PVP and physical mixture with PVP and carrageenan showed better resistance to recrystallization than amorphous celecoxib during compression but recrystallized on storage. However, tablets of co-precipitate with PVP and carageenan showed no evidence of crystallinity during stability studies with comparable dissolution profiles. This extraordinary stability of spray-dried co-precipitate tablets may be attributed to the cushioning action provided by the viscoelastic polymer CAR and hydrogen bonding interaction between celecoxib and PVP. The present study demonstrates the synergistic effect of combining two types of stabilizers, PVP and CAR, on the stability of amorphous drug during compression and storage as compared to their effect when used alone.

Crystal engineering of active pharmaceutical ingredients to improve solubility and dissolution rates

The increasing prevalence of poorly soluble drugs in development provides notable risk of new products demonstrating low and erratic bioavailability with consequences for safety and efficacy, particularly for drugs delivered by the oral route of administration. Although numerous strategies exist for enhancing the bioavailability of drugs with low aqueous solubility, the success of these approaches is not yet able to be guaranteed and is greatly dependent on the physical and chemical nature of the molecules being developed. Crystal engineering offers a number of routes to improved solubility and dissolution rate, which can be adopted through an in-depth knowledge of crystallisation processes and the molecular properties of active pharmaceutical ingredients. This article covers the concept and theory of crystal engineering and discusses the potential benefits, disadvantages and methods of preparation of co-crystals, metastable polymorphs, high-energy amorphous forms and ultrafine particles. Also considered within this review is the influence of crystallisation conditions on crystal habit and particle morphology with potential implications for dissolution and oral absorption.