Sabiruddin Mirza

Solid form screening – A review

Solid form screening, the activity of generating and analysing different solid forms of an active pharmaceutical ingredient (API), has become an essential part of drug development. The multi-step screening process needs to be designed, performed and evaluated carefully, since the decisions made based on the screening may have consequences on the whole lifecycle of a pharmaceutical product. The selection of the form for development is made after solid form screening. The selection criteria include not only pharmaceutically relevant properties, such as therapeutic efficacy and processing characteristics, but also intellectual property (IP) issues. In this paper, basic principles of solid form screening are reviewed, including the methods used in experimental screening (generation, characterisation and analysis of solid forms, data mining tools, and high-throughput screening technologies) as well as basics of computational methods. Differences between solid form screening strategies of branded and generic pharmaceutical manufacturers are also discussed.

Pharmaceutical co-crystals–an opportunity for drug product enhancement

By maximizing our understanding of materials and the relative importance of interactions on all levels (i.e., molecular, particle, powder, product), we can improve the manufacture of drug dosage forms and thus meet target specifications for mechanical durability, stability and biopharmaceutical performance. Pharmaceutical co-crystals are the latest material being explored in order to enhance drug properties using this bottom-up approach. In this review we provide a general introduction to pharmaceutical co-crystals. We also address common aspects of co-crystal formation, discuss screening strategies and outline methodologies for co-crystal functionality. Pharmaceutical co-crystals that have a distinct solid phase possess a unique set of properties, thus co-crystal formation can act as an advantageous alternative to other solid-state modification techniques. More research is needed in order to scale up co-crystal systems and implement manufacturing of final dosage forms on large scale.

Microfluidic assembly of multistage porous silicon–lipid vesicles for controlled drug release

A reliable microfluidic platform for the generation of stable and monodisperse multistage drug delivery systems is reported. A glass-capillary flow-focusing droplet generation device was used to encapsulate thermally hydrocarbonized porous silicon (PSi) microparticles into the aqueous cores of double emulsion drops, yielding the formation of a multistage PSi-lipid vesicle. This composite system enables a large loading capacity for hydrophobic drugs.

Microfluidics-assisted engineering of polymeric microcapsules with high encapsulation efficiency for protein drug delivery

In this study, microfluidic technology was employed to develop protein formulations. The microcapsules were produced with a biphasic flow to create water-oil-water (W/O/W) double emulsion droplets with ultrathin shells. Optimized microcapsule formulations containing 1% (w/w) bovine serum albumin (BSA) in the inner phase were prepared with poly(vinyl alcohol), polycaprolactone and polyethylene glycol. All the particles were found to be intact and with a particle size of 23-47 μm. Furthermore, the particles were monodisperse, non-porous and stable up to 4 weeks. The encapsulation efficiency of BSA in the microcapsules was 84%. The microcapsules released 30% of their content within 168 h. This study demonstrates that microfluidics is a powerful technique for engineering formulations for therapeutic proteins.

Microfluidic Templated Mesoporous Silicon–Solid Lipid Microcomposites for Sustained Drug Delivery

A major challenge for a drug-delivery system is to engineer stable drug carriers with excellent biocompatibility, monodisperse size, and controllable release profiles. In this study, we used a microfluidic technique to encapsulate thermally hydrocarbonized porous silicon (THCPSi) microparticles within solid lipid microparticles (SLMs) to overcome the drawbacks accompanied by THCPSi microparticles. Formulation and process factors, such as lipid matrixes, organic solvents, emulsifiers, and methods to evaporate the organic solvents, were all evaluated and optimized to prepare monodisperse stable SLMs. FTIR analysis together with confocal images showed the clear deposition of THCPSi microparticles inside the monodisperse SLM matrix. The formation of monodisperse THCPSi-solid lipid microcomposites (THCPSi-SLMCs) not only altered the surface hydrophobicity and morphology of THCPSi microparticles but also remarkably enhanced their cytocompatibility with intestinal (Caco-2 and HT-29) cancer cells. Regardless of the solubility of the loaded therapeutics (aqueous insoluble, fenofibrate and furosemide; aqueous soluble, methotrexate and ranitidine) and the pH values of the release media (1.2, 5.0, and 7.4), the time for the release of 50% of the payloads from THCPSi-SLMC was at least 1.3 times longer than that from the THCPSi microparticles. The sustained release of both water-soluble and -insoluble drugs together with a reduced burst-release effect from monodisperse THCPSi-SLMC was achieved, indicating the successful encapsulation of THCPSi microparticles into the SLM matrix. The fabricated THCPSi-SLMCs exhibited monodisperse spherical morphology, enhanced cytocompatibility, and prolonged both water-soluble and -insoluble drug release, which makes it an attractive controllable drug-delivery platform.

Influence of solvents on the variety of crystalline forms of erythromycin

The influence of the organic solvents widely used in the pharmaceutical industry (acetone, methylethylketone, ethanol, and isopropanol) both in the presence and in the absence of water on the crystallization behavior of erythromycin (Em), a clinically relevant antibiotic of the macrolide group, was investigated. It was observed that despite a high preference for water as a guest molecule, Em rather easily forms solvates with the organic solvents studied. Consequently, 4 distinct solvates of Em have been isolated by recrystallization: acetonate, methylethylketonate, ethanolate, and isopropanolate. It was established that in a pure organic solvent, or 1∶9 or 1∶1 water-organic solvent mixtures, the corresponding solvate is always crystallized. However, the recrystallization of erythromycin from 2∶1 water-organic solvent (excluding methylethylketone) mixture results in the formation of a crystal hydrate form. X-ray powder diffraction revealed the isostructurality of the solvates with acetone and methylethylketone. Thermogravimetric analysis showed that the loss of volatiles by all of the solvated crystals is nonstoichiometric. The desolvation behavior of the solvates with the organic solvents studied by means of variable-temperature x-ray powder diffraction indicates that in contrast to erythromycin dihydrate, they belong to a different class of solvates—those that produce an amorphous material upon desolvation.

Insight into the solubility and dissolution behavior of piroxicam anhydrate and monohydrate forms

The aim of the present study was two-fold: (1) to investigate the effect of pH and presence of surfactant sodium lauryl sulphate (SLS) on the solubility and dissolution rate of two solid-state forms of piroxicam (PRX), anhydrate (PRXAH) and monohydrate (PRXMH), and (2) to quantitatively assess the solid-phase transformation of PRXAH to PRXMH in slurry with a special interest to the impact on the solubility and dissolution behavior of the drug. X-ray powder diffractometry (XRPD), Raman spectroscopy and scanning electron microscopy (SEM) were used for characterization of the solid-state forms. Phase transformation was monitored in slurry by means of in-line Raman spectroscopy, and the partial least squares (PLS) regression model was used for predicting the amount of PRXMH. The results showed that the solubility and dissolution rate of PRXAH were higher compared to PRXMH at different pHs. The pH and presence of SLS together affected the solubility and dissolution rate of different PRX forms. The lowest solubility values and dissolution rates for PRX forms were observed in distilled water (pH 5.6) at 37 °C. The changes in the dissolution rate could be explained by the hydrate formation during solubility testing. The rate of hydrate formation was also dependent on the pH of the dissolution medium.

Nanodispersions of taxifolin: impact of solid-state properties on dissolution behavior.

Nanosizing is an advanced formulation approach to address the issues of poor aqueous solubility of active pharmaceutical ingredients. Here we present a procedure to prepare a nanoparticulate formulation with the objective to enhance dissolution kinetics of taxifolin dihydrate, a naturally occurring flavonoid with antioxidant, anti-inflammatory, and hepatoprotective activities. Polyvinylpirrolidone was selected as a carrier and the solid nanodispersions of varying compositions were prepared by a co-precipitation technique followed by lyophilization. The formulation technology reported herein resulted in aggregate-free, spherical particles with the mean size of about 150 nm, as observed by scanning electron microscopy and measured by photon correlation spectroscopy. Furthermore, the co-precipitation process caused taxifolin dihydrate to convert into an amorphous form as verified by X-ray powder diffraction, differential scanning calorimetry, hot stage microscopy and Raman spectroscopy. Finally, in vitro dissolution behavior of the nanodispersion of taxifolin was shown to be superior to that of either pure drug or a drug-polymer physical mixture, reaching 90% of taxifolin released after 30 min. Such enhanced drug release kinetics from the nanodispersion was attributed to both the reduced particle size and the loss of crystallinity.

Crystal Morphology Engineering of Pharmaceutical Solids: Tabletting Performance Enhancement

Crystal morphology engineering of a macrolide antibiotic, erythromycin A dihydrate, was investigated as a tool for tailoring tabletting performance of pharmaceutical solids. Crystal habit modification was induced by using a common pharmaceutical excipient, hydroxypropyl cellulose, as an additive during crystallization from solution. Observed morphology of the crystals was compared with the predicted Bravais–Friedel–Donnay–Harker morphology. An analysis of the molecular arrangements along the three dominant crystal faces [(002), (011), and (101)] was carried out using molecular simulation and thus the nature of the host–additive interactions was deduced. The crystals with modified habit showed improved compaction properties as compared with those of unmodified crystals. Overall, the results of this study proved that crystal morphology engineering is a valuable tool for enhancing tabletting properties of active pharmaceutical ingredients and thus of utmost practical value.

Biopharmaceutical study of nanosystems containing betulin for inhalation administration

Betulin, a triterpenoid present in birch bark, possesses a broad spectrum of biological activity. Its bioavailability is limited by low solubility in water whereas the shape and size of particles are not suited for administration via inhalation. One of the main drawbacks of inhalation preparations is low bioavailability because of the sedimentation of particles in the mouth. The present work was aimed at a biopharmaceutical study of nanosystems with betulin for administration via inhalation. Nanosystems were characterized by photon-correlation spectroscopy, differential scanning calorimetry, and x-ray powder diffraction. In addition, their dissolution profile was obtained by the Dissolution test. It is established that the obtained nanosystems with betulin exhibit high bioavailability, have optimal physicochemical properties for inhalation administration, and ensure deposition of betulin in the lower part of the respiratory tract.