Modernizing lyophilization of pharmaceuticals in unit doses via continuous manufacturing

This work shows an alternative pharmaceutical freeze-drying concept, which makes it possible to move from batch to continuous manufacturing. The continuous flow of vials is achieved by suspending them over a moving track. The vials move through chambers which have different pressure and temperature conditions and are separated by a load-lock system. Uniformity in freezing conditions is demonstrated by combining the Vacuum Induced Surface Freezing method and convective freezing

A new concept for the continuous freeze-drying of pharmaceutical products in unit doses

The feasibility of the continuous freeze-drying technology has been studied simulating the process using a functional version of the continuous freeze-dryer. Heat transfer during freezing and primary drying was studied reproducing the same conditions occurring in the continuous process. Various process conditions and formulations (containing both amorphous and crystallizing excipients) were investigated in order to better understand the range of applicability of this new process. It has been demonstrated that the cycle duration of the continuous freeze-drying was comparable to that of a conventional batch process, and the aesthetic acceptability of the product was achieved. The continuous freeze-drying technology also impacted positively on inter- and intra-vial heterogeneity. The internal structure of the products, as analyzed by SEM, showed that the continuous freeze-drying led to a structure with larger pores, homogeneously distributed within the product. In addition to these advantages, we have found that the continuous technology can reduce processing time up to 5 times with respect to the batch technology, and the equipment size up to 10 times

Intensification of the freeze drying process by the control of both freezing and primary drying steps

The problem of optimization of freeze-drying cycles is addressed, with emphasis in both freezing and primary drying steps. In particular, this study shows that the control of the nucleation event produces more uniform batches (as ice nucleation is induced in all the vials of batch almost at the same time and temperature) and allows a marked reduction in the duration of the optimized cycle (if compared to cycles carried out with conventional stochastic nucleation

Protein crystallisation in agarose gel, a cheap and versatile technique

Crystallization in hydrogels is not a frequent practice in bio-crystallography, although the benefits are multiple: prevents convection and crystal sedimentation, acts as impurity filter, etc., and have been proven to be the cheapest means to produce protein crystals of high quality similar to those obtained under microgravity conditions. Moreover, gel grown protein crystals are excellent candidates as seeds to produce crystals of bigger size for neutron diffraction or as media for crystals delivery in serial femtosecond crystallography. Hydrogel should also be considered to exert control over the nucleation and growth processes. In this work we will present our most recent studies on the influence of agarose over the nucleation and growth of protein crystals. Crystal number and size was successfully tuned in a wide range of agarose concentration while keeping constant other conditions. Using five model proteins we demonstrate that the influence of gel content is independent of the protein nature, allowing the mathematical prediction of crystals flux and size with little experimental effort. The convection free environment obtained even at low agarose concentration permits the obtention of high homogeneous micro-crystals slurries that could be used for serial crystallography application or for the mass production of enzyme crystals for industrial application. Last, we will also show how it allows to explore the phase diagram under a kinetic regime that may facilitate the growth of different polymorphs

Rational design of freeze-drying formulations: a molecular dynamics approach

The freezing step plays a fundamental role in the freeze drying process, as it determines product morphology and overall efficiency. The current approach to the selection of freezing conditions is however non-systematic, resulting in poor process control. Here we show how mathematical models, and a design space approach, can guide the selection of the optimal freezing protocol, focusing on both process performance and protein stability

Agarose, the gel to tailor your protein crystals

The growth of protein crystals in gel has proved to date to be the cheapest means to produce protein crystals of high quality similar to those obtained under microgravity conditions (Gavira et al., 2020; Robert & Lefaucheux, 1988; Snell & Helliwell, 2005). Gels create a stable environment for crystals to grow in convection-free conditions avoiding sedimentation and the formation of aggregates and increasing crystals uniformity. The use of agarose has allowed progress in the limitations of crystal size and quality and even to obtain protein crystals inaccessible by other techniques (Sica et al., 1994). In this work we have exploited the nucleation inducing ability of agarose gels in diffusiondominated environments. Crystal size was successfully tuned in a wide range of agarose, protein and precipitant concentrations. The impact of gel content on crystal size resulted to be independent of the specific protein, allowing the mathematical prediction of crystals size and pointing out the exclusivity of the physical interactions between the gel and the protein to explain the observed behaviour. The versatility of the technique and the fine-tuning of the nucleation flux was demonstrated by crystallizing five different model proteins using two different techniques, batch and counter-diffusion. In addition, the potential of agarose to be used as a growth and delivery medium for serial crystallography applications has been proven by preparing unidimensional micro-crystals slurries in 0.1 % (w/v) gel