An Impedance-Based Method to Determine Reconstitution Time for Freeze-Dried Pharmaceuticals

The reconstitution of freeze-dried products is usually determined by visual inspection with the naked eye. This can inevitably lead to significant variability in the ability to detect complete reconstitution of the dried solid. It was thus the goal of our study to assess an automated method to monitor reconstitution of a freeze-dried protein drug product in its primary packaging. A newly developed measuring device was used to measure impedance. This was achieved by detecting minor changes in impedance of the reconstitution medium, which occurred because of solid material dissolving during the dissolution process. This measurement system was capable of consistently detecting the dissolution of the last visible residues of freeze-dried lyophilisates. The endpoint of reconstitution was defined at an impedance change of less than 1 Ω for at least 7 s. Finally, we compared reconstitution times determined by the automated impedance method with results obtained by a visual method. In contrast to human operators, the new method delivered both accurate and precise results. Besides detection of the reconstitution endpoint, the impedance method and apparatus can monitor reconstitution endpoints as well as reconstitution kinetics. This standardized method can therefore advantageously be used for the determination of the reconstitution endpoint

The Effect of Formulation, Process, and Method Variables on the Reconstitution Time in Dual Chamber Syringes

Reconstitution time of dried products is influenced by various factors including formulation, process, and reconstitution method itself. This manuscript describes factors affecting reconstitution in a dual chamber syringe using highly concentrated human monoclonal antibody and bovine serum albumin model formulations. Freezing and drying conditions had only minor impact on the reconstitution time, whereas the primary container and thus the geometry of the lyophilization cake played a major role. Prewarmed diluent and agitation decreased reconstitution time. For effective agitation, short displacements and high agitation frequencies were found to be desirable conditions to minimize reconstitution time for a given lyophilization cake while foam formation was minimized. The article also provides general strategies (e.g., reduction of lyophilized cake density, use of an optimized fill finish process, and suitable method parameters) to reduce reconstitution time, especially for drug product presented in a dual chamber syringe configuration. LAY ABSTRACT: Dried drug products need to be reconstituted to a liquid form before being applied parenteral. Reconstitution time is an important attribute and needs to be as fast as possible in order to serve patients' compliance. Reconstitution time is influenced by various factors including formulation, process, and the reconstitution method itself. The article provides general strategies (e.g., reduction of dried drug product cake density, use of an optimized fill finish process, and suitable method parameters) to reduce reconstitution time, especially for drug product presented in a dual chamber syringe. Fast reconstitution of lyophilisates in dual chamber syringe can be achieved by a combination of optimized manufacturing procedures and clear instructions for the end-user (e.g., roll syringe between palms to warm and agitate it to accelerate reconstitution)

A Method to Determine the Kinetics of Sulute Mixing in Liquid/Liquid Formulation Dual-Chamber Syringes

Dual-chamber syringes were originally designed to separate a solid substance and its diluent. However, they can also be used to separate liquid formulations of two individual drug products, which cannot be co-formulated due to technical or regulatory issues. A liquid/liquid dual-chamber syringe can be designed to achieve homogenization and mixing of both solutions prior to administration, or it can be used to sequentially inject both solutions. While sequential injection can be easily achieved by a dual-chamber syringe with a bypass located at the needle end of the syringe barrel, mixing of the two fluids may provide more challenges. Within this study, the mixing behavior of surrogate solutions in different dual-chamber syringes is assessed. Furthermore, the influence of parameters such as injection angle, injection speed, agitation, and sample viscosity were studied. It was noted that mixing was poor for the commercial dual-chamber syringes (with a bypass designed as a longitudinal ridge) when the two liquids significantly differ in their physical properties (viscosity, density). However, an optimized dual-chamber syringe design with multiple bypass channels resulted in improved mixing of liquids. LAY ABSTRACT: Dual-chamber syringes were originally designed to separate a solid substance and its diluent. However, they can also be used to separate liquid formulations of two individual drug products. A liquid/liquid dual-chamber syringe can be designed to achieve homogenization and mixing of both solutions prior to administration, or it can be used to sequentially inject both solutions. While sequential injection can be easily achieved by a dual-chamber syringe with a bypass located at the needle end of the syringe barrel, mixing of the two fluids may provide more challenges. Within this study, the mixing behavior of surrogate solutions in different dual-chamber syringes is assessed. Furthermore, the influence of parameters such as injection angle, injection speed, agitation, and sample viscosity were studied. It was noted that mixing was poor for the commercially available dual-chamber syringes when the two liquids significantly differ in viscosity and density. However, an optimized dual-chamber syringe design resulted in improved mixing of liquids

Small-Interfering RNA–Eluting Surfaces as a Novel Concept for Intravascular Local Gene Silencing

New drug-eluting stent (DES) methods have recently been demonstrated to improve outcomes of intravascular interventions. A novel technique is the design of gene-silencing stents that elute specific small-interfering RNAs (siRNAs) for better vascular wall regeneration. Although siRNAs used to alter gene expression have surpassed expectations in in vitro experiments, the functional and local delivery of siRNAs is still the major obstacle for the in vivo application of RNA interference. In this preliminary in vitro study we investigated a surface-immobilized siRNA delivery technique that would be readily adaptable for local intravascular applications in vivo. The transfection potency of gelatin coatings consisting of a specific siRNA complexed with polyethylenimine (PEI) was examined in primary human endothelial cells by flow cytometry and quantitative real-time polymerase chain reaction. Several media conditions, such as the presence or absence of serum during cultivation, were investigated. Furthermore, different siRNA and PEI amounts, as well as nitrogen/phosphate ratios, were tested for their transfection efficiency. Gelatin coatings consisting of PEI and siRNA against an exemplary endothelial adhesion molecule receptor achieved a significant knockdown of around 70%. The transfection efficiency of the coatings was not influenced by the presence of serum. The results of this preliminary study support the expectation that this novel coating may be favorable for local in vivo gene silencing (for example, when immobilized on stents or balloons for percutanous transluminal coronary angioplasty). However, further animal experiments are needed to confirm the translation into clinical practice. This intriguing technology leads the way to more sophisticated and individualized coatings for the post-DES era, toward silencing of genes involved in the pathway of intimal hyperplasia