Feasibility of Focused Beam Reflectance Measurement (FBRM) for Analysis of Pharmaceutical Suspensions in Preclinical Development

Drying behaviour and visualization of surfactants after co-spray drying of surfactant-stabilized aqueous suspensions

Surfactants are widely used in many industries as dispersants or flocculants for suspensions. As the addition of low concentrations of surfactant is sufficient to execute their effect, they barely alter the formulation composition. In this research it was examined whether surfactants, in particular polysorbate 80 (PS80), were suitable as suspension stabilizers for co-spray drying of drug-filler combinations. Therefore, their drying behaviour at different process and formulation settings was studied and mapped by means of fluorescently labelled PS80. Co-spray drying of 10% w/w aqueous suspensions stabilized with 0.1% w/w PS80 resulted in excessive loss of sticky powder in the conical lower part of the drying chamber and the powder conveyor ducts. Up to 16% of powder was lost in the first transporter (i.e. the first part of the conveyor ducts). The amount of powder deposited in the first transporter, and by extension the stickiness of the recovered powder, was correlated with the presence of PS80 on the surface of the spray dried particles. Redistribution of free surfactant molecules during droplet drying depended on the process and formulation parameters. Enrichment of PS80 at the particle surface was most pronounced after co-spray drying of liquid feedstocks with low suspended fraction at process conditions favouring rapid droplet drying.

Small-Scale Continuous Drug Product Manufacturing using Dropwise Additive Manufacturing and Three Phase Settling for Integration with Upstream Drug Substance Production

The pharmaceutical industry has traditionally relied on mass manufacturing to make its products. This has created multiple problems in the drug supply network, including long production times, inflexible and sluggish manufacturing and lack of personalized dosing. The industry is gradually adapting to these challenges and is developing novel technologies to address them. Continuous manufacturing and 3D printing are two promising techniques that can revolutionize pharmaceutical manufacturing. However, most research studies into these methods tend to treat them separately. This study seeks to develop a new processing route to continuously integrate a 3D printing platform (Drop-on-Demand, DoD, printing) with crystallization that is generally the final step of the active ingredient manufacturing. Accomplishing this integration would enable harnessing the benefits of each method- personalized dosing of 3D printing and flexibility and speed of continuous manufacturing. A novel unit operation, three-phase settling (TPS), is developed to integrate DoD with the upstream crystallizer. To ensure on-spec production of each printed dosage, two process analytical technology tools are incorporated in the printer to monitor drug loading in manufactured drug products in real time. Experimental demonstration of this system is carried out via two case studies: the first study uses an active ingredient celecoxib to test the standalone operation of TPS; the second study demonstrates the operation of the integrated system (crystallizer - TPS - DoD) to continuously make drug products for the active ingredient- lomustine. A dissolution test is also performed on the manufactured and commercial lomustine drug products to compare their dissolution behavior.

Design and Optimization of the Single-Stage Continuous Mixed Suspension-Mixed Product Removal Crystallization of 2-Chloro-N-(4-methylphenyl)propenamide

A continuously operated single-stage mixed suspension-mixed product removal (MSMPR) crystallizer was developed for the continuous cooling crystallization of 2-chloro-N-(4-methylphenyl)propanamide (CNMP) in toluene from 25 to 0 °C. The conversion of the previous batch to a continuous process was key to developing a methodology linking the synthesis and purification unit operations of CNMP and gave further insight in the development of continuous process trains for active pharmaceutical ingredient materials. By monitoring how parameters such as cooling and agitation rates influence particle size and the yield, two batch start-up strategies were compared. The second part of the study focused on developing and optimizing the continuous cooling crystallization of CNMP in the MSMPR crystallizer in relation to the yield by determining the effects of varying the residence time and the agitation rates. During the MSMPR operation, the plot of the focused beam reflectance measurement total counts versus time oscillates and reaches an unusual state of control. Despite the oscillations, the dissolved concentration was constant. The yield and production rate from the system were constant after two residence times, as supported by FTIR data. The overall productivity was higher at shorter residence times (τ), and a productivity of 69.51 g/h for τ = 20 min was achieved for the isolation of CNMP.

A flow-injection system exploiting focused beam reflectance applied to the determination of high concentrations of sulfate

To evaluate the grain size and particle number formed in a non-equilibrium flow mixing state, flow-injection analysis (FIA) was combined with focused beam reflectance measurement (FBRM). The influence of BaCl₂, PEG-4000, ethanol, flowrate, temperature and acidity on the dynamic formation of BaSO₄ particles was evaluated. Optimization parameters obtained were 5% BaCl₂ as the reagent, 2% PEG-4000 + 6% ethanol as the stabilizer and 0.3 mol L^-1 HCl as the carrier with 4 ml min^-1 flowrate, and the BaSO₄ particle size distribution in the system was in the 1-50 μm range. Under optimized conditions, the system was successfully used for the determination of high sulfate concentrations in the wet-process phosphoric acid process in the 3.2-48 g L^-1 (S_ct = 55c + 208, r = 0.998, n = 3) range for SO₄^2-. The relative standard deviation was less than 1.86% (n = 11), the detection limit was 0.95 g L^-1, the sample throughput reached 30 samples per h, recovery data were within the 97-106% range, and the results were consistent with those of gravimetry (RD < 3%). The system avoids the large error caused by high dilution and the slow analysis speed when measuring high sulfate concentrations.