Drying capacity of a continuous vibrated fluid bed dryer - Statistical and mechanistic model development

The drying capacity of a continuous vibrated fluid bed dryer was studied using a DoE by varying microcrystalline cellulose content in the formulation, water amount in the twin-screw granulation, inlet air temperature, air flow rate and the acceleration of the horizontal fluid-bed. Temperature and humidity profiles were measured along the dryer using wireless sensors. For the parameter space explored in this study, acceleration was the most influential process parameter of the dryer regarding the resulting granule moisture content. An empirical model was developed that allowed for fast and accurate moisture content prediction that could be incorporated into an enhanced control strategy. In addition, a mechanistic model was formulated that allow for prediction of temperature and moisture profiles, and most importantly the moisture content of the granules inside the dryer. The mechanistic model can be integrated to other unit operation models to provide overall understanding of an integrated continuous process line. The mechanistic model also makes it possible to define the equipment design requirements (e.g., length of the dryer) to meet the specific needs in terms of drying capacity, temperature and moisture profile.

Bench to batch: Linking pharmaceutical powder flow characterisation, intermediate bulk container discharge and video observations

Five well known excipients and a model drug substance with varied particle properties and bulk behaviour were chosen for the study. Based on the results APAP, NaCMC-XL, mannitol and DCPA were selected for a design to understand the impact of different blends. Two pilot scale unvented IBCs were used in the study. The IBC discharge rates were measured using a catch balance and the mode of flow and powder behaviour inside the IBC was recorded using a camera. The videos inside the IBC showed that regardless of flow mode, for powder to flow from the IBC an air burst was necessary. This was similar to observations when emptying water from a bottle. The extent of the air flow inside the IBC was strong and could possibly result in fluidisation segregation. The discharge curves of 15° and 30° hopper half angles were very similar, which was explained by the vertical air movement in the steeper hopper, which reduces the particle acceleration. Several good indicators of flow/no flow in the IBCs were found. However, for predicting the discharge rate there was a linear correlation between flow through an orifice and IBC discharge rate.

Effect of shape on the physical properties of pharmaceutical tablets

Despite a well-established process understanding, quality issues for compressed oral solid dosage forms are frequently encountered during various drug product development and production stages. In the current work, a non-destructive contact ultrasonic experimental rig integrated with a collaborative robot arm and an advanced vision system is presented and employed to quantify the effect of the shape of a compressed tablet on its mechanical properties. It is observed that these properties are affected by the tablet geometric shapes and found to be linearly sensitive to the compaction pressures. It is demonstrated that the presented approach significantly improves the repeatability of the experimental waveform acquisition. In addition, with the increased confidence levels in waveform acquisition accuracy and corresponding pressure and shear wave speeds due to improved measurement repeatability, we conclude that pharmaceutical compact materials can indeed have a negative Poisson's ratio, therefore can be auxetic. The presented technique and instrument could find critical applications in continuous tablet manufacturing, and its real-time quality monitoring as measurement repeatability has been significantly improved, minimizing product quality variations.

Faster to First-time-in-Human: Prediction of the liquid solid ratio for continuous wet granulation

In early development, when active pharmaceutical ingredient (API) is in short supply, it would be beneficial to reduce the number of experiments by predicting a suitable L/S ratio before starting the product development. The aim of the study was to decrease development time and the amount of API needed for the process development of high drug load formulations for continuous twin-screw wet granulation (TSWG). Mixer torque rheometry was used as a pre-formulation tool to predict the suitable L/S ratios for granulation experiments. Three different values that were based on the MTR curves, were determined and assessed for their ability to predict the suitable L/S ratio for TSWG. Three APIs (allopurinol, paracetamol and metformin HCl) were used as model substances in high drug load formulations containing 60% drug substance. The MCC-mannitol ratio was varied to assess the optimal composition for the high-dose formulations. The API solubility affected the mixer torque rheometer (MTR) curves and the optimum L/S ratio for TSWG. The highly soluble metformin needed a much lower L/S ratio compared with allopurinol and paracetamol. A design space was determined for each API based on granule flowability and tablet tensile strength. The flowability of the granules and tensile strength of the tablets improved with an increasing L/S ratio. The MCC-mannitol filler ratio had a significant effect on tabletability for paracetamol and metformin, and these APIs having poor compaction properties needed higher MCC ratios to achieve the 2 MPa limit. The MCC-mannitol ratio had no effect on the granule flow properties. Instead, API properties had the largest influence on both granule flow properties and tensile strength. Based on this study, both the L/S ratio and MCC-mannitol ratio are crucial in controlling the critical quality attributes in high drug load formulations processed by TSWG. The optimum flow and tablet mechanical properties were achieved when using 75:25 MCC-mannitol ratio. Both start of the slope and 2/3 of the L/S ratio at the maximum torque in MTR provided a solid guideline to aim for in a TSWG experiment.

Monoaminoxidase inhibitors as a cause of serotonin syndrome – a systematic case review based on meta-analytic principles

Introduction

Serotonin syndrome (SS) is a toxic state characterized by increased serotonin activity. It has been suggested that severe serotonin syndrome usually involves monoaminoxidase inhibitors (MAOIs).

Objectives

To quantify in how far severe SS is associated with MAOIs.

Methods

Systematic review and quantitative analysis of all SS cases published between 1 January 2004 and 31 December 2014. Severe SS was defined as cases, either requiring intensive care or resulting in death. Cases were included if they met the diagnostic criteria for SS according to at least one of the three diagnostic criteria systems (Hunter, Radomski and Sternbach).

Results

Of the 299 included cases, 118 (39%) met the definition for severe SS. Eight cases had insufficient information to enable severity classification. Of the severe cases, 48 (40%) involved a MAOI. Of these, 67% related to psychiatric MAOIs, such as phenelzine and moclobemide and 33% to a somatic MAOI, such as methylene blue and linezolid. Of the remaining 173 non-severe SS cases, 24 cases (13%) involved a MAOI. In these, 12% related to a psychiatric MAOI and 83% to a somatic MAOI. One case (4%) had a combination of both. The odds ratio for MAOI involvement in severe versus non-severe serotonin syndrome was 4.3 (CI 2.4 – 7.5; p < 0.001).

Conclusions

In the majority of published case reports, drugs other than MAOIs are involved in serotonin syndrome, even in severe cases. MAOIs are, however, more common in severe serotonin syndrome than in non-severe cases.

Conflict of interest

M. Ott: scientific advisory board member of Astra Zeneca, Sweden. U. Werneke: received funding for educational activities on behalf of Norrbotten Region; Astra Zeneca, Eli Lilly, Janssen, Novartis, Otsuka/Lundbeck, Servier, Shire, Sunovion. Others: None

Powder flow from an intermediate bulk container - Discharge predictions and experimental evaluation

Powders are usually dispensed, blended, and transferred between different manufacturing steps in so-called Intermediate Bulk Containers (IBCs), and discharge from an IBC plays a critical role in the ability to manufacture high-quality tablets. To better understand IBC discharge, the flow behavior of selected excipients was comprehensively characterized using a number of techniques including the Hausner ratio/Carr's index, Erweka flow test, FlowPro flow test, shear test and wall friction test as well as FT4 powder rheometer experiments. Jenike's hopper design methodology was then used to predict the minimum non-arching outlet diameter and the mode of flow. Furthermore, the discharge rate from an IBC was predicted using a simple model that takes into account gravity and aerodynamic drag. The predictions were experimentally verified by measuring the discharge rate from a 20 L IBC using five commonly-used excipients. The small-scale Erweka flow test provided the best prediction of the full-scale IBC discharge experiment. Furthermore, a simple model that relied only on the particle size of the material and the diameter of the discharge opening was found to predict the IBC discharge rate remarkably well.

Twin-screw granulation and high-shear granulation: The influence of mannitol grade on granule and tablet properties

Granule structure has a key influence on tablet critical quality attributes. The ability to control this structure through excipient choice is an important part of formulation development. Mannitol is a popular diluent and the choice of input grade has been shown to impact granule properties. Allopurinol formulations containing two grades of mannitol (Pearlitol 160C and 200SD) were prepared by wet-granulation (twin-screw and high-shear) at different liquid/solid ratios (0.3 and 0.6 g/g). The particle and bulk properties were characterised by a range of techniques and linked to flow performance and tablet tensile strength during compression on a rotary tablet press. During granulation, 200SD underwent a polymorphic transition from a mixture of α and β to predominantly β. This transition was accompanied by a morphology change. Mannitol needles were formed, giving more porous granules with a higher specific surface area, which led to poorer flow properties but higher tablet tensile strength. This study concludes that understanding the effect of mannitol grade is a crucial part of formulation selection.

Characterization of microcrystalline cellulose spheres and prediction of hopper flow based on a μ(I)-rheology model

The objective of this study was to characterize the rheology of a pharmaceutical material in the context of the µ(I)-rheology model and to use this model to predict powder flow in a manufacturing operation that is relevant to pharmaceutical manufacturing. The rheology of microcrystalline cellulose spheres was therefore characterized in terms of the μ(I)-rheology model using a modified Malvern Kinexus rheometer. As an example of an important problem in pharmaceutical manufacturing, the flow of these particles from a hopper was studied experimentally and numerically using a continuum Navier-Stokes solver based on the Volume-Of-Fluid (VOF) interface-capturing numerical method. The work shows that the rheology of this typical pharmaceutical material can be measured using a modified annular shear rheometer and that the results can be interpreted in terms of the μ(I)-rheology model. It is demonstrated that both the simulation results and the experimental data show a constant hopper discharge rate. It is noted that the model can suffer from ill-posedness and it is shown how an increasingly fine grid resolution can result in predictions that are not entirely physically realistic. This shortcoming of the numerical framework implies that caution is required when making a one-to-one comparison with experimental data.

Comparison between integrated continuous direct compression line and batch processing - The effect of raw material properties

There is a current trend in pharmaceutical manufacturing to shift from traditional batch manufacture to continuous manufacturing. The purpose of this study was to test the ability of an integrated continuous direct compression (CDC) line, in relation to batch processing, to achieve consistent tablet quality over long processing periods for formulations with poor flow properties or with a tendency to segregate. The study design included four industrially relevant formulations with different segregation indices and flow properties induced through different grades of the Active Pharmaceutical Ingredient (API), paracetamol, and major filler as well as varying the amount of API. The performance metrics investigated were content, uniformity of content, tablet weight, and tablet strength. The overall process stability over time was significantly improved with the CDC line as compared to the batch process. For all the formulations with a high API content, the CDC line provided better or equal uniformity of content and tablet weight as compared to batch. The CDC line was especially efficient in providing a stable content and tablet weight for poorly flowing formulations containing the standard, cohesive, grade of API. The only formulation that performed better in the batch process was the formulation with a low API content. Thus, for this formulation, the batch process achieved lower variation in tablet content since maintaining a low feed rate for the API proved challenging in the CDC line. In addition, some of the API became stuck in the CDC line between feeding and tableting, most likely at the funnel in the mixer inlet, highlighting the need for properly designed interfaces between units. The insensitivity of the CDC line towards poor flow indicates that one could use direct compression at high drug load compositions of poorly flowing powder blends that could not be processed via batch manufacturing.

Understanding the tendency of amorphous solid dispersions to undergo amorphous-amorphous phase separation in the presence of absorbed moisture

Formulation of an amorphous solid dispersion (ASD) is one of the methods commonly considered to increase the bioavailability of a poorly water-soluble small-molecule active pharmaceutical ingredient (API). However, many factors have to be considered in designing an API-polymer system, including any potential changes to the physical stability of the API. In this study, the tendency of ASD systems containing a poorly water-soluble API and a polymer to undergo amorphous-amorphous phase separation was evaluated following exposure to moisture at increasing relative humidity. Infrared spectroscopy was used as the primary method to investigate the phase behavior of the systems. In general, it was observed that stronger drug-polymer interactions, low-ASD hygroscopicity, and a less hydrophobic API led to the formation of systems resistant to moisture-induced amorphous-amorphous phase separation. Orthogonal partial least squares analysis provided further insight into the systems, confirming the importance of the aforementioned properties. In order to design a more physically stable ASD that is resistant to moisture-induced amorphous-amorphous phase separation, it is important to consider the interplay between these properties.

Smoking increases the incidence of complicated diverticular disease of the sigmoid colon

BACKGROUND AND AIMS

The aim of this study was to establish whether smoking is associated with complicated diverticular disease and adverse outcomes of operative treatment of diverticular disease. Smoking has been associated with increased rate of perforations in acute appendicitis as well as failure of colonic anastomosis in patients resected for colonic tumours. It has also been suggested that smoking is a risk factor for complicated diverticular disease of the colon.

MATERIAL AND METHODS

Retrospective investigation of records of 261 patients electively operated for diverticular disease in Helsinki University Central Hospital during a period of five years.

RESULTS

The smokers underwent sigmoidectomy at a younger age than the non-smokers (p = 0.001) and they had an increased rate of perforations (p = 0.040) and postoperative recurrent diverticulitis episodes (p = 0.019).

CONCLUSIONS

We conclude that smoking increases the likelihood of complications in diverticulosis coli. The development of complicated disease also seems to proceed more rapidly in smokers.Key words: Sigmoid resection; laparoscopy; laparoscopic sigmoidectomy; smoking and diverticular disease; complicated diverticular disease; diverticulitis.

Estimation of the transition temperature for an enantiotropic polymorphic system from the transformation kinetics monitored using Raman spectroscopy

Polymorphism is a frequently encountered phenomenon in organic materials and is particularly important for pharmaceuticals. For enantiotropically related polymorphs, one important property of the polymorphic pair is the thermodynamic transition temperature. The transition temperature is sometimes difficult to determine experimentally due to the rapid transformation between the two polymorphic forms in solution. Due to its relatively rapid spectral acquisition rate, as well as the possibility of in-line monitoring, Raman spectroscopy is ideally suited to monitoring the kinetics of transformation between different solid-state forms. In this study, it was demonstrated that the transition temperature could be estimated from polymorphic transformation profiles obtained from real-time in situ Raman data. Using this method, the estimated transition temperature for flufenamic acid was in good agreement with the previously published value. These results suggest that Raman spectroscopy may be a useful method to determine transition temperatures in systems not amenable to other methods.

Manipulating Theophylline Monohydrate Formation During High-Shear Wet Granulation Through Improved Understanding of the Role of Pharmaceutical Excipients

PURPOSE

To investigate the effect of common pharmaceutical excipients on the kinetics of theophylline monohydrate formation during high-shear wet granulation.

MATERIALS AND METHODS

A mixture of anhydrous theophylline and the excipient was granulated in a high-shear granulator, using water as the granulation liquid. Non-contact Raman spectroscopy was used to monitor the rate of transformation of anhydrate to hydrate during the granulation process. The kinetics of conversion was also monitored in slurries of theophylline whereby the excipients were added to the aqueous phase. Optical microscopy was used to visualize the transformation and to measure the linear growth rates of hydrate crystals in the presence and absence of the excipients.

RESULTS

At pharmaceutically relevant amounts of excipient, the transformation kinetics of theophylline was unchanged for the majority of excipients tested. However, when granulating with low concentrations of some commonly used polymeric binders, the transformation kinetics could be significantly retarded. For example, methylcellulose polymers delayed both the onset of hydrate formation as well as retarding the transformation rate. When 0.3% (w/w) of hydroxypropyl methylcellulose was added to a model formulation containing 30% (w/w) theophylline anhydrous, the formation of the monohydrate could be completely prevented over the time period of the granulation experiment, without significantly affecting the granular properties. Microscopic observations of hydrate formation in the presence of the polymer revealed that the polymers that inhibited hydrate formation reduced the hydrate crystal growth rates and influenced hydrate morphology.

CONCLUSIONS

Raman spectroscopy is a useful technique to monitor hydrate formation during wet granulation. Some commonly used polymeric pharmaceutical excipients can be used to manipulate theophylline hydrate formation in aqueous pharmaceutical environments. These excipients may affect either the nucleation and/or the growth of the hydrate phase.

Monitoring of mannitol phase behavior during freeze-drying using non-invasive Raman spectroscopy

In this study, the feasibility of using Raman spectroscopy as a fast, non-invasive, non-destructive technique to monitor crystallization and polymorphic transformations during freeze-drying is assessed using mannitol as the model compound. In-line process monitoring was achieved by interfacing a Raman spectrometer with a fiber-optically coupled, long-working-distance probe to a freeze-drier. By analyzing the process data using principal component analysis, it was possible to extract valuable information pertaining to ice and mannitol crystallization points, the polymorphic form of mannitol, and dehydration of the mannitol hydrate. In conclusion, Raman spectroscopy is a potentially useful technique to monitor physical changes during freeze-drying.

Pharmacokinetics and pharmacodynamics analysis of transdermal iontophoresis of 5-OH-DPAT in rats: in vitro-in vivo correlation

Pharmacokinetics and dopaminergic effect of dopamine agonist 5-OH-DPAT in vivo were determined following transdermal iontophoresis in rats based on drug concentration in plasma (C(p)) and dopamine levels in striatum (C(DA)). Correlation of the in vitro transport with the pharmacokinetic-pharmacodynamic (PK-PD) profiles was characterized in the transport in dermatomed rat skin (DRS) and rat stratum corneum (RSC). The integrated in vivo PK-PD and in vitro transport models successfully described time course of C(p), C(DA), and in vitro flux in DRS and RSC. Population value of steady-state flux (J(ss)) in vivo (31 nmol/cm(2) . h with 95% confidence interval (CI) = 20-41) is closer to J(ss) in vitro in DRS (61 nmol/cm(2) . h, CI = 54-67) than in vitro J(ss) in RSC (98 nmol/cm(2) . h, CI = 79-117). On the other hand, skin release rate constant (K(R)) in vivo was similar to the K(R) in RSC (4.8/h, CI = 2.4-7.1 vs. 2.6/h, CI = 2.5-2.6). Kinetic lag time (t(L)) in vivo was negligible, which is close to in vitro t(L) in RSC (0.0 h, CI = 0.0-0.1). Based on nonlinear mixed-effect modeling, profiles of C(p) and C(DA) were successfully predicted using in vitro values of J(ss) in DRS with K(R) and t(L) in RSC. A considerable dopaminergic effect was achieved, indicating the feasibility to reach therapeutically effective concentrations of 5-OH-DPAT upon transdermal iontophoresis.