Polymorphism in phenobarbital: discovery of a new polymorph and crystal structure of elusive form V

Predictors and associated factors with adverse drug reaction in people with epilepsy

OBJECTIVES

There is a need for early identification and intervention of Adverse Drug Reaction (ADR) to alleviate the unacceptably growing burden, morbidity, and mortality associated with People With Epilepsy (PWE). This study is aimed at identifying associated factors and predictors of ADR among PWE.

METHODS

It is an interviewer-administered questionnaire-based study consisting of 940 consenting participants aged 16 years and above attending epilepsy clinics for 5 years with diagnosis confirmed by International League against Epilepsy (ILAE) criteria and supported by Electroencephalography (EEG). Twenty-one-item Liverpool Adverse Effect Profile (LAEP) and 8-item Morinsky Medication Adherence Scale (MMAS) were used to assess ADR and adherence respectively.

RESULTS

The highest reported ADR in PWE were nervousness (34.3%), aggression (33.6%), and weight gain (32.3%). Specifically, 20.1% of the participants complained of memory problems. On the other hand, ADR associated with skin, mouth/gum and hair loss was 9.3%, 8.9%, and 7.2% respectively, and these were the lowest reported ADRs. Using the MMAS, 545(90.2%), 28(4.6%), and 31(5.1%) of PWE in this study were classified as having high, medium, and low adherence, respectively. Duration of Anti-Seizure Medication (ASM) use and duration of epilepsy were the major determinants of ADR in PWE on the regression model.

CONCLUSION

Duration of ASM use and duration of epilepsy are the major determinants of ADR in PWE. Effective strategies to identify and reduce ADR should be incorporated into the management of PWE by Health Care Providers (HCPs) to improve their quality of life.

Along the road to Crystal Structure Prediction (CSP) of pharmaceutical-like molecules

Computational methods used for predicting crystal structures of organic compounds are mature enough to be routinely used with many rigid and semi-rigid organic molecules. The usefulness of Crystal Structure Prediction...

Sensing technologies and experimental platforms for the characterization of advanced oral drug delivery systems

Complex and miniaturized oral drug delivery systems are being developed rapidly for targeted, controlled drug release and improved bioavailability. Standard analytical techniques are widely used to characterize i) drug carrier and active pharmaceutical ingredients before loading into a delivery device (to ensure the solid form), and ii) the entire drug delivery system during the development process. However, in light of the complexity and the size of some of these systems, standard techniques as well as novel sensing technologies and experimental platforms need to be used in tandem. These technologies and platforms are discussed in this review, with a special focus on passive delivery systems in size range from a few 100 µm to a few mm. Challenges associated with characterizing these systems and evaluating their effect on oral drug delivery in the preclinical phase are also discussed.

Insight into amoxicillin sodium heterosolvates and non-solvated form: crystal structures, phase transformation behaviors, and desolvation mechanism

Methanol and methyl acetate molecules played different roles in the formation of S_M–M amoxicillin sodium heterosolvate. A two-step desolvation mechanism of novel heterosolvates was proposed.

Emerging role of primary heterogeneous nucleation in pharmaceutical crystallization

Crystallization is an important and difficult to control unit operation in the pharmaceutical industry. Crystallization can control molecular (i.e., polymorphism) and particulate (i.e., particle size and crystal habit) properties of active pharmaceutical ingredient (API). Moreover, these molecular and particulate properties govern the manufacturability, stability, and biopharmaceutical performance of the API and drug product. Nucleation is a key step and primary heterogeneous nucleation is a common mode of nucleation during crystallization. Hence, it is important to understand the parameters affecting primary heterogeneous nucleation, to achieve desirable properties in crystalline APIs. Primary heterogeneous crystallization has usually been linked to the surface characteristics like topography and functionality of the heteronucleant. The review outlines recent findings in the primary heterogeneous crystallization with specific emphasis on its pharmaceutical applications including regulatory considerations. Molecular-level mechanisms governing heteronucleation and subsequent outcome in terms of molecular as well as particulate-level properties of API have also been discussed. Moreover, general guidance for the selection of heteronucleant has also been included. Heterogeneous crystallization is a promising tool for efficient crystallization of API having properties for optimal pharmaceutical performance.

Surface-induced crystallization of pharmaceuticals and biopharmaceuticals: A review

Despite the wide occurrence of crystallization in the pharmaceutical industry, deep understanding and fine control of the process remain a tricky issue. Nevertheless, the successful manufacturing of finished pharmaceutical products, as well as the structural determination of biopharmaceuticals, depend on the size, form, shape and purity of the crystals. The ability of substrates with precise chemistry and topological features to induce nucleation has been thoroughly assessed during the recent years. This paper reviews the major advances and discoveries in controlling small molecule drug and protein crystallization by means of engineered surfaces. By designing superficial properties and morphology, it has been possible to tune the polymorph outcome, shorten the nucleation induction time, impose specific crystal shapes, control the crystal size and carry out crystallization at very low supersaturation levels. Such achievements underline the potential of surface-induced crystallization to provide an ideal platform for the study of the nucleation process and gain control over its stochastic nature.

Survey and analysis of crystal polymorphism in organic structures

With the intention of producing the most comprehensive treatment of the prevalence of crystal polymorphism among structurally characterized materials, all polymorphic compounds flagged as such within the Cambridge Structural Database (CSD) are analysed and a list of crystallographically characterized organic polymorphic compounds is assembled. Classifying these structures into subclasses of anhydrates, salts, hydrates, non-hydrated solvates and cocrystals reveals that there are significant variations in polymorphism prevalence as a function of crystal type, a fact which has not previously been recognized in the literature. It is also shown that, as a percentage, polymorphic entries are decreasing temporally within the CSD, with the notable exception of cocrystals, which continue to rise at a rate that is a constant fraction of the overall entries. Some phenomena identified that require additional scrutiny include the relative prevalence of temperature-induced phase transitions among organic salts and the paucity of polymorphism in crystals with three or more chemical components.

Multidrug Cocrystal of Anticonvulsants: Influence of Strong Intermolecular Interactions on Physiochemical Properties

A drug-drug cocrystal of two anticonvulsants, lamotrigine and phenobarbital, is presented. In the crystal structure, molecules form heterodimers via N-H···O and N-H···N hydrogen bonding. The intrinsic dissolution rate (IDR) and solubility of the cocrystal were measured in phosphate buffer (pH 7.2) and simulated gastric fluid (without pepsin), and compared to pure APIs. Dissolution experiments found suppressed IDR of the cocrystal with rates in the order pure PB > pure LTG > cocrystal. The solubility measurements were consistent with the dissolution behavior. The presence of strong heterodimers in the cocrystal compared to weaker homodimers in the parent drugs is implicated for the reduced solubility and dissolution rate.

Influence of Chemical Functionality on the Rate of Polymer-Induced Heteronucleation

Polymer-induced heteronucleation can dramatically increase the nucleation rate of pharmaceuticals. However, directly comparing the heteronucleation rates of different polymer functionalities is often convoluted with changing physical or structural aspects of heteronuclei. Here, we report a methodology for comparing nucleation efficiencies of different functionalities on polymer heteronuclei of uniform topology with the goal of identifying those functionalities that best accelerate nucleation of a model pharmaceutical. It was found that the previously employed design for additives to speed acetaminophen crystallization underperforms a modified framework that accounts for the effect of competitive solvent binding. These findings are informed by a survey of interactions from the CSD and not only serve to aid in the controlled crystallization of pharmaceuticals, but also provide insight into the mechanism of heteronucleation.

A new polymorph of isoimperatorin

Isoimperatorin is a naturally occurring furocoumarin and is being considered as a potential chemoprevention. Only one crystal form of isoimperatorin (Form I) was reported during previous research so that an investigation of polymorphism of isoimperatorin was successfully undertaken. A new polymorph of isoimperatorin was discovered through comprehensive polymorph screening experiments. Their structures were elucidated by single-crystal structure analysis and extensively characterized by XRPD, DSC, FT-IR, and SEM. The results showed that the crystal structure and thermal properties of the new polymorph (Form II) were significantly different from those of Form I. Thermodynamic stability and phase transformation were also discussed in detail.

Reversible crystal-to-crystal chiral resolution: making/breaking non-bonding S⋯O interactions

Unconventional non-covalent interactions are the key to reversible chiral resolution in polycrystalline samples of a small, achiral molecule.

Enhanced NMR Discrimination of Pharmaceutically Relevant Molecular Crystal Forms through Fragment-Based Ab Initio Chemical Shift Predictions

Chemical shift prediction plays an important role in the determination or validation of crystal structures with solid-state nuclear magnetic resonance (NMR) spectroscopy. One of the fundamental theoretical challenges lies in discriminating variations in chemical shifts resulting from different crystallographic environments. Fragment-based electronic structure methods provide an alternative to the widely used plane wave gauge-including projector augmented wave (GIPAW) density functional technique for chemical shift prediction. Fragment methods allow hybrid density functionals to be employed routinely in chemical shift prediction, and we have recently demonstrated appreciable improvements in the accuracy of the predicted shifts when using the hybrid PBE0 functional instead of generalized gradient approximation (GGA) functionals like PBE. Here, we investigate the solid-state ¹³C and ¹⁵N NMR spectra for multiple crystal forms of acetaminophen, phenobarbital, and testosterone. We demonstrate that the use of the hybrid density functional instead of a GGA provides both higher accuracy in the chemical shifts and increased discrimination among the different crystallographic environments. Finally, these results also provide compelling evidence for the transferability of the linear regression parameters mapping predicted chemical shieldings to chemical shifts that were derived in an earlier study.