Polymorphism: an evaluation of the potential risk to the quality of drug products from the Farmácia Popular Rede Própria

The quality of drugs and drug products - Always guaranteed?

To ensure the efficacy, safety, and quality of drugs, several national and international guidelines and regulatory requirements exist. The most important international regulatory framework for quality is the collection of the guidelines ICH Q1-Q14 (International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use), which form the basis for the development and approval of medicinal products. Additionally, international and national pharmacopoeias and national regulatory authorities like Food and Drug Administration (FDA) and European Directory for the Quality of Medicines and HealthCare (EDQM) have to be considered during the lifecycle of a drug. Further, regular updates and optimization of processes and methods together with periodic audits and inspections of the manufacturing plants help to ensure compliance with the complex regulatory requirements for medicinal products. Although the pharmaceutical world seems to be very well regulated and controlled, several drug recalls per year have to be announced and conducted to remove defect products from the market and protect the patient from any potential health risk. This review article provides an overview of the most common reasons for such recalls presenting several historical and current cases with a detailed discussion of root causes. A specific focus lies on quality issues like drug degradation, impurity and nitrosamine contamination, lack of drug stability, occurrence and transformation of polymorphs, contamination with particulates and foreign matters, amongst others. The role of APIs, excipients and packaging will be discussed as well as the analytical challenges to detect, control and mitigate such quality issues. A final chapter will discuss the current situation and an outlook on emerging topics and future challenges for drug quality.

New Polymorphic Modifications of 6-Methyluracil: An Experimental and Quantum Chemical Study

Polymorphism of 6-methyluracil, which affects the regulation of lipid peroxidation and wound healing, has been studied by experimental and quantum chemical methods. Two known polymorphic modifications and two new crystalline forms were crystallized and characterized by single crystal and powder X-ray diffraction (XRD) methods as well as by the differential scanning calorimetry (DSC) method and infrared (IR) spectroscopy. The calculations of pairwise interaction energies between molecules and lattice energies in periodic boundary conditions have shown that the polymorphic form 6MU_I used in the pharmaceutical industry and two new forms 6MU_III and 6MU_IV, which can be formed due to temperature violations, may be considered as metastable. The centrosymmetric dimer bound by two N-H···O hydrogen bonds was recognized as a dimeric building unit in all of the polymorphic forms of 6-methyluracil. Four polymorphic forms have a layered structure from the viewpoint of interaction energies between dimeric building units. The layers parallel to the (100) crystallographic plane were recognized as a basic structural motif in the 6MU_I, 6MU_III, and 6MU_IV crystals. In the 6MU_II structure, a basic structural motif is a layer parallel to the (001) crystallographic plane. The ratio between the interaction energies within the basic structural motif and between neighboring layers correlates with the relative stability of the studied polymorphic forms. The most stable polymorphic form 6MU_II has the most anisotropic "energetic" structure, while the interaction energies in the least stable form 6MU_IV are very close in various directions. The modeling of shear deformations of layers in the metastable polymorphic structures has not revealed any possibility of these crystals to be deformed under external mechanical stress or pressure influence. These results allow the use of metastable polymorphic forms of 6-methyluracil in the pharmaceutical industry without any limitations.

Is it possible to predict the stability of a crystal structure under the influence of pressure? Quantum chemical study of ibuprofen crystals

Quantum chemical modeling was used to analyze the crystalline structure of ibuprofen under atmospheric pressure to determine the structural features, providing its stability under pressure.

Energy framework and solubility: a new predictive model in the evaluation of the structure–property relationship of pharmaceutical solid forms

Crystal structures with lower interaction energy tend to present higher aqueous solubility.

Polymorphism in early development: The account of MBQ-167

With McCrone's famous statement in mind, we set out to investigate the polymorphic behavior of a small-molecule dual inhibitor of Rac and Cdc42, currently undergoing preclinical trials. Herein, we report the existence of two polymorphs for 9-ethyl-3-(5-phenyl-1H-1,2,3-triazol-3-yl)-9H-carbazole (MBQ-167). These were characterized by differential scanning calorimetry, thermogravimetric analysis, Raman and Infrared spectroscopy, as well as powder and single crystal X-ray diffraction. The results obtained from the thermal analysis revealed that MBQ-167 form II undergoes an exothermic phase transition to form I, making this the thermodynamically stable form. An examination of the Burger-Ramberger rules for assigning thermodynamic relationships in polymorphic pairs indicate that this system is monotropic. The structure elucidation reveals that these forms crystallize in the orthorhombic (Pbca) and monoclinic (P2₁/n) space groups. A conformational analysis shows that the metastable form (form II) presents the most planar conformation along the significant torsion angles identified. Hirshfeld surface analysis confirms that van der Waals contacts are the primary interactions and only subtle differences in short contacts help differentiate each form. These findings support the notion that polymorphism is prevalent in organic molecules and that one should invest time and money probing possible polymorphs, particularly in early development as in the case of MBQ-167.

Challenges and opportunities of pharmaceutical cocrystals: a focused review on non-steroidal anti-inflammatory drugs

The focus of the review is to discuss the relevant and essential aspects of pharmaceutical cocrystals in both academia and industry with an emphasis on non-steroidal anti-inflammatory drugs (NSAIDs). Although cocrystals have been prepared for a plethora of drugs, NSAID cocrystals are focused due to their humongous application in different fields of medication such as antipyretic, anti-inflammatory, analgesic, antiplatelet, antitumor, and anti-carcinogenic drugs. The highlights of the review are (a) background of cocrystals and other solid forms of an active pharmaceutical ingredient (API) based on the principles of crystal engineering, (b) why cocrystals are an excellent opportunity in the pharma industry, (c) common methods of preparation of cocrystals from the lab scale to bulk quantity, (d) some latest case studies of NSAIDs which have shown better physicochemical properties for example; mechanical properties (tabletability), hydration, solubility, bioavailability, and permeability, and (e) latest guidelines of the US FDA and EMA opening new opportunities and challenges.

Biguanides: Species with versatile therapeutic applications

Biguanides are compounds in which two guanidine moieties are fused to form a highly conjugated system. Biguanides are highly basic and hence they are available as salts mostly hydrochloride salts, these cationic species have been found to exhibit many therapeutic properties. This review covers the research and development carried out on biguanides and accounts the various therapeutic applications of drugs containing biguanide group-such as antimalarial, antidiabetic, antiviral, anticancer, antibacterial, antifungal, anti-tubercular, antifilarial, anti-HIV, as well as other biological activities. The aim of this review is to compile all the medicinal chemistry applications of this class of compounds so as to pave way for the accelerated efforts in finding the drug action mechanisms associated with this class of compounds. Importance has been given to the organic chemistry of these biguanide derivatives also.

In Vitro Comparative Quality Assessment of Different Brands of Doxycycline Hyclate Finished Dosage Forms: Capsule and Tablet in Jimma Town, South-West Ethiopia

BACKGROUND

Persistent postmarket quality evaluation helps produce clear information on the current quality status of the different brands of a given drug and hence introduces a biopharmaceutical and therapeutically equivalent list of the products to the prescribers and users of it. This in turn facilitates access to essential medicines by breaking the high-cost barrier imposed by a few expensive brands of the product. This study was aimed at determining the quality and evaluating the equivalence of doxycycline hyclate capsules and tablets in Jimma, Ethiopia.

METHODS

Ten brands of doxycycline hyclate capsules and tablets were tested for product identity, dosage uniformity, assay, and in vitro dissolution; and tablets were tested for friability and hardness.

RESULTS

All investigated brands of doxycycline complied with the USP for dosage uniformity, an assay of the active ingredient, and single-point dissolution tests. One brand, D09, failed both hardness and friability tests. Comparisons of dissolution profiles applying fit factors confirmed that only brands D04, D06, and D07 had similarities with the innovator. Ratio test approaches also showed that significant variability exists between test products and comparators. Weibull model was found to provide the best adjustment curve for all brands, from model-dependent approaches employed for explaining the overall release of drug from the dosage forms.

CONCLUSIONS

Doxycycline is a biowaiver product. Hence, in vitro dissolution evaluation suffices its market approval. In this quality assessment study, however, the samples passed quality control tests, except D09 brand which failed friability; it has been revealed that five out of eight brands had problems with interchangeability. Only three doxycycline hyclate brands were found to be equivalent to the comparators.

A thermodynamic relationship and phase transition study involving two polymorphs of sulfamethoxazole: form I vs. form II

Two sulfamethoxazole polymorphs (form I and II) have been studied. The form II → form I transformation is observed via milling and dissolution in acetonitrile. A phase transition mechanism is proposed based on their supramolecular geometries.

Irbesartan desmotropes: Solid-state characterization, thermodynamic study and dissolution properties

Irbesartan (IBS) is a tetrazole derivative and antihypertensive drug that has two interconvertible structures, 1H- and 2H-tautomers. The difference between them lies in the protonation of the tetrazole ring. In the solid-state, both tautomers can be isolated as crystal forms A (1H-tautomer) and B (2H-tautomer). Studies have reported that IBS is a polymorphic system and its forms A and B are related monotropically. These reports indicate form B as the most stable and less soluble form. Therefore, the goal of this contribution is to demonstrate through a complete solid-state characterization, thermodynamic study and dissolution properties that the IBS forms are desmotropes that are not related monotropically. However, the intention is also to call attention to the importance of conducting strict chemical and in solid-state quality controls on the IBS raw materials. Hence, powder X-ray diffraction (PXRD) and Raman spectroscopy (RS) at ambient and non-ambient conditions, differential scanning calorimetry (DSC), hot stage microscopy (HSM), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM) techniques were applied. Furthermore, intrinsic dissolution rate (IDR) and structural stability studies at 98% relative humidity (RH), 25 °C and 40 °C were conducted as well. The results show that in fact, form A is approximately four-fold more soluble than form B. In addition, both IBS forms are stable at ambient conditions. Nevertheless, structural and/or chemical instability was observed in form B at 40 °C and 98% RH. IBS has been confirmed as a desmotropic system rather than a polymorphic one. Consequently, forms A and B are not related monotropically.

Solid-State Characterization of Spironolactone 1/3 Hydrate

Spironolactone (SPR) is a poorly water-soluble drug widely used for the treatment of various diseases. The objective of this study was to carry out the preparation and solid-state characterization of SPR 1/3 hydrate. The solid form was generated by an unreported recrystallization process in acetone and characterized for the first time by a combination of X-ray powder diffraction (XRD), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), equilibrium solubility, and an accelerated stability study. XRD, DSC, and TGA studies revealed that SPR 1/3 hydrated converts completely to form II after heating to 180°C. Solubility studies at 37°C showed that SPR 1/3 hydrate was statistically less soluble than SPR form II in all tested media and that SPR form II partially converts to SPR 1/3 hydrate in aqueous media. Accelerated stability studies demonstrated that both forms were physically and chemically stable up to 6 months (40°C/75% RH). We concluded that contamination of SPR 1/3 hydrate in SPR raw materials is undesirable. Taking this into account we recommend its polymorphic monitoring either in active pharmaceutical ingredients or commercial tablets by solid-state identification/quantification methods (XRD, DSC, TGA, and FTIR). Of these, XRD proved to be the most conclusive and accurate.

Revealing Polymorphic Phase Transformations in Polymer-Based Hot Melt Extrusion Processes

The inadvertent occurrence of polymorphic phase transformations in active pharmaceutical ingredients (APIs) during hot melt extrusion (HME) processes has been claimed to limit the application of this technique. Hence, the control of polymorphism would need to be addressed if there is any prospect of HME to be successfully implemented as an alternative solid dosage formulation strategy in integrated, continuous end-to-end pharmaceutical manufacturing settings. This work demonstrates that flufenamic acid (FFA), one of the most polymorphic APIs known, thus far, can be processed using temperature-simulated HME with polyethylene glycol (PEG) as polymeric carrier. At temperatures above the transition point of FFA forms III and I (42 °C), the induction time of the polymorphic phase transformation is longer than the average reported residence time in conventional HME processes (5 min). Moreover, it was demonstrated that thorough understanding of the thermodynamic and kinetic design space for the PEG-FFA system leads to polymorphic control in the produced crystalline solid dispersions. Ultimately, this investigation helps to gain fundamental understanding of the processing needs of crystalline solid dispersions, which will lead to the broader application of HME as a continuous manufacturing strategy for drug products containing APIs prone to polymorphism, representing about 80% of all APIs.

Avoiding irreversible 5-fluorocytosine hydration via supramolecular synthesis of pharmaceutical cocrystals

Supramolecular reaction of 5-FC with caffeine, p-aminobenzoic and caprylic acid gave rise to solid forms physically stable in humid environments.

New Polymorph Form of Dexamethasone Acetate

A new monohydrated polymorph of dexamethasone acetate was crystallized and its crystal structure characterized. The different analytical techniques used for describing its structural and vibrational properties were: single crystal and polycrystal X-ray diffraction, solid state nuclear magnetic resonance, infrared spectroscopy. A Hirshfeld surface analysis was carried out through self-arrangement cemented by H-bonds observed in this new polymorph. This new polymorph form appeared because of self-arrangement via classical hydrogen bonds around the water molecule.

Biowaiver Monographs for Immediate-Release Solid Oral Dosage Forms: Folic Acid

This work presents a review of literature and experimental data relevant to the possibility of waiving pharmacokinetic bioequivalence studies in human volunteers for approval of immediate-release solid oral pharmaceutical forms containing folic acid as the single active pharmaceutical ingredient. For dosage forms containing 5 mg folic acid, the highest dose strength on the World Health Organization Essential Medicines List, the dose/solubility ratio calculated from solubility studies was higher than 250 mL, corresponding to a classification as "not highly soluble." Small, physiological doses of folic acid (≤320 μg) seem to be absorbed completely via active transport, but permeability data for higher doses of 1-5 mg are inconclusive. Following a conservative approach, folic acid is classified as a Biopharmaceutics Classification System class IV compound until more reliable data become available. Commensurate with its solubility characteristics, the results of dissolution studies indicated that none of the folic acid products evaluated showed rapid dissolution in media at pH 1.2 or 4.5. Therefore, according to the current criteria of the Biopharmaceutics Classification System, the biowaiver approval procedure cannot be recommended for immediate-release solid oral dosage forms containing folic acid.