Efficient drug development of oseltamivir capsules based on process control, bioequivalence and PBPK modeling.

Oseltamivir phosphate is used to treat influenza. For registration of a generic product, bioequivalence studies are crucial, however, in vitro studies can sometimes replace the conventional human pharmacokinetic. To assess whether the dissolution profile is comparable with the in vivo release, physiologically based pharmacokinetic absorption models (PBPK) are being used. The aim of the study was to develop a generic capsule of oseltamivir phosphate 30 mg with process understanding and control, development of PBPK model and comparison of virtual bioequivalence study (VBE) to the real bioequivalence study that was also performed. For that, 30 mg capsules were prepared by wet granulation according to 22 full factorial design. The biobatch was prepared with the selected process and a batch was made with the API from the second manufacture. Both manufactures presented polymorph A and the second manufacture showed higher particle size. Product batches produced without adding water during granulation showed higher dissolution. The addition of water associated with higher conical mill speed, lowered the average weight of the capsules. The biobatch dissolution was similar to Tamiflu; also, they were bioequivalent. The crossover VBE between the biobatch and Tamiflu corroborated with the real bioequivalence study. The same result was found for the batch with higher particle size. PBPK model showed that computer simulations can help pharmaceutical companies to replace in vivo studies.

Challenging identification of polymorphic mixture: Polymorphs I, II and III in olanzapine raw materials.

Olanzapine (OLZ), a drug for the treatment of schizophrenia, presents in more than 60 crystal forms. Polymorphs I, II and III were reported, however, the preparation conditions for pure II and III have not been reported. Polymorph IV was reported but this form is actually polymorph II described at different temperature. The diversity of solid forms of OLZ, the change in the nomenclature found in the literature and the presence of polymorphic mixture in samples, increase the difficulty for a correct solid state characterization. Therefore, the goal was the polymorphic identification of three OLZ raw materials, highlighting the limitation of conventional techniques (typically used in analytical control) and the necessity to use a combination of advanced ones to solve this challenge. The samples were studied by conventional techniques such as powder X-ray diffraction, thermoanalytical techniques, infrared spectroscopy. In apart from that, synchrotron powder X-ray diffraction (SPXRD) and solid state nuclear magnetic resonance (ss-NMR) were used. All samples were in accordance with the pharmacopoeia criteria. However, the conventional techniques were not specific for the complete polymorphic identification. Therefore, a combination of advanced techniques (SPXRD and ss-NMR) was necessary to identify the mixture of polymorphs (I, II and III) in all samples.

Vibrational spectroscopic and Hirshfeld surface analysis of carvedilol crystal forms.

The drug carvedilol, used to treat cardiovascular conditions, is known to exist in distinct crystalline forms. Polymorphs II and III and the hydrate are characterized by variations in their molecular packing and conformation. This study deals with the spectroscopic (supported by quantum chemistry calculations) characterization of carvedilol structures. Band assignments were performed considering the isolated molecules and periodic calculations. We discuss the correlation between the vibrational modes and the intermolecular forces in the crystalline structures. Towards a better understanding of the intermolecular interactions, Hirshfeld surface was used. Besides band shifts related to stretching vibrations of N-H and O-H groups, differences between other modes have shown the possibility of using infrared spectroscopy to distinguish the crystal forms; technique routinely used in quality control of pharmaceutics. According to the spectroscopic analysis, the N-H groups participate in stronger bonds in the polymorph III, which contributes to its greater stability. With Hirshfeld surface we concluded that the bond with the nitrogen of the aliphatic chain participating as hydrogen acceptor in polymorph II is responsible for the pointy peaks in the fingerprint plot. This can explain why polymorph II shows lower dissolution in acid medium, as described in a previous work of our group.

Efavirenz dissolution enhancement III: Colloid milling, pharmacokinetics and electronic tongue evaluation.

Efavirenz (EFV), a non-nucleoside reverse transcriptase inhibitor (NNRTI), is part of first-line therapy for the treatment of human immunodeficiency virus type 1 infection (HIV-1/AIDS). This drug shows relatively low oral absorption and bioavailability, as well as high intra- and inter-subject variability. Several studies have shown that treatment failure and adverse effects are associated with low and high EFV plasma concentrations, respectively. Some studies suggest different EFV formulations to minimize inter-patient variability and improve its solubility and dissolution; however, all of these formulations are complex, using for instance, cyclodextrins, dendrimers and polymeric nanoparticles, rendering them inviable industrially. The aim of this work was to prepare simple and low-cost suspensions of EFV for improvement of solubility and dissolution rate by using colloid mill, spray or freeze-drying, and characterization of the powders obtained. The results demonstrated an increase in the dissolution rate of EFV, using 0.2% of sodium lauryl sulfate (SLS) and 0.2% of hydroxypropylcellulose (HPC) or hydroxypropylmetilcellulose (HPMC) in both freeze and spray dried powders. The pharmacokinetic studies demonstrated improved pharmacokinetic parameters for the formulation containing SLS and HPC. The powders obtained, which present enhanced dissolution properties, can be incorporated in a solid dosage form for treatment of AIDS in paediatric patients with promising results.

Further study of (+/-)-mefloquinium chloride solvates. Crystal structures of the hemihydrate and monohydrate of (+/-)-mefloquinium chloride, from data collected at 120 K.

The crystal structure of a monohydrate of (+/-)-mefloquinium chloride, (+/-)-[MEFHCl.(H(2)O)], has been obtained from data collected at 120 K. Further details of the crystal structure of a hemihydrate, (+/-)-[MEFHCl*(1/2)(H(2)O)], previously determined at room temperature, are also reported from data collected at 120 K. The structural data, along with X-ray powder patterns, infrared spectra (both mid and near IR ranges) and DSC data, provide definitive evidence for the two hydrates. Further attempts to completely resolve the crystal structure of a tetragonal solvated phase failed due to the considerable disorder, involving the solvates, either water or methanol, even at 120 K, however X-ray powder pattern and infrared spectral and DSC data for this phase are also reported. Comparisons of the data obtained for the hydrates in this study, with X-ray powder patterns and mid-infrared spectra of previously reported forms of (+/-)-mefloquinium chloride have highlighted erroneous assignments and allowed structural identification of previously and differently designated forms.