Pharmaceutical evaluation of early development candidates “the 100 mg-approach”

Pharmacokinetic evaluation of poorly soluble compounds formulated as nano- or microcrystals after intraperitoneal injection to mice

Intraperitonial (i.p.) delivery during initial stages of drug discovery can allow efficacy readouts for compounds which have suboptimal pharmacokinetics (PK) due to poor physiochemical properties and/or oral bioavailability. A major limitation for widespread use of i.p. administration is the paucity of published data and unclear mechanisms of absorption, particularly when using complex formulations. The aim of the present study was to investigate the PK of poorly soluble compounds with low oral bioavailability when administered i.p. as crystalline nano- and microsuspensions. Three compounds, with varying aqueous solubility (2, 7, and 38 µM, at 37 °C), were dosed to mice at 10 and 50 mg/kg. In vitro dissolution confirmed that nanocrystals dissolved faster than microcrystals and hence were expected to result in higher exposure after i.p. dosing. Surprisingly, the increase in dissolution rate with decrease in particle size did not result in higher in vivo exposure. In contrast, the microcrystals showed higher exposure. The potential of smaller particles to promote access to the lymphatic system is hypothesized and discussed as one plausible explanation. The present work demonstrates the importance of understanding physicochemical properties of drug formulations in the context of the microphysiology at the delivery site and how that knowledge can be leveraged to alter systemic PK.

Synthesis, Characterization, and Stability Assessment for the Benzoate, Hydrochloride, Malonate, and Nicotinate Salts of Bedaquiline

Bedaquiline has been approved as a combination therapy to treat multi-drug-resistant tuberculosis in adults ≥ 18 years old. The citrate, fumarate, phosphate, and tartrate salts have obtained patents, but the structures for these moieties have not been extensively described in the literature; only the powder X-ray patterns have been published. To expand the knowledge of the bedaquiline structure, this study provides detailed information for the synthesis, elucidation, characterization, and stability of four additional new potential molecular entities, namely, benzoate, hydrochloride (HCl), nicotinate, and malonate salts. The salts were formed using a 1:1 ratio of the counter ions (acids) to a 30 mg equivalent of the bedaquiline free base. The principles of the International Conference on Harmonization Q6 were used to characterize the new salts and their stability-indicating parameters were evaluated at 0, 3, and 6 months under accelerated conditions of 40 °C and 75% relative humidity. The benzoate salt exhibited the lowest tendency to lose its chemical potency. Aside from the HCl salt, the others retained their chemical structure, displaying long-term stability. All salts were non-hygroscopic and the hydrated benzoate and nicotinate salts were stable to dehydration. Regarding their chemical potencies, thermal analysis, chemical stability, and water sorption potential, the salts were ranked as follows: benzoate > malonate > nicotinate > HCl.

In Vitro–In Vivo Relationship in Mini-Scale—Enabling Formulations of Corallopyronin A

In vivo studies in mice provide a valuable model to test novel active pharmaceutical ingredients due to their low material need and the fact that mice are frequently used as a species for early efficacy models. However, preclinical in vitro evaluations of formulation principles in mice are still lacking. The development of novel in vitro and in silico models supported the preclinical formulation evaluation for the anti-infective corallopyronin A (CorA). To this end, CorA and solubility-enhanced amorphous solid dispersion formulations, comprising povidone or copovidone, were evaluated regarding biorelevant solubilities and dissolution in mouse-specific media. As an acidic compound, CorA and CorA-ASD formulations showed decreased solubilities in mice when compared with human-specific media. In biorelevant biphasic dissolution experiments CorA-povidone showed a three-fold higher fraction partitioned into the organic phase of the biphasic dissolution, when compared with CorA-copovidone. Bioavailabilities determined by pharmacokinetic studies in BALB/c mice correlated with the biphasic dissolution prediction and resulted in a Level C in vitro–in vivo correlation. In vitro cell experiments excluded intestinal efflux by P-glycoprotein or breast cancer resistance protein. By incorporating in vitro results into a physiologically based pharmacokinetic model, the plasma concentrations of CorA-ASD formulations were predicted and identified dissolution as the limiting factor for bioavailability.

Supersaturated formulations of poorly soluble weak acid drugs evaluated in rodents; a case study

In the present study we describe a way of working to overcome oral administration challenges in an early preclinical project. As candidate drugs were obtained, the preclinical delivery route was replaced by the intended route of the product and resources were allocated to optimize the oral absorption. Two main approaches were followed in order to formulate a selected weak acid, AZ'403, for oral administration in large scale toxicological studies and the early clinical phases. Both approaches relies on the suppression of precipitation from obtained supersaturated solutions achieved either by amorphous solid dispersions (using hydroxypropyl methylcellulose acetate succinate, HPMC-AS) or crystalline salts (sodium and potassium salts). In vivo studies in rodents were performed to evaluate oral AZ'403 absorption from amorphous and crystalline formulations, using nano- and micro crystalline particles of the neutral form, as references. The oral absorption of AZ'403 formulated using both approaches was significantly higher compared with the references. The improvements in overall exposures were 7-100 times during the investigated conditions. The pharmacokinetic profiles implied that both solid dispersions and crystalline salts of AZ'403 generated supersaturation in the small intestine in rodents and indicated that both approaches may be ways forward for subsequent late stage product development.

Novel solid forms of insomnia drug suvorexant with improved solubility and dissolution: accessing salts from a salt solvate route

Suvorexant (SRX) is a dual orexin receptor antagonist used for the treatment of insomnia.

Recent developments in pharmaceutical salts: FDA approvals from 2015 to 2019

Around half of the new molecular entities approved by the US Food and Drug Administration (FDA) are pharmaceutical salts. The pharmaceutical salts have been on a continuous growth trajectory since the approval of the first salt form in 1939. This review aims to provide updates on pharmaceutical salts approved by the FDA between 2015 and 2019. The five-year drug-approval database contains 61 pharmaceutical salts, featuring a diverse range of counterions; however, hydrochlorides are the most abundant. The chemical structures of all pharmaceutical salts in each class are presented here, along with their therapeutic indications and date of approval. The reason behind the selection of a particular counterion and the technical superiority achieved by the salt form over the free active pharmaceutical ingredient base are also discussed.

Bioanalysis and Quadrupole-Time of Flight-Mass Spectrometry Driven In Vitro Metabolite Profiling of a New Boronic Acid-Based Anticancer Molecule

(E/Z)-(4-(3-(2-((4-chlorophenyl)amino)-4-(dimethylamino)thiazol-5-yl)-2-(ethoxy carbonyl)-3-oxoprop-1-en-1-yl)phenyl) boronic acid, a newly developed molecule having anticancer activity serves as a potential candidate for the further drug development process. In this study, to ascertain the anticancer potential of the molecule, we screened it against different cell lines and compared the activity against the standard drug doxorubicin. The molecule showed promising activity at a low concentration against almost all cell lines used in the study. Apart from that, the molecule was characterized for its pKa and a precise reverse phase high-performance liquid chromatography bioanalytical method has been developed. The method was validated according to the United States of Food and Drug Administration bioanalytical guideline and was found to produce linear response over the calibration range of 0.8–25 μg/mL. Inter- and intra-day accuracy were found to be in the range of 93.44–99.74%, whereas precision [% coefficient of variation (CV)] for inter- and intra-day was ranged between 1.63 and 5.79%, and 0.87 and 6.96%, respectively. The bioanalytical stability testing was carried out in different conditions including 8 h benchtop, 12 h autosampler and three freeze–thaw cycles. The analyte was stable in all the tested stability conditions. Finally, an in vitro metabolite identification study was conducted using quadrupole-time of flight-mass spectrometer, and two metabolites have been identified.

Effect of Solid Forms on Physicochemical Properties of Valnemulin

To improve the physicochemical properties of valnemulin (VLM), different solid forms formed by VLM and organic acids, including tartaric acid (TAR), fumaric acid (FUM), and oxalic acid (OXA), were successfully prepared and characterized by using differential scanning calorimetry (DSC), scanning electron microscope (SEM), X-ray powder diffraction (XRPD), and Fourier-transform infrared spectroscopy (FT-IR). The excess enthalpy Hex between VLM and other organic acids was calculated by COSMOthermX software and was used to evaluate the probability of forming multi-component solids between VLM and organic acids. By thermal analysis, it was confirmed that multi-component solid forms of VLM were thermodynamically more stable than VLM itself. Through dynamic vapor sorption (DVS) experiments, it was found that three multi-component solid forms of VLM had lower hygroscopicity than VLM itself. Furthermore, the intrinsic dissolution rate of VLM and its multi-component forms was determined in one kind of acidic aqueous medium by using UV-vis spectrometry. It was found that the three multi-component solid forms of VLM dissolved faster than VLM itself.

A case study where pharmaceutical salts were used to address the issue of low in vivo exposure

The present active pharmaceutical ingredient (API) is a lipophilic compound with a significant risk of not achieving therapeutic plasma concentrations due to solubility-limited absorption. The aim of the presented studies was to investigate whether three novel salts of a new selected candidate in the cardiovascular therapy area could be applied to improve intestinal absorption and the subsequent in vivo exposure. Three salts (chloride, hydrogen sulfate, and hemi-1.5-naphtalenedisulphonate) of the compound were manufactured and investigated regarding solubility, dissolution rate, and in vivo exposure in rats. The chemical and physical stability of the salt forms (and the crystalline parent compound) were followed in solid state, when dissolved and when formulated as microsuspensions. All salts showed improved solubility in investigated media, increased dissolution rate, and elevated in vivo exposures compared to a nanocrystal formulation (top-down) of the parent free base of the compound. The chloride- and the hydrogen sulfate salts of the API showed similar patterns regarding the chemical stability in solid state as the crystalline free base, while the salt formed of the hemi-1.5-naphtalenedisulphonic acid showed significantly improved stability. In conclusion, this study showed that three salts of a new selected candidate drug could be used to improve solubility, increase dissolution rate, and enhance oral absorption compared with a more commonly used nanocrystal formulation of the API. However, the identity of the counter ion appeared to be of less importance. On the other hand, only the salt of the hemi-1.5-naphtalenedisulphonic acid seemed to improve chemical stability compared with the API.

Salt formation improved the properties of a candidate drug during early formulation development

The purpose of this study was to investigate if AZD5329, a dual neurokinin NK1/2 receptor antagonist, is a suitable candidate for further development as an oral immediate release (IR) solid dosage form as a final product. The neutral form of AZD5329 has only been isolated as amorphous material. In order to search for a solid material with improved physical and chemical stability and more suitable solid-state properties, a salt screen was performed. Crystalline material of a maleic acid salt and a fumaric acid salt of AZD5329 were obtained. X-ray powder diffractiometry, thermogravimetric analysis, differential scanning calorimetry and dynamic vapor sorption were used to investigate the physicochemical characteristics of the two salts. The fumarate salt of AZD5329 is anhydrous, the crystallization is reproducible and the hygroscopicity is acceptable. Early polymorphism assessment work using slurry technique did not reveal any better crystal modification or crystallinity for the fumarate salt. For the maleate salt, the form isolated originally was found to be a solvate, but an anhydrous form was found in later experiments; by suspension in water or acetone, by drying of the solvate to 100-120 °C or by subjecting the solvate form to conditions of 40 °C/75%RH for 3 months. The dissolution behavior and the chemical stability (in aqueous solutions, formulations and solid-state) of both salts were also studied and found to be satisfactory. The compound displays sensitivity to low pH, and the salt of the maleic acid, which is the stronger acid, shows more degradation during stability studies, in line with this observation. The presented data indicate that the substance fulfils basic requirements for further development of an IR dosage form, based on the characterization on crystalline salts of AZD5329.

Cannabinoid Type 1 Receptor (CB1) Ligands with Therapeutic Potential for Withdrawal Syndrome in Chemical Dependents of Cannabis sativa

Cannabis sativa withdrawal syndrome is characterized mainly by psychological symptoms. By using computational tools, the aim of this study was to propose drug candidates for treating withdrawal syndrome based on the natural ligands of the cannabinoid type 1 receptor (CB1). One compound in particular, 2-n-butyl-5-n-pentylbenzene-1,3-diol (ZINC1730183, also known as stemphol), showed positive predictions as a human CB1 ligand and for facile synthetic accessibility. Therefore, ZINC1730183 is a favorable candidate scaffold for further research into pharmacotherapeutic alternatives to treat C. sativa withdrawal syndrome.

Evaluation of the drug loading capacity of different lipid nanoparticle dispersions by passive drug loading

When using lipid nanoparticles as drug carrier system it is important to know how much drug can be loaded to the nanoparticles. The mainly used drug loading procedure is an empirical approach dissolving the drug in the liquid lipid during preparation of the nanoparticles. This approach does not necessarily lead to the truly loadable amount, as the lipid can, e.g. be overloaded, in particular when it is processed in the heat. In this work, a different procedure, passive drug loading, was evaluated to determine the drug loading capacity of various lipid nanoparticles (supercooled trimyristin emulsion droplets, solid trimyristin nanoparticles, tristearin nanoparticles in the α-modification and cholesteryl myristate nanoparticles in the supercooled smectic as well as in the crystalline state). The nanoparticle dispersions were exposed to eight different model drug compounds (betamethasone-17-valerate, carbamazepine, diazepam, flufenamic acid, griseofulvin, ibuprofen, retinyl palmitate, ubidecarenone) in the bulk state, which varied in partition coefficient and aqueous solubility, and equilibrated over time. The passive loading procedure had no relevant impact on the particle sizes or the physicochemical state of the nanoparticles. The loadable drug amount differed distinctly for the different model compounds and also between the different types of lipid nanoparticles. For most compounds, the loaded amount was much higher than the aqueous solubility. Trimyristin-based dispersions generally had the highest loading capacity, the emulsion usually being equal or superior to the solid trimyristin nanoparticles. For betamethasone-17-valerate, however, solid lipid nanoparticles exhibited by far the highest drug load. The extremely lipophilic model drugs retinyl palmitate and ubidecarenone could not be loaded with the passive approach.

Comparison of 2 strategies to enhance pyridoclax solubility: Nanoemulsion delivery system versus salt synthesis

Pyridoclax is an original oligopyridine lead, very promising in treatment of chemoresistant cancers. However, from solubility measurement and permeability evaluation, it appeared that this compound can be considered as a BCS II drug, with a poor water solubility. To overcome this unfavorable property, two strategies were proposed and compared: pyridoclax di-hydrochloride salt synthesis and formulation of pyridoclax-loaded nanoemulsions (PNEs) efficiently performed by transposing the spontaneous emulsification process previously developed by our team. Whereas the salt improved the thermodynamic solubility of the drug by a factor 4, the apparent solubility of the encapsulated pyridoclax was 1000-fold higher. Their stability was assessed upon dilution in various complex biomimetic media relevant for oral administration (SGF, FaSSIF-V2, FeSSIF-V2) or for the intravenous route (PBS). The solubility of the salt was affected by the nature of the medium, indicating that it could precipitate after administration, negatively impacting its bioavailability and its efficiency in vivo. On the contrary, in all media, PNEs remained stable in terms of granulometric properties (determined by DLS), ζ-potential and encapsulation efficiency (measured by HPLC). Thus, such nanomedicines appear as a valuable option to perform preclinical studies on the promising pyridoclax.

Advancing drug discovery: a pharmaceutics perspective

Current industry perspective of how discovery is conducted seems to be fragmented and does not have a unified overall outlook of how discovery challenges are being addressed. Consequently, well-defined processes and drug-likeness criteria are being viewed as "broken" and will not maintain future R&D productivity. In this commentary, an analysis of existing practices for defining successful development candidates resulted in a 5 "must do" list to help advance Drug Discovery as presented from a Pharmaceutics perspective. The 5 "must do" list includes: what an ideal discovery team model should look like, what criteria should be considered for the desired development candidate profile, what the building blocks of the development candidate should look like, and how to assess the development risks of the candidate.

Miniaturized approach for excipient selection during the development of oral solid dosage form

The present study introduces a miniaturized high-throughput platform to understand the influence of excipients on the performance of oral solid dosage forms during early drug development. Wet massing of binary mixtures of the model drug (sodium naproxen) and representative excipients was followed by sieving, drying, and compaction of the agglomerated material. The mini-compacts were subjected to stability studies at 25°C/5% relative humidity (RH), 25°C/60% RH and 40°C/75% RH for 3 months. The physical stability of the drug was affected by the storage condition and by the characteristics of the excipients, whereas all the samples were chemically stable. Force-distance curves obtained during the compression of agglomerated material were used for the comparison of compressibility of different drug-excipient mixtures. The agglomerated drug-excipient mixtures were also subjected to studies of the dissolution trend under sequential pH conditions to simulate pH environment of gastrointestinal tract. Major factors affecting the dissolution behavior were the diffusion layer pH of the binary mixtures and the ability of the excipients to alter the diffusion layer thickness. The proposed approach can be used for excipient selection and for early-stage performance testing of active pharmaceutical ingredient intended for oral solid dosage form.

Comparative efficacy and bioequivalence of novel h1-antihistamine bepotastine salts (nicotinate and salicylate)

Bepotastine salts (nicotinate and salicylate) were investigated for their physicochemical properties to develop novel salt forms of bepotastine, bioequivalent to the bepotastine besilate-loaded tablet (Talion). These bepotastine salts of either nicotinate- or salicylate-loaded tablets were prepared by conventional wet granulation method, and dissolution profiles and pharmacokinetics in beagle dogs were compared to those of Talion. A novel bepotastine nicotinate has a higher solubility at varying pH levels (1.2, 4, or 6.8) than salicylate-loaded or besilate-loaded salt. In addition, those bepostastine salt forms (nicotinate and salicylate) are stable in heat, light, and water. Further, the novel nicotinate- and salicylate-loaded tablets showed similar dissolution rates to Talion in several selected dissolution media and were bioequivalent to Talion in beagle dogs in terms of area under the concentration-time curve (AUC) and maximum observed concentration (Cmax). A pharmacokinetic study performed in beagle dogs demonstrated that test and reference products were found to be bioequivalent in terms of safety, efficacy, and pharmacokinetic properties. These results suggest that bepostastine nicotinate and salicylate formulations are considered applicable candidates and are well tolerated versus the conventional bepostastine besilate formulation.

Compound selection for development - is salt formation the ultimate answer? Experiences with an extended concept of the "100mg approach"

In order to select the best candidates for development, physicochemical criteria such as solubility, chemical and physical stability, hygroscopicity, and thermal characteristics need to be evaluated as early as possible and balanced against other important criteria such as pharmacology or pharmacokinetics. It could be shown, that our miniaturized pharmaceutical profiling concept ("100mg approach"), is capable to reliably identify potential development issues of drug candidates, which, therefore, can be approached early on. Salt formation is a well established strategy to improve unfavorable properties, in particular poor solubility. This article describes our stepwise approach on salt screening, including selection criteria, and summarizes the observations we had during compound investigation. Considering a data base of 337 compounds (salts and uncharged substances), experiences with various counterions evaluated over the last 10years are discussed. We realized that salt formation usually improves poor solubility of a given candidate, but this is often at the cost of other attributes being relevant for pharmaceutical development. Surprisingly, in more than 50% of all cases the "free form" was finally selected after carefully weighing all compound characteristics. Therefore, we conclude that an early salt selection strategy is of utmost importance to predict potential development issues and to enable the provision of alternative physical forms. However, salt formation itself is not necessarily the best solution to meet all development requirements. The selection of a free form (acid or base) in combination with advanced formulation strategies should always be considered, sometimes as best compromise.

Strategies to address low drug solubility in discovery and development

Drugs with low water solubility are predisposed to low and variable oral bioavailability and, therefore, to variability in clinical response. Despite significant efforts to "design in" acceptable developability properties (including aqueous solubility) during lead optimization, approximately 40% of currently marketed compounds and most current drug development candidates remain poorly water-soluble. The fact that so many drug candidates of this type are advanced into development and clinical assessment is testament to an increasingly sophisticated understanding of the approaches that can be taken to promote apparent solubility in the gastrointestinal tract and to support drug exposure after oral administration. Here we provide a detailed commentary on the major challenges to the progression of a poorly water-soluble lead or development candidate and review the approaches and strategies that can be taken to facilitate compound progression. In particular, we address the fundamental principles that underpin the use of strategies, including pH adjustment and salt-form selection, polymorphs, cocrystals, cosolvents, surfactants, cyclodextrins, particle size reduction, amorphous solid dispersions, and lipid-based formulations. In each case, the theoretical basis for utility is described along with a detailed review of recent advances in the field. The article provides an integrated and contemporary discussion of current approaches to solubility and dissolution enhancement but has been deliberately structured as a series of stand-alone sections to allow also directed access to a specific technology (e.g., solid dispersions, lipid-based formulations, or salt forms) where required.

A discriminatory intrinsic dissolution study using UV area imaging analysis to gain additional insights into the dissolution behaviour of active pharmaceutical ingredients

For efficient and effective drug development it is desirable to acquire a deep understanding of the dissolution behaviour of potential candidate drugs and their physical forms as early as possible and with the limited amounts of material that are available at that time. Using 3-10mg sample quantities, the ability of a UV imaging system is investigated to provide deep mechanistic insight into the intrinsic dissolution profiling of a range of compounds and physical forms assessed under flow conditions. Physical forms of indomethacin, theophylline and ibuprofen were compressed and their solid-state form confirmed before and after compression with X-ray methods and/or Raman spectroscopy. Intrinsic dissolution rates (IDRs) were determined using the compact's UV-imaging profile. The ratio in the IDRs for theophylline anhydrate over hydrate was 2.1 and the ratio for the alpha form of indomethacin over the gamma form was approximately 1.7. The discriminatory power of the novel UV area visualisation approach was shown to be high in that process-induced solid-state dissolution differences post-micronisation could be detected. Additionally, the scale-down system was able to visualise a previously observed increase in ibuprofen IDR with an increase in concentration of sodium dodecyl sulphate. The mechanistic dissolution insights from the visualisation approach are evident.

Drug delivery strategies for poorly water-soluble drugs: the industrial perspective

INTRODUCTION

For poorly soluble compounds, a good bioavailability is typically needed to assess the therapeutic index and the suitability of the compound for technical development. In industry, the selection of the delivery technology is not only driven by technical targets, but also by constraints, such as production costs, time required for development and the intellectual property situation.

AREAS COVERED

This review covers current developments in parenteral and oral delivery technologies and products for poorly water-soluble compounds, such as nano-suspensions, solid dispersions and liposomes. In addition, the use of biorelevant dissolution media to assess dissolution and solubility properties is described. Suggestions are also included to systematically address development hurdles typical of poorly water-soluble compounds intended for parenteral or oral administration.

EXPERT OPINION

A holistic assessment is recommended to select the appropriate delivery technology by taking into account technical as well as intellectual property considerations. Therefore, first and foremost, a comprehensive physico-chemical characterization of poorly water-soluble compounds can provide the key for a successful selection and development outcome. In this context, the identified physical form of the compound in the formulation is used as a guide for a risk-benefit assessment of the selected oral delivery technology. The potential of nano-suspensions for intravenous administration is unclear. In the case of oral administration, nano-suspensions are mainly used to improve the oral absorption characteristics of micronized formulations. The development of an in situ instantaneous solubilization method, based on stable, standardized liposomes with low toxicity, opens new avenues to solubilize poorly water-soluble compounds.

Initial salt screening procedures for manufacturing ibuprofen

The aim of this paper is to design initial salt screening procedures for manufacturing ibuprofen. Salt forms of a pharmaceutical acid racemic (R,S)-(+/-)-ibuprofen and their "developable" synthetic routes were ferreted out simultaneously through the screening of seven bases of sodium hydroxide, potassium hydroxide, L-arginine, L-histidine, L-lysine, diethanolamine, and tris(hydroxymethyl)aminomethane (THAM), and the match with the use of nine organic solvents of methanol, dimethyl sulfoxide, ethanol, N, N-dimethylformamide, acetonitrile, isopropyl alcohol, 1,4-dioxane, acetone, and tetrahydrofuran mainly in the presence of water in 20 mL scintillation vials. Racemic (R,S)-(+/-)-sodium ibuprofen dihydrate, a well-known ibuprofen salt and the newly discovered racemic (R,S)-(+/-)-THAM ibuprofen, appeared as white-squared powders with a molecular weight of 327.42 g/mol, a melting point of 160.17 degrees C, and the apparent solubility product, K'(sp), of 6.0 x 10(-4) M(2) at 25 degrees C were successfully synthesized by the initial salt screening methods. The new amine salt of ibuprofen was monoclinic and had a space group of P2(1)/c and lattice parameters of a = 17.578(8) degrees, b = 10.428(4) degrees, c = 9.991(4) A, alpha = 90.00 degrees , beta = 97.17(1) degrees, gamma = 90.00 degrees, and V = 1,817.05(244) A(3). The aspect ratio of the amine salt crystals of ibuprofen of approximately 1.0 implied that the crystals had a better flowability than the sodium salt counterparts. This amine salt of ibuprofen was more stable in moist or dried atmospheres and was more hydrophobic than the sodium salt of ibuprofen. Moreover, the slow dissolution of this amine salt of ibuprofen might have made it less bitter and more suitable as a sustained release drug than the sodium salt of ibuprofen. The future work is to search for the different polymorphs of this amine salt of ibuprofen and to extend the initial salt screening working logics to the formation of co-crystals.

Preparation and characterization of salt forms of enalapril

Selection of an optimal salt form of a drug candidate is a vital component of preformulation stage of drug development. In this study, six salts of enalapril--citrate, mesylate, tartrate, malate, besylate and tosylate--were prepared and characterized by Mass Spectroscopy, Differential Scanning Calorimetry, Thermogravimetric Analysis, Microscopy, Powder X-ray Diffraction, Karl Fischer Titration, High Performance Liquid Chromatography, Fourier-Transform Infra-red Spectroscopy and Head Space Gas Chromatography. All the six salts were subjected to a tiered screening involving five stages in the following order: crystallinity, hygroscopicity, solubility, stability and flow/compactability. Enalapril malate showed encouraging profile because of its lower hygroscopicity, higher solubility, good solid state stability, and better flow and compactability, in comparison to the marketed maleate salt.

Preparation and Evaluation of Mucin-Gelatin Mucoadhesive Microspheres for Rectal Delivery of Ceftriaxone Sodium

Soluble mucin (S-mucin) processed from the small intestines (ileal region) of freshly slaughtered pigs via homogenization, dialysis, centrifugation and lyophilization and its admixtures with type A gelatin were dispersed in an aqueous medium and used to formulate ceftriaxone sodium-loaded mucoadhesive microspheres by the emulsification cross-linking method using arachis oil as the continuous phase. The release profile of ceftriaxone sodium from the microspheres was evaluated in both simulated gastric fluid (SGF) without pepsin (pH 1.2) and simulated intestinal fluid (SIF) without pancreatin (pH 7.4). The microspheres were further evaluated as possible novel delivery system for rectal delivery of ceftriaxone sodium in rats. Release of ceftriaxone sodium from the microspheres in both release media was found to occur predominantly by diffusion following non-Fickian transport mechanism and was higher and more rapid in SIF than in SGF. The results obtained from this study may indicate that ceftriaxone sodium could be successfully delivered rectally when embedded in microspheres formulated with either type A gelatin alone or its admixtures with porcine mucin; hence providing a therapeutically viable alternative route for the delivery of this acid-labile third generation cephalosporin.

Trends in active pharmaceutical ingredient salt selection based on analysis of the Orange Book database

The Orange Book database published by the U.S. Drug and Food Administration (FDA) was analyzed for the frequency of occurrence of different counterions used for the formation of pharmaceutical salts. The data obtained from the present analysis of the Orange Book are compared to reviews of the Cambridge Structural Database (CSD) and of the Martindale "The Extra Pharmacopoeia". As well as showing overall distributions of counterion usage, results are broken down into 5-year increments to identify trends in counterion selection. Chloride ions continue to be the most frequently utilized anionic counterions for the formation of salts as active pharmaceutical ingredients (APIs), while sodium ions are most widely utilized for the formation of salts starting from acidic molecules. A strong trend toward a wider variety of counterions over the past decade is observed. This trend can be explained by a stronger need to improve physical chemical properties of research and development compounds.