In vivo toxicology of excipients commonly employed in drug discovery in rats

Cyclodextrin Inclusion of Medicinal Compounds for Enhancement of their Physicochemical and Biopharmaceutical Properties

Owing to their wide structural diversity and unique complexing properties, cyclodextrins (CDs) find manifold applications in drug discovery and development. The focus of this mini-review is on their uses as 'enabling excipients' both in the context of early drug discovery and in subsequent optimisation of drug performance. Features highlighted here include descriptions of the structures of CDs, synthetic derivatisation to fine-tune their properties, the nature of inclusion complexation of drugs within the CD cavity, methodology for the study of free and complexed hosts in the solid state and in solution, the inherent pharmacological activity of several CDs and its utility, novel CD-based drug delivery systems, and the role of CDs in drug discovery and optimisation. Illustrative examples are generally based on research reported during the last two decades. Application of CDs to the optimisation of the performance of established drugs is commonplace, but there are many opportunities for the intervention of CDs during the early stages of drug discovery, which could guide the selection of suitable candidates for development, thereby contributing to reducing the attrition rate of new molecular entities.

In vivo models and decision trees for formulation development in early drug development: A review of current practices and recommendations for biopharmaceutical development

The ability to predict new chemical entity performance using in vivo animal models has been under investigation for more than two decades. Pharmaceutical companies use their own strategies to make decisions on the most appropriate formulation starting early in development. In this paper the biopharmaceutical decision trees available in four EFPIA partners (Bayer, Boehringer Ingelheim, Bristol Meyers Squibb and Janssen) were discussed by 7 companies of which 4 had no decision tree currently defined. The strengths, weaknesses and opportunities for improvement are discussed for each decision tree. Both pharmacokineticists and preformulation scientists at the drug discovery & development interface responsible for lead optimization and candidate selection contributed to an overall picture of how formulation decisions are progressed. A small data set containing compound information from the database designed for the IMI funded OrBiTo project is examined for interrelationships between measured physicochemical, dissolution and relative bioavailability parameters. In vivo behavior of the drug substance and its formulation in First in human (FIH) studies cannot always be well predicted from in vitro and/or in silico tools alone at the time of selection of a new chemical entity (NCE). Early identification of the risks, challenges and strategies to prepare for formulations that provide sufficient preclinical exposure in animal toxicology studies and in FIH clinical trials is needed and represents an essential part of the IMI funded OrBiTo project. This article offers a perspective on the use of in vivo models and biopharmaceutical decision trees in the development of new oral drug products.

Design, characterization and in vivo evaluation of nanostructured lipid carriers (NLC) as a new drug delivery system for hydrochlorothiazide oral administration in pediatric therapy

The hydrochlorothiazide (HCT) low solubility and permeability give rise to limited and variable bioavailability; its low stability makes it difficult to develop stable aqueous liquid formulations; its low dose makes the achievement of a homogeneous drug distribution very difficult. Thus, the aim of this study was to investigate the effectiveness of a strategy based on the development of nanostructured lipid carriers (NLC) as an innovative oral pediatric formulation of HCT with improved therapeutic efficacy. The performance of various synthetic and natural liquid lipids was examined and two different preparation methods were employed, i.e. homogenization-ultrasonication (HU) and microemulsion (ME), in order to evaluate their influence on the NLC properties in terms of size, polydispersity index, ζ-potential, entrapment efficiency, gastric stability, and drug release properties. Precirol®ATO5 was used as solid lipid and Tween^®80 and Pluronic^®F68 as surfactants, formerly selected in a previous study focused on the development of HCT-solid lipid nanoparticles (SLNs). The presence of Pluronic^®F68 did not allow ME formation. On the contrary, using Tween^®80, the ME method enabled a higher entrapment efficiency than the HU. Regardless of the preparation method, NLCs exhibited great entrapment efficiency values clearly higher than previous SLNs. Moreover, NLC-ME formulations provided a prolonged release, which lasted for 6 h. In particular, NLC-ME containing Tween^®20 as Co-Surfactant showed the best performances, giving rise to a complete drug release, never achieved with previous SLN formulations, despite their successful results. In vivo studies on rats confirmed these results, displaying their best diuretic profile. Moreover, all HCT-loaded NLC formulations showed higher stability than the corresponding SLNs.

Safety Assessment of Tocopherols and Tocotrienols as Used in Cosmetics

The Cosmetic Ingredient Review (CIR) Expert Panel (Panel) assessed the safety of 14 tocopherols and tocotrienols and concluded these ingredients are safe as used in cosmetics. The tocopherols are reported to function in cosmetics as antioxidants or skin-conditioning agents; in contrast, tocotrienols are not reported to function as an antioxidants in cosmetics but as a light stabilizer, oral care agent, or skin-conditioning agent. The Panel reviewed the new and existing animal and clinical data to determine the safety of these ingredients and found it appropriate to extrapolate the existing information to conclude on the safety of all the tocopherols and tocotrienols.

Safety Assessment of Formulation Vehicles Following Intravitreal Administration in Rabbits

PURPOSE

Evaluate 21 formulation vehicles administered to rabbits after intravitreal injection for tolerability and safety.

METHODS

Forty-two Dutch Belted rabbits were anesthetized, and the eyes received a single intravitreal injection of the excipient formulation. Clinical signs and ocular irritation responses were recorded twice daily for 7 days and microscopic evaluation of the eyes, optic nerve, and eyelids was completed at 1-week post treatment.

RESULTS

Saline (≥ 300 mOsm and ≤ 592 mOsm at pH 7.0 or 300 mOsm at pH 8.0) and 10 formulation excipients; (10% w/v PEG 3350 at pH 7.4, 1% polysorbate 21 at pH 7.4, PVA at pH 7.0, 0.2% polysorbate 80 at pH 7.2, 0.2% Pluronic F108® at pH 7.3, 2%, 100 mM sodium sulfate at pH 3.2, 2 mM sodium glycocholate at pH 7.4, and 275 mM D-mannitol pH 7.0 in sterile water, and 100 mM sodium phosphate in combination with 0.9% NaCl 300 mOsm and 0.01% or 0.05% polysorbate 80 at pH 7.4) considered as formulation vehicles for intravitreal injectables, were well-tolerated in rabbits. Clinical signs were transient and microscopic changes were not observed.

CONCLUSIONS

Of the 21 formulation vehicles evaluated, 10 formulation vehicles were well-tolerated in rabbits and feasible candidates for future investigations.

Stanozolol administration combined with exercise leads to decreased telomerase activity possibly associated with liver aging

Anabolic agents are doping substances which are commonly used in sports. Stanozolol, a 17α‑alkylated derivative of testosterone, has a widespread use among athletes and bodybuilders. Several medical and behavioral adverse effects are associated with anabolic androgenic steroids (AAS) abuse, while the liver remains the most well recognized target organ. In the present study, the hepatic effects of stanozolol administration in rats at high doses resembling those used for doping purposes were investigated, in the presence or absence of exercise. Stanozolol and its metabolites, 16‑β‑hydroxystanozolol and 3'‑hydroxystanozolol, were detected in rat livers using liquid chromatography‑mass spectrometry (LC‑MS). Telomerase activity, which is involved in cellular aging and tumorigenesis, was detected by examining telomerase reverse transcriptase (TERT) and phosphatase and tensin homolog (PTEN) expression levels in the livers of stanozolol‑treated rats. Stanozolol induced telomerase activity at the molecular level in the liver tissue of rats and exercise reversed this induction, reflecting possible premature liver tissue aging. PTEN gene expression in the rat livers was practically unaffected either by exercise or by stanozolol administration.

Cocoa Pod Husk Pectin Intended as a Pharmaceutical Excipient Has No Adverse Effects on Haematological Parameters in Sprague Dawley Rats

Natural polymer research has recently become the focus of intensive research in the quest for new enabling excipients for novel drugs in pharmaceutical formulation for optimal treatment outcomes. Evaluations of some excipients have shown deleterious haematological effects of varying extents on the safety profile of these excipients. A 90-day subchronic toxicity study was conducted to evaluate the influence of cocoa pod husk (CPH) pectin on indicators for haematotoxicity. Male and female Sprague Dawley rats (SDRs) were fed with CPH pectin in doses up to 71.4 mg/kg. The effects of CPH pectin on the haematological indices, direct and total bilirubin, and the spleen were determined. The results indicated that CPH pectin did not induce any untoward toxic effects on the haematological indices, bilirubin levels, and the spleen. There were, however, elevations in MCV at day 30, which was not sustained after the 90 days. The data obtained from this study did not reveal any remarkable findings of toxicological relevance to the haematopoietic system.

Inclusion complexes of propiconazole nitrate with substituted β-cyclodextrins: the synthesis and in silico and in vitro assessment of their antifungal properties

Inclusion complexes with sulfobutylether-β-cyclodextrin, β-cyclodextrin sulphated sodium salt and monochlorotriazinyl-β-cyclodextrin were characterized and assessed for antifungal activity and cytotoxicity.

Impact of Mixed β-Cyclodextrin Ratios on Pluronic Rotaxanation Efficiency and Product Solubility

Water-soluble polyrotaxanes have been prepared under heterogeneous conditions from mixtures of β-cyclodextrin (β-CD), 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), methyl-β-cyclodextrin, or 6-monoazido-β-cyclodextrin with 4-sulfobutyl ether-β-cyclodextrin (SBE-β-CD) and Pluronic L81 copolymer modified with cholesterol end caps. Threading reactions gave polyrotaxane products in modest chemical yield that were reflective of the β-CD feed ratios in the reaction. Polyrotaxanes containing mixtures of HP-β-CD and SBE-β-CD were screened and found to be biologically active in an in vitro model of Niemann-Pick Type C disease where they mobilize aberrantly stored cholesterol similarly to monomeric cyclodextrin controls.

Polymer incorporation method affects the physical stability of amorphous indomethacin in aqueous suspension

This study reports the potential of different polymers and polymer incorporation methods to inhibit crystallisation and maintain supersaturation of amorphous indomethacin (IND) in aqueous suspensions during storage. Three different polymers (poly(vinyl pyrrolidone) (PVP), hydroxypropyl methylcellulose (HPMC) and Soluplus® (SP)) were used and included in the suspensions either as a solid dispersion (SD) with IND or dissolved in the suspension medium prior to the addition of amorphous IND. The total concentrations of both IND and the polymer in the suspensions were kept the same for both methods of polymer incorporation. All the polymers (with both incorporation methods) inhibited crystallisation of the amorphous IND. The SDs were better than the predissolved polymer solutions at inhibiting crystallisation. The SDs were also better at maintaining drug supersaturation. SP showed a higher IND crystallisation inhibition and supersaturation potential than the other polymers. However, this depended on the method of addition. IND in SD with SP did not crystallise, nor did the SD generate any drug supersaturation, whereas IND in the corresponding predissolved SP solution crystallised (into the recently characterised η polymorphic form of the drug) but also led to a more than 20-fold higher IND solution concentration than that observed for crystalline IND. The ranking of the polymers with respect to crystallisation inhibition potential in SDs was SP≫PVP>HPMC. Overall, this study showed that both polymer type and polymer incorporation method strongly impact amorphous form stability and drug supersaturation in aqueous suspensions.

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.

Preclinical formulations: insight, strategies, and practical considerations

A lot of resources and efforts have been directed to synthesizing potentially useful new chemical entities (NCEs) by pharmaceutical scientists globally. Detailed physicochemical characterization of NCEs in an industrial setup begins almost simultaneously with preclinical testing. Most NCEs possess poor water solubility posing bioavailability issues during initial preclinical screening, sometimes resulting in dropping out of an NCE with promising therapeutic activity. Selection of right formulation approach for an NCE, based on its physicochemical properties, can aid in improving its solubility-related absorption and bioavailability issues. The review focuses on preclinical formulations stressing upon different preclinical formulation strategies and deciphers the understanding of formulation approaches that could be employed. It also provides detailed information related to a vast pool of excipients available today, which is of immense help in designing preclinical formulations. Few examples mentioned, throw light on key aspects of preclinical formulation development. The review will serve as an important guide for selecting the right strategy to improve bioavailability of NCEs for academic as well as industrial formulation scientists.