Juvenile animal testing of hydroxypropyl-β-cyclodextrin in support of pediatric drug development

Aqueous eye drop formulations: Cyclodextrins as enabling excipients

Cyclodextrins are enabling pharmaceutical excipients that solubilize and stabilize drugs in aqueous formulations. Cyclodextrins possess very favorable pharmacokinetic and toxicological profiles and are commonly used in marketed drug products for oral and parenteral administration. However, their use in ophthalmic products is still very limited. Cyclodextrins have a broad range of physical properties that are specifically appropriate for designing topical ophthalmic dosage forms. Additionally, both the regulatory and intellectual property environments have been cleared over the last years and should foster their use for designing new drugs for ophthalmic use.

Juvenile toxicity study of deer antler extract in rats

ETHNOPHARMACOLOGICAL RELEVANCE

Deer (Cervus elaphus Linnaeus) antler extract has been traditionally used in many Asian countries to prevent and treat various diseases. Deer antler extract is generally considered to be safe because humans have been exposed to it for a long time and it has been used as a tonic medicine originating from naturally occurring product. However, the comprehensive toxicological potential of deer antler extract during the juvenile period has not been investigated and its safety for juveniles remains unclear.

AIM OF THE STUDY

The aim of the present study was to comprehensively investigate the potential toxicological effects of deer antler extract during the juvenile period.

MATERIALS AND METHODS

As part of a safety assessment of the juvenile period, two separate studies, a juvenile toxicity study and a uterotrophic bioassay, were conducted in accordance with Good Laboratory Practice regulations and test guidelines. In the juvenile toxicity study, deer antler extract was administered daily by oral gavage to Sprague-Dawley rats at doses of 0, 500, 1000, and 2000 mg/kg during the juvenile period to investigate potential toxicities on general systemic, developmental, and reproductive functions. For the uterotrophic bioassay, deer antler extract was administered daily by oral gavage to Sprague-Dawley rats at doses of 0, 1000, and 2000 mg/kg on postnatal days 19-21 to investigate the estrogen-mimicking effects.

RESULTS

The results showed that deer antler extract was non-toxic and no observable adverse effects on general systemic function, developmental and reproductive function, and estrogen-mimetic effects were observed with dosing up to 2000 mg/kg during the juvenile period.

CONCLUSION

The safety of deer antler extracts was demonstrated in these studies and the results of this study can be used to evaluate human risk or determine the maximum recommended starting dose of deer antler extract for further clinical trials.

The Current States, Challenges, Ongoing Efforts, and Future Perspectives of Pharmaceutical Excipients in Pediatric Patients in Each Country and Region

A major hurdle in pediatric formulation development is the lack of safety and toxicity data on some of the commonly used excipients. While the maximum oral safe dose for several kinds of excipients is known in the adult population, the doses in pediatric patients, including preterm neonates, are not established yet due to the lack of evidence-based data. This paper consists of four parts: (1) country-specific perspectives in different parts of the world (current state, challenges in excipients, and ongoing efforts) for ensuring the use of safe excipients, (2) comparing and contrasting the country-specific perspectives, (3) past and ongoing collaborative efforts, and (4) future perspectives on excipients for pediatric formulation. The regulatory process for pharmaceutical excipients has been developed. However, there are gaps between each region where a lack of information and an insufficient regulation process was found. Ongoing efforts include raising issues on excipient exposure, building a region-specific database, and improving excipient regulation; however, there is a lack of evidence-based information on safety for the pediatric population. More progress on clear safety limits, quantitative information on excipients of concern in the pediatric population, and international harmonization of excipients’ regulatory processes for the pediatric population are required.

Aqueous eye drops containing drug/cyclodextrin nanoparticles deliver therapeutic drug concentrations to both anterior and posterior segment

Using topical application to deliver therapeutic concentrations of drugs to the posterior segment of the eye remains very challenging. As a result, posterior segment diseases are usually treated by intravitreal injection or implant. While topical treatments are commonly used for anterior segment conditions, they sometimes require frequent applications. Eye drop formulations based on γ-cyclodextrin (γCD)-based nanoparticle aggregates were developed, which in animal models and clinical studies deliver therapeutic concentrations of drugs (dorzolamide and dexamethasone) to both anterior and posterior segments of the eye. An early study in humans showed dorzolamide/γCD eye drops could achieve comparable intraocular pressure decreases to commercial dorzolamide eye drops, but with less frequent application. Pilot studies with dexamethasone/γCD eye drops suggested that they could be effective in a range of conditions, including diabetic macular oedema, cystoid macular oedema and vitritis secondary to uveitis, postcataract surgery inflammation and postoperative treatment in trabeculectomy. Phase II studies with similar dexamethasone/γCD nanoparticle eye drops in diabetic macular oedema and postcataract surgery inflammation have recently been completed. This technology has the potential to be used with other classes of drug molecules and to replace or complement invasive treatments, providing safer, non-invasive therapies, particularly for posterior segment conditions, that can be self-administered as eye drops by patients.

Cyclodextrins in Parenteral Formulations

Most drugs have very limited solubility in water and some can be extremely difficult to formulate as parenteral solutions where the dose should preferably be dissolved in couple of ml of aqueous media without use of organic solvents and surface active agents, or application of somewhat extreme techniques such as prodrug formation. Thus, pharmaceutical formulators are constantly looking for new, biologically acceptable, and low-cost armamentarium for parenteral formulation development. Cyclodextrins (CDs) are enabling pharmaceutical excipients that can temporarily camouflage undesirable physiochemical drug properties such as low aqueous solubility through formation of drug/CD inclusion complexes. CDs are cyclic oligosaccharides that have similar physiological and biological properties like linear saccharides of comparable molecular weight. Due to their very favorable toxicological and pharmacokinetic profiles their usage in parenteral drug formulations is frequently preferred over other solubilizing techniques. Here the physiochemical and biological properties of CDs are reviewed as well as their pharmacokinetics after intravenous administration. Their regulatory status is briefly reviewed and their tendency to self-assemble to form clusters or aggregates discussed. Finally, some examples are given of how CDs are applied in aqueous parenteral formulations, how their solubilizing effect has been enhanced and how their target concentration is determined.

Repurposing Disulfiram (Tetraethylthiuram Disulfide) as a Potential Drug Candidate against Borrelia burgdorferi In Vitro and In Vivo

Lyme disease caused by the Borrelia burgdorferi (Bb or B. burgdorferi) is the most common vector-borne, multi-systemic disease in the USA. Although most Lyme disease patients can be cured with a course of the first line of antibiotic treatment, some patients are intolerant to currently available antibiotics, necessitating the development of more effective therapeutics. We previously found several drugs, including disulfiram, that exhibited effective activity against B. burgdorferi. In the current study, we evaluated the potential of repurposing the FDA-approved drug, disulfiram for its borreliacidal activity. Our results indicate disulfiram has excellent borreliacidal activity against both the log and stationary phase B. burgdorferi sensu stricto B31 MI. Treatment of mice with disulfiram eliminated the B. burgdorferi sensu stricto B31 MI completely from the hearts and urinary bladder by day 28 post infection. Moreover, disulfiram-treated mice showed reduced expressions of inflammatory markers, and thus they were protected from histopathology and cardiac organ damage. Furthermore, disulfiram-treated mice showed significantly lower amounts of total antibody titers (IgM and IgG) at day 21 and total IgG2b at day 28 post infection. FACS analysis of lymph nodes revealed a decrease in the percentage of CD19+ B cells and an increase in total percentage of CD3+ T cells, CD3+ CD4+ T helpers, and naive and effector memory cells in disulfiram-treated mice. Together, our findings suggest that disulfiram has the potential to be repurposed as an effective antibiotic for treating Lyme disease.

Lyoprotectant Optimization for the Freeze-Drying of Receptor-Targeted Trojan Horse Liposomes for Plasmid DNA Delivery

Trojan horse liposomes (THLs) are a form of ligand-targeted nanomedicine, where a plasmid DNA is encapsulated in the interior of a 100-150 nm pegylated liposome, and the tips of a fraction of the surface pegylated strands are covalently linked to a receptor-specific monoclonal antibody (MAb) via a thio-ether linkage. The goal of this work was to develop a lyophilization methodology that enables retention of the structure and function of the THLs following the freeze-drying/hydration process. THL fusion and leakage of plasmid DNA were observed with several lyoprotectants, including trehalose, hyaluronic acid, γ-cyclodextrin, or sulfobutylether-β-cyclodextrin. However, the use of hydroxypropyl-γ-cyclodextrin, at a 40:1 wt/wt ratio relative to the THL phospholipid, eliminated liposome fusion and produced high retention of encapsulated plasmid DNA and THL-mediated gene expression after lyophilization followed by hydration. The freeze-dried THL cake was amorphous without cavitation, and the diameters and functional properties of the THLs were preserved following hydration of cakes stored for at least six months. Intravenous administration of the hydrated freeze-dried THLs in the Rhesus monkey demonstrated the safety of the formulation. Blood plasmid DNA was measured with a quantitative polymerase chain reaction method, which enabled a pharmacokinetics analysis of the blood clearance of the THL-encapsulated plasmid DNA in the primate. The work shows that optimization of the lyoprotectant enables long-term storage of the MAb-targeted DNA encapsulated liposomes in the freeze-dried state.

Cyclodextrins: structure, physicochemical properties and pharmaceutical applications

Since their discovery over 100 years ago cyclodextrins (CDs) have been the subject of numerous scientific publications. In 2016 alone CDs were the subject of over 2200 research articles published in peer-reviewed journals and mentioned in over 2300 patents and patent applications, many of which were on pharmaceutical applications. Natural CDs and their derivatives are used as enabling pharmaceutical excipients that enhance aqueous solubility of poorly soluble drugs, increase drug permeability through biological membranes and improve drug bioavailability. Unlike conventional penetration enhancers, their hydrophilic structure and high molecular weight prevents them from penetrate into lipophilic membranes leaving biological membranes intact. The natural CDs and some of their derivatives have monographs in pharmacopeias and are also commonly used as food additives and in toiletry products. CDs form inclusion complexes with lipophilic moieties of hydrophobic drugs. Furthermore, CDs are able to form non-inclusion complexes and self-assembled aggregates; small and large complex aggregates with micellar-like structures that can enhance drug solubility. Excipients commonly used in pharmaceutical formulations may have additive or inhibiting effect on the CD solubilization. Here various methods used to investigate CD aggregate formation are reviewed as well as techniques that are used to increase the solubilizing effects of CDs; methods that enhance the apparent intrinsic solubility of drugs and/or the complexation efficacy and decrease the amount of CD needed to develop CD-containing pharmaceutical formulations. It will be explained how too much or too little CD can hamper drug bioavailability, and the role of CDs in solid dosage forms and parenteral formulations, and examples given on how CDs can enhance drug delivery after ocular, nasal and pulmonary administration.