Lipid-polyethylene glycol based nano-ocular formulation of ketoconazole

https://doi.org/10.1016/j.ijpharm.2015.08.088Get rights and content

Highlights

  • Solid lipid nanoparticles (SLNs) of ketoconazole (KTZ) comprising biocompatible constituents such as Compritol® 888 ATO, Tween 80, PEG 600 and Phospholipon 90G, were developed and extensively characterized to understand their composition and stability.

  • Nearly 70% of the drug was entrapped in the SLNs probably in the PEG core (as confirmed by FTIR and NMR studies).

  • Enhanced ocular bioavailability and better antifungal efficacy was observed for KTZ-SLNs in comparison to the corresponding free drug suspension.

  • Developed KTZ-SLNs were found to be safe for ocular use in terms of pH, osmolarity, refractive index, in vitro cytotoxicity studies and in vivo safety studies.

Abstract

Ophthalmic mycoses including corneal keratitis or endophthalmitis affects 6-million persons/year and can cause blindness. Its management requires antifungals to penetrate the ocular tissue. Oral use of Ketoconazole (KTZ), the first broad-spectrum antifungal to be marketed, is now restricted to life-threatening infections due to severe adverse effects and drug-interactions. Local use of KTZ loaded nanocarrier system can address its toxicity, poor solubility, photodegradation, permeation and bioavailability issues.

Solid lipid nanoparticles (SLNs) comprising Compritol® 888 ATO and PEG 600 matrix, were presently prepared using hot high-pressure homogenization. Employing extensive characterization: TEM, NMR, DSC, XRD and FTIR, it is proposed that SLNs comprise of a polyethylene glycol (PEG) core into which KTZ is dissolved. PEG endows the lipid matrix with amorphousness and imperfections; rigidity; and, stability to aggregation, on storage and autoclaving. PEG is a simple, cost-effective and safe polymer with superior solubilizing and surfactant-supporting properties. Without its inclusion KTZ could not be loaded into SLNs. It ensured high incorporation efficiency (70%) of KTZ; small size (126 nm); and, better permeation into the eye. Pharmacokinetic studies indicated 2.5 and 1.6 fold higher bioavailability (AUC) in aqueous and vitreous humor, respectively. Biocompatibility and in vitro (both in corneal and retinal cell lines) and in vivo (in rabbits) ocular safety is the other highlight of developed formulation.

Introduction

Local delivery to the eye, though a preferred route with lower incidence of systemic side effects, cannot address internal eye diseases (Sigurdsson et al., 2007, Bucolo et al., 2012, Geroski and Edelhauser, 2000, Ahmed and Patton, 1985, Hughes et al., 2005). Nanostructured systems may however deliver drug successfully to the posterior segment of the eye (Kaur and Kakkar, 2014). Solid lipid nanoparticles (SLNs), comprising of a nanosized lipidic core stabilized by a layer of surfactants is now attaining popularity as a suitable system for ocular delivery (Leonardi et al., 2014, Seyfoddin et al., 2010). Both the nano size, and the lipidic nature of SLNs helps to improve ocular bioavailability of encapsulated drug; both due to prolonged ocular retention and improved permeation (Hippalgaonkar et al., 2013, Mohanty et al., 2015, Seyfoddin et al., 2010).

Fungal infections of the eye, though less common than infections with bacteria and viruses, are usually more severe and may lead to loss of vision. With an increased immunocompromised population, including HIV infected persons, patients undergoing surgeries/transplants, and those receiving chemotherapy, the ophthalmic mycosis is howsoever on the rise. Efficient administration of appropriate antifungal therapy can help to preserve vision, provided the agent reaches the affected tissue in sufficient concentration (Kaur et al., 2008b).

Ketoconazole (KTZ) is a broad spectrum antifungal agent, with high lipo-solubility (log P = 4.74) (Logua et al., 1997) but a short ocular half life (elimination half life is 19 min in aqueous humor and 43 min in cornea) (Zhang et al., 2008) and very poor solubility (0.04 mg/ml). It is recommended to be administered orally at a dose of 100 to 400 mg every 12 h (Müller et al., 2013). However, it is associated with low oral bioavailability (Baxter et al., 1986) and severe adverse effects like nausea, vomiting, gastrointestinal disturbance, hepatitis, gynecomastia, adrenal cortex suppression (O’Brien, 1999) and hepatotoxicity (FDA, 2013, Sharma et al., 1993). Its absorption from the gut is dependent on the gastric pH. Significant drug–drug interactions are also reported upon its oral administration (Thomas, 2003).

High lipophilicity of KTZ may promote permeation, however its large molecular weight (531.44 Da), tends to impede its transport across the biological membranes. Similarly, high lipid solubility although can help passage across corneal epithelium, however, its passage through the aqueous corneal stroma will be compromised (Barar et al., 2008) following topical administration. Furthermore, its limiting water solubility (0.04 mg/ml) makes it difficult to present KTZ in a solubilised form on the corneal surface, latter being an important pre-requisite for ocular formulations.

Presently SLN ocular dispersion of KTZ was designed to provide an alternate topical route rather than an oral route of administration, which is associated with significant adverse effects. Further intent of the study is to develop a nanocarrier system which can permeate upto the posterior eye in an intact form so as to carry the incorporated drug along with it. Fungal infection of the internal eye invariably leads to vision loss within a short span and achieving high drug concentration in the vitreous is difficult post oral administration due to the existence of blood-aqueous and blood-retinal barriers. Developed KTZ-SLN system was extensively characterized and confirmed to permeate the cornea via ex vivo corneal permeation studies. In vivo pharmacokinetic profile of KTZ-SLN was compared with the corresponding free drug dispersion. In vitro and in vivo safety and autoclavability of the developed KTZ-SLN system was confirmed. The dispersion was comprehensively developed as a suitable ocular formulation in terms of pH, refractive index, osmolarity, stability on keeping (both entrapment efficiency and particle size were evaluated upto 1 year) and preservation against contamination (using challenge test). Though a well established preservative benzalkonium chloride (BAK) was employed, but it is important to confirm that physical adsorption or interaction with any of the components does not compromise the activity of BAK.

Section snippets

Materials and selection of components

Ketoconazole was a kind gift from Torrent Pharmaceuticals Pvt. Ltd., H.P., India; Compritol® 888 ATO was a gift sample from Gattefosse, France; and Phospholipon 90 G (soya lecithin) was gifted by Lipoid, Germany. Phosphotungstic acid (PTA) and BAK were procured from Sigma–Aldrich, USA. All other reagents used in the study were of analytical grade.

Compritol® 888 ATO was presently chosen as the lipid component, because it is reported to result in stable SLN formulations with small particle size (

Characterization of SLNs

Transmission electron microscopy indicated SLNs to be small in size (between 70 and 135 nm) and spherical in shape, with no aggregation/irregularities in the system (Fig. 1). Particle size, total drug content, EE, zeta potential, pH, osmolarity and RI of the developed KTZ-SLNs is included in Table 1.

The PDI of <0.3 (presently 0.28 ± 0.02) indicates narrow particle size distribution (Madheswaran et al., 2013). No micronized particles were observed in the entire population and majority (90%) of the

Discussion

Majority of fungal pathogens including Aspergillus sp., Candida sp., and Fusarium sp. and their clinical isolates are susceptible and sensitive to KTZ (Therese et al., 2006). Inspite of showing effectiveness against the commonly occurring infections of the eye (Therese et al., 2006, Grossman and Lee, 1989), no ocular formulation of KTZ is in the market. Effective concentrations of KTZ have been established, but only in the debrided cornea (Hemady et al., 1992), indicating that permeation

Conclusion

Ketoconazole was successfully entrapped in lipidic core providing enhanced permeation through cornea and higher bioavailability both in the aqueous and vitreous humor. The developed nanoparticles were able to cross ocular barrier, reach posterior segment of the eye and had significant antifungal potential. Thus, the developed SLNs can be used both for the treatment of keratitis and endophthalmitis. Corresponding safety in corneal and retinal cell lines followed by in vivo acute and subchronic

Declaration of interest

The authors report no declarations of interest.

Acknowledgments

The funding provided by DST, New Delhi, India, is highly acknowledged. Dr Jayant Raut is thankful for the UGC-D S Kothari post doctorate fellowship.

Characterization studies conducted at PU-SAIF centre are highly acknowledged. Special thanks are due to Mr. Avtar Singh and Mr. Manish Kumar for interpretation of NMR data and to Mr. Dinesh Sharma for TEM pictures.

References (98)

  • E.H. Gokce et al.

    Cyclosporine A loaded SLNs: evaluation of cellular uptake and corneal cytotoxicity

    Int. J. Pharm.

    (2008)
  • R. Grossman et al.

    Transscleral and transcorneal iontophoresis of ketoconazole in the rabbit eye

    Ophthalmology

    (1989)
  • J.T. Heinämäki et al.

    The mechanical and moisture permeability properties of aqueous-based hydroxypropyl methylcellulose coating systems plasticized with polyethylene glycol

    Int. J. Pharm.

    (1994)
  • T. Helgason et al.

    Effect of surfactant surface coverage on formation of solid lipid nanoparticles (SLN)

    J. Colloid Interf. Sci.

    (2009)
  • B. Heurtault et al.

    Physico-chemical stability of colloidal lipid particles

    Biomaterials

    (2003)
  • K. Hironaka et al.

    Design and evaluation of a liposomal delivery system targeting the posterior segment of the eye

    J. Control. Release

    (2009)
  • P.M. Hughes et al.

    Topical and systemic drug delivery to the posterior segments

    Adv. Drug Deliv. Rev.

    (2005)
  • V. Jannin et al.

    Approaches for the development of solid and semi-solid lipid-based formulations

    Adv. Drug Deliv. Rev.

    (2008)
  • V. Jenning et al.

    Solid lipid nanoparticles (SLN) based on binary mixtures of liquid and solid lipids: a (1)H-NMR study

    Int. J. Pharm.

    (2000)
  • J. Jiao

    Polyoxyethylated nonionic surfactants and their applications in topical ocular drug delivery

    Adv. Drug Deliv. Rev.

    (2008)
  • M.A. Kassem et al.

    Nanosuspension as an ophthalmic delivery system for certain glucocorticoid drugs

    Int. J. Pharm.

    (2007)
  • I.P. Kaur et al.

    Potential of solid lipid nanoparticles for brain targeting

    J. Control. Release

    (2008)
  • I.P. Kaur et al.

    Nanotherapy for posterior eye diseases

    J. Control. Release

    (2014)
  • M. Kumar et al.

    Intranasal delivery of streptomycin sulfate (STRS) loaded solid lipid nanoparticles to brain and blood

    Int. J. Pharm.

    (2014)
  • F. Laboulfie et al.

    Effect of the plasticizer on permeability, mechanical resistance and thermal behaviour of composite coating films

    Powder Technol.

    (2013)
  • A. Leonardi et al.

    Influence of different surfactants on the technological properties and in vivo ocular tolerability of lipid nanoparticles

    Int. J. Pharm.

    (2014)
  • X. Li et al.

    A controlled-release ocular delivery system for ibuprofen based on nanostructured lipid carriers

    Int. J. Pharm.

    (2008)
  • W. Mehnert et al.

    Solid lipid nanoparticles: production, characterization and applications

    Adv. Drug Deliv. Rev.

    (2001)
  • A.S. Monem et al.

    Prolonged effect of liposomes encapsulating pilocarpine HCl in normal and glaucomatous rabbits

    Int. J. Pharm.

    (2000)
  • R.H. Muller et al.

    Solid lipid nanoparticles (SLN) for controlled drug delivery—a review of the state of the art

    Eur. J. Pharm. Biopharm.

    (2000)
  • R.H. Muller et al.

    Solid lipid nanoparticles (SLN) and nanostructured lipid carriers (NLC) in cosmetic and dermatological preparations

    Adv. Drug Deliv. Rev.

    (2002)
  • R.H. Muller et al.

    Oral bioavailability of cyclosporine: solid lipid nanoparticles (SLN) versus drug nanocrystals

    Int. J. Pharm.

    (2006)
  • R.C. Nagarwal et al.

    Polymeric nanoparticulate system: a potential approach for ocular drug delivery

    J. Control. Release

    (2009)
  • R.B. Shinde et al.

    Chloroquine sensitizes biofilms of Candida albicans to antifungal azoles

    Braz. J. Infect. Dis.

    (2013)
  • K.L. Therese et al.

    In-vitro susceptibility testing by agar dilution method to determine the minimum inhibitory concentrations of amphotericin B, fluconazole and ketoconazole against ocular fungal isolates

    Indian J. Med. Microbiol.

    (2006)
  • K. Westesen et al.

    Physicochemical characterization of lipid nanoparticles and evaluation of their drug loading capacity and sustained release potential

    J. Control. Release

    (1997)
  • K. Yoncheva et al.

    Pegylated nanoparticles based on poly(methyl vinyl ether-co-maleic anhydride): preparation and evaluation of their bioadhesive properties

    Eur. J. Pharm. Sci.

    (2005)
  • L.M. Yu et al.

    Poly(ethylene glycol) enhances the surface activity of a pulmonary surfactant

    Colloids Surf. B Biointerf.

    (2004)
  • D. Aggarwal et al.

    Development of a topical niosomal preparation of acetazolamide: preparation and evaluation

    J. Pharm. Pharmacol.

    (2004)
  • I. Ahmed et al.

    Importance of the noncorneal absorption route in topical ophthalmic drug delivery

    Invest. Ophthalmol. Vis. Sci.

    (1985)
  • D. Anjana et al.

    Development of curcumin based ophthalmic formulation

    Am. J. Inf. Dis.

    (2012)
  • P. Aragona et al.

    Sodium hyaluronate eye drops of different osmolarity for the treatment of dry eye in Sjogren’s syndrome patients

    Br. J. Ophthalmol.

    (2002)
  • J. Barar et al.

    Ocular novel drug delivery: impacts of membranes and barriers

    Exp. Opin. Drug Deliv.

    (2008)
  • BP

    Efficacy of Antimicrobial Preservation; Appendix XVI C

    (1999)
  • C. Bucolo et al.

    Ocular drug delivery: a clue from nanotechnology

    Front. Pharmacol.

    (2012)
  • CLSI, Clinical Laboratory Standards Institute (formerly NCCLS), 2002. Reference Method for Broth Dilution Antifungal...
  • Y. Dai et al.

    Liposomes containing bile salts as novel ocular delivery systems for tacrolimus (FK506): in vitro characterization and improved corneal permeation

    Int. J. Nanomed.

    (2013)
  • R.M. Donlan et al.

    Biofilms: survival mechanisms of clinically relevant microorganisms

    Clin. Microbiol. Rev.

    (2002)
  • FDA, 2013. Drug Safety Communication: FDA limits usage of Nizoral (ketoconazole) oral tablets due to potentially fatal...
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