Local Ugandan Production of Stable 0.2% Chlorhexidine Eye Drops.

Purpose: The purpose of this study was to develop a protocol to prepare buffered chlorhexidine (CHX) eye drops (0.2% w/v) in the United Kingdom that can be reproduced at a production facility in Uganda. Buffered CHX eye drops can prevent CHX degradation and improve ocular tolerability during the treatment of fungal keratitis. Methods: Buffered CHX eye drops in amber glass containers were prepared using sodium acetate buffer at pH 5.90 to 6.75. Two commercial CHX solutions and CHX in water were used as controls. Eye drops were stored at 40°C (70% humidity, 21 months) in the United Kingdom and at ambient temperature in Uganda (30 months). High-performance liquid chromatography was used to determine CHX stability over time, and pH was monitored. Sterility was achieved using an autoclave (121°C, 15 minutes) and water bath (100°C, 30 minutes). Results: The pH of acetate-buffered CHX eye drops did not change over 21 months at 40°C or at ambient temperature (30 months), whereas the pH of the unbuffered aqueous CHX displayed significant fluctuations, with an increase in acidity. The CHX concentration remained the same in both buffered and unbuffered eye-drop solutions. Eye drops sterilization was successful using an autoclave and a water bath. Conclusions: Stable, sterile, buffered CHX eye drops (pH 6.75) were successfully prepared first in the United Kingdom and then reproducibly in Uganda. This eye drops can be prepared in a hospital or pharmacy setting with limited resources, thus providing a cost-effective treatment for fungal keratitis. Translational Relevance: A protocol has been developed to prepare buffered CHX eye drops in low- and middle-income countries to treat fungal keratitis.

Management of Filamentous Fungal Keratitis: A Pragmatic Approach.

Filamentous fungal infections of the cornea known as filamentous fungal keratitis (FK) are challenging to treat. Topical natamycin 5% is usually first-line treatment following the results of several landmark clinical trials. However, even when treated intensively, infections may progress to corneal perforation. Current topical antifungals are not always effective and are often unavailable. Alternatives topical therapies to natamycin include voriconazole, chlorhexidine, amphotericin B and econazole. Surgical therapy, typically in the form of therapeutic penetrating keratoplasty, may be required for severe cases or following corneal perforation. Alternative treatment strategies such as intrastromal or intracameral injections of antifungals may be used. However, there is often no clear treatment strategy and the evidence to guide therapy is often lacking. This review describes the different treatment options and their evidence and provides a pragmatic approach to the management of fungal keratitis, particularly for clinicians working in tropical, low-resource settings where fungal keratitis is most prevalent.

Chlorhexidine gluconate 0.2% as a treatment for recalcitrant fungal keratitis in Uganda: a pilot study.

OBJECTIVE: Fungal keratitis is a major ophthalmic public health problem, particularly in low-income and middle-income countries. The options for treating fungal keratitis are limited. Our study aimed to describe the outcomes of using chlorhexidine 0.2% eye-drops as additional treatment in the management of patients with recalcitrant fungal keratitis. METHODS: This study was nested within a large cohort study of people presenting with microbial keratitis in Uganda. We enrolled patients with recalcitrant fungal keratitis not improving with topical natamycin 5% and commenced chlorhexidine 0.2%. Follow-up was scheduled for 3 months and 1 year. The main outcome measures were healing, visual acuity and scar size at final follow-up. RESULTS: Thirteen patients were followed in this substudy. The patients were aged 27-73 years (median 43 years). Filamentous fungi were identified by microscopy of corneal scrape samples in all cases. Isolated organisms included Aspergillus spp, Fusarium spp, Candida spp, Bipolaris spp and Acremoninum spp. At the final follow-up, nine patients (75%) had healed; three had vision of better than 6/18. Three patients lost their eyes due to infection. In the remaining nine cases, corneal scarring was variable ranging from 4.6 to 9.4 mm (median 6.6 mm, IQR 5.9-8.0 mm); of these five had dense scars, three had moderate scars and one had a mild scar. None of the patients demonstrated signs of chlorhexidine toxicity during the follow-up. CONCLUSION: Chlorhexidine 0.2% was found to be a useful sequential adjunctive topical antifungal in cases of fungal keratitis not responding to natamycin 5%, which warrants further evaluation.

Rats can predict aversiveness of Active Pharmaceutical Ingredients.

Taste is crucial for patient acceptability and compliance with prescribed medicines, in particular with pediatric patients. Evaluating the taste of new active pharmaceutical ingredients (APIs) is therefore essential to put in place adequate taste-masking techniques, if needed, which will lead to acceptable palatable formulations. Thus, there is an urgent need to develop and optimize taste assessment methods that could be used at different stages of the drug development process. The aim of this study was to investigate the suitability of the rat brief-access taste aversion (BATA) model as a screening tool for assessment of APIs aversiveness that could predict human taste responses. Presently, the taste intensity of nine marketed APIs known to have different levels of bitter intensity (quinine hydrochloride dihydrate, 6-n-propylthiouracil, sildenafil citrate, diclofenac sodium, ranitidine hydrochloride, caffeine citrate, isoniazid, telbivudine and paracetamol) was investigated at different overlapping concentrations with two in vivo taste assessment methods: the rat BATA model and human taste panels with the intention of determining the drugs' concentrations to produce half of the maximal rating. Overall there was a strong correlation (R2 = 0.896) between rats IC50 and humans EC50 values. This correlation verifies the BATA model as a rapid and reliable tool for quantitative assessment of API aversiveness. A comparable ranking order was obtained mainly for high and medium aversive compounds, whereas it was less aligned for weakly aversive compounds. It was nonetheless possible to propose a classification of poor taste intensity determined in rats that would predict human taste tolerability.

LC-MS analysis to determine the biodistribution of a polymer coated ilomastat ocular implant.

Ilomastat is a matrix metalloproteinase inhibitor (MMPi) that has shown the potential to inhibit scarring (fibrosis) by mediating healing after injury or surgery. A long lasting ocular implantable pharmaceutical formulation of ilomastat is being developed to mediate the healing process to prevent scarring after glaucoma filtration surgery. The ilomastat implant was coated with water permeable and biocompatible phosphoryl choline polymer (PC1059) displayed extended slow release of ilomastat in vitro and in vivo. The ocular distribution of ilomastat from the implant in rabbits at day 30 post surgery was determined by the extraction of ilomastat and its internal standard marimastat from the ocular tissues, plasma, aqueous humour and vitreous fluid followed by capillary-flow liquid chromatography (cap-LC), the column effluent was directed into a triple quadrupole mass spectrometer operating in product scan mode. The lower limits of quantification (LLOQs) were 0.3 pg/µL for ocular fluids and plasma, and 3 pg/mg for ocular tissues. The extraction recoveries were 90-95% for ilomastat and its internal standard from ocular tissues. Ilomastat was found in ocular fluids and tissues at day 30 after surgery. The level of ilomastat was 18 times higher in the aqueous humour than vitreous humour. The concentration ranking of ilomastat in the ocular tissues was sclera > bleb conjunctiva > conjunctiva (rest of the eye) > cornea. Mass spectrometry analysis to confirm the presence of ilomastat in the ocular tissues and fluids at day 30 post-surgery establishes the extended release of ilomastat can be achieved in vivo, which is crucial information for optimisation of the ilomastat coated implant.

Taste evaluation of a novel midazolam tablet for pediatric patients: In vitro drug dissolution, in vivo animal taste aversion and clinical taste perception profiles.

Harmonized methodologies are urgently required for the taste evaluation of novel pediatric medicines. This study utilized in vitro, in vivo and clinical data to evaluate the palatability of a novel midazolam chocolate tablet. In vitro dissolution experiments showed the crushed tablet to release within 5 min 1.68 mg of midazolam into simulated saliva. This translated to a drug level of 0.84 mg/ml in the oral cavity, which would be higher than the midazolam bitterness detection threshold concentration of 0.03 mg/ml determined in a rat 'brief access taste aversion' (BATA) model. The visual analogue scale scores of patients aged 4-16 years prescribed with midazolam pre-surgery showed a clear preference for the midazolam chocolate tablets (3.35 ± 1.04, n = 20) compared to the control midazolam solution (1.47 ± 0.62, n = 17). The clinical data was in agreement with the in vivo rodent data in showing the novel chocolate tablet matrix to be effective at taste-masking the bitter midazolam.

Principles of pharmacology in the eye.

The eye is a highly specialized organ that is subject to a huge range of pathology. Both local and systemic disease may affect different anatomical regions of the eye. The least invasive routes for ocular drug administration are topical (e.g. eye drops) and systemic (e.g. tablets) formulations. Barriers that subserve as protection against pathogen entry also restrict drug permeation. Topically administered drugs often display limited bioavailability due to many physical and biochemical barriers including the pre-corneal tear film, the structure and biophysiological properties of the cornea, the limited volume that can be accommodated by the cul-de-sac, the lacrimal drainage system and reflex tearing. The tissue layers of the cornea and conjunctiva are further key factors that act to restrict drug delivery. Using carriers that enhance viscosity or bind to the ocular surface increases bioavailability. Matching the pH and polarity of drug molecules to the tissue layers allows greater penetration. Drug delivery to the posterior segment is a greater challenge and, currently, the standard route is via intravitreal injection, notwithstanding the risks of endophthalmitis and retinal detachment with frequent injections. Intraocular implants that allow sustained drug release are at different stages of development. Novel exciting therapeutic approaches include methods for promoting transscleral delivery, sustained release devices, nanotechnology and gene therapy.

An Ilomastat-CD Eye Drop Formulation to Treat Ocular Scarring.

Purpose: The purpose of this study was to develop a topical matrix metalloproteinase inhibitor preparation for antiscarring therapy. Methods: The broad spectrum matrix metalloproteinase inhibitor ilomastat was formulated using 2-hydroxypropyl-ß-cyclodextrin in aqueous solution. In vitro activity of ilomastat-cyclodextrin (ilomastat-CD) was examined using fibroblasts seeded in collagen. Permeation of ilomastat-CD eye drop through pig eye conjunctiva was confirmed using Franz diffusion cells. Ilomastat-CD eye drop was applied to rabbit eyes in vivo, and the distribution of ilomastat in ocular tissues and fluids was determined by liquid chromatography-mass spectroscopy. Results: The aqueous solubility of ilomastat-CD was ∼1000 µg/mL in water and 1400 µg/mL in PBS (pH 7.4), which is greater than ilomastat alone (140 and 160 µg/mL in water and PBS, respectively). The in vitro activity of ilomastat-CD to inhibit collagen contraction in the presence of human Tenon fibroblast cells was unchanged compared to uncomplexed ilomastat. Topically administered ilomastat-CD in vivo to rabbit eyes resulted in a therapeutic concentration of ilomastat being present in the sclera and conjunctiva and within the aqueous humor. Conclusions: Ilomastat-CD has the potential to be formulated as an eye drop for use as an antifibrotic, which may have implications for the prevention of scarring in many settings, for example glaucoma filtration surgery.

Comparative in vitro and in vivo taste assessment of liquid praziquantel formulations.

The taste of pharmaceuticals strongly affects the compliance of patients. This study investigated the applicability of the electronic tongue and rodent brief-access taste aversion (BATA) model for the bitter compound praziquantel (PZQ) and taste masked liquid formulations for PZQ. In a comparative study maltodextrin (MD) Kleptose® linecaps 17 was selected as an alternative taste masking agent to two cyclodextrins; hydroxypropyl-beta-cyclodextrin (HP-ß-CD) and sulfobutyl ether-beta-cyclodextrin (SBE-ß-CD). A phase solubility study showed the highest affinity and solubilization capabilities for SBE-ß-CD over HP-ß-CD and MD, suggesting the highest taste masking ability for SBE-ß-CD. No reliable results were achieved for PZQ with the Insent electronic tongue. Thus this system was not used for further evaluation of solutions with MD and CDs to confirm the results of the solubility study. In contrast the BATA model demonstrated conclusive responses for the aversiveness of PZQ. The concentration of PZQ inhibiting 50% of water lick numbers (called IC50 value) was 0.06mg/ml. In contrast to the phase solubility study, the MD enabled an equal taste masking effect in vivo in comparison to both CDs. Moreover HP-ß-CD showed superior taste masking capabilities for PZQ compared to SBE-ß-CD as the SBE-ß-CD itself was less acceptable for the rodents than HP-ß-CD. In conclusion, the BATA model was identified as a more efficient taste assessment tool for the pure PZQ and liquid formulations in contrast to the electronic tongue and the phase solubility study.

Quality and stability of extemporaneous pyridoxal phosphate preparations used in the treatment of paediatric epilepsy.

OBJECTIVES: To assess the pyridoxal 5'-phosphate (PLP) content and stability of extemporaneous PLP liquids prepared from dietary supplements used for the treatment of vitamin B6 -dependent epilepsy. METHODS: Pyridoxal 5'-phosphate liquids were prepared in accordance with the guidelines given to patients from marketed 50 mg PLP dietary capsules and tablets. The PLP content and its stability were evaluated under conditions resembling the clinical setting using reverse phase HPLC and mass spectrometry. KEY FINDINGS: Pyridoxal 5'-phosphate content in most of the extemporaneously prepared liquids from dietary supplements was found to be different from the expected amount (~16-60 mg). Most of these PLP extemporaneous liquids were stable at room temperature (protected from light) after 24 h but unstable after 4 h when exposed to light. A key photodegradation product of PLP in water was confirmed as 4-pyridoxic acid 5'-phosphate (PAP). CONCLUSION: Pyridoxal 5'-phosphate tablets from Solgar® were found to be the most reliable product for the preparation of extemporaneous PLP liquids. This work highlighted the difference between the marketed PLP dietary supplements quality and the importance of proper storage of aqueous PLP. There is a need to develop pharmaceutical forms of PLP that ensure dose accuracy and avoid potentially unsafe impurities with the aim of enhancing safety and compliance.

Non-human tools for the evaluation of bitter taste in the design and development of medicines: a systematic review.

Taste evaluation is a crucial factor for determining acceptance of medicines by patients. The human taste panel test is the main method used to establish the overall palatability and acceptability of a drug product to a patient towards the end of development. Non-human in vitro and in vivo taste-evaluation tools are very useful for pre-formulation, quality control and screening of formulations. These non-human taste assessment tools can be used to evaluate all aspects of taste quality. The focus of this review is bitterness because it is a key aspect of taste in association with the development of medicines. In this review, recent in vitro (analytical) and in vivo (non-human) tools are described for the assessment of the bitter taste of medicines. Their correlations with human taste data are critically discussed. The potential for their use in early screening of the taste of active pharmaceutical ingredients (APIs) to expedite paediatric formulation development is also considered.

Antileishmanial activity, uptake, and biodistribution of an amphotericin B and poly(α-Glutamic Acid) complex.

A noncovalent, water-soluble complex of amphotericin B (AMB) and poly(α-glutamic acid) (PGA), with AMB loadings ranging from 25 to 55% (wt/wt) using PGA with a molecular weight range of 50,000 to 70,000, was prepared as a potential new treatment for visceral leishmaniasis (VL). The AMB-PGA complex was shown to be as active as Fungizone (AMB deoxycholate) against intracellular Leishmania donovani amastigotes in differentiated THP-1 cells. The in vitro uptake of the AMB-PGA complex by differentiated THP-1 cells was similar to that of Fungizone and higher than that of AmBisome (liposomal AMB). The AMB-PGA complex also displayed a dose-response profile similar to that of AmBisome in vivo in BALB/c mice against L. donovani, with 50% effective doses (ED50s) of 0.24 ± 0.03 mg/kg of body weight for the AMB-PGA complex and 0.24 ± 0.06 mg/kg for AmBisome. A biodistribution study with mice indicated that the AMB-PGA complex cleared more rapidly from plasma than AmBisome, with a comparable low level of distribution to the kidneys.

Noncovalent complexation of amphotericin-B with Poly(α-glutamic acid).

A noncovalent complex of amphotericin B (AmB) and poly(α-glutamic acid) (PGA) was prepared to develop a safe and stable formulation for the treatment of leishmaniasis. The loading of AmB in the complex was in the range of ∼20-50%. AmB was in a highly aggregated state with an aggregation ratio often above 2.0. This complex (AmB-PGA) was shown to be stable and to have reduced toxicity to human red blood cells and KB cells compared to the parent compound; cell viability was not affected at an AmB concentration as high as 50 and 200 µg/mL respectively. This AmB-PGA complex retained AmB activity against intracellular Leishmania major amastigotes in the differentiated THP-1 cells with an EC50 of 0.07 ± 0.03-0.08 ± 0.01 µg/mL, which is similar to Fungizone (EC50 of 0.06 ± 0.01 µg/mL). The in vitro antileishmanial activity of the complex against Leishmania donovani was retained after storage at 37 °C for 7 days in the form of a solution (EC50 of 0.27 ± 0.03 to 0.35 ± 0.04 µg/mL) and for 30 days as a solid (EC50 of 0.41 ± 0.07 to 0.63 ± 0.25 µg/mL). These encouraging results indicate that the AmB-PGA complex has the potential for further development.

Recent advances in development of amphotericin B formulations for the treatment of visceral leishmaniasis.

PURPOSE OF REVIEW: Amphotericin B (AmpB) is considered the first-line treatment for visceral leishmaniasis in areas in which resistance to antimony is prevalent. This review describes recent advances in clinically available and novel drug delivery systems of AmpB to treat visceral leishmaniasis. RECENT FINDINGS: Over the past two decades, lipid-based AmpB formulations developed to tackle the toxicity of AmpB have been used clinically for the treatment of visceral leishmaniasis. Liposomal AmpB (AmBisome) has been the most successful lipid formulation, and recent clinical studies on visceral leishmaniasis have shown the potential of single-dose AmBisome treatment as well as its use in short course combinations with other antileishmanial drugs. Current research is focussed on the development of more stable and affordable nonlipid formulations of AmpB. Although a diverse range of nonlipid-based AmpB formulations have been evaluated, none have yet reached the clinic. SUMMARY: Liposomal AmpB (AmBisome) has become a standard treatment, by intravenous infusion, for visceral leishmaniasis and the basis for new short course treatments. There have been extensive efforts to develop new AmpB formulations on the basis of polymers, lipids or physical aggregates of AmpB to replace the costly lipid-based formulations. However, no nonlipid-based AmpB delivery systems have yet reached the clinic.