In vitro evaluation of gentamicin- and vancomycin-containing minitablets as a replacement for fortified eye drops

Current State of Minitablet Product Design: A Review

Interest in minitablets (MTs) has grown exponentially over the last 20 years and especially the last decade, as evidenced by the number of publications cited in Scopus and PubMed. MTs offer significant opportunities for personalized medicine, dose titration and flexible dosing, taste masking, and customizing drug delivery systems. Advances in specialized MT tooling, manufacturing, and characterization instrumentation have overcome many of the earlier development issues. Breakthrough MT swallowability, acceptability, and palatability research have challenged the long-standing idea that only liquids are acceptable dosage forms for infants and young children. MTs have been shown to be a highly acceptable dosage form for infants, small children, and geriatric patients who have difficulty swallowing. This review discusses the current state of MT applications, acceptability in pediatric and geriatric populations, medication adherence, manufacturing processes such as tableting and coating, running powder and tablet characterization, packaging and MT dispensing, and regulatory considerations.

Smartphone-based digital image colorimetry for the determination of vancomycin in drugs

A simple smartphone-based digital image colorimetry is proposed for the determination of vancomycin in drugs. The analytical method relied on the reaction of vancomycin with copper(II) in ethanol–water medium with pH 4.3. The reaction resulted in the formation of a blue–grey complex, presenting an absorption maximum at 555 nm. A mobile application was used for smartphone-based analysis to decompose the individual channels of the colour model representations. The determination was performed using three smartphones followed by a comparison of the outcomes with spectrophotometric measurements. The most optimal analytical parameters were achieved for the H channel. The linear ranges obtained for the smartphone-based method proved to be comparable to the spectrophotometric range of 0.044–1.500 g dm−3 and were 0.049–1.500 g dm−3, 0.057–1.500 g dm−3, and 0.040–1.500 g dm−3 for Smartphones 1–3, respectively. Moreover, the determined coefficients of variance (CV, n = 9) and limits of detection (LOD) were 2.3% and 0.015 g dm−3, 6.2% and 0.017 g dm−3, and 2.5% and 0.012 g dm−3, respectively. Whereas for spectrophotometry, the obtained precision, CV was of 0.9% and a LOD of 0.013 g dm−3. The accuracy of the method was verified using model samples, generally the results were obtained with accuracy better than 10.9% (relative error). The method was applied to the determination of vancomycin in drugs. The results obtained by smartphone-based colorimetry did not differ from the expected values for more than 2.6%, were consistent with each other and with the results of spectrophotometric determinations.

Graphical abstract

Turbidimetric Method: A New, Ecological, and Fast Way to Evaluate of Vancomycin Potency

Background

Vancomycin, an antimicrobial, has many microbiological methods in literature, but it was not found any that follows the green chemistry principles.

Objective

The aim of this work was to develop and validate a new microbiological analytical method with a green view to determine the vancomycin potency in lyophilized powder using less quantity of diluents and culture medium, minimizing the costs and reducing the time of analysis.

Methods

The objective will be achieved using the microbiological method by turbidimetry.

Results

Water was used as the diluent to prepare the vancomycin solution. BHI broth as used as culture media for the growth of the S. aureus ATCC 25923. The method was linear in the range of 30, 39 and 50.7 µg/mL. It was selective, with vancomycin reference and sample absorbance values very similar. The precision of the method was proved at intraday (RSD 4.42 %), interday (RSD 3.56 %) and intermediate levels (RSD 2.03%). It was accurate with mean recovery of 100.71 % and robust when changes were performed in three parameters of the method and analyzed by the F-Test and t-Test.

Conclusions

The method for evaluating the potency of vancomycin in pharmaceutical product was successfully developed and validated.

Highlights

The method can be applied to routine quality control of vancomycin product as an alternative that contemplates the green analytical chemistry and the current pharmaceutical analyzes.

Stimulus Responsive Ocular Gentamycin-Ferrying Chitosan Nanoparticles Hydrogel: Formulation Optimization, Ocular Safety and Antibacterial Assessment

PURPOSE

The present study was designed to study the gentamycin (GTM)-loaded stimulus-responsive chitosan nanoparticles to treat bacterial conjunctivitis.

METHODS

GTM-loaded chitosan nanoparticles (GTM-CHNPs) were prepared by ionotropic gelation method and further optimized by 3-factor and 3-level Box-Behnken design. Chitosan (A), sodium tripolyphosphate (B), and stirring speed (C) were selected as independent variables. Their effects were observed on particle size (PS as Y1), entrapment efficiency (EE as Y2), and loading capacity (LC as Y3).

RESULTS

The optimized formulation showed the particle size, entrapment efficiency, and loading capacity of 135.2±3.24 nm, 60.18±1.65%, and 34.19±1.17%, respectively. The optimized gentamycin-loaded chitosan nanoparticle (GTM-CHNPopt) was further converted to the stimulus-responsive sol-gel system (using pH-sensitive carbopol 974P). GTM-CHNPopt sol-gel (NSG5) exhibited good gelling strength and sustained release (58.99±1.28% in 12h). The corneal hydration and histopathology of excised goat cornea revealed safe to the cornea. It also exhibited significant (p<0.05) higher ZOI than the marketed eye drop.

CONCLUSION

The finding suggests that GTM-CHNP-based sol-gel is suitable for ocular delivery to enhance the corneal contact time and improved patient compliance.

Current Status of Vancomycin Analytical Methods

BACKGROUND

The glycopeptide antibiotics are a class of antimicrobial drugs that are an important alternative for cases of bacterial infections resistant to penicillins, besides being able to be used to treat infections in people allergic to pencilin. They have great activity against Gram-positive microorganisms, including methicillin-resistant Staphylococcus aureus (MRSA), by inhibiting the cell wall synthesis.

OBJECTIVE

There are many analytical methods in the literature for determination of antimicrobial glycopeptide vancomycin in different matrixes that are very effective; however, all of them use toxic solvents, contributing to the generation of waste, causing damage to the environment and to the operator, as well as increased costs of analysis.

RESULTS

The most prevailing method found was high performance liquid chromatography (HPLC), followed by microbiological assays and, in less quantity, spectrometric methods. The chromatographic methods use organic solvents that are toxic, such as acetonitrile and methanol, and buffer solutions, that can damage the equipment and the column. In the microbiological assays the disc diffusion methods are still in the majority. The spectrophotometric methods were based in the UV-Vis region using buffer solutions as a diluent.

CONCLUSIONS

All these methods can become greener, following green analytical chemistry principles, which could bring benefits both to the environment and the operator, and reduce costs.

HIGHLIGHTS

In this paper, a literature review regarding analytical methods for determination of vancomycin was carried out with a suggestion of greener alternatives.

Formulation of sustained release bioadhesive minitablets containing solid dispersion of levofloxacin for once daily ocular use

This study aimed to increase ocular residence time of levofloxacin by formulation into zero-order sustained release mucoadhesive minitablets for once daily administration using a hydrophobic-hydrophilic polymeric matrix. Levofloxacin was first formulated into solid dispersion with different ratios of Eudragit^® RS then the resulting solid dispersion was mixed with different concentrations of Carbopol^® and other excipients to be finally compressed into minitablets. A 2⁴ full factorial design was employed to estimate the effects and interactions of two formulation factors, and to establish their relationships with selected responses in the developed minitablets. The studied factors were: drug to Eudragit^® RS ratio, and percent of Carbopol^® in the minitablets. Sixteen ocular minitablets formulations were prepared and evaluated for the cumulative percentages drug release at 6, 12, and 24 h, as well as mucoadhesion time, mucoadhesive strength, and swelling index as response variables. After optimizing the responses, the optimized formulation was found to be stable on sterilization using gamma-irradiation and storage at 40 °C/75% RH for six months. In vivo testing of the optimized formulation showed that the minitablets extended levofloxacin release up to 24 h without causing any ocular irritation. The optimized formulation exhibited superior microbiological activity compared to the commercial product.

Effect of Methylcellulose Molecular Weight on the Properties of Self-Assembling MC-g-PNtBAm Nanogels

The efficiency of drug delivery to the eye using topical drop therapy is limited by the ocular clearance mechanisms. Nanocarriers, able to encapsulate bioactive compounds and slow down their release, may allow for prolonged on-eye residence times when combined with topical application for treatment of ocular conditions. Previously, self-assemblies of methylcellulose (MC) hydrophobized with N-tert-butylacrylamide side chains (MC-g-PNtBAm) were developed. The purpose of the current study was to investigate the impact of the methylcellulose backbone length on the properties of the nanogels. We synthesized MC-g-PNtBAm nanogels using four different molecular weights of MC with two degrees of hydrophobic modification and investigated the physical and chemical properties of the resulting polymeric nanogels. While no significant change could be observed at a high degree of hydrophobization, properties were affected at a lower one. Increasing the molecular weight of MC improved the swelling capacity of the nanogels, increasing their size in water. An effect on the drug release was also noted. Nanogels prepared using MC with a molecular weight of 30 kDa did not retain as much dexamethasone and released it faster compared to those prepared using 230 kDa MC. Thus, besides the degree of hydrophobization, the length of MC chains provides another means of tuning the properties of MC-g-PNtBAm nanogels.

Nanogels of methylcellulose hydrophobized with N-tert-butylacrylamide for ocular drug delivery

While eye drops account for the majority of ophthalmic formulation for drug delivery, their efficiency is limited by rapid pre-corneal loss. In this study, we investigate nanogel suspensions in order to improve the topical ocular therapy by reducing dosage and frequency of administration. We synthesized self-assembling nanogels of 140 nm by grafting side chains of poly(N-tert-butylacrylamide) (PNtBAm) on methylcellulose via cerium ammonium nitrate. Successful grafting of PNtBAm onto methylcellulose (MC) was confirmed by both NMR and ATR. Synthesized molecules (MC-g-PNtBAm) self-assembled in water driven by hydrophobic interaction of the grafted side chains creating colloid solutions. Materials were synthesized by changing feed ratios of acid, initiator and monomer in order to control the degree of hydrophobic modification. The nanogels were tested for different degrees of grafting. Viability studies performed with HCE cells testified to the biocompatibility of poly(N-tert-butylacrylamide) grafted methylcellulose nanogels. Dexamethasone was entrapped with an efficiency superior to 95 % and its release presented minimal burst phase. Diffusion of drug from the nanogels was found to be delayed by increasing the degree of grafting. The release profile of the entrapped compound from the MC-g-PNtBAm nanogels can thus be tuned by simply adjusting the degree of hydrophobic modification. MC-g-PNtBAm nanogels present promising properties for ocular drug delivery.

A review of topically administered mini-tablets for drug delivery to the anterior segment of the eye

OBJECTIVES

The human eye is a unique and intricate structure which has made drug delivery to the eye a formidable undertaking. Anterior-segment eye diseases are ubiquitous, especially among elderly patients, and conventional eye drops, although a first-choice dosage form, are not always an efficient treatment option. The development of novel drug delivery systems for improved treatment is therefore imperative.

KEY FINDINGS

In an attempt to circumvent the obstacles presented by the structure of the eye, advanced systems such as ocular mini-tablets have been developed. In this review, a concerted effort has been made to provide a detailed overview of topically administered ocular mini-tablets and other solid devices for drug delivery to the anterior segment of the eye. These mini-tablets have been shown in vitro and in vivo to have significant advantages in comparison with liquid preparations. This is a step toward attaining better patient convenience and compliance, which are critical factors.

SUMMARY

Solid ophthalmic dosage forms have several advantages that can contribute to assisting with patient compliance and, ultimately, effective disease treatment. In addition to the challenges associated with topical ocular drug delivery, the shortcomings of conventional eye drops, advantages of mini-tablets, and improvements to date to these systems are discussed. The requirement for further advancements in the ocular field is also emphasized.

Quality assessment of U.S. marketplace vancomycin for injection products using high-resolution liquid chromatography-mass spectrometry and potency assays

In response to a published concern about the potency and quality of generic vancomycin products, the United States Food and Drug Administration investigated a small sampling of the vancomycin products available in North America with regard to purity, content, and potency. To facilitate identification of impurities, a new liquid chromatography method was developed using high-resolution mass spectrometry in addition to diode array detection to characterize impurities in several commercial products. Furthermore, a microbiological assay was utilized to link the analytical profiles with an in vitro potency. All products tested met the quality specifications outlined in the United States Pharmacopeia (USP) (vancomycin hydrochloride for injection monograph) for impurities and potency (USP, Vancomycin hydrochloride for injection. United States Pharmacopeia and National Formulary, vol USP 34-NF 29, 2011).