Intravitreal acetazolamide implant for pseudophakic cystoid macular edema.

BACKGROUND: Pseudophakic cystoid macular edema (PCME) is the most common cause of visual acuity deterioration after uncomplicated cataract surgery. There is no consensus regarding how to manage recurrent or refractory cases. REPORT: A 54-year-old woman complained of decreased vision and central metamorphopsia in the right eye (OD) 3 months after uneventful cataract surgery. Visual acuity was 0.3 logMAR (20/40) OD and 0.1 logMAR (20/25) OS. Reduced macular brightness was seen OD on funduscopy associated with increased macular thickness on optical coherence tomography (OCT). Pseudophakic cystoid macular edema (PCME) was diagnosed, and treatment with oral acetazolamide was tried without success. The patient underwent a single intravitreal injection of an acetazolamide implant (260 µg) OD as off-label treatment. Four weeks following the injection, she reported complete resolution of her metamorphopsia and visual loss OD. Four months later, her visual acuity was 0.0 logMAR (20/20) in OD and 0.1 logMAR (20/25) in OS. The patient reported no discomfort after the injection procedure. Laboratory and ophthalmologic tests did not identify any adverse effects of the medication. CONCLUSION: We show that PCME refractory to conventional treatment improved after intravitreal acetazolamide implant injection. Further investigation is warranted to confirm these preliminary findings.

Microextraction by packed sorbent and high-performance liquid chromatography for determination of benznidazole in human plasma.

Benznidazole is the main drug used in Chagas disease and its determination in plasma samples is useful in several situations. Hence, robust and accurate bioanalytical methods are needed. In this context, sample preparation deserves special attention, as it is the most error-prone, labor-intensive and time-consuming step. Microextraction by packed sorbent (MEPS) is a miniaturized technique, developed to minimize the use of hazardous solvents and sample amount. In this context, this study aimed to develop and validate a MEPS coupled to high performance liquid chromatography method for the analysis of benznidazole in human plasma. MEPS optimization was performed by a 24 full factorial experimental design, which resulted in about 25 % of recovery. The best condition was achieved when 500 µL of plasma,10 draw-eject cycles, sample volume drawn of 100 µL, and desorption with three times of 50 µL of acetonitrile were used. The chromatographic separation was performed with a C18 (150 × 4.5 mm, 5 µm) column. The mobile phase was composed of water:acetonitrile (60:40) at a flow rate of 1.0 mL min-1. The developed method was validated and proved to be selective, precise, accurate, robust and linear in the range from 0.5 to 6.0 µg mL-1. The method was applied to three healthy volunteers that made use of benznidazole tablets and showed to be adequate to assess this drug in plasma samples.

Chromatographic bioanalysis of antiglaucoma drugs in ocular tissues.

Glaucoma is a heterogeneous group of multifactorial optic neuropathies and the leading cause of irreversible blindness and visual impairment. Epidemiological data has estimated that in 2020 there will be more than 80 million individuals affected by the disease worldwide. Nowadays, intraocular pressure (IOP) lowering is carried out mainly by pharmacotherapy, with different drugs. The study of ocular pharmacokinetics of antiglaucoma drugs, crucial for better understanding of ocular distribution, bioavailability, and pharmacodynamic parameters, can benefit the development of antiglaucoma drugs or formulations. Bioanalysis of drugs in ocular matrices is still underestimated, since it is challenging and rarely performed. Therefore, this review summarized the chromatographic methods employed for the quantification of several antiglaucoma drugs in different ocular matrices, discussing bioanalytical steps, such as sample preparation, separation, and detection. Animals and matrices as well as the challenges faced in ocular bioanalysis were also discussed. Ocular bioanalysis has been performed mainly in rabbits, the most adequate animal model for ocular studies. The matrix most used is aqueous humor, because it is cleaner and easier to sample. Sample preparation was carried out primarily employing classic techniques, such as liquid-liquid extraction, protein precipitation, and solid-phase extraction, with conventional solvents and sorbents. Chromatographic separation was achieved predominantly by reversed-phase liquid chromatography. Ultraviolet spectrophotometry and tandem mass spectrometry prevailed for detection, although other techniques, such as fluorimetry, have also been used. It was evidenced that more efforts must be directed towards miniaturized, eco-friendly, and non-terminal sampling for sample preparation. In its turn, ultra high-performance liquid chromatography and mass spectrometry should gain prominence in ocular bioanalysis for separation and detection, respectively, since it combines high separation capacity with selectivity and sensitivity, in addition to being an environmental friendly approach.

Synthesis and characterization of a molecularly imprinted polymer (MIP) for solid-phase extraction of the antidiabetic gliclazide from human plasma.

Gliclazide is a sulfonylurea frequently prescribed for the management of type 2 diabetes mellitus in elderly patients and for patients with chronic renal or hepatic diseases. Even though it is considered a safer alternative, the drug can provoke side effects in some patients, especially hypoglycemia, due to the high interindividual variability. Therefore, the quantification of gliclazide in biological samples is usually recommended in order to assure efficacy and safety of the pharmacotherapy. However, due to the complexity of biological matrices, therapeutic monitoring can be very challenging, especially in the sample preparation step. For that reason, the synthesis and characterization of a novel and selective molecularly imprinted polymer (MIP) was proposed to be employed as sorbent for the extraction of gliclazide from human plasma samples by a molecularly imprinted solid-phase extraction (MISPE) procedure. Synthesis conditions were optimized (monomer, crosslinker and porogen) and the polymer was characterized for its morphological, physicochemical and stability properties. The influence of drug concentration, solvent composition and pH on the coefficient of distribution (Kd) and imprinting factor (IF) were studied, as well as repeatability between batches and selectivity. A bioanalytical method was developed applying the developed MIP as sorbent in solid phase extraction and liquid chromatography using a Poroshell 120 C18 (100 × 4.6 mm, 4 µm) column, acetonitrile and 10 mM potassium phosphate buffer pH 3.0 (50:50) at a flow-rate of 1.2 mL/min as mobile phase, temperature of 30 °C, injection volume of 40 µL and detection at 230 nm. The best reaction yield, extraction capacity, and selectivity was obtained using 2-hydroxyethyl methacrylate (2-HEMA), ethyleneglycol dimethacrylate (EGDMA) and acetonitrile. The optimized MIP showed coefficient of distribution (Kd) of 59.85 µg/g, imprinting factor (IF) of 1.60, and selectivity for gliclazide and other sulfonylureas compared to possible concurrent drugs. The developed method by MISPE-HPLC-UV showed to be appropriate to determine gliclazide in human plasma samples.

Quantitative determination of the antimalarials artemether and lumefantrine in biological samples: A review.

Malaria is a worldwide health issue, with 216 million cases reported in 2016. Due to the widespread resistance of Plasmodium falciparum to conventional drugs, the first line treatment recommended by World Health Organization for uncomplicated malaria is artemisinin-based combined therapy (ACT), which combines two drugs with different mechanisms of action. The association of artemether and lumefantrine is the most common ACT used in the clinical practice. However, there have been reports of clinical artemisinin and derivatives partial resistance, which is defined as delayed parasite clearance. In this context, the monitoring of drug concentration in biological matrices is essential to evaluate treatment response, the need of dose adjustment and the occurrence of dose dependent adverse effects. Furthermore, it is also important for pharmacokinetic studies and in the development of generic and similar drugs. Determination of antimalarial drugs in biological matrices requires a sample pre-treatment, which involves drug extraction from the matrix and analyte concentration. The most used techniques are protein precipitation (PP), liquid-liquid extraction (LLE) and solid phase extraction (SPE). Subsequently, a liquid chromatography step is usually applied to separate interferences that could be extracted along with the analyte. Finally, the analytes are detected employing techniques that must be selective and sensitive, since the analyte might be present in trace levels. The most used approach for detection is tandem mass spectrometry (MS-MS), but ultraviolet (UV) is also employed in several studies. In this article, a review of the scientific peer-review literature dealing with validated quantitative analysis of artemether and/or lumefantrine in biological matrices, from 2000 to 2018, is presented.

Molecularly imprinted polymer for determination of lumefantrine in human plasma through chemometric-assisted solid-phase extraction and liquid chromatography.

Lumefantrine is the first-choice treatment of Falciparum uncomplicated malaria. Recent findings of resistance to lumefantrine has brought attention for the importance of therapeutic monitoring, since exposure to subtherapeutic doses of antimalarials after administration is a major cause of selection of resistant parasites. Therefore, this study focused on the development of innovative, selective, less expensive and stable molecularly imprinted polymers (MIPs) for solid-phase extraction (SPE) of lumefantrine from human plasma to be used in drug monitoring. Polymers were synthesized by precipitation polymerization and chemometric tools (Box-Behnken design and surface response methodology) were employed for rational optimization of synthetic parameters. Optimum conditions were achieved with 2-vinylpyridine as monomer, ethylene glycol dimethacrylate as crosslinker and toluene as porogen, at molar ratio of 1:6:30 of template/monomer/crosslinker and azo-bisisobutyronitrile as initiator at 65 °C. The MIP obtained was characterized and exhibited high thermal stability, adequate surface morphology and porosity characteristics and high binding properties, with high affinity (adsorption capacity of 977.83 µg g-1) and selectivity (imprinting factor of 2.44; and selectivity factor of 1.48 and selectivity constant of 1.44 compared with halofantrine). Doehlert matrix and fractional designs were satisfactorily used for development and optimization of a MISPE-HPLC-UV method for determination of lumefantrine. The method fulfilled all validation parameters, with recoveries ranging from 83.68% to 85.42%, and was applied for quantitation of the drug in plasma from two healthy volunteers, with results of 1407.89 and 1271.35 ng mL-1, respectively. Therefore, the MISPE-HPLC-UV method optimized through chemometrics provided a rapid, highly selective, less expensive and reproducible approach for lumefantrine drug monitoring.