Pharmaceutical Emulsions: A Viable Approach for Ocular Drug Delivery

Ocular disorders can lead to serious sight impairment and irreversible blindness. Generally simple topical and systemic treatments are recommended for treating these vision-threatening illnesses. The distinctive architecture of the eye complicates ocular drug delivery. The ophthalmic emulsion formulations have been found to increase bioavailability in the eye by prolonging residence time and improving permeability through the cornea. Therefore, this study highlights ophthalmic emulsions meant for both the anterior and posterior parts of the eye while examining a wide range of ocular disorders that affect individuals globally. This review presents, in brief, recent emulsion-based patented innovations, clinical trials, and marketed emulsion formulations for ocular drug delivery, which are strengthening development of the new ophthalmic drug products for managing different ocular diseases and disorders.

Solanum nigrum Toxicity and Its Neuroprotective Effect Against Retinal Ganglion Cell Death Through Modulation of Extracellular Matrix in a Glaucoma Rat Model

Purpose: Glaucoma is a complex degenerative optic neuropathy characterized by loss of retinal ganglion cells (RGCs) leading to irreversible vision loss and blindness. Solanum nigrum has been used for decades in traditional medicine system. However, no extensive studies were reported on its antiglaucoma properties. Therefore, this study was designed to investigate the neuroprotective effects of S. nigrum extract on RGC against glaucoma rat model. Methods: High performance liquid chromatography and liquid chromatography tandem mass spectrometry was used to analyze the phytochemical profile of aqueous extract of S. nigrum (AESN). In vitro, {3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide} (MTT) and H2DCFDA assays were used to determine cell viability and reactive oxygen species (ROS) production in Statens Seruminstitut Rabbit Cornea cells. In vivo, AESN was orally administered to carbomer-induced rats for 4 weeks. Intraocular pressure, antioxidant levels, and electrolytes were determined. Histopathological and immunohistochemical analysis was carried out to evaluate the neurodegeneration of RGC. Results: MTT assay showed AESN exhibited greater cell viability and minimal ROS production at 10 μg/mL. Slit lamp and funduscopy confirmed glaucomatous changes in carbomer-induced rats. Administration of AESN showed minimal peripheral corneal vascularization and restored histopathological alterations such as minimal loss of corneal epithelium and moderate narrowing of the iridocorneal angle. Immunohistochemistry analysis showed increased expression of positive BRN3A cells and decreased matrix metalloproteinase (MMP)-9 activation in retina and cornea, whereas western blot analysis revealed downregulation of extracellular matrix proteins (COL-1 and MMP-9) in AESN-treated rats compared with the diseased group rats. Conclusions: AESN protects RGC loss through remodeling of MMPs and, therefore, can be used for the development of novel neurotherapeutics for the treatment of glaucoma.

Polymers and their engineered analogues for ocular drug delivery: Enhancing therapeutic precision

Ocular drug delivery is constrained by anatomical and physiological barriers, necessitating innovative solutions for effective therapy. Natural polymers like hyaluronic acid, chitosan, and gelatin, alongside synthetic counterparts such as PLGA and PEG, have gained prominence for their biocompatibility and controlled release profiles. Recent strides in polymer conjugation strategies have enabled targeted delivery through ligand integration, facilitating tissue specificity and cellular uptake. This versatility accommodates combined drug delivery, addressing diverse anterior (e.g., glaucoma, dry eye) and posterior segment (e.g., macular degeneration, diabetic retinopathy) afflictions. The review encompasses an in-depth exploration of each natural and synthetic polymer, detailing their individual advantages and disadvantages for ocular drug delivery. By transcending ocular barriers and refining therapeutic precision, these innovations promise to reshape the management of anterior and posterior segment eye diseases.

Pirfenidone: A Promising Drug in Ocular Therapeutics

Pirfenidone, initially indicated for lung fibrosis, has gone beyond its original purpose, and shown promise in eye care. This detailed review tracks its evolution from lung treatment to aiding eye healing as evidenced by published literature. Pirfenidone's multifaceted attributes extend to mitigating corneal fibrosis, inflammation, and trauma. Through rigorous investigations, its efficacy emerges in diabetic retinopathy, macular degeneration, and postoperative glaucoma interventions. As an unheralded protagonist, pirfenidone reshapes ocular care paradigms, inviting renewed research opportunities.

Design, synthesis and biological evaluation of novel pyrimidine derivatives as bone anabolic agents promoting osteogenesis via the BMP2/SMAD1 signaling pathway

Anti-resorptive inhibitors such as bisphosphonates are widely used but they have limited efficacy and serious side effects. Though subcutaneous injection of teriparatide [PTH (1-34)] is an effective anabolic therapy, long-term repeated subcutaneous administration is not recommended. Henceforth, orally bio-available small-molecule-based novel therapeutics are unmet medical needs to improve the treatment. In this study, we designed, synthesized, and carried out a biological evaluation of 31 pyrimidine derivatives as potent bone anabolic agents. A series of in vitro experiments confirmed N-(5-bromo-4-(4-bromophenyl)-6-(2,4,5-trimethoxyphenyl)pyrimidin-2-yl)hexanamide (18a) as the most efficacious anabolic agent at 1 pM. It promoted osteogenesis by upregulating the expression of osteogenic genes (RUNX2 and type 1 col) via activation of the BMP2/SMAD1 signaling pathway. In vitro osteogenic potential was further validated using an in vivo fracture defect model where compound 18a promoted the bone formation rate at 5 mg kg-1. We also established the structure-activity relationship and pharmacokinetic studies of 18a.

Concurrent determination of anti-microbial and anti-inflammatory drugs in lachrymal fluid and tissue by LC-MS/MS: A potential treatment for microbial keratitis and its PK-PD evaluation

Unforeseen surfacing of microbial keratitis (MKT) over the years has led to a requisite for promising treatment strategy involving combination of antifungal and antibacterial agents. Subsequently, symptoms associated with MKT including inflammation and watery eyes require treatment with anti-inflammatory agents. Thus, a requirement of functional clinical treatment strategy involving combination of anti-inflammatory corticosteroids (Betamethasone) with antifungal polyene (Amphotericin B, AmB) and antibacterials macrolide (Azithromycin, AZT) and aminoglycoside (Neomycin, NEO). In the ensuing pursuit, a sensitive and fast simultaneous LC-MS/MS method of four drastically different analytes in rabbit tear fluid and cornea was developed and validated as per US-FDA guidelines. The gradient LC set-up was used with C18 column and flow rate of 0.55 mL/min along with short run time of 7 min. The calibration curves showed good linearity over the concentration range of 0.07-300 ng/mL, 1.00-400 ng/mL, 3.00-600 ng/mL and 8.00-900 ng/mL for AZT, AmB, NEO and BEM respectively. The bioanalytical method requires only 10 µL of ocular sample and analytes were extracted with fast protein precipitation with acidic methanol. Finally, the developed method was validated for selectivity, linearity (r2 > 0.99), precision, accuracy, matrix effects, and stability. PK-PD indices and dosing frequency was predicted using Phoenix WinNonlin Software, based on single dose ocular pharmacokinetics and MIC values of AmB, AZT and NEO. According to the PK-PD simulation, S. aureus and E. coli required 6 and 12 instillations of AZT per 24 h, respectively whereas 12 instillation of NEO requires per 24 h for S. aureus. The result suggests that to minimize antimicrobial resistance; drug, dose and dosing schedule depend upon the pathogen as well as the strain.

Ocular bioanalysis of moxifloxacin and ketorolac tromethamine in rabbit lacrimal matrix using liquid chromatography-tandem mass spectrometry

Aim: The fixed-dose combination of moxifloxacin (MOXI) and ketorolac tromethamine (KTR) is widely used for the treatment of bacterial keratitis. Thus, a new LC-MS/MS method was developed to determine MOXI and KTR in lacrimal fluid. Methods: Bioanalysis was performed using a Shimadzu 8050 LC-MS/MS in electrospray ionization-positive mode and the method was validated per US FDA guidelines. Isocratic separation was performed with a Waters Symmetry C18 column using methanol and 0.1% formic acid containing deionized water (85:15, v/v). Results & conclusion: An easy, quick and selective method was established and applied to assess the ocular pharmacokinetic profile of a commercially available formulation containing MOXI and KTR. Based on the pharmacokinetic data, this work describes pharmacokinetics-based dosage regimen calculations and their clinical significance.

Simultaneous determination of amphotericin B, tobramycin and vancomycin in rabbit ocular biofluids and tissues by LC-MS/MS: An antimicrobial therapy for keratitis and its PK-PD application

A rationale poly-microbial keratitis (PMK) therapy requires quick identification of pathogen (bacteria and fungi) and their efficient treatment. However, majority of healthcare providers are still having trouble finding an effective medicine to treat PMK due to constraints such as antimicrobial resistance, dose and dosing schedule. Thus, a broad spectrum anti-fungal and antibacterial having less resistance in community involving combination therapy such as amphotericin B (AmB), tobramycin (TBR) and vancomycin (VCM) is required. Hence, to characterize the pharmacokinetic (PK) and PK-pharmacodynamic (PD) indices, a rapid and sensitive simultaneous LC-MS/MS bioanalytical method was developed and validated for the quantification of AmB, TBR and VCM in rabbit ocular biofluids and tissues. Chromatographic resolution was achieved on a Zorbax C18 column with a mobile phase composed of acetonitrile and 0.4 % formic acid in deionized water using a gradient mode of elution. The calibration curves showed good linearity over the concentration range of 1.95-500 ng/mL for AmB and TBR, 3.9-800 ng/mL for VCM, respectively. The lower limit of quantification (LLOQ) was found to be 1.95 ng/mL for AmB and TBR, and 4.5 ng/mL for VCM. Analyte extraction was performed by simple protein precipitation method with minimal sample volume of 10 µL. Finally, the developed method was validated for selectivity, linearity (r2 > 0.99), precision, accuracy, matrix effects, and stability. The ocular pharmacokinetic profile of commercial AmB, TBR, and VCM formulations was further assessed using the validated method and the PK-PD indices along with dosing frequency was predicted by PK-PD modelling using Phoenix WinNonlin Software.

Recent Insights into the Etiopathogenesis of Diabetic Retinopathy and Its Management

Purpose: Diabetic retinopathy (DR) is a microvascular retinal disease associated with chronic diabetes mellitus, characterized by the damage of blood vessels in the eye. It is projected to become the leading cause of blindness, given the increasing burden of the diabetic population worldwide. The diagnosis and management of DR pose significant challenges for physicians because of the involvement of multiple biochemical pathways and the complexity of ocular tissues. This review aims to provide a comprehensive understanding of the molecular pathways implicated in the pathogenesis of DR, including the polyo pathway, hexosamine pathway, protein kinase C (PKC), JAK/STAT signaling pathways, and the renin-angiotensin system (RAS). Methods: Academic databases such as PubMed, Scopus, Google Scholar and Web of Science was systematically searched using a carefully constructed search strategy incorporating keywords like "Diabetic Retinopathy," "Molecular Pathways," "Pharmacological Treatments," and "Clinical Trials" to identify relevant literature for the comprehensive review. Results: In addition to activating other inflammatory cascades, these pathways contribute to the generation of oxidative stress within the retina. Furthermore, it aims to explore the existing pharmacotherapy options available for the treatment of DR. In addition to conventional pharmacological therapies such as corticosteroids, antivascular endothelial growth factors, and nonsteroidal anti-inflammatory drugs (NSAIDs), this review highlights the potential of repurposed drugs, phyto-pharmaceuticals, and novel pipeline drugs currently undergoing various stages of clinical trials. Conclusion: Overall, this review serves as a technical exploration of the complex nature of DR, highlighting both established and emerging molecular pathways implicated in its pathogenesis. Furthermore, it delves into the available pharmacological treatments, as well as the promising repurposed drugs, phyto-pharmaceuticals, and novel drugs currently being evaluated in clinical trials, with a focus on their specific mechanisms of action.

Design, synthesis, and biological evaluation of quinoline-piperazine/pyrrolidine derivatives as possible antileishmanial agents

In pursuance of our efforts to expand the scope of novel antileishmanial entities, a series of thirty-five quinoline-piperazine/pyrrolidine, and other heterocyclic amine derivatives were synthesized via a molecular hybridization approach and examined against intracellular amastigotes of luciferase-expressing Leishmania donovani. The preliminary in vitro screening suggests that twelve compounds in the series exhibited better inhibition against amastigote form with good IC50 values ranging from 2.09 to 8.89 μM and lesser cytotoxicity in contrast to the standard drug miltefosine (IC50 9.25 ± 0.17 μM). Based on the satisfactory selectivity index (SI), two compounds were tested for in vivo leishmanicidal efficacy against Leishmania donovani/golden hamster model. Compounds 33 and 46 have shown significant inhibition of 56.32%, and 49.29%, respectively, in vivo screening at a daily dose of 50 mg/kg for 5 days. The pharmacokinetic results confirmed that 33 and 46 have satisfactory IP exposure with adequate parameters. Collectively, Compound 33 was identified as the most significant potential lead that could be employed as a prototype for future optimizations.

Preclinical pharmacokinetic exploration of a novel osteoporotic quinazolinone-benzopyran-indole hybrid (S019-0385) using LC-MS/MS

1. The current investigation was to develop and validate the LC-MS/MS method in order to analyse the various pharmacokinetic parameters of S019-0385. A sensitive, selective, and robust LC-MS/MS approach was established and validated for measuring S019-0385 in female mice plasma and tissue, using optimal multiple reaction monitoring (MRM) transition m/z 488.25/329.12 on positive mode. On a Waters Symmetry Shield C18 column, the analyte was separated using acetonitrile and deionised water with formic acid within 6 min at 0.7 mL/min. Linearity (R2 ≥ 0.99) was observed across 0.195-100 ng/mL concentration range using linear least-squares regression.2. Blood-to-plasma ratio and plasma protein drug binding (%) in mice and human was assessed and found to be less than 1 and >83%, respectively. Absolute bioavailability (%F) of S019-0385 in female Swiss mice was exhibited to be 6.90%. Percent dose excreted S019-0385 in unchanged form through urine and faecal was found to be less than 2% and 0.5%, respectively.3. Following oral administration at 5 mg/kg, the concentration of S019-0385 in tissue distribution was found to be in the order of C small intestine > C bone > C lung > C spleen > C kidney > C liver > C heart > C brain.

Hesperidin: Enrichment, forced degradation, and structural elucidation of potential degradation products using spectral techniques

RATIONALE

Hesperidin (HES) is a well-known citrus bioflavonoid phyto-nutraceutical agent with polypharmacological properties. After 2019, HES was widely used for prophylaxis and COVID-19 treatment. Moreover, it is commonly prescribed for treating varicose veins and other diseases in routine clinical practice. Pharmaceutical impurities and degradation products (DP) impact the drug's quality and safety and thus its effectiveness. Therefore, forced degradation studies help study drug stability, degradation mechanisms, and their DPs. This study was performed because stress stability studies using detailed structural characterization of hesperidin are currently unavailable in the literature.

METHODS

In the HES enrichment method crude HES was converted to its pure form (98% purity) using column chromatography and then subjected to forced degradation under acid, base, and neutral hydrolyses followed by oxidative, reductive, photolytic, and thermal stress testing (International Conference on Harmonization guidelines). The stability-indicating analytical method (SIAM) was developed to determine DPs using reversed-phase high-performance liquid chromatography (C18 column with methanol and 0.1% v/v acetic acid in deionized water [70:30, v/v] at 284 nm). Further, structural characterization of DPs was performed using liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) and nuclear magnetic resonance (NMR) spectroscopy. In addition, in silico toxicity predictions were performed using pKCSM and DataWarior freeware.

RESULTS

HES was found to be susceptible to acidic and basic hydrolytic conditions and yielded three DPs in each, which were detected using designed SIAM. Of six DPs, three were pseudo-DPs (short lived), and the remaining were characterized using LC-MS/MS and NMR spectroscopy. The tentative mechanism of the formation of proposed DPs was explained. The proposed DPs were found inactive from in silico toxicity predictions.

CONCLUSIONS

Hesperidin was labile under acidic and basic stress conditions. The potential DPs were characterized using LC-ESI-MS/MS and NMR spectral techniques. The proposed mechanism of formation was hypothesized. In addition, to identify and characterize the DPs, a SIAM, which has broad biomedical applications, was successfully developed.

Trends in Formulation Approaches for Sustained Drug Delivery to the Posterior Segment of the Eye

The eye, an intricate organ comprising physical and physiological barriers, poses a significant challenge for ophthalmic physicians seeking to treat serious ocular diseases affecting the posterior segment, such as age-related macular degeneration (AMD) and diabetic retinopathy (DR). Despite extensive efforts, the delivery of therapeutic drugs to the rear part of the eye remains an unresolved issue. This comprehensive review delves into conventional and innovative formulation strategies for drug delivery to the posterior segment of the eye. By utilizing alternative nanoformulation approaches such as liposomes, nanoparticles, and microneedle patches, researchers and clinicians can overcome the limitations of conventional eye drops and achieve more effective drug delivery to the posterior segment of the eye. These innovative strategies offer improved drug penetration, prolonged residence time, and controlled release, enhancing therapeutic outcomes for ocular diseases. Moreover, this article explores recently approved delivery systems that leverage diverse polymer technologies, such as chitosan and hyaluronic acid, to regulate drug-controlled release over an extended period. By offering a comprehensive understanding of the available formulation strategies, this review aims to empower researchers and clinicians in their pursuit of developing highly effective treatments for posterior-segment ocular diseases.

Chemical metabolite synthesis and profiling: Mimicking in vivo biotransformation reactions

Biotransformation was previously viewed as merely the structural characterization of drug metabolites, and it was performed only when drug candidates entered clinical development. The synthesis of drug metabolites is crucial to the drug development process because it generates either pharmacologically active, inactive, or reactive molecules and hence their characterization and comprehensive pharmacological evaluation is necessary. The chemical metabolite synthesis is very challenging due to the complex structures of many drug molecules, presence of multiple stereocenters, poor reaction yields, and the formation of unwanted by-products. Drug metabolites and their chemical synthesis have immense significance in the drug discovery process. The chemical synthesis of metabolites facilitates on- or off-target pharmacological and toxicological evaluations at the easiest. In a broader view metabolite could be a target lead molecule for drug design, toxic reactive metabolites, pharmaceutical standards for bioanalytical methods, etc. Collectively these metabolite information dossiers will aid regulatory agencies such as the EMA and FDA in maintaining strict vigilance over drug manufacturers with regard to the safety of NCE's and their hidden metabolites. Herein, we are presenting a systematic compilation of chemical and biocatalytic strategies reported to date for pharmaceutical drug metabolite synthesis. This review report is very useful for the laboratory synthesis of new drug metabolites, and their preclinical biological evaluation could aid in the detection of early threats (alerts) in drug discovery, eliminate the toxicity profile, explore newer pharmacology, and delivering a promising and safe drug candidate to humankind.

LC-MS/MS based quantification of steroidal biomarkers in polycystic ovary syndrome induced rats

Polycystic ovary syndrome (PCOS) is a common endocrine disorder that causes reproductive hormones imbalance, missed periods, infertility and distributed steroidogenesis. Reportedly, during PCOS, the endogenous levels of P4 (Progesterone), 17OHP4 (17-α hydroxy progesterone), and T4 (Testosterone) were significantly altered. Thus, quantification of steroid biomarkers involved in the steroidogenesis pathway of PCOS, such as P4, 17OHP4, and T4, holds significant importance. One important drawback of current methods is steroid metabolome traceability. Without adequate traceability, the findings of these techniques will be less reliable for identifying P4, 17OHP4, and T4. These methods also need a high sample size, especially for the most important biomarker that initiates steroidogenesis. To address these challenges, we require a new liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for steroid biomarker analysis. Herein the present work, using validated LC-MS/MS, PCOS biomarkers were measured and compared between normal control rats and PCOS-induced rats before and after analyte administration. The experiment utilized an isocratic separation method employing an analytical C18 column. The mobile phase consisted of acetonitrile (ACN) and aqueous 0.1% formic acid (FA) in a ratio of 90:10 (v/v). The plasma samples were processed with protein precipitation (PPT) followed by the liquid-liquid extraction (LLE) method. The lower limit of quantification (LLOQ) was 0.5 ng/mL in plasma. According to USFDA criteria, the method's systematic validation took into account linearity (r2 > 0.99), accuracy and precision of intra- and inter-batch measurements, stability, biomarker recovery (60-85%) and matrix effect (<± 15%), all of which were determined to be within range ( ± 15%). The pharmacokinetic data showed that, as compared to normal rats, PCOS-induced animals had significantly higher Cmax values for 17OHP4 and T4 (∼2 fold), while lower Cmax values for P4 (∼2 fold). The present work is novel and provides scientific information to explore systematic processes involved in steroidogenesis and boost clinical applicability for PCOS therapy.

A QbD-led simple and sensitive RP-UHPLC method for simultaneous determination of moxifloxacin, voriconazole, and pirfenidone: An application to pharmaceutical analysis

A novel, quick and precise RP-UHPLC analytical method for the simultaneous determination of moxifloxacin (MFX), voriconazole (VCZ) and pirfenidone (PIR) was developed and validated according to the International Conference on Harmonization guidelines using a QbD-driven response surface Box-Behnken design. The developed method was validated considering the selectivity, sensitivity, linearity, accuracy-precision, robustness, stability, limit of detection and limit of quantification, respectively. Resolution between MFX, VCZ and PIR was achieved using a gradient elution protocol against a Waters Symmetry Shield C18 column (150 × 4.6 mm2 , 5 μm) using an Agilent 1290, Infinity II series LC system. The method was applied to quantitatively estimate proprietary and in-house prepared pharmaceutical topical ophthalmic formulations containing MFX, VCZ and PIR at wavelength (λmax ) of 296, 260 and 316 nm. The method is sensitive enough to detect up to 0.1 ppm of analytes in the formulation. The method was further exploited to study and identify the possible degradation products of the analytes. The proposed chromatographic method is simple, economical, reliable and reproducible. In conclusion, the developed method could be applicable for routine quality control analysis of single or combined MFX, VCZ and PIR-containing units or bulk dosage forms in pharmaceutical industries and research organizations working on drug discovery and development.

Ophthalmic nano-bioconjugates: critical challenges and technological advances

Ophthalmic disease can cause permanent loss of vision and blindness. Easy-to-administer topical and systemic treatments are preferred for treating sight-threatening disorders. Typical ocular anatomy makes topical and systemic ophthalmic drug delivery challenging. Various novel nano-drug delivery approaches are developed to attain the desired bioavailability in the eye by increasing residence time and improved permeability across the cornea. The review focuses on novel methods that are biocompatible, safe and highly therapeutic. Novelty in nanocarrier design and modification can overcome their drawbacks and make them potential drug carriers for eye disorders in both the anterior and posterior eye segments. This review briefly discussed technologies, patented developments, and clinical trial data to support nanocarriers' use in ocular drug delivery.

Preclinical pharmacokinetics of 4-hydroxy isoleucine using LC-MS/MS: a potential polycystic ovary syndrome phytopharmaceutical therapeutics

Aim: To study the preclinical pharmacokinetics of 4-hydroxy isoleucine (4-HIL) targeted for polycystic ovary syndrome. Methodology: The quantitative bioanalysis of 4-HIL in different biological matrices in female Sprage-Dawley rats using LC-MS/MS. Results: At 50 mg/kg, 4-HIL had 56.8% absolute oral bioavailability. It was quickly absorbed and distributed in various tissues in order of small intestine > kidney > ovary > spleen > lung > liver > heart > brain after oral administration. Moreover, 11.07% of 4-HIL was recovered in urine and feces within 72 h. Conclusion: 4-HIL levels in vital organs were found safe, as per tissue distribution results. Hence, 4-HIL could be used as promising therapeutics for management of polycystic ovary syndrome.

Antileishmanial evaluation of triazole-butenolide conjugates: design, synthesis, in vitro screening, SAR and in silico ADME predictions

In the quest to discover novel scaffolds with leishmanicidal effects, a series of 23 compounds containing the most promising 1,2,3-triazole and highly potent butenolide in one framework were synthesized. The synthesized conjugates were screened against Leishmania donovani parasite; five of them showed moderate antileishmanial activity against promastigotes (IC50 30.6 to 35.5 μM) and eight of them exhibited significant activity against amastigotes (IC50 ≤12 μM). Compound 10u was found to be the most active (IC50 8.4 ± 0.12 μM) with the highest safety index (20.47). The series was further evaluated against Plasmodium falciparum (3D7 strain) and seven compounds were found to be moderately active. Among them, again 10u emerged as the most active compound (IC50 3.65 μM). In antifilarial assays against adult female Brugia malayi, five compounds showed grade II inhibition (50-74%). Structure-activity relationship (SAR) analysis suggested a substituted phenyl ring, triazole and butenolide as essential structural features for bioactivity. Moreover, the results of in silico ADME parameter and pharmacokinetic studies indicated that the synthesized triazole-butenolide conjugates abide by the required criteria for the development of orally active drugs, and thus this scaffold can be used as a pharmacologically active framework that should be considered for the development of potential antileishmanial hits.

Simultaneous estimation of voriconazole, moxifloxacin, and pirfenidone in rabbit lacrimal matrix using LC-MS/MS: an application to preclinical ocular pharmacokinetics

Dynamic emergence of microbial keratitis (MK) requires a promising therapeutic arsenal of antifungal and antibacterial agents like voriconazole (VCZ) and moxifloxacin (MOXI), respectively. Parallelly, another paradigm of MK associated with ulcerative wounds cannot be left unnoticed and requires antifibrotic remedy (pirfenidone, PIR) as an authalic antimicrobial to retain the primordial vision. For designing an effective clinical cure, a combination of these three agents is required at a therapeutic dosage regimen. Following the quest, we have developed a simple and sensitive LC-MS/MS bioanalytical method for simultaneous quantification of VCZ, MOXI, and PIR in rabbit lacrimal fluid. The method was validated as per US-FDA norms using ketoconazole as an internal standard for linearity, accuracy-precision, matrix effect, dilution integrity, selectivity, and stability. The five minutes chromatographic set-up includes isocratic elution with a C18 column using MeOH (80%, v/v) and ultrapure water containing 0.2% formic acid (20%, v/v), respectively. The MS-based analyte detection was achieved in ESI⁺ multiple reaction monitoring mode. The sample extraction was performed using the protein precipitation method with minimal sample size. The validated methodology was employed to determine the ocular pharmacokinetics profile of marketed formulations containing VCZ, MOXI, and PIR in rabbit lacrimal matrix.

Design, synthesis and evaluation of novel pyrrole-hydroxybutenolide hybrids as promising antiplasmodial and anti-inflammatory agents

In the pursuance of novel scaffolds with promising antiplasmodial and anti-inflammatory activity, a series of twenty-one compounds embraced with most promising penta-substituted pyrrole and biodynamic hydroxybutenolide in single skeleton was designed and synthesized. These pyrrole-hydroxybutenolide hybrids were evaluated against Plasmodium falciparum parasite. Four hybrids 5b, 5d, 5t and 5u exhibited good activity with IC₅₀ of 0.60, 0.88, 0.97 and 0.96 μM for chloroquine sensitive (Pf3D7) strain and 3.92, 4.31, 4.21 and 1.67 μM for chloroquine resistant (PfK1) strain, respectively. In vivo efficacy of 5b, 5d, 5t and 5u was studied against the P. yoelii nigeriensis N67 (a chloroquine-resistant) parasite in Swiss mice at a dose of 100 mg/kg/day for 4 days via oral route. 5u was found to show maximum 100% parasite inhibition with considerably increased mean survival time. Simultaneously, the series of compounds was screened for anti-inflammatory potential. In preliminary assays, nine compounds showed more than 85% inhibition in hu-TNFα cytokine levels in LPS stimulated THP-1 monocytes and seven compounds showed more than 40% decrease in fold induction in reporter gene activity analyzed via Luciferase assay. 5p and 5t were found to be most promising amongst the series, thus were taken up for further in vivo studies. Wherein, mice pre-treated with them showed a dose dependent inhibition in carrageenan induced paw swelling. Moreover, the results of in vitro and in vivo pharmacokinetic parameters indicated that the synthesized pyrrole-hydroxybutenolide conjugates abide by the required criteria for the development of orally active drug and thus this scaffold can be used as pharmacologically active framework that should be considered for the development of potential antiplasmodial and anti-inflammatory agents.

Simultaneous pharmacokinetic assessment of phytopharmaceuticals in fenugreek extract using LC-MS/MS in Sprague-Dawley rats

Fenugreek seeds are used in numerous marketed herbal formulations with therapeutic benefits. Some of its bioactive components such as 4-hydroxyisoleucine, trigonelline, raffinose, and pinitol are reported to possess potential therapeutic activities, such as antibacterial, antidiabetic, stomach stimulant, and anti-invasive, against hyperandrogenism and other allied diseases, including polycystic ovary syndrome. A fully validated, selective, and sensitive bioanalytical method for the simultaneous rapid quantification of the aforementioned bioactive components has been developed using hyphenated liquid chromatography electrospray tandem mass spectrometry. The analytes were separated within 5 min using gradient elution in a C18 column at a flow rate of 0.5 ml/min. Plasma protein precipitation technique was employed to isolate the analytes from the samples. Oral pharmacokinetic profile of the four bioactive components in Sprague-Dawley rats was further evaluated using noncompartmental analysis using Phoenix WinNonlin software.

Preclinical Pharmacokinetics and CYP Modulation Activity of Chebulinic Acid: A Potent Molecule Against Metabolic Disease

BACKGROUND

Chebulinic acid (CA) is an active constituent of Terminalia chebula fruits with therapeutic potential against multiple metabolic diseases, including dementia, benign prostate hyperplasia, and osteoporosis.

OBJECTIVE

The present work intends to explore the preclinical pharmacokinetics, including the absolute bioavailability of CA and its influence on the gene expression of cytochrome P450 enzymes in the liver.

METHODS

Quantifying CA and probe drugs in vitro samples and preclinical serum samples of male SD rats were performed using LC-MS/MS. The influence of CA on the hepatic CYPs and their gene expression was analyzed in rat liver by quantitative real-time polymerase chain reaction.

RESULTS

The plasma protein binding was found to be 84.81 ± 7.70 and 96.34 ± 3.12, blood-to-plasma ratio of 0.62 ± 0.16 and 0.80 ± 0.23 at 1 μM and 10 μM concentrations, respectively. Again, the absolute oral bioavailability of CA at 100 mg/kg was found to be 37.56 ± 7.3%. The in-vivo pharmacokinetic profile of probe drugs revealed CA to have significant inducing effects on CYP1A2, 2C11, 2D2, and 2E1 after 14 days, which correlates to both in-vitro rat microsomal data and gene expression results.

CONCLUSION

Altogether, pharmacokinetic parameters reveal CA to have an affinity to distribute across different extravascular tissues and induce rat liver CYP enzymes.

Recent Update on Pharmacokinetics and Drug Metabolism in CNS-based Drug Discovery

Despite significant advancements in CNS research, CNS illnesses are the most important and serious cause of mental disability worldwide. These facts show a tremendous unmet demand for effective CNS medications and pharmacotherapy since it accounts for more hospitalizations and extended care than practically all other disorders combined. The site-targeted kinetics of the brain and, pharmacodynamics of CNS effects are determined/regulated by various mechanisms after the dose, including blood-brain barrier (BBB) transport and many other processes. These processes are condition-dependent in terms of their rate and extent because they are dynamically controlled. For effective therapy, drugs should access the CNS "at the right place, time, and concentration". Details on inter-species and inter-condition variances are required to translate target site pharmacokinetics and associated CNS effects between species and illness states, improving CNS therapeutics and drug development. The present review encircles a short discussion about the barriers that affect effective CNS treatment and precisely focuses on the pharmacokinetics aspects of efficient CNS therapeutics.

Simultaneous estimation of total homocysteine and methylmalonic-acid using LC-MS/MS: Clinical application in adult and pediatric

Quantitative determination of biomarkers homocysteine (Hcy) and methylmalonic acid (MMA), the regulators of cobalamin (Cbl) and folate levels, together used as a biomarkers to diagnose chemical insufficiency/deficiency of Cbl and folate. We report simultaneous clinical estimation of total Hcy and MMA with efficient clean-up, sensitive and selective LC-MS/MS method. Efficient sample clean-up was achieved by a two-step extraction protocol with 100 μL serum. The validated method was applied to 893 clinical samples from 2 cohorts including pediatrics and mothers, respectively, for identifying their Cbl and folate status. The method shows excellent order of linearity for Hcy (22.2nM-3.7 μM) and MMA (42.34 nM - 5.92 μM), respectively. Complete method validation was performed where intraday-interday accuracy-precision and mean stability recovery data were found within ±15%. The validated method was extended for the quantification of serum total Hcy-MMA levels in clinical samples. The efficient extraction with negligible matrix-effect (ME) has reduced LC-MS/MS chocking and clean-up downtime. The rapid, sensitive and robust LC-MS/MS method has been successfully validated for simultaneous estimation of total Hcy and MMA using only 100 μL serum. The method was applicable to large number of clinical samples and was found to be good throughput with low contamination of mass detector, high sensitivity and selectivity.

Furostanol saponins from Asparagus racemosus as potential hypoglycemic agents

Bioactivity guided phytochemical investigation led to isolation of six undescribed furostanol saponins, furoasparoside A-F along with five known compounds, gallic acid, methyl gallate, quercetin-3-O-β-glucopyranoside, liquiritigenin 4^׳-O-β-apiofuranosyl-(1 → 2)-β-glucopyranoside and β-glucogallin for the first time from the roots of Asparagus racemosus. Isolated saponins were screened for their antidiabetic potential in L6-GLUT4myc myotubes in vitro followed by an in vivo evaluation in streptozocin-induced diabetic rats and db/db mice. Furoasparoside E produced a notable decrease in the postprandial blood glucose profile, in leptin receptor-deficient db/db mice, type 2 diabetes model. The effect of furoasparoside E on GLUT4 translocation was found to be mediated by the AMPK-dependent signaling pathway in L6-GLUT4myc myotubes. Moreover, it emerged as a stable plant metabolite with higher bioavailability and efficacy in in vivo pharmacokinetic studies. Therefore, these studies indicated that furoasparoside E may serve as a propitious lead for the management of type 2 diabetes and its secondary complications from natural source.

Preclinical pharmacokinetics, CYP phenotyping, and tissue distribution study of novel anti-breast cancer candidate S-011-1559

S-011-1559 is a tyrosine-derived novel benzoxazine CDRI molecule targeted to the estrogen-related receptor (ER-α/β) modulator in breast cancer. To explore the pharmacokinetics of S-011-1559, a selective and sensitive bioanalytical method using LC-MS/MS was established and validated in different biological matrices of female rats.Blood-to-plasma ratio and plasma protein binding (PPB) of S-011-1559 was found to be <1 and >97% in both rats and humans respectively. The human serum albumin (HSA) and alpha-1-acid glycoprotein (AAG) binding was found in the range of >68 to 45% and >14% respectively. Half-life and intrinsic clearance by microsomal stability study were found to be 28.83 min and 0.05 mL/min/mg in rats, 78.35 min and 0.036 mL/min/mg in humans respectively. The IC₅₀ value of S-011-1559 against CYP isoforms was revealed to moderately inhibit CYP2D6 by a reversible noncompetitive mechanism.Tissue distribution of S-011-1559 on single intravenous injection at 2mg/kg was found in the order of C lungs > C mammary gland > C spleen > C heart > C kidney > C liver > C brain.The data from the present study provides crucial information about S-011-1559 for further development as a novel potential drug candidate in modulating ER-α/β receptors of lung and breast neoplasia.

Simultaneous determination of fluconazole and ofloxacin in rabbit tear fluid by LC-MS/MS: Application to ocular pharmacokinetic studies

The expansion of polymicrobial keratomycosis (PMK) requires dynamic pharmacotherapy of antimycotics along with antibacterial agents such as fluconazole (FCZ) and ofloxacin (OFX). To effective clinical cure, different microbes require different dosage regimens. A responsive, selective, and fast method for estimation of FCZ and OFX in rabbit tears using high-performance liquid chromatography together with tandem mass spectrometry (LC-MS/MS) was established and validated using ketoconazole as an internal standard (IS). An isocratic separation was achieved using a C₁₈ column with methanol and aqueous 0.2% formic acid (80:20, v/v) as a mobile phase with a total run time and flow rate of 4 min and 400 µL/ min, respectively. The FCZ and OFX were detected utilizing positive ion electrospray ionization (ESI) in multiple reactions monitoring mode. The tear sample extraction was carried out using simple deproteination using methanol. The systematic method validation was carried out according to USFDA regulatory guidelines for selectivity, linearity (r²>0.99), intra-day and inter-day precision and accuracy, matrix effect, dilution integrity, and stability. The validated bioanalytical method was successfully pertained to determine the pharmacokinetics profile of FCZ and OFX marketed formulation in preclinical rabbit tears.

Rapid and Simultaneous Analysis of Multiple Classes of Antimicrobial Drugs by Liquid Chromatography-Tandem Mass Spectrometry and Its Application to Routine Biomedical, Food, and Soil Analyses

Antimicrobial agents (AMAs) are widely exploited nowadays to meet the high demand for animal-derived food. It has a significant impact on the food chain whose end consumers are human beings. The burden of AMAs on humans comes from either meat or crops cultivated on soil containing high residual antibiotics, which are responsible for the global crisis of antibiotic resistance. Thus, the objective of this study was to design a selective and sensitive liquid chromatography-mass spectrometry (LC-MS)/MS-based simultaneous bioanalytical method for estimation of twenty AMAs in human plasma, raw meat, and soil samples. The selective extraction of all analytes from the above matrices was performed by the solid-phase extraction clean-up method to overcome the interferences. Analytes were separated on a Waters Symmetry Shield C18 (150 × 4.6 mm², 5 μm) column, using an isocratic solvent system of methanol-0.5% formic acid (80:20, v/v) with 0.75 mL/min flow rate. The average extraction recoveries for all analytes in plasma were ranged from 42.0 to 94.0% with relative standard deviations (RSDs) below ±15%. All of the validation parameters are in accordance with the United State Food and Drug Administration (USFDA) guidelines. Moreover, the method was also valid for a broad plasma concentration range and can be proposed as an excellent method for routine pharmacokinetic studies, therapeutic drug monitoring, clinical analysis, and detection and quantitation of AMA remnants in raw meat as a standard quality control test for human consumption.