Combination Doxycycline and Topical Corticosteroids in the Treatment of Ulcerative Pyoderma Gangrenosum: A Case Report.

Pyoderma gangrenosum (PG) is a chronic inflammatory neutrophilic dermatosis often presenting as a solitary enlarging painful ulcer with red to violaceous undermined borders. This report delves into the role of doxycycline in the treatment of PG in a 44-year-old male COVID-19 positive patient who has concomitant active tuberculosis infection and end-stage kidney disease, for which both first-line treatments (systemic corticosteroid and cyclosporine) are contraindicated. After three months on doxycycline and topical corticosteroids, there was resolution of the ulcers and no note of recurrence up to three months from completion of the treatment regimen.

Doxycycline versus Curcumin for Inhibition of Matrix Metalloproteinase Expression and Activity Following Chemically Induced Inflammation in Corneal Cells.

Purpose: Sulfur mustard (SM) is a potent blistering agent. This alkylating chemical agent has extremely toxic effects on the eye. MMP-2 and MMP-9 are the two most important matrix metalloproteinase enzymes involved in the pathology of chemical eye injuries. Curcumin is regarded as a natural anti-inflammatory agent. This study aims to compare the anti-inflammatory effects of curcumin versus doxycycline on chemically induced corneal injuries. Methods: The HCE-2 cell line was used as a model for corneal cells. The effective concentrations of 2-chloroethyl ethyl sulfide (CEES) - as an analog of SM - doxycycline, and curcumin were determined using the MTT assay. The gene expression of MMP-2, MMP-9, and tissue inhibitors of metalloproteinase (TIMP-1) was evaluated by the real-time PCR method. Also, the activity of MMP-2 and MMP-9 enzymes was determined by zymography. Results: The expression of the MMP-2 and MMP-9 genes increased 5- and 3.3-fold after exposure to CEES, respectively. Following the treatment with curcumin and doxycycline, MMP-2 expression decreased significantly. Also, after treatment with curcumin and doxycycline, the MMP-9 expression decreased 2.5- and 1.6-fold, respectively. The reduction in activity was 32% for MMP-2 and 56% for MMP-9 after treatment with curcumin. The corresponding values were 12% and 40% following doxycycline treatment. There was no significant difference between the effects of curcumin and doxycycline on reducing MMP-2 expression, but the difference was statistically significant in the case of MMP-9. Conclusion: Doxycycline and curcumin can inhibit MMP expression and activity in chemically exposed corneal cells. Curcumin has a greater ability than doxycycline to inhibit MMP-2 and MMP-9 enzymes; however, the difference is statistically significant only in the case of MMP-9. After further validation, these substances can be introduced as anti- inflammatory agents to treat corneal chemical burns.

Vitamin C, doxycycline, and azithromycin (VDA) targeted changes in cellular senescence-related genes in human adipose-derived mesenchymal stem cells.

Objectives: Adipose-derived Mesenchymal stem cells (ASCs) have garnered attention for their regenerative potential; therefore, their cellular senescence-related gene expression remains crucial in therapeutic contexts. Nowadays, combination therapies have shown promising results in reducing senescent cells. This study investigated the effects of vitamin C, doxycycline, and azithromycin co-treatment on the key cellular senescence-associated genes in ASCs. Materials and Methods: Human ASCs were cultured and treated for 24 hr with vitamin C, doxycycline, azithromycin, and a combination of three drugs. Total RNAs were extracted, and the expression of p21, p16, Nanog, Oct4, and Sox2 genes was assessed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Additionally, cell cycle alterations were analyzed via flow cytometry after treatment with these compounds. Results: Notably, vitamin C treatment resulted in a significant down-regulation of p21 gene expression (P<0.01), implicating the potential role of vitamin C in promoting cell cycle progression. Doxycycline treatment led to a significant up-regulation of p21 and p16 gene expression (P<0.05), as it has previously been shown to induce cell cycle arrest. Similarly, azithromycin treatment predominantly increased p21 expression (P<0.05). Besides, cell cycle analysis revealed that each compound had changed the distribution of cells across different phases of the cell cycle. Conclusion: The combined use of all three drugs yielded intricate interactions, suggesting a complex yet promising approach to future research. According to our findings, the major difference in the combination drug-treated group (VDA) can be explained by the neutralizing effect of these three components in the environment.

Case Report: A Typical Lyme Disease With Uncommon Neurologic Presentation.

Lyme disease is a very common infectious disease worldwide. The seventh cranial nerve palsy occurred in 9% of Lyme disease cases and the majority of them present as unilateral facial palsy. We present a rare case of bilateral facial palsy in Lyme disease due to Borrelia burgdorferi infection. A total of eleven cases of Lyme disease with bilateral facial palsy reported in literature were summarized and compared to our case. The diagnosis and management of Lyme disease with facial nerve palsy were also discussed in this article.

Nitrogen and Sulfur Co-Doped Carbon Quantum Dots as Fluorescent Nanosensors for Determination of Two Tetracycline Antibiotics in Dosage Forms and Human Plasma: Compliance With Greenness Metrics.

In this study, a novel, sensitive, and cost-effective spectrofluorimetric approach was established for the estimation of two important tetracycline antibiotics, tetracycline and doxycycline, without any pre-treatment procedures or harsh reaction conditions, for the first time. The proposed methodology is based on the quantitative quenching effect of each tetracycline and doxycycline on the native fluorescence of nitrogen and sulfur co-doped carbon quantum dots (NS-CQDs). A simple and ultrafast approach was applied to synthesize NS-CQDs using thiosemicarbazide and citric acid as starting materials after incubation in a microwave for only 1 min. Utilizing an excitation wavelength of 360 nm, NS-CQDs showed maximum emission peak at 430 nm. Calibration curves revealed excellent linearity within the ranges of 1.0-10.0 and 0.8-12.0 µg/mL with detection limits of 0.20 and 0.09 µg/mL for tetracycline and doxycycline, respectively. Due to the method's high sensitivity and selectivity, the proposed approach was applied for the determination of the studied drugs in their capsules and human plasma samples with high %recoveries. The developed approach was validated according to ICHQ2(R2) guidelines. GAPI and AGREE metric tools were used to verify the method's greenness and eco-friendliness, suggesting its use as a green substitute for the analysis of the studied drugs.

Evaluating the Effectiveness of Probiotic Supplementation in Combination With Doxycycline for the Treatment of Moderate Acne: A Randomized Double-Blind Controlled Clinical Trial.

BACKGROUND: Acne is a chronic inflammatory skin disease that negatively affects patients' quality of life. Increasing antibiotic resistance is making acne less responsive to treatment. Probiotics are live microorganisms that can provide health benefits by fighting pathogens and maintaining intestinal homeostasis and skin microbiome balance. This study investigates the effects of probiotics in the treatment of acne vulgaris. METHODS: In this randomized controlled clinical trial, 80 patients with moderate acne were divided into two groups of 40. All patients received the same topical treatment, which consisted of a daily antibacterial face wash and Adapalene gel every other night. The control group received one capsule of doxycycline (100 mg) daily, whereas the intervention group received one probiotic capsule daily in addition to doxycycline. Patients underwent photography of facial acne lesions, and treatment response was assessed using the global acne grading system (GAGS) and acne grading method at baseline, as well as during follow-up visits at 1, 2, and 3 months. RESULTS: The global acne grading system indicated that both groups showed improvement. However, analyses revealed that outcomes were significantly better in the doxycycline plus probiotics group for the forehead (p = 0.018), chin (p = 0.021), and nose (p = 0.021). No significant differences were observed for the left and right cheeks, back, and chest areas, with the mean GAGS score reduction between the two groups differing by only 2%. Treatment with probiotics significantly reduced the severity of lesions compared to the control group (p < 0.001). The acne grading method also indicated that the intervention group had a significantly better treatment response than the control group (p < 0.001). Furthermore, treatment with probiotics did not result in any side effects. CONCLUSION: Probiotics can serve as an effective and safe treatment option, enhancing the outcomes of routine acne treatments, particularly for patients with acne on the forehead, chin, and nose.

New-generation tetracyclines for severe macrolide-resistant Mycoplasma pneumoniae pneumonia in children: a retrospective analysis.

BACKGROUND: Macrolide-resistant Mycoplasma pneumoniae (MRMP) strains are increasingly prevalent, leading to a rise in severe Mycoplasma pneumoniae pneumonia incidence annually, which poses a significant threat to children's health. This study aimed to compare the effectiveness and safety of oral minocycline and doxycycline for the treatment of severe MRMP pneumonia in children. METHODS: This retrospective analysis included children treated for severe MRMP pneumonia at the Pediatric Department of Tongji Hospital, Shanghai, China, between September 2023 and January 2024 using minocycline and doxycycline. The patients were divided into four groups according to treatment: oral doxycycline alone (DOX group), oral minocycline alone (MIN group), oral doxycycline with intravenous glucocorticoids (DOXG group), and oral minocycline with intravenous glucocorticoids (MING group). Student's t-test, Mann-Whitney U test, and χ2 or Fisher's exact tests were used for group comparisons. RESULTS: A total of 165 patients were included in this study: 84 received minocycline, and 81 received doxycycline. The DOX group had higher fever resolution rates within 24, 48, and 72 h compared to the MIN group (63.2% vs. 31.8%, 79.0% vs. 63.6%, and 100% vs. 90.9%, respectively; all p < 0.05). The DOXG group showed higher fever resolution rates within 24 and 48 h than the MING group (92.3% vs. 83.4%, 100% vs. 92.7%, all p > 0.05). There were no statistically significant differences in time to imaging improvement, cough improvement, and disappearance of wet rales between groups, regardless of glucocorticoid combination. The longer the duration of fever prior to tetracycline therapy, the greater the likelihood of hypoxemia (p = 0.039) and a greater than two-fold elevation in the D-dimer level (p = 0.004).Univariate binary logistic regression model analysis revealed that CRP and erythrocyte sedimentation rate at disease onset were associated with defervescence within 24 h after treatment with tetracyclines alone (p = 0.020, p = 0.027), with erythrocyte sedimentation rate also influencing defervescence within 48 h (p = 0.022). CONCLUSION: Doxycycline treatment resulted in a higher rate of defervescence than minocycline. Prompt treatment reduced the probability of pleural effusion, hypoxemia, pulmonary atelectasis, and D-dimer levels > 2 times the reference value.

Lyme Disease Prophylaxis by Single-Dose Doxycycline in the United States, 2010-2020.

Single-dose doxycycline after high-risk tick bites can prevent Lyme disease, which disproportionately affects children. We described single-dose doxycycline dispensings in an outpatient cohort in the United States. During 2010-2020, a total of 427 105 patients received ≥1 dispensing(s); most were aged ≥65 years. Lyme disease postexposure prophylaxis may be underprescribed for some groups, including children.

Efficacy of combined doxycycline and intense pulsed light therapy for the management of intractable recurrent chalazion.

Management of chalazion, characterized by noninfectious chronic granulomatous inflammation of the meibomian glands (MGs), remains challenging in ophthalmic practice, particularly because of its propensity for recurrence even after surgical intervention. This study aimed to evaluate the combined efficacy of doxycycline and intense pulsed light (IPL) therapy for treating intractable recurrent chalazion, focusing on reducing recurrence rates and improving MG status. This retrospective study included patients with intractable recurrent chalazion refractory to conventional treatments including surgical intervention and antibiotics. All patients were treated with a combination of doxycycline and IPL therapy. Clinical assessments included best-corrected visual activity, intraocular pressure, and MG evaluations using slit-lamp biomicroscopy and Keratograph 5 M topography. The study included 12 patients (5 male and 7 female) with an average age of 36.3 years. Treatment outcomes were categorized as 'success' (83.3%), 'stationary' (8.3%), and 'failure' (8.3%). Significant improvements were noted in the MG expression scores (p = 0.038), MG quality scores (p = 0.045), and lid margin telangiectasia scores (p = 0.002). In addition, significant improvement in meiboscores was observed (p = 0.002). The combination of doxycycline and IPL therapy demonstrated promising efficacy in treating intractable recurrent chalazion, with significant improvements in MG function and reduced recurrence rates. This treatment approach offers a viable alternative for patients with recurrent chalazions, particularly for those who are unresponsive to conventional treatments.

Antimicrobial Potential of Brassica oleracea Extracts (White and Broccoli) and Their Resistance Compared to Doxycycline Against Gram-Positive and Gram-Negative Bacteria.

Brassica oleracea L is low in carbohydrates and fiber, making it ideal for low-carb diets. But they are rich in vitamins, minerals, and other essential nutrients. The present article investigated the antimicrobial effect of B. oleracea extract (white and broccoli) (BOE-WB) on Gram-positive and Gram-negative strains and its resistance to doxycycline. BOE-WB was used as the soaking method. It was analyzed by gas chromatography-mass spectroscopy (GC-MS), high-performance liquid chromatography (HPLC), and 2,2-Diphenyl-1-picrylhydrazyl (DPPH) methods. The samples were prepared with three concentrations. It used Mueller Hinton Agar culture medium of fresh bacteria. It was incubated for 24 h in a 37°C incubator. It identified 33 compounds. For BOE-W, 77% of the compounds are oxygenated, while for BOE-B, this percentage is 79%. For BOE-B, 79% had oxygenated compounds. BOE-WB has significant antibacterial effects on Pseudomonas aerogenosa and Bacillus cereus. The lethal impact of BOE-WB on strains is very close to that of doxycycline, and it can be introduced as a new antimicrobial drug to the medical world. The research shows that the percentage of oxygenated compounds in foods containing BOE-B is much higher than that of BOE-W. It has a significant impact on the antioxidant effect. Foods containing BOE-W have a high percentage of azo compounds and sulfur. One of the benefits of sulfur in the body is disinfecting the blood. In addition, sulfur increases the body's resistance to bacteria.

Doxycycline Post-Exposure Prophylaxis for Bacterial Sexually Transmitted Infections: The Current Landscape and Future Directions.

PURPOSE OF REVIEW: The incidence of bacterial sexually transmitted infections (STI) continues to rise particularly among men who have sex with men (MSM). Doxycycline post-exposure prophylaxis (doxy-PEP) has emerged as a promising biomedical prevention strategy. This review aims to summarize the results of recent studies, highlight the current normative guidance on the use of doxy-PEP, and discuss remaining questions. RECENT FINDINGS: In the past decade, there have been four randomized controlled trials and three real-world analyses of doxy-PEP, which consistently demonstrated a reduction in Chlamydia trachomatis and Treponema pallidum infections among MSM. Questions remain regarding the efficacy of doxy-PEP for Neisseria gonorrhoeae infection and among cisgender women. Possible detrimental impacts include an increase in antimicrobial resistance as well as alterations to the gut microbiome Doxy-PEP is an effective strategy for preventing Chlamydia trachomatis and Treponema pallidum among MSM. Further work is needed to investigate the benefits among other populations, as well as to monitor for adverse effects.

Evidence-Informed Provision of Doxycycline Post-Exposure Prophylaxis for Prevention of Bacterial Sexually Transmitted Infections.

Doxycycline post-exposure prophylaxis (doxy-PEP) reduces the risk of bacterial sexually transmitted infections (STIs) among men who have sex with men and transgender women. In the United States, doxy-PEP is in an early stage of integration into clinical practice, and national guidelines for its use were recently released. The goal of this manuscript is to provide practical guidance for clinicians who are considering or currently prescribing doxy-PEP. We address five clinical questions using post hoc analyses of data from the DoxyPEP randomized controlled trial and discuss the potential implications and limitations of each question with the goal of informing clinical practice and implementation of doxy-PEP programs. The questions address patient eligibility criteria for doxy-PEP, the expected benefit and associated doxy-PEP doses for the average patient, the initial number of doses prescribed, and laboratory monitoring of persons taking doxy-PEP.

Magnetic solid-phase extraction of amoxicillin and doxycycline from water and urine samples based on cetylpyridinium chloride-modified Fe3O4 nanoparticles followed by spectrophotometric determination.

This research describes an easy, rapid, and inexpensive magnetic solid-phase extraction (MSPE) approach employing Fe3O4 magnetic nanoparticles modified with cetylpyridinium chloride (Fe3O4@CPC/MNPs) for extracting amoxicillin (AMX) and doxycycline (DOX) after derivatization with 4-chloroaniline as a color reagent. The azo-coupling of AMX and DOX with the color reagent in the alkaline medium caused yellow and yellow-orange azo dyes with maximum absorption wavelengths of 435 and 438 nm, respectively. The UV-Vis spectroscopy was utilized to determine the target analyte after the extraction procedure. Good linearities (R2 > 0.99) in the concentration ranges of 0.03-4.50 and 0.05-6.00 µg/mL were obtained for AMX and DOX, respectively. The experimental detection limits of AMX and DOX were obtained as 0.01 and 0.02 µg/mL, respectively. The developed approach was effectively applied to pre-concentrate and quantify AMX and DOX in environmental water and urine samples.

PhoPQ-mediated lipopolysaccharide modification governs intrinsic resistance to tetracycline and glycylcycline antibiotics in Escherichia coli.

Tetracyclines and glycylcycline are among the important antibiotics used to combat infections caused by multidrug-resistant Gram-negative pathogens. Despite the clinical importance of these antibiotics, their mechanisms of resistance remain unclear. In this study, we elucidated a novel mechanism of resistance to tetracycline and glycylcycline antibiotics via lipopolysaccharide (LPS) modification. Disruption of the Escherichia coli PhoPQ two-component system, which regulates the transcription of various genes involved in magnesium transport and LPS modification, leads to increased susceptibility to tetracycline, minocycline, doxycycline, and tigecycline. These phenotypes are caused by enhanced expression of phosphoethanolamine transferase EptB, which catalyzes the modification of the inner core sugar of LPS. PhoPQ-mediated regulation of EptB expression appears to affect the intracellular transportation of doxycycline. Disruption of EptB increases resistance to tetracycline and glycylcycline antibiotics, whereas the other two phosphoethanolamine transferases, EptA and EptC, that participate in the modification of other LPS residues, are not associated with resistance to tetracyclines and glycylcycline. Overall, our results demonstrated that PhoPQ-mediated modification of a specific residue of LPS by phosphoethanolamine transferase EptB governs intrinsic resistance to tetracycline and glycylcycline antibiotics. IMPORTANCE: Elucidating the resistance mechanisms of clinically important antibiotics helps in maintaining the clinical efficacy of antibiotics and in the prescription of adequate antibiotic therapy. Although tetracycline and glycylcycline antibiotics are clinically important in combating multidrug-resistant Gram-negative bacterial infections, their mechanisms of resistance are not fully understood. Our research demonstrates that the E. coli PhoPQ two-component system affects resistance to tetracycline and glycylcycline antibiotics by controlling the expression of phosphoethanolamine transferase EptB, which catalyzes the modification of the inner core residue of lipopolysaccharide (LPS). Therefore, our findings highlight a novel resistance mechanism to tetracycline and glycylcycline antibiotics and the physiological significance of LPS core modification in E. coli.

Effective Management of Leptospirosis: A Case Report of Combined Doxycycline and Ceftriaxone Therapy.

Leptospirosis is a bacterial infection caused by the pathogen Leptospira. The disease is primarily transmitted through contact with animals (mainly rats) or through exposure to contaminated water or soil. Underdeveloped countries and places with poor housing and sanitation are at higher risk. Leptospirosis often presents with nonspecific symptoms, making it difficult to diagnose. This can delay the initiation of appropriate treatment. In the case presented, the patient had a history of cough, high fever, and a rash over various parts of the body. This combination of respiratory symptoms, systemic fever, and dermatological manifestations led to the suspicion of an infection. Initial blood examinations revealed a significantly increased white blood cell (WBC) count, indicating an infection. Further enzyme-linked immunosorbent assay (ELISA) testing was confirmed by active immunoglobulin M (IgM) antibodies specific to leptospira species, followed by a chest X-ray scan. The antibiotics doxycycline (for seven days) and ceftriaxone (two weeks) were used to treat the leptospirosis. The patient was also given antipyretics to bring down fever and antitussive agents to suppress the cough. Hydration and breathing exercises were also given high priority in healing from this illness. After treatment, the patient did very well, he sweated less before dawn, the rash started to go away, and finally, even coughing was controlled. Further blood tests have shown that now the WBC is in the normal range and the IgM antibody level has dropped. In other words, the infection has been eradicated. For detailed information, refer to the case study "A Moral Call," which argues that early treatment and intervention are critical in managing leptospirosis. Getting this severe infection with early antibiotic therapy and nursing care gives people a chance for complete recovery from their illness. There must be more studies into this disease's long-term effects and how to prevent it when the risk group is more significant.

The effect of early administration of antibiotics or feeding a diet containing coccidiostats on the level of their accumulation in liver and the redox status of turkeys.

Early administration of antibiotics may worsen the functioning of the turkeys' antioxidant system. It was also assumed that the longer the time of administration of an antibiotic, e.g. a coccidiostat, the greater the risk of its accumulation in the liver. The study aimed to determine whether early administration of antibiotics or feeding a diet containing coccidiostats causes accumulation in the liver and whether it affects the deterioration of the antioxidant system, and whether preventive vaccinations can intensify it. A total of 3 080 female turkeys were randomly allocated to eight groups. The experiment had a two-factorial design, with four treatments (C, M, E, D) and two groups of birds (vaccinated +, unvaccinated -). The C group did not receive the coccidiostat or antibiotics. Group M was administered monensin at 90 mg/kg feed for 56 days of life. Group E received enrofloxacin at 10 mg/kg BW, and group D received doxycycline at 50 mg/kg BW, added to drinking water, for the first 5 days of life. One-day-old turkeys from groups C+, M+, E+, and D+ were administered live-attenuated vaccines against turkey rhinotracheitis and Newcastle disease by coarse spray; 28-day-old birds were administered a subcutaneously injected inactivated vaccine against Ornithobacterium rhinotracheale. Turkeys from groups C-, M-, E-, and D- were not vaccinated. It was determined that as a result of administration of enrofloxacin or doxycycline until the 5th day of life, biotransformation of these antibiotics occurred in the liver until the 56th day of life of the turkeys, which was confirmed by their lower level than the Maximum Residue Level. Because the concentration of monensin in the liver of turkeys gradually increased with the extension of the time of its administration in the diet, it is probable that discontinuing its addition a day before the slaughter of birds will result in the presence of this coccidiostat in the liver of turkeys. Despite the accumulation of monensin in the liver of turkeys, this coccidiostat did not increase oxidative reactions in the organism of turkeys. Vaccination of turkeys can reduce oxidative reactions and apoptosis in the body. However, the effect of the redox system reaction is different immediately after vaccination, which is due to the mechanism of action of the immune system. If it is necessary to administer an antibiotic in the early rearing period, the effects of doxycycline on the organism's immunity including antioxidant defence will be less severe than those of enrofloxacin.

Forget me not: The effect of doxycycline on human declarative memory.

Investigations into neuroprotective drugs are in high demand for the treatment of neurodegenerative diseases, such as multiple sclerosis or Alzheimer's disease, but also psychiatric disorders, such as depression, trauma, and substance use. One potential drug class being investigated are tetracyclines impacting on a variety of neuroprotective mechanisms. At the same time, tetracyclines like doxycycline have been suggested to affect human fear and spatial memory as well as reducing declarative memory retention. Based on the assumed necessity for synaptic consolidation in hippocampus-dependent learning, we hypothesised declarative memory may be similarly impaired by doxycycline as fear and spatial memory. Therefore, in this study we investigate the potential diminishing effects of doxycycline on consolidation of declarative memory in healthy humans. Additionally, to test for effect specificity we assessed motor memory, sustained attention, and processing speed. We administered a neuropsychological test battery in three independent randomized placebo-controlled double-blind trials (RCTs), in which healthy young volunteers (total N = 252) either received a single oral dose doxycycline (200 mg, n = 126) or placebo (n = 126) in a between-subject design. We found no evidence for a detrimental effect of doxycycline on declarative memory; instead, doxycycline improved declarative learning (p-value=0.022, Cohen's d=0.15) and memory consolidation (p=0.040, d=0.26). Contrarily, doxycycline slightly reduced motor learning (p=0.001, d=0.10) but subtly strengthened long-term motor memory (p=0.001, d=0.10). These results suggest that doxycycline can improve declarative learning and memory without having long term negative effects on other cognitive domains in healthy humans. Our results give hope to further investigate doxycycline in neuroprotective treatment applications.

Exploiting the Applicability of Polytetrahydrofuran-Modified Polyester for the Fabric Phase Sorptive Extraction of Doxycycline from Human Urine.

In this report, a polytetrahydrofuran-coated polyester fabric phase sorptive extraction (FPSE) for the determination of doxycycline in human urine was described. The sol-gel polytetrahydrofuran sorbent proved to be superior against other sol-gel coated cellulose and polyester membranes tested. The effect of the extraction parameters including membrane surface area, sample pH and volume, salt concentration, extraction time, stirring rate, etc., on the extraction efficiency of the analyte was studied using the "one-factor-at-a-time" (OFAT) and Box-Behnken design approaches. The analytical method proposed was validated in compliance with FDA guidelines for bioanalytical procedures. The method was linear in the determination range of 100-5000 ng/mL with the determination coefficient of 0.9953. The limit of detection (LOD) and the lower limit of quantification for doxycycline was 17 and 100 ng/mL, respectively. The relative recoveries for intra-day and inter-day studies ranged from 98.5-112.2% and 89.6-96.8%, respectively. The relative standard deviation was lower than 14.7% in all cases, exhibiting good precision. The sol-gel polytetrahydrofuran-modified FPSE membranes were reusable for at least 30 times. The greenness of the developed method was evaluated using Sample Preparation Metric of Sustainability (SPMS) and Blue Applicability Grade Index (BAGI) metric tools. Finally, the analytical scheme was successfully employed for the quantitation of urinary doxycycline collected at various time points following the administration of doxycycline-containing tablets.

Application of zwitterionic ionic liquid-based capsule phase microextraction for the HPLC-UV determination of doxycycline in human urine samples.

Herein, we describe the utilization of an ionic liquid (IL)/Carbowax 20 M-functionalized sol-gel sorbent for the capsule phase microextraction of doxycycline in authentic human urine samples. This green sample preparation method combines stirring and filtration in a single, standalone sample preparation device, streamlining the sample preparation process. Additionally, it provides rapid extraction kinetics and high extraction efficiency. The experimental conditions (i.e. sorbent type, sample pH and volume, extraction time, ionic strength, elution solvent, and volume) affecting the extraction efficiency of the analyte were studied and optimized. The method was linear in the range of 0.1 - 5.0 µg/mL with a coefficient of determination higher than 0.995. The achieved LOD was found to be 0.02 µg/mL while the lower limit of quantitation (LLOQ) was 0.1 µg/mL. The IL/Carbowax 20 M-functionalized microextraction capsules were reusable at least 30 times for urine samples. The relative recoveries (% RR) ranged between 93.4 - 115.9 % while the precision (expressed as % RSD) was better than 8.1 % in all cases. The robustness of the microextraction procedure and the instrumental HPLC method were separately investigated using Plackett-Burman experimental designs. The analytical protocol demonstrated cost-effectiveness, ease of handling, and speed, leading to increased sample throughput. The green character of the developed method was evaluated using the Green Analytical Procedure Index (GAPI) and Blue Applicability Grade Index (BAGI). Finally, the method's applicability was demonstrated by analyzing authentic human urine samples after oral administration of a doxycycline-containing pharmaceutical formulation.

N-acetylcysteine promotes doxycycline resistance in the bacterial pathogen Edwardsiella tarda.

Bacterial resistance poses a significant threat to both human and animal health. N-acetylcysteine (NAC), which is used as an anti-inflammatory, has been shown to have distinct and contrasting impacts on bacterial resistance. However, the precise mechanism underlying the relationship between NAC and bacterial resistance remains unclear and requires further investigation. In this study, we study the effect of NAC on bacterial resistance and the underlying mechanisms. Specifically, we examine the effects of NAC on Edwardsiella tarda ATCC15947, a pathogen that exhibits resistance to many antibiotics. We find that NAC can promote resistance of E. tarda to many antibiotics, such as doxycycline, resulting in an increase in the bacterial survival rate. Through proteomic analysis, we demonstrate that NAC activates the amino acid metabolism pathway in E. tarda, leading to elevated intracellular glutathione (GSH) levels and reduced reactive oxygen species (ROS). Additionally, NAC reduces antibiotic influx while enhancing efflux, thus maintaining low intracellular antibiotic concentrations. We also propose that NAC promotes protein aggregation, thus contributing to antibiotic resistance. Our study describes the mechanism underlying E. tarda resistance to doxycycline and cautions against the indiscriminate use of metabolite adjuvants.