Pharmacogenetics of disease-modifying anti-rheumatic drugs

Azathioprine and hydroxychloroquine overdose in Sjögren's syndrome patient with hypocalcemia: a case report

INTRODUCTION

Hydroxychloroquine and azathioprine have been routinely used to control and treat primary and secondary Sjögren's syndrome, which potentially triggered some overdoses by these drugs. Toxicity from hydroxychloroquine and azathioprine manifests in the form of cardiac conduction abnormalities, nausea, vomiting, and muscle weakness. Recognizing these unique drug overdoses and management of these toxicities is important. This case report aims to expand our current understanding of these drug overdoses and their management and also underscores the importance of anticipating and identifying fewer common complications, such as hypocalcemia.

CASE REPORT

A 34-year-old Persian woman with a history of Sjögren's syndrome presented to the emergency department 3.5-4 hours after an intentional overdose of hydroxychloroquine and azathioprine and severe hypotension and loss of consciousness. Although the patient was regularly taking other medications, such as fluoxetine, naproxen, and prednisolone, she explicitly clarified that these were not the substances involved in her overdose. Early investigations showed hypokalemia (2.4 mEq/L), hypocalcemia (7.5 mg/dL), and hypoglycemia (65 mg/dL). She was also diagnosed with metabolic acidosis and respiratory alkalosis. The electrocardiogram showed changes in favor of hypokalemia; other lab tests were run on the patient. Supportive treatments were applied, including rapid intravenous fluid dextrose 5%, normal saline, potassium chloride 30 mEq, and calcium gluconate 100 mg. The patient was managed and monitored overnight in the emergency room and recovered without residual side effects.

CONCLUSION

Hydroxychloroquine and azathioprine toxicity are considered rare, but it is likely to increase in frequency given the prevalence and increase in autoimmune diseases and the increasing usage of these drugs in treating such diseases. We found hypocalcemia as the presentation to this patient, which needs further investigation into the probable mechanism. Clinicians need to consider the unique effects of hydroxychloroquine and azathioprine poisoning and initiate appropriate emergency interventions to improve the outcomes in similar patients.

Development of a Physiologically Based Pharmacokinetic Model for Hydroxychloroquine and Its Application in Dose Optimization in Specific COVID-19 Patients

In Feb 2020, we developed a physiologically-based pharmacokinetic (PBPK) model of hydroxychloroquine (HCQ) and integrated in vitro anti-viral effect to support dosing design of HCQ in the treatment of COVID-19 patients in China. This, along with emerging research and clinical findings, supported broader uptake of HCQ as a potential treatment for COVID-19 globally at the beginning of the pandemics. Therefore, many COVID-19 patients have been or will be exposed to HCQ, including specific populations with underlying intrinsic and/or extrinsic characteristics that may affect the disposition and drug actions of HCQ. It is critical to update our PBPK model of HCQ with adequate drug absorption and disposition mechanisms to support optimal dosing of HCQ in these specific populations. We conducted relevant in vitro and in vivo experiments to support HCQ PBPK model update. Different aspects of this model are validated using PK study from 11 published references. With parameterization informed by results from monkeys, a permeability-limited lung model is employed to describe HCQ distribution in the lung tissues. The updated model is applied to optimize HCQ dosing regimens for specific populations, including those taking concomitant medications. In order to meet predefined HCQ exposure target, HCQ dose may need to be reduced in young children, elderly subjects with organ impairment and/or coadministration with a strong CYP2C8/CYP2D6/CYP3A4 inhibitor, and be increased in pregnant women. The updated HCQ PBPK model informed by new metabolism and distribution data can be used to effectively support dosing recommendations for clinical trials in specific COVID-19 patients and treatment of patients with malaria or autoimmune diseases.

Metabolism and Interactions of Chloroquine and Hydroxychloroquine with Human Cytochrome P450 Enzymes and Drug Transporters

BACKGROUND

In clinical practice, chloroquine and hydroxychloroquine are often co-administered with other drugs in the treatment of malaria, chronic inflammatory diseases, and COVID-19. Therefore, their metabolic properties and the effects on the activity of cytochrome P450 (P450, CYP) enzymes and drug transporters should be considered when developing the most efficient treatments for patients.

METHODS

Scientific literature on the interactions of chloroquine and hydroxychloroquine with human P450 enzymes and drug transporters, was searched using PUBMED.Gov (https://pubmed.ncbi.nlm.nih.gov/) and the ADME database (https://life-science.kyushu.fujitsu.com/admedb/).

RESULTS

Chloroquine and hydroxychloroquine are metabolized by P450 1A2, 2C8, 2C19, 2D6, and 3A4/5 in vitro and by P450s 2C8 and 3A4/5 in vivo by N-deethylation. Chloroquine effectively inhibited P450 2D6 in vitro; however, in vivo inhibition was not apparent except in individuals with limited P450 2D6 activity. Chloroquine is both an inhibitor and inducer of the transporter MRP1 and is also a substrate of the Mate and MRP1 transport systems. Hydroxychloroquine also inhibited P450 2D6 and the transporter OATP1A2.

CONCLUSIONS

Chloroquine caused a statistically significant decrease in P450 2D6 activity in vitro and in vivo, also inhibiting its own metabolism by the enzyme. The inhibition indicates a potential for clinical drug-drug interactions when taken with other drugs that are predominant substrates of the P450 2D6. When chloroquine and hydroxychloroquine are used clinically with other drugs, substrates of P450 2D6 enzyme, attention should be given to substrate-specific metabolism by P450 2D6 alleles present in individuals taking the drugs.

Repurposing Drugs for COVID-19: Pharmacokinetics and Pharmacogenomics of Chloroquine and Hydroxychloroquine

Background

A new coronavirus SARS-CoV-2 has been identified as the etiological agent of the severe acute respiratory syndrome, COVID-19, the source and cause of the 2019–20 coronavirus pandemic. Hydroxychloroquine and chloroquine have gathered extraordinary attention as therapeutic candidates against SARS-CoV-2 infections. While there is growing scientific data on the therapeutic effect, there is also concern for toxicity of the medications. The therapy of COVID-19 by hydroxychloroquine and chloroquine is off-label. Studies to analyze the personalized effect and safety are lacking.

Methods

A review of the literature was performed using Medline/PubMed/Embase database. A variety of keywords were employed in keyword/title/abstract searches. The electronic search was followed by extensive hand searching using reference lists from the identified articles.

Results

A total of 126 results were obtained after screening all sources. Mechanisms underlying variability in drug concentrations and therapeutic response with chloroquine and hydroxychloroquine in mediating beneficial and adverse effects of chloroquine and hydroxychloroquine were reviewed and analyzed. Pharmacogenomic studies from various disease states were evaluated to elucidate the role of genetic variation in drug response and toxicity.

Conclusion

Knowledge of the pharmacokinetics and pharmacogenomics of chloroquine and hydroxychloroquine is necessary for effective and safe dosing and to avoid treatment failure and severe complications.

Rationale of a loading dose initiation for hydroxychloroquine treatment in COVID-19 infection in the DisCoVeRy trial

Around the world, several dose regimens of hydroxychloroquine have been used for COVID-19 infection treatment, with the objective of identifying a short-term course. Hydroxychloroquine was found to decrease the viral replication in a concentration-dependent manner in vitro and to be more active when added prior to the viral challenge. A loading dose is used to rapidly attain a target drug concentration, which is usually considered as approximately the steady-state concentration. With a loading dose, the minimum effective concentration is reached much more rapidly than when using only the maintenance dose from the start. Thus, we propose a hydroxychloroquine sulphate dose regimen of 400 mg twice daily at Day 1 then 400 mg once daily from Day 2 to Day 10. We aim to evaluate this in the C-20-15 DisCoVeRy trial.

Challenges in heart transplantation during COVID-19: A single-center experience

BACKGROUND

Orthotopic heart transplantation (OHT) recipients may be particularly vulnerable to coronavirus disease 2019 (COVID-19). OHT during the pandemic presents unique challenges in terms of feasibility and safety.

METHODS

Chart review was performed for consecutive OHT recipients with COVID-19 and waitlisted patients who underwent OHT from March 1, 2020 to May 15, 2020.

RESULTS

Of the approximately 400 OHT recipients followed at our institution, 22 acquired COVID-19. Clinical characteristics included median age 59 (range, 49-71) years, 14 (63.6%) were male, and median time from OHT to infection was 4.6 (2.5-20.6) years. Symptoms included fever (68.2%), gastrointestinal complaints (55%), and cough (46%). COVID-19 was severe or critical in 5 (23%). All patients had elevated inflammatory biomarkers. Immunosuppression was modified in 85% of patients. Most (n = 16, 86.4%) were hospitalized, 18% required intubation, and 14% required vasopressor support. Five patients (23%) expired. None of the patients requiring intubation survived. Five patients underwent OHT during the pandemic. They were all males, ranging from 30 to 59 years of age. Two were transplanted at United Network of Organ Sharing Status 1 or 2, 1 at Status 3, and 2 at Status 4. All were successfully discharged and are alive without allograft dysfunction or rejection. One contracted mild COVID-19 after the index hospitalization.

CONCLUSION

OHT recipients with COVID-19 appear to have outcomes similar to the general population hospitalized with COVID-19. OHT during the pandemic is feasible when appropriate precautions are taken. Further study is needed to guide immunosuppression management in OHT recipients affected by COVID-19.

Antiviral treatment of COVID-19: a clinical pharmacology narrative review

The outbreak of coronavirus disease 2019 (COVID-19) in December 2019 in China, has become a pandemic in March 2020. Repurposing old and relatively safe drugs becomes an advantageous option to obtain the urgently needed effective treatment. Repurposing chloroquine, hydroxychloroquine, oseltamivir, lopinavir/ritonavir, andfavipiravir, and the use of investigational drug remdesivir for treatment of COVID-19, are reviewed from the clinical pharmacology perspective, particularly its efficacy and safety. Limited clinical studies of chloroquine, hydroxychloroquine, favipiravir, and remdesivir showed some efficacy in COVID-19 treatment with tolerable adverse effects. Potential serious adverse effect of chloroquine and hydroxychloroquine is cardiac arrhythmia. Oseltamivir has no documented activity against SARS-CoV-2, while lopinavir/ritonavir showed limited efficacy in COVID-19. Currently, there is no sufficient evidence to recommend any specific anti-COVID-19 treatment. The decision to use these drugs during the COVID-19 pandemic must be based on careful consideration of the potential benefits and risks to the patient.

Antimalarials - are they effective and safe in rheumatic diseases?

Antimalarial drugs (AD) are a group of widespread therapeutic agents in multiple rheumatic indications. Although the effect of AD is mild and extended in time, low toxicity is their appreciated value. This paper describes the current state of knowledge on the mechanism of action, use, toxicity and pleiotropic effects of AD in the pharmacotherapy of autoimmune diseases.

Supramolecular interaction of methotrexate with cucurbit[7]uril and analytical application

The supramolecular interaction between cucurbit[7]uril (CB[7]) as the host and the anti-cancer drug methotrexate (MTX) as the guest was studied using fluorescence spectroscopy, UV-visible absorption spectroscopy, ¹H NMR, 2D NOESY, and theoretical calculations. The experimental results confirmed the formation of 1:2 inclusion complex with CB[7] and indicated a simple and sensitive competitive method for the fluorescence detection of MTX. It was found that the fluorescence intensities of CB[7]-palmatine, CB[7]-berberine and CB[7]-coptisine were quenched linearly upon the addition of MTX. The linear ranges obtained in the detection of MTX were 0.1-15μgmL^-1, 0.2-15μgmL^-1, and 0.4-15μgmL^-1 with detection limits of 0.03μgmL^-1, 0.06μgmL^-1, and 0.13μgmL^-1, respectively. This method can be used for the determination of MTX in biological fluids. These results suggested that cucurbit[7]uril is a promising drug carrier for targeted MTX delivery and monitoring, with improved efficacy and reduced toxicity in normal tissues.

Factors Related to Blood Hydroxychloroquine Concentration in Patients With Systemic Lupus Erythematosus

OBJECTIVE

To identify factors associated with blood concentrations of hydroxychloroquine (HCQ) and its major metabolite, N-desethylhydroxychloroquine (DHCQ), in patients with systemic lupus erythematosus (SLE; lupus) receiving long-term oral HCQ treatment.

METHODS

SLE patients who had been taking HCQ for more than 3 months were recruited. Various clinical characteristics, laboratory values, and SLE Disease Activity Index (SLEDAI) scores were examined. The concentrations of HCQ and DHCQ ([HCQ] and [DHCQ]) were measured by liquid chromatography mass spectrometry, and the relationship between [HCQ], [DHCQ], and [HCQ]:[DHCQ] ratio to various factors was investigated.

RESULTS

In total, 189 SLE patients receiving long-term HCQ treatment were included in the analysis. The median (interquartile range [IQR]) [HCQ] was 515 (IQR 353-720) ng/ml, the median [DHCQ] was 417 (IQR 266-591) ng/ml, and the median [HCQ]:[DHCQ] ratio was 1.3 (range 1.0-1.7). [HCQ] was closely associated with [DHCQ] (r = 0.81, P < 0.0001). The weight-adjusted oral HCQ dose was strongly associated with both [HCQ] (P < 0.001) and [DHCQ] (P < 0.001). Time since last dose was associated with [HCQ] (P < 0.001). No statistically significant association was found between renal function or smoking and [HCQ] or [DHCQ]. Use of additional immunosuppressants increased both [HCQ] and [DHCQ] after adjusting for possible confounders (P = 0.04 and P = 0.03, respectively). The lower SLEDAI score was significantly related to higher [HCQ], after adjusting for age, sex, weight-adjusted HCQ dose, time since last dose, number of other immunosuppressants, and smoking status (P = 0.007).

CONCLUSION

Various factors affected blood levels of [HCQ], [DHCQ], or the [HCQ]:[DHCQ] ratio of SLE patients receiving long-term oral HCQ treatment. Notably, higher [HCQ] was associated with a lower SLEDAI score in our typical outpatient clinic population with lupus.

Association of Polymorphisms of Cytochrome P450 2D6 With Blood Hydroxychloroquine Levels in Patients With Systemic Lupus Erythematosus

OBJECTIVE

To evaluate associations of genetic polymorphisms in cytochrome P450 (CYP) isoforms 2D6, 3A5, and 3A4 with blood concentrations of hydroxychloroquine (HCQ) and its metabolite, N-desethyl HCQ (DHCQ), in patients with systemic lupus erythematosus (SLE).

METHODS

SLE patients taking HCQ for >3 months were recruited and were genotyped for 4 single-nucleotide polymorphisms in CYP2D6*10, CYP3A5*3, and CYP3A4*18B. Blood HCQ and DHCQ concentrations ([HCQ] and [DHCQ]) were measured and their association with corresponding genotypes was investigated.

RESULTS

A total of 194 patients were included in the analysis. CYP2D6*10 polymorphisms (rs1065852 and rs1135840) were significantly associated with the [DHCQ]:[HCQ] ratio after adjustment for age, sex, dose per weight per day, and SLE Disease Activity Index score (P = 0.03 and P < 0.01, respectively). In adjusted models, the [DHCQ]:[HCQ] ratio was highest in patients with the G/G genotype of the CYP2D6*10 (rs1065852) polymorphism and lowest in those with the A/A genotype (P = 0.03). Similarly, the [DHCQ]:[HCQ] ratio was highest in patients with the C/C genotype of the CYP2D6*10 (rs1135840) polymorphism and lowest in those with the G/G genotype (P < 0.01). The CYP2D6*10 (rs1065852) polymorphism was significantly related to the [DHCQ] (P = 0.01). However, the polymorphisms of CYP3A5*3 and CYP3A4*18B did not show any significant association with the [HCQ], [DHCQ], or [DHCQ]:[HCQ] ratio.

CONCLUSION

Our study showed that the [DHCQ]:[HCQ] ratio was related to CYP2D6 polymorphisms in Korean lupus patients taking oral HCQ. CYP polymorphisms may explain why there is wide variation in blood HCQ concentrations. The role of an individual's CYP polymorphisms should be considered when prescribing oral HCQ.

Nanocomposites of nitrogen-doped graphene decorated with a palladium silver bimetallic alloy for use as a biosensor for methotrexate detection

Pd₁Ag₁/NG–GCE is a promising platform for the highly sensitive electrochemical detection of MTX.

Arylamine N-acetyltransferase polymorphisms in Han Chinese patients with ankylosing spondylitis and their correlation to the adverse drug reactions to sulfasalazine

BACKGROUND

Polymorphisms of Arylamine N-acetyltransferase (NAT) that contribute to diverse susceptibilities of some autoimmune diseases are also linked to the metabolism of several drugs including sulfasalazine (SSZ). The aim of this study was to investigate the distribution of NAT polymorphisms in Han Chinese patients with ankylosing spondylitis (AS) and their correlation to sulfasalazine-induced adverse drug reactions (ADRs).

METHODS

Arylamine N-acetyltransferase 1 (NAT1) and arylamine N-acetyltransferase 2 (NAT2) genotypes were determined in 266 AS patients who received SSZ treatment and 280 healthy controls. The correlation between NAT polymorphisms and SSZ-induced ADRs was analyzed.

RESULTS

The co-occurrence frequency of NAT2 fast acetylator genotype and NAT1*10/NAT1*10 genotype was lower in AS patients than in controls. No positive correlations were detected between NAT polymorphisms and AS clinical features. The prevalence of SSZ-induced ADRs and drug withdrawal was 9.4% and 7.1%, respectively. The frequencies of overall ADRs, dose-related ADRs, and termination of drug treatment because of intolerance were higher in the NAT2 slow acetylator genotype carriers than in the fast-type carriers and in those with co-existence of NAT1 and NAT2 slow acetylator genotypes. Furthermore, the ADRs emerged earlier in the AS cases carrying both NAT1 and NAT2 slow acetylator genotypes.

CONCLUSIONS

The prevalence of co-occurring NAT2 fast acetylator genotype and NAT1*10/NAT1*10 genotype was lower in AS patients than in controls. The NAT2 slow acetylator genotype and co-existing NAT1 and NAT2 slow acetylator genotypes appear to be associated with higher risks of SSZ-induced ADRs.

Determination of methotrexate and folic acid by ion chromatography with electrochemical detection on a functionalized multi-wall carbon nanotube modified electrode

A simple and sensitive method was developed for simultaneous determination of methotrexate (MTX) and folic acid (FA) by ion chromatography with electrochemical detection (IC-ECD). Quaternary amine functionalized multi-wall carbon nanotubes (q-MWNTs) modified glassy carbon electrode (GCE) was used as an amperometric sensor to determine MTX and FA. The electrochemical behaviors of MTX and FA at the q-MWNTs/GCE were studied by cyclic voltammetry (CV). Results indicated that this modified electrode exhibited electrocatalytic oxidation toward MTX and FA with high sensitivity, stability and long life. Good separation of MTX and FA was demonstrated by IC on an anion-exchange column with phosphate buffer solution (PBS) as eluent. Under the optimal conditions, the linear ranges were from 0.01 to 20mg/L for both MTX and FA with correlation coefficients r ≥ 0.9994. The obtained detection limits (LODs) for MTX and FA were 0.2 and 0.4 μg/L (S/N=3), respectively. The method has been successfully applied to the determination of MTX and FA in plasma and urine of patients of rheumatoid arthritis.

Hydroxychloroquine in systemic lupus erythematosus and rheumatoid arthritis and its safety in pregnancy

INTRODUCTION

The antimalarial drug hydroxychloroquine (HCQ) is widely used to treat various rheumatic diseases. Many autoimmune diseases occur in women of child-bearing age who may become pregnant while on therapy, which raises concerns regarding the teratogenicity of HCQ and its effect on the outcome of the pregnancy. There is a lack of data regarding the safety of HCQ during pregnancy.

AREAS COVERED

In this review, the authors attempt to identify relevant publications by searching MEDLINE, Cochrane database, Ovid-Currents Clinical Medicine, Ovid-Embase:Drugs and Pharmacology, EBSCO, Web of Science and SCOPUS using the search terms HCQ and/or pregnancy. A basis for the mechanism of action of HCQ is provided.

EXPERT OPINION

HCQ has been shown by numerous studies over the past 15 years to be efficacious in the treatment of autoimmune diseases, including systemic lupus erythematosus, discoid lupus erythematosus and rheumatoid arthritis. HCQ does not appear to be associated with any increased risk of congenital defects, spontaneous abortions, fetal death, prematurity or decreased numbers of live births in patients with autoimmune diseases. Therefore, in the author's opinion, HCQ is safe for the treatment of autoimmune diseases during pregnancy.

Causes of DMARD withdrawal following ADR within 6 months of initiation among Indian rheumatoid arthritis patients

The present study was conducted in Indian rheumatoid arthritis (RA) patients prescribed disease-modifying anti-rheumatic drugs (DMARDs) to determine the incidence and type of adverse drug reactions (ADRs) leading to their withdrawal in the initial 6 months of therapy. This was considered important as pharmacogenetic variations in the pattern of RA in different populations and genetic differences in efficacy and safety to drugs demand separate studies to be conducted in different populations. Hospital records were used to identify 1,000 consecutive patients with RA fulfilling the American College of Rheumatology criteria and having at least 6-month follow-up. Age, gender, duration of arthritis, drug usage and ADR-related drug withdrawal were recorded from the charts. Most of the patients were put on single DMARD. Combined use of DMARD was less frequent and non-use of DMARD was common; however, disease control was good. The commonest DMARD used in our hospital was hydroxychloroquine 444 (44%) and the commonest combination used was methotrexate with hydroxychloroquine by 55 (6%). Sulphasalazine use showed preference to young and males. Supportive drugs used were NSAIDs by 883 (88%), corticosteroids by 646 (65%), paracetamol by 594 (59%) and amitriptyline by 88 (9%). Incidence of ADR-related DMARD withdrawal was maximum with leflunomide 2/15 (13.33%) followed by methotrexate 9/116 (7.76%), sulphasalazine 6/185 (3.24%), chloroquine 3/131 (2.29%) and hydroxychloroquine 8/444 (1.8%). Severity and symptomatology of disease, genetic pattern of patients, financial status, previous experience of the clinicians and patients, availability of drugs, patient expectations and compliance were the main factors that lead to a difference in pattern of therapy in our patients compared to other population.

Enantioselective metabolism of hydroxychloroquine employing rats and mice hepatic microsomes

Hydroxychloroquine (HCQ) is an important chiral drug used, mainly, in the treatment of rheumatoid arthritis, systemic lupus erythematosus and malaria, and whose pharmacokinetic and pharmacodynamic properties look to be stereoselective. Respecting the pharmacokinetic properties, some previous studies indicate that the stereoselectivity could express itself in the processes of metabolism, distribution and excretion and that the stereoselective metabolism looks to be a function of the studied species. So, the in vitro metabolism of HCQ was investigated using hepatic microsomes of rats and mice. The microsomal fraction of livers of Wistar rats and Balb-C mice was separated by ultracentrifugation and 500 μL were incubated for 180 minutes with 10 μL of racemic HCQ 1000 μg mL-1. Two stereospecific analytical methods, high performance liquid chromatography (HPLC) and capillary electrophoresis (CE), were used to separate and quantify the formed metabolites. It was verified that the main formed metabolite is the (-)-(R)-desethyl hydroxychloroquine for both animal species.

The effect of newer anti-rheumatic drugs on osteogenic cell proliferation: an in-vitro study

Background

Disease modifying anti-rheumatic drugs (DMARDs) may interfere with bone healing. Previous studies give conflicting advice regarding discontinuation of these drugs in the peri-operative setting. No consensus exists in current practice especially with the newer DMARDs such as Leflunomide, Etanercept, and Infliximab. The aim of this study was to assess the in-vitro effect of these drugs alone and in relevant clinical combinations on Osteoblast activity.

Methods

Osteoblasts were cultured from femoral heads obtained from five young otherwise healthy patients undergoing total hip replacement. The cells were cultured using techniques that have been previously described. A full factorial design was used to set up the experiment on samples obtained from the five donors. Normal therapeutic concentrations of the various DMARDs were added alone and in combination to the media. The cell proliferation was estimated after two weeks using spectrophotometric technique using Roche Cell proliferation Kit. Multilevel regression analysis was used to estimate which drugs or combination of drugs significantly affected cell proliferation.

Results

Infliximab and Leflunomide had an overall significant inhibitory effect (p < 0.05). Dexamethasone had a small stimulatory effect that was however strongly donor-dependent. The cox-2 inhibitor Etoricoxib was found to negate or increase the action of two other drugs (Leflunomide and Dexamethasone). Methotrexate and Etanercept had no discernable donor-dependant or donor-independent effect on osteoblast proliferation.

Conclusion

Our study indicates that in-vitro osteoblast proliferation can be inhibited by the presence of certain DMARDs. Combinations of drugs had an influence and could negate the action of a drug on osteoblast proliferation. The response to drugs may be donor-dependent.

Molecularly imprinted solid-phase extraction combined with electrochemical oxidation fluorimetry for the determination of methotrexate in human serum and urine

The method of synthesis and evaluation of molecularly imprinted polymers was reported. As a selective solid-phase extraction sorbent, the polymers were coupled with electrochemical fluorimetry detection for the efficient determination of methotrexate in serum and urine. Methotrexate was preconcentrated in the molecularly imprinted solid-phase extraction microcolumn packed with molecularly imprinted polymers, and then eluted. The eluate was detected by fluorescence spectrophotometer after electrochemical oxidation. The conditions of preconcentration, elution, electrochemical oxidation and determination were carefully studied. Under the selected experimental conditions, the calibration graph of the fluorescence intensity versus methotrexate concentration was linear from 4x10(-9) g mL(-1) to 5x10(-7) g mL(-1), and the detection limit was 8.2x10(-10) g mL(-1) (3sigma). The relative standard deviation was 3.92% (n=7) for 1x10(-7) g mL(-1) methotrexate. The experiments showed that the selectivity and sensitivity of fluorimetry could be greatly improved by the proposed method. This method has been successfully applied to the determination of methotrexate. At the same time, the binding characteristics of the polymers to the methotrexate were evaluated by batch and dynamic methods.

New concepts in antimalarial use and mode of action in dermatology

Although chloroquine, hydroxychloroquine and quinacrine were originally developed for the treatment of malaria, these medications have been used to treat skin disease for over 50 years. Recent clinical data have confirmed the usefulness of these medications for the treatment of lupus erythematosus. Current research has further enhanced our understanding of the pharmacologic mechanisms of action of these drugs involving inhibition of endosomal toll-like receptor (TLR) signaling limiting B cell and dendritic cell activation. With this understanding, the use of these medications in dermatology is broadening. This article highlights the different antimalarials used within dermatology through their pharmacologic properties and mechanism of action, as well as indicating their clinical uses. In addition, contraindications, adverse effects, and possible drug interactions of antimalarials are reviewed.

Genetic markers of treatment response in rheumatoid arthritis

Rheumatoid arthritis patients exhibit a considerable interindividual variability in response to drug treatment. Although many disease-related and demographic factors have been studied to predict treatment outcome, the effective disease-modifying antirheumatic drug (DMARD) therapy is not yet allocated based on factors that predict efficacy. Individual genetic characteristics are thought to play an important role in treatment response; therefore, current research aims to identify these genetic predictors for clinical response. Pharmacogenetic studies are beginning to provide results, which suggests that personalized treatment maximization of DMARD efficacy and minimization of adverse drug reactions are feasible.

Pharmacogenomics in the treatment of rheumatoid arthritis: clinical implication and perspective

Rheumatoid arthritis (RA) is a chronic inflammatory disease. The inflammatory process of the joint destroys articular architecture and causes a significant disability. The efficacy of disease modifying antirheumatic drugs such as methotrexate, sulfasalazine and biological response modifiers, is widely accepted. However, the outcome of the treatment with these agents is known to vary among patients. The application of the pharmacogenomics is expected to reduce toxicities and enhance the desirable effects of therapeutic agents for RA. Recently, pharmacogenomic studies on methotrexate, sulfasalazine and tumor necrosis factor-α inhibitors have been reported. These investigations suggest that the pharmacogenomic approach is useful for the treatment of RA, although there are points to be considered before the translation of the pharmacogenomic data into clinical practice. This review focuses on the latest information on the pharmacogenomics of antirheumatic drugs and its clinical implication in the treatment of RA.

Combination treatment strategies in early rheumatoid arthritis

Combinations of disease modifying antirheumatic drugs (DMARDs) are increasingly being used in patients with early rheumatoid arthritis (RA) when long term results with sequential DMARD monotherapy are disappointing. Combination DMARD therapy may be more effective than monotherapy, and has no additional short term adverse events. The evidence for using combination DMARD therapy is still weak, however, and further trials are needed.