Aspirin alters methotrexate disposition in rheumatoid arthritis patients

Methotrexate for inflammatory skin disease in pediatric patients: Consensus treatment guidelines

Methotrexate (MTX) is a readily accessible drug, first used in 1948 and employed for a wide variety of indications since then. However, despite widespread off-label use, FDA labeling does not include approved indications for the use of MTX for many inflammatory skin diseases in pediatric patients, including morphea, psoriasis, atopic dermatitis, and alopecia areata, among others. Without published treatment guidelines, some clinicians may be hesitant to use MTX off-label, or uncomfortable prescribing MTX in this population. To address this unmet need, an expert consensus committee was convened to develop evidence- and consensus-based guidelines for use of MTX to treat pediatric inflammatory skin disease. Clinicians with experience and expertise in clinical research, drug development, and treating inflammatory skin disease in pediatric patients with MTX were recruited. Five committees were created based on major topic areas: (1) indications and contraindications, (2) dosing, (3) interactions with immunizations and medications, (4) adverse effects (potential for and management of), and (5) monitoring needs. Pertinent questions were generated and addressed by the relevant committee. The entire group participated in a modified Delphi process to establish agreement on recommendations for each question. The committee developed 46 evidence- and consensus-based recommendations, each with >70% agreement among members, across all five topics. These are presented in tables and text, along with a discussion of supporting literature, and level of evidence. These evidence- and consensus-based recommendations will support safe and effective use of MTX for the underserved population of pediatric patients who may benefit from this valuable, time-honored medication.

Fatal low-dose methotrexate toxicity: A case report and literature review

Methotrexate (MTX) is a chemotherapeutic agent that acts primarily by inhibiting the folic acid cycle. In addition to its application for treating malignancies, MTX is also used to treat chronic inflammatory diseases including psoriasis. Adverse effects have been reported even at low doses (up to 25 mg/week), and there is risk of toxicity in the form of myelosuppression, hepatotoxicity, or pulmonary fibrosis. Here, we report a case of a 67-year-old male with a past medical history of end stage renal disease on peritoneal dialysis and moderate-to-severe psoriasis with psoriatic arthritis presented with abdominal pain, diarrhea, rash, mucositis, and mucocutaneous ulcers and erosions. The patient was taking methotrexate 10 mg weekly without folic acid supplementation and was found to be pancytopenic. Despite treatment, the patient developed multiorgan failure and passed away after 16 days of hospitalization. Myelosuppression is considered the most serious side effect with the highest risk of mortality. Risk factors for toxicity include renal insufficiency, advanced age, lack of folate supplementation, drug interactions, and medication errors. Importantly, serum levels of MTX do not correlate with toxicity; therefore, folinic acid rescue therapy should be started as soon as MTX toxicity is suspected. MTX toxicity is rare with low dose, proper dose scheduling, and adherence to the recommended guidelines. It is imperative that physicians considering therapy with low dose MTX for dermatologic indications take into consideration a patient's risk factors for toxicity and monitor appropriately.

Herb-Drug Interaction in Inflammatory Diseases: Review of Phytomedicine and Herbal Supplements

Many people worldwide use plant preparations for medicinal purposes. Even in industrialized regions, such as Europe, where conventional therapies are accessible for the majority of patients, there is a growing interest in and usage of phytomedicine. Plant preparations are not only used as alternative treatment, but also combined with conventional drugs. These combinations deserve careful contemplation, as the complex mixtures of bioactive substances in plants show a potential for interactions. Induction of CYP enzymes and pGP by St John's wort may be the most famous example, but there is much more to consider. In this review, we shed light on what is known about the interactions between botanicals and drugs, in order to make practitioners aware of potential drug-related problems. The main focus of the article is the treatment of inflammatory diseases, accompanied by plant preparations used in Europe. Several of the drugs we discuss here, as basal medication in chronic inflammatory diseases (e.g., methotrexate, janus kinase inhibitors), are also used as oral tumor therapeutics.

Development of PBPK model for intra-articular injection in human: methotrexate solution and rheumatoid arthritis case study

A physiologically based model describing the dissolution, diffusion, and transfer of drug from the intra-articular (IA) space to the plasma, was developed for GastroPlus® v9.8. The model is subdivided into compartments representing the synovial fluid, synovium, and cartilage. The synovium is broken up into two sublayers. The intimal layer acts as a diffusion barrier between the synovial fluid and the subintimal layer. The subintimal layer of the synovium has fenestrated capillaries that allow the free drug to be transported into systemic circulation. The articular cartilage is broken up into 10 diffusion sublayers as it is much thicker than the synovium. The cartilage acts as a depot tissue for the drug to diffuse into from synovial fluid. At later times, the drug will diffuse from the cartilage back into synovial fluid once a portion of the dose enters systemic circulation. In this study, a listing of all relevant details and equations for the model is presented. Methotrexate was chosen as a case study to show the application and utility of the model, based on the availability of intravenous (IV), oral (PO) and IA administration data in patients presenting rheumatoid arthritis (RA) symptoms. Systemic disposition of methotrexate in RA patients was described by compartmental pharmacokinetic (PK) model with PK parameters extracted using the PKPlus™ module in GastroPlus®. The systemic PK parameters were validated by simulating PO administration of methotrexate before being used for simulation of IA administration. For methotrexate, the concentrations of drug in the synovial fluid and plasma were well described after adjustments of physiological parameters to account for RA disease state, and with certain assumptions about binding and diffusion. The results indicate that the model can correctly describe PK profiles resulting from administration in the IA space, however, additional cases studies will be required to evaluate ability of the model to scale between species and/or doses.

[18F] Clofarabine for PET Imaging of Hepatocellular Carcinoma

Clinical diagnosis of hepatocellular carcinoma (HCC) relies heavily on radiological imaging. However, information pertaining to liver cancer treatment such as the proliferation status is lacking. Imaging tumor proliferation can be valuable in patient management. This study investigated ¹⁸F-labeled clofarabine ([¹⁸F]CFA) targeting deoxycytidine kinase (dCK) for PET imaging of dCK-dependent proliferation in HCC. Since clinical PET scans showed a high liver background uptake of [¹⁸F]CFA, the aim of this study was to reduce this liver background uptake. A clinically relevant animal model of spontaneously developed HCC in the woodchucks was used for imaging experiments. Several modifiers were tested and compared with the baseline PET scan: Forodesine, probenecid, and cold clofarabine, all applied before the hot [¹⁸F]CFA injection to evaluate the reduction in liver background uptake. Application of forodesine before hot [¹⁸F]CFA injection did not reduce the background uptake. Instead, it increased the background by 11.6–36.3%. Application of probenecid also increased the liver background uptake by 16.6–32.1%. Cold CFA application did reduce the liver background uptake of [¹⁸F]CFA, comparing to the baseline scan. Combining cold CFA with [¹⁸F]CFA for PET imaging of liver cancers is a promising strategy, worthy of further clinical evaluation.

Transporter-Mediated Drug-Drug Interactions and Their Significance

Drug transporters are considered to be determinants of drug disposition and effects/toxicities by affecting the absorption, distribution, and excretion of drugs. Drug transporters are generally divided into solute carrier (SLC) family and ATP binding cassette (ABC) family. Widely studied ABC family transporters include P-glycoprotein (P-GP), breast cancer resistance protein (BCRP), and multidrug resistance proteins (MRPs). SLC family transporters related to drug transport mainly include organic anion-transporting polypeptides (OATPs), organic anion transporters (OATs), organic cation transporters (OCTs), organic cation/carnitine transporters (OCTNs), peptide transporters (PEPTs), and multidrug/toxin extrusions (MATEs). These transporters are often expressed in tissues related to drug disposition, such as the small intestine, liver, and kidney, implicating intestinal absorption of drugs, uptake of drugs into hepatocytes, and renal/bile excretion of drugs. Most of therapeutic drugs are their substrates or inhibitors. When they are comedicated, serious drug-drug interactions (DDIs) may occur due to alterations in intestinal absorption, hepatic uptake, or renal/bile secretion of drugs, leading to enhancement of their activities or toxicities or therapeutic failure. This chapter will illustrate transporter-mediated DDIs (including food drug interaction) in human and their clinical significances.

Significant Drug–Drug Interactions with Antineoplastics

Goal

The goal of this program is to inform the participant about the clinical and economic significance of drug interactions, review their potential mechanisms, present significant interactions related to antineoplastics, and provide resources for managing them.

Objectives

At the completion of this program, the participant will be able to: 1. Describe the scope and economic impact of preventable drug interactions. 2. Explain why oncology patients are at increased risk for drug interactions. 3. Define the pharmacokinetic, pharmacodynamic, and pharmaceutic principles underlying antineoplastic related drug–drug interactions. 4. List specific classes of antineoplastics involved in significant drug–drug interactions. 5. Identify multiple resources for obtaining drug interaction information.

Interaction Between Low-Dose Methotrexate and Nonsteroidal Anti-inflammatory Drugs, Penicillins, and Proton Pump Inhibitors

Objective: To review the potential drug interactions between low-dose methotrexate (LD-MTX) and nonsteroidal anti-inflammatory drugs (NSAIDs), penicillins, and proton-pump inhibitors (PPIs) given the disparity between interactions reported for high-dose and low-dose MTX to help guide clinicians. Data Sources: A literature search was performed in MEDLINE (1946 to September 2016), EMBASE (1974 to September 2016), and International Pharmaceutical Abstracts (1970 to January 2015) to identify reports describing potential drug interactions between LD-MTX and NSAIDS, penicillins, or PPIs. Reference lists of included articles were reviewed to find additional eligible articles. Study Selection and Data Extraction: All English-language observational, randomized, and pharmacokinetic (PK) studies assessing LD-MTX interactions in humans were analyzed to determine clinical relevance in making recommendations to clinicians. Clinical case reports were assigned a Drug Interaction Probability Scale score. Data Synthesis: A total of 32 articles were included (28 with NSAIDs, 3 with penicillins, and 2 with PPIs [1 including both PPI and NSAID]). Although there are some PK data to describe increased LD-MTX concentrations when NSAIDs are used concomitantly, the clinical relevance remains unclear. Based on the limited data on LD-MTX with penicillins and PPIs, no clinically meaningful interaction was identified. Conclusion: Given the available evidence, the clinical importance of the interaction between LD-MTX and NSAIDs, penicillins, and PPIs cannot be substantiated. Health care providers should assess the benefit and risk of LD-MTX regardless of concomitant drug use, including factors known to predispose patients to MTX toxicity, and continue to monitor clinical and laboratory parameters per guideline recommendations.

Effect of ceftriaxone and cefepime on high-dose methotrexate clearance

Numerous drug interactions with methotrexate have been identified, which can lead to serious life-threatening effects. Up to 90% of methotrexate is excreted unchanged in the urine with primary excretion dependent on organic anion transport in the renal proximal tubule. The two pathways responsible for methotrexate secretion are organic anion transport 1 and primarily organic anion transport 3. Penicillins undergo tubular secretion via organic anion transport, and cephalosporins are believed to also possess a similar risk when administered with methotrexate; however, there are no human studies observing this interaction with cephalosporins and methotrexate. Ceftriaxone undergoes biliary clearance and has low affinity for the same organic anion transports as methotrexate; therefore, ceftriaxone has a low potential to interact with methotrexate. Cefepime is primarily secreted by organic cation transport N2, and also has a low potential to interact with methotrexate. This case report describes the pharmacokinetic effect of concomitant beta-lactam therapy in a patient receiving high-dose methotrexate.

Medication overuse and chronic migraine: a critical review according to clinical pharmacology

INTRODUCTION

Chronic migraine is often complicated by medication-overuse headache (MOH), a headache due to excessive intake of acute medications. Chronic migraine and MOH are serious and disabling disorders. Since chronic migraine derives from the progression of originally episodic migraine, the fundamental therapeutic strategy is prevention. This narrative review describes how to try to prevent the development of MOH and how to manage it once it has appeared.

AREAS COVERED

A PubMed database search (from 1988 to January 2015) and a review of published studies on chronic migraine and MOH were conducted.

EXPERT OPINION

In spite of progress in migraine treatment, the prevalence of chronic headaches and MOH has not changed in the course of time. Today, a large number of migraine patients have turned to numerous expert physicians and experienced all sorts of prophylactic treatments without decisive benefits. Their condition seems to have crystallized even more as chronic and intractable. This means that to prevent chronification and MOH, we need more effective drugs and better strategies to use them. In particular, we must detect disease biomarkers and predictive factors for drug response that allow for personalized treatment when migraine is still episodic and make analgesic overuse pointless.

Aspirin antagonizes the cytotoxic effect of methotrexate in lung cancer cells

Methotrexate (MTX) has been widely used for the treatment of cancer and rheumatoid arthritis (RA). Aspirin (ASA) is a non-selective cyclooxygenase (COX) inhibitor that contributes to the treatment of inflammatory conditions such as RA. It has been observed that the antitumor effect of ASA can be attributed to inhibition of cell cycle progression, induction of apoptosis and inhibition of angiogenesis. In the present study, we revealed that the treatment with a combination of MTX and ASA resulted in antagonism of the cytotoxic effect as demonstrated by SRB and colony formation assays. ASA alleviated the MTX-mediated S phase accumulation and recovered the G1 phase. MTX-mediated accumulation of the S phase marker cyclin A was also alleviated by ASA. Notably, FAS protein levels were upregulated by MTX in A549 cells. The antagonism of MTX efficacy caused by ASA was accompanied by altered expression of caspase-3, Bcl-2 and FAS but not dihydrofolate reductase (DHFR). This suggests that the alteration of caspase-3, Bcl-2 and FAS was involved in the antagonism between ASA and MTX. Exogenously added folic acid reversed the MTX-mediated DHFR inhibition following either MTX or MTX + ASA treatments. Most importantly, we demonstrated for the first time that the commonly used non-steroidal anti-inflammatory drug for headache ASA and possibly other COX-1/2 inhibitors can produce a strong antagonistic effect on the growth inhibition of lung cancer cells when administered in combination with MTX. The clinical implication of our finding is obvious, i.e., the clinical efficacy of MTX therapy can be compromised by ASA and their concomitant use should be avoided.

Coadministration of Lansoprazole and Naproxen Does Not Affect the Pharmacokinetic Profile of Methotrexate in Adult Patients With Rheumatoid Arthritis

Drugs prescribed for rheumatoid arthritis are often associated with gastrointestinal toxicity, and proton pump inhibitors may be coadministered for gastroprotection. In this open-label study, the effect of lansoprazole 30 mg qd and naproxen 500 mg bid on the pharmacokinetic profile of methotrexate was investigated. Twenty-seven adult rheumatoid arthritis patients on stable oral methotrexate doses (7.5-15 mg/week) for a minimum of 3 months were enrolled. Methotrexate pharmacokinetics were assessed on days -1 (methotrexate alone) and 7 (methotrexate with lansoprazole and naproxen). Pharmacokinetics of methotrexate and 7-hydroxymethotrexate were not altered by coadministration of methotrexate with lansoprazole and naproxen; point estimates and 90% confidence intervals for the peak plasma concentration and area under the plasma concentration-time curve of methotrexate and 7-hydroxymethotrexate were within the 0.80 to 1.25 boundaries. Therefore, coadministration of naproxen and lansoprazole for 7 days does not affect the pharmacokinetic profile of low doses of methotrexate.

Effect of ketoprofen and indomethacin on methotrexate pharmacokinetics in mice plasma and tumor tissues

Methotrexate (MTX) has been used in combination with nonsteroidal anti-inflammatory drugs in the treatment of inflammatory diseases as well as malignancies. Severe adverse effects with this combination may occur, usually resulting from inhibition of renal transporters. Solid Ehrlich carcinoma was experimentally induced by implantation of Ehrlich ascites Carcinoma cells subcutaneously into the thigh of mice, and after 30 days, mice were divided into three groups: Group I that served as control group received MTX (50 mg/kg, i.p.); Group II received ketoprofen (100 mg/kg, i.p.) and then after half an hour received MTX (50 mg/kg, i.p.); Group III received indomethacin (10 mg/kg, i.p.) and then after half an hour received MTX (50 mg/kg, i.p.). Plasma and tissue samples were collected at different time points and then MTX concentrations were determined by HPLC. The injection of ketoprofen or indomethacin before MTX injection resulted in significant increase in the AUC and CPmax of MTX (p < 0.05) and significant decrease in CL/F and Vd/F of MTX (p < 0.05) in mice plasma. The effects were more significant after injection of indomethacin than in case of ketoprofen. The study showed that administration of ketoprofen or indomethacin prior to MTX caused significant decrease in MTX elimination and significant increase in MTX extent of absorption which may lead to severe adverse effects if coadministered in human.

Safety of non-steroidal anti-inflammatory drugs, including aspirin and paracetamol (acetaminophen) in people receiving methotrexate for inflammatory arthritis (rheumatoid arthritis, ankylosing spondylitis, psoriatic arthritis, other spondyloarthritis)

BACKGROUND

Methotrexate is routinely used in the treatment of inflammatory arthritis. There have been concerns regarding the safety of using concurrent non-steroidal anti-inflammatory drugs (NSAIDs), including aspirin, or paracetamol (acetaminophen), or both, in these people.

OBJECTIVES

To systematically appraise and summarise the scientific evidence on the safety of using NSAIDs, including aspirin, or paracetamol, or both, with methotrexate in inflammatory arthritis; and to identify gaps in the current evidence, assess the implications of those gaps and to make recommendations for future research to address these deficiencies.

SEARCH METHODS

We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, second quarter 2010); MEDLINE (from 1950); EMBASE (from 1980); the Cochrane Database of Systematic Reviews (CDSR) and the Database of Abstracts of Reviews of Effects (DARE). We also handsearched the conference proceedings for the American College of Rheumatology (ACR) and European League against Rheumatism (EULAR) (2008 to 2009) and checked the websites of regulatory agencies for reported adverse events, labels and warnings.

SELECTION CRITERIA

Randomised controlled trials and non-randomised studies comparing the safety of methotrexate alone to methotrexate with concurrent NSAIDs, including aspirin, or paracetamol, or both, in people with inflammatory arthritis.

DATA COLLECTION AND ANALYSIS

Two authors independently assessed the search results, extracted data and assessed the risk of bias of the included studies.

MAIN RESULTS

Seventeen publications out of 8681 identified studies were included in the review, all of which included people with rheumatoid arthritis using various NSAIDs, including aspirin. There were no identified studies for other forms of inflammatory arthritis.For NSAIDs, 13 studies were included that used concurrent NSAIDs, of which nine studies examined unspecified NSAIDs. The mean number of participants was 150.4 (range 19 to 315), mean duration 2182.9 (range 183 to 5490) days, although the study duration was not always clearly defined, and the studies were mainly of low to moderate quality. Two of these studies reported no evidence for increased risk of methotrexate-induced pulmonary disease; one study assessed the effect of concurrent NSAIDs on renal function and found no adverse effect; one study identified no adverse effect on liver function; three studies demonstrated no increase in methotrexate withdrawal; and one study showed no increase in all adverse events, including major toxic reactions. However, transient thrombocytopenia was demonstrated in one study, specifically when NSAIDs were taken on the same week day as methotrexate. This study was a retrospective review that involved small numbers only and was of moderate quality; these finding have not been replicated since.Four studies looked at specific NSAIDs (etodolac, piroxicam, celecoxib and etoricoxib), with a mean number of participants of 25.8 (range 14 to 50) and mean study duration of 16.8 (range 14 to 23) days. These studies were mainly of moderate quality. The studies were primarily pharmacokinetic studies but also reported adverse events as secondary outcomes. There were no clinically significant adverse effects with concomitant piroxicam or etodolac; and only mild adverse events with celecoxib or etoricoxib, such as nausea and vomiting, and headaches.For aspirin, seven studies provided data on adverse events with the use of aspirin and methotrexate. These studies included a mean number of participants of 100 (range 11 to 232), had a mean duration of 1325 (range 8 to 2928) days and were mainly of low to moderate quality. Two of the studies reported no evidence for increased risk of methotrexate-induced pulmonary disease and two studies showed no increase in all adverse events including major toxic reactions; however, none of these studies specified the dose of aspirin that was used. One study demonstrated that concurrent aspirin adversely affected liver function at a mean dose of 6.84 tablets of aspirin per day, which is a possible daily dose of 2.1 g presuming that 300 mg aspirin tablets were given. A further study described a partially reversible decline in renal function with 2 g daily of aspirin. One study reported no increase in adverse events with 975 g aspirin daily, however the study duration was only one week.For paracetamol, no studies were identified for inclusion.

AUTHORS' CONCLUSIONS

In the management of rheumatoid arthritis, the concurrent use of NSAIDs with methotrexate appears to be safe provided appropriate monitoring is performed. The use of anti-inflammatory doses of aspirin should be avoided.

Fostamatinib, a Syk-kinase inhibitor, does not affect methotrexate pharmacokinetics in patients with rheumatoid arthritis

Fostamatinib (R788) is being investigated as an add-on therapy for the treatment of rheumatoid arthritis (RA) in patients with inadequate response to methotrexate (MTX). This study evaluated the potential pharmacokinetic interaction between R788 and MTX. Sixteen RA subjects on a stable weekly MTX regimen were enrolled and received MTX on days 1 and 8. Twelve subjects received 100 mg of R788 orally, and 4 subjects received a matching placebo twice daily from days 4 to 8 and once daily on days 3 and 9. Blood samples were collected on days 1 and 8 for MTX and 7-hydroxymethotrexate (7-OH-MTX), and days 3 and 9 for R788 and its active metabolite, R406. MTX and 7-OH-MTX pharmacokinetic parameters were similar on days 1 and 8. In the R788 group, the mean day 8 to day 1 ratios (90% confidence intervals) of maximum concentration and area under the plasma concentration-time curve estimates were 1.01 (0.85-1.20) and 1.12 (0.90-1.40) for MTX and 1.06 (0.82-1.35) and 1.06 (0.83-1.36) for 7-OH-MTX, respectively. Urinary excretion of MTX and 7-OH-MTX was also similar with or without R788, averaging 58% to 69% and 4% to 5% of the MTX dose, respectively. The data suggest that there is no clinically significant pharmacokinetic interaction of R788 and MTX in RA patients.

Canadian recommendations for use of methotrexate in patients with rheumatoid arthritis

OBJECTIVE

To develop recommendations for the use of methotrexate (MTX) in patients with rheumatoid arthritis.

METHODS

Canadian rheumatologists who participated in the international 3e Initiative in Rheumatology (evidence, expertise, exchange) in 2007-2008 formulated 5 unique Canadian questions. A bibliographic team systematically reviewed the relevant literature on these 5 topics. An expert committee consisting of 26 rheumatologists from across Canada was convened, and a set of recommendations was proposed based on the results of systematic reviews combined with expert opinions using a nominal group consensus process.

RESULTS

The 5 questions addressed drug interactions, predictors of response, strategies to reduce non-serious side effects, variables to assess clinical response, and incorporating patient preference into decision-making. The systematic review retrieved 93 pertinent articles; this evidence was presented to the expert committee during the interactive workshop. After extensive discussion and voting, a total of 9 recommendations were formulated: 2 on drug interactions, 1 on predictors of response, 2 on strategies to reduce non-serious side effects, 3 on variables to assess clinical response, and 1 on incorporating patient preferences into decision-making. The level of evidence and the strength of recommendations are reported. Agreement among panelists ranged from 85% to 100%.

CONCLUSION

Nine recommendations pertaining to the use of MTX in daily practice were developed using an evidence-based approach followed by expert/physician consensus with high level of agreement.

Methotrexate drug interactions in the treatment of rheumatoid arthritis: a systematic review

OBJECTIVE

Patients with rheumatoid arthritis (RA) often have comorbidities that require multiple medications. Several of these medications may alter the efficacy or increase the toxicity of methotrexate (MTX). The purpose of our study was to determine which drugs used in combination with MTX (excluding disease modifying antirheumatic drugs, folic and folinic acid, corticosteroids, and biologic agents) enhance side effects or toxicity of MTX or lower its efficacy.

METHODS

A systematic literature search was performed with Medline, Embase, Cochrane Register and Database, and abstracts from the 2006/2007 annual congresses of the American College of Rheumatology and the European League Against Rheumatism. A manual search of the citation lists of retrieved publications was performed.

RESULTS

Of the 1172 articles identified, 67 were included: 21 pharmacokinetics studies, 5 observational studies, and 78 case reports. Most medications do not significantly affect the pharmacokinetics profile of MTX. Among the clinical studies, cytopenia and elevation of liver enzymes were the main reported toxicities. The use of trimethoprim-sulfamethoxazole (TMP-SMX) was mentioned as a risk factor for developing cytopenia in one observational study and in 17 case reports. Thirty case reports of cytopenia were attributed to the use of concomitant nonsteroidal antiinflammatory drugs, including acetylsalicylic acid. Two studies described mild abnormalities of liver enzymes with the use of isoniazid, and one study with the use of high-dose ASA.

CONCLUSION

Based on the published literature, MTX has limited drug interactions, with the exception of TMP-SMX and high-dose ASA, which can exacerbate toxicity of MTX. The clinical significance of these interactions has not been substantiated by extensive clinical observations.

Pharmacokinetics and interactions of headache medications, part I: introduction, pharmacokinetics, metabolism and acute treatments

Recent progress in the treatment of primary headaches has made available specific, effective and safe medications for these disorders, which are widely spread among the general population. One of the negative consequences of this undoubtedly positive progress is the risk of drug-drug interactions. This review is the first in a two-part series on pharmacokinetic drug-drug interactions of headache medications. Part I addresses acute treatments. Part II focuses on prophylactic treatments. The overall aim of this series is to increase the awareness of physicians, either primary care providers or specialists, regarding this topic. Pharmacokinetic drug-drug interactions of major severity involving acute medications are a minority among those reported in literature. The main drug combinations to avoid are: i) NSAIDs plus drugs with a narrow therapeutic range (i.e., digoxin, methotrexate, etc.); ii) sumatriptan, rizatriptan or zolmitriptan plus monoamine oxidase inhibitors; iii) substrates and inhibitors of CYP2D6 (i.e., chlorpromazine, metoclopramide, etc.) and -3A4 (i.e., ergot derivatives, eletriptan, etc.), as well as other substrates or inhibitors of the same CYP isoenzymes. The risk of having clinically significant pharmacokinetic drug-drug interactions seems to be limited in patients with low frequency headaches, but could be higher in chronic headache sufferers with medication overuse.

Measuring Process of Arthritis Care: The Arthritis Foundation’s Quality Indicator Set for Rheumatoid Arthritis

OBJECTIVE

To describe the scientific evidence that supports each of the explicit process measures in the Arthritis Foundation's Quality Indicator Set for Rheumatoid Arthritis.

METHODS

For each of the 27 measures in the Arthritis Foundation's Quality Indicator set, a comprehensive literature review was performed for evidence that linked the process of care defined in the indicator with relevant clinical outcomes and to summarize practice guidelines relevant to the indicators.

RESULTS

Over 7500 titles were identified and reviewed. For each of the indicators the scientific evidence to support or refute the quality indicator was summarized. We found direct evidence that supported a process-outcome link for 15 of the indicators, an indirect link for 7 of the indicators, and no evidence to support or refute a link for 5. The processes of care described in the indicators for which no supporting/refuting data were found have been assumed to be so essential to care that clinical trails assessing their importance have not, and probably never will be, performed. The process of care described in all but 2 of the indicators is recommended in 1 or more practice guidelines.

CONCLUSION

There are sufficient scientific evidence and expert consensus to support the Arthritis Foundation's Quality Indicator Set for Rheumatoid Arthritis, which defines a minimal standard of care that can be used to assess health care quality for patients with rheumatoid arthritis.

Two Drug Interaction Studies Evaluating the Pharmacokinetics and Toxicity of Pemetrexed When Coadministered with Aspirin or Ibuprofen in Patients with Advanced Cancer

PURPOSE

Pemetrexed is an antimetabolite that is structurally similar to methotrexate. Because nonsteroidal anti-inflammatory drugs (NSAID) impair methotrexate clearance and increase its toxicity, we evaluated the pharmacokinetics and toxicity of pemetrexed when coadministered with aspirin or ibuprofen in advanced cancer patients.

EXPERIMENTAL DESIGN

In two independent, randomized, crossover drug interaction studies, cancer patients with a creatinine clearance (CrCl) > or =60 mL/min received an NSAID (aspirin or ibuprofen) with either the first or the second dose of pemetrexed (cycle 1 or 2). Pemetrexed (500 mg/m(2)) was infused i.v. on day 1 of a 21-day cycle, and all patients were supplemented with oral folic acid and i.m. vitamin B(12). Aspirin (325 mg) or ibuprofen (400 mg; 2 x 200 mg) was given orally every 6 hours, starting 2 days before pemetrexed administration, with the ninth and final dose taken 1 hour before infusion. Pemetrexed pharmacokinetics with and without concomitant NSAID treatment were compared for cycles 1 and 2.

RESULTS

Data from 27 patients in each study were evaluable for the analysis of pemetrexed pharmacokinetics. Coadministration of aspirin did not alter pemetrexed pharmacokinetics; however, ibuprofen coadministration was associated with a 16% reduction in clearance, a 15% increase in maximum plasma concentration, and a 20% increase in area under the plasma concentration versus time curve but no significant change in V(ss) compared with pemetrexed alone. No febrile neutropenia occurred in any patient, and no increase in pemetrexed-related toxicity was associated with NSAID administration.

CONCLUSIONS

Pemetrexed (500 mg/m(2)) with vitamin supplementation is well tolerated and requires no dosage adjustment when coadministered with aspirin (in patients with CrCl > or =60 mL/min) or ibuprofen (in patients with CrCl > or =80 mL/min).

Risk:benefit ratio of nonsteroidal anti-inflammatory drugs in systemic lupus erythematosus

Nearly 80% of patients with systemic lupus erythematosus (SLE) are treated with NSAIDs for fever, arthritis, serositis and headaches. This article reviews currently available literature on non-selective and selective inhibitors of cyclooxygenases, with an emphasis on the efficacy and safety profile reported in SLE patients. All NSAIDs, regardless of their cyclooxygenase selectivity, induced renal side effects including sodium retention and reduction in glomerular filtration rate. In addition, lupus nephritis is a risk factor for NSAID-induced acute renal failure. NSAID-induced hepatotoxicity is increased in SLE patients in addition to cutaneous and allergic reactions. Finally, aseptic meningitis has been reported more frequently in NSAID-treated SLE patients. Nevertheless, NSAIDs can safely be prescribed to most lupus patients provided that their administration is re-evaluated on a regular basis and the patient is closely monitored.

Significant Drug–Drug Interactions with Antineoplastics

Goal

The goal of this program is to inform the participant about the clinical and economic significance of drug interactions, review their potential mechanisms, present significant interactions related to antineoplastics, and provide resources for managing them.

Objectives

At the completion of this program, the participant will be able to: 1. Describe the scope and economic impact of preventable drug interactions. 2. Explain why oncology patients are at increased risk for drug interactions. 3. Define the pharmacokinetic, pharmacodynamic, and pharmaceutic principles underlying antineoplastic related drug–drug interactions. 4. List specific classes of antineoplastics involved in significant drug–drug interactions. 5. Identify multiple resources for obtaining drug interaction information.

The population pharmacokinetics of long-term methotrexate in rheumatoid arthritis

AIMS

Methotrexate is considered by many practitioners to be the agent of choice in the treatment of rheumatoid arthritis. The pharmacokinetics of methotrexate have been reported to exhibit significant intersubject variability. Therefore, this study was undertaken to evaluate the population pharmacokinetics of methotrexate during long-term administration in adults with rheumatoid arthritis.

METHODS

Methotrexate pharmacokinetics were evaluated in a 36 month study of 62 adults with rheumatoid arthritis. Patients received oral or intramuscular doses of methotrexate weekly with pharmacokinetic studies performed every 6 months. Data were analyzed with nonlinear mixed effects modeling.

RESULTS

Three thousand two hundred and sixty post oral or intramuscular dose serum methotrexate concentrations comprising 425 individual concentration vs time profiles were modeled using NONMEM. Covariates that significantly (P < 0.005) influenced the disposition of methotrexate were age (AGE, years), body weight (BW, kg), creatinine clearance (CL(CR), 1 h(-1)), gender (GEN; 0 = male, 1 = female), dose (DOSE, micromol), and fed vs fasted state (FED; 0 = fasted, 1 = fed). The final model describing the biexponential disposition of methotrexate was clearance(CL, 1 h(-1)) = (0.0810*BW + 0.257*CL(CR))*(1-(0.167*GEN); central volume (Vc, 1) = 0.311*BW; peripheral volume (Vp, 1) = 0.469*BW-0.169*AGE; intercompartmental clearance (Q, 1 h(-1)) = 4.27*(1-0.355*GEN); oral absorption rate constant (ka(p.o.), h(-1)) = 4.70-0.0439*DOSE*(1-0.507*FED); intramuscular absorption rate constant (ka(i.m.), h(-1)) = 0.122*DOSE; relative bioavailability (F) = 93.4%; and oral absorption lag time (LAG(p.o.), min) = 13.5. Pharmacokinetic parameters (%CV) for a typical fasted male subject in this study were CL, 7.341 h(-1) (27%); Vc, 23.51 (28%); Vp, 25.31 (31%); Q, 4.25 1 h(-1) (41%); ka(p.o.), 3.67 h(-1) (77%); and ka(i.m.), 3.09 h(-1) (44%).

CONCLUSIONS

The population pharmacokinetics of methotrexate in adults with rheumatoid arthritis were well described by this investigation. Substantial interpatient variability was explained by incorporating patient specific data into regression equations predicting pharmacokinetic parameters.

Thrombocytopenia after a single test dose of methotrexate

Low dose methotrexate (MTX) can cause numerous gastrointestinal, pulmonary, central nervous system, and hematologic toxicities. Risk factors include folate deficiency, decreased renal function, older age, increased mean corpuscular volume or concomitant use of trimethoprim-sulphamethoxazole, probenecid, or nonsteroidal antiinflammatory drugs (NSAIDs). We describe a case of isolated thrombocytopenia after a single oral dose of MTX in a 36-year-old woman with sarcoidosis. She had rheumatoid arthritis and her only other medications included NSAIDs. One week after her first oral dose of 7.5 mg MTX, diffuse petechiae developed on her chest, abdomen, and extremities; she had a platelet count of 25,000/mm3. Nine days after discontinuation of both MTX and the NSAID, her platelet count increased to 189,000/mm3.

Pharmacology and pharmacokinetics of methotrexate in rheumatic disease. Practical issues in treatment and design

Methotrexate (MTX) is among the most effective drugs for treatment of rheumatoid arthritis and has been proven valuable in the treatment of multiple other disorders of immune regulation. MTX has been administered at a wide range of doses and dose intervals, in conjunction with multiple other drugs, and in patients with a broad range of concomitant disorders. To design a safe and effective MTX treatment plan for an individual patient, the provider must have knowledge of the pharmacology and drug interactions of this effective but potentially dangerous medication. The first section of the article reviews MTX structure, pharmacology pharmacokinetics, and mechanisms of action in rheumatic disease. The second section examines factors that can be used to increase MTX efficacy and decrease toxicity.

Determination of methotrexate and its main metabolite 7-hydroxymethotrexate in human urine by high-performance liquid chromatography with normal solid-phase extraction

A practical and sensitive high-performance liquid chromatographic method using normal solid-phase extraction has been developed for the determination of methotrexate (MTX) and its main metabolite 7-hydroxymethotrexate (7-OH-MTX) in human urine. A urine specimen followed by the addition of pH 5.0 acetate buffer was purified by solid-phase extraction on a Sep-Pak silica cartridge. The analyte was chromatographed on a reversed-phase Inertsil ODS-2 column using phosphate buffer-acetonitrile at pH 5.3 as the mobile phase, and the effluent from the column was monitored at 303 nm. A good linear relationship between peak height and concentration was found for both of MTX and 7-OH-MTX in the range 5 to 1000 ng/ml of human urine. The inter-day coefficients of variation for the assay (n = 5) were 8.8% (5 ng/ml), 3.4% (50 ng/ml) and 2.0% (500 ng/ml) for MTX, and 7.2, 2.7 and 2.3% for 7-OH-MTX in urine, respectively. The present method should prove useful for the evaluation of urinary drug excretion in patients undergoing MTX low-dose therapy.

Total and free methotrexate pharmacokinetics in rheumatoid arthritis patients

The pharmacokinetics of total and free methotrexate (MTX) were investigated in 50 patients with rheumatoid arthritis. Each patient received 10 mg MTX intramuscularly. The free and total plasma concentrations of MTX were measured over a 36-h period after drug administration by using the Abbott TDx fluorescence polarization immunoassay. Plasma concentrations of MTX were described by a biexponential function. The mean terminal elimination half-lives of total and free MTX were 9.4 and 8.4 h, respectively, and the corresponding mean residence times, 8.5 and 9.2 h. No difference in these parameters was found by comparing total and free MTX. Total plasma clearance of the free fraction averaged 215 ml/min. The statistical comparison of the variations with time of the ratio of free to total MTX during the 36 h after the dose showed that the free fraction was significantly increased for 8 h after drug administration (p < 0.001). To describe these variations, the changes of the free MTX concentrations (unbound) were related to the changes of the total MTX concentrations by using the Hill equation. Mean plasma protein binding ranged from 20 to 57% for these patients.

Simultaneous quantitation of methotrexate and its two main metabolites in biological fluids by a novel solid-phase extraction procedure using high-performance liquid chromatography

We have developed an assay for the simultaneous determination of methotrexate (MTX) and its main metabolites, 7-hydroxymethotrexate (7-OHMTX) and 2,4-diamino-N10-methylpteroic acid (DAMPA) in plasma, urine and saliva meeting the requirement of rapidity for routine use in high-dose MTX therapy and the requirement of sensitivity for its potential use in therapeutic drug monitoring in low-dose MTX therapy. Sample preparation is based on solid-phase extraction using C8 Isolute cartridges. Chromatographic separation was achieved with a reversed-phase column (C18), and quantitation by subsequent exposure to UV light of 254 nm, which converted MTX and its two metabolites by photolytic oxidation to fluorescent products. The recoveries of MTX, 7-OHMTX and DAMPA from plasma at 100 nmol/l were 85.8, 91.1 and 102.3%, respectively. The limits of detection for MTX, 7-OHMTX and DAMPA in plasma and saliva were 0.1 nmol/l. In urine the limit of detection was 10 nmol/l for all compounds. The limits of quantitation in plasma and saliva were 0.5 nmol/l for all compounds.

Chloroquine reduces the bioavailability of methotrexate in patients with rheumatoid arthritis. A possible mechanism of reduced hepatotoxicity

OBJECTIVE

To evaluate the effects of a single dose of chloroquine (CQ) on the pharmacokinetics of methotrexate (MTX) in patients with rheumatoid arthritis.

METHODS

Eleven patients (ages 41-75 years) who were taking oral doses of MTX (15 mg/week) were studied after a dose of MTX alone and after a dose of MTX plus CQ (250 mg). Plasma and urine samples were collected for 24 hours after dose intake, and the concentrations of MTX and its major metabolite 7-hydroxymethotrexate were determined by high-performance liquid chromatography.

RESULTS

Administration of CQ together with MTX caused a reduction in the area under the plasma MTX concentration versus time curve (AUC). The median value of individual AUC ratios (MTX/MTX + CQ) was 1.6 (95% confidence interval 1.2-3.6).

CONCLUSION

The most likely mechanism for the interaction is that CQ reduces the bioavailability of MTX. This gives a possible explanation for a suggested reduction in MTX-associated liver toxicity by coadministration of CQ. The significance of the interaction for the therapeutic effect remains to be elucidated.

Methotrexate disposition following concomitant administration of ketoprofen, piroxicam and flurbiprofen in patients with rheumatoid arthritis

The effects of three non-steroidal anti-inflammatory drugs (NSAIDs) on the pharmacokinetics of methotrexate were studied in 10 patients with rheumatoid arthritis. Ketoprofen (3 mg kg-1 day-1), flurbiprofen (3 mg kg-1 day-1), piroxicam (20 mg day-1), or a non-NSAID control (paracetamol/acetaminophen) were administered to patients for at least 6 days (13 days in the case of piroxicam to establish steady state) in a randomized crossover design prior to receiving a weekly oral dose of methotrexate. In the non-NSAID control portion of the study, MTX oral clearance (CLo) was 11.0 +/- 3.9 l h-1, renal clearance (CLR) was 7.9 +/- 2.8 l h-1, percent excreted unchanged was 72 +2- 19% and fraction unbound (fu) was 0.54 +/- 0.11. Values of oral clearance, renal clearance, fraction unbound and percentage excreted unchanged of methotrexate varied no more than 12.2% from non-NSAID control during concomitant administration of ketoprofen, flurbiprofen or piroxicam and were not statistically different from non-NSAID control. In contrast to other NSAIDs such as ibuprofen and salicylates, ketoprofen, flurbiprofen or piroxicam in clinically relevant doses do not appear to affect methotrexate disposition and may be used safely in combination with methotrexate.

Methotrexate in rheumatoid arthritis. An update

Methotrexate has been approved for the treatment of refractory rheumatoid arthritis by several regulatory agencies, including the Food and Drug Administration. The tendency is now to prescribe it at earlier stages of the disease. Methotrexate is a well known antifolate. Its exact mechanism of action in rheumatoid arthritis remains uncertain. The polyglutamated derivatives of methotrexate are potent inhibitors of various enzymes, including dihydrofolate reductase and 5-aminoimidazole-4-carboxamide ribonucleotide transformylase. Inhibitory effects on cytokines, particularly interleukin-1, and on arachidonic acid metabolism, as well as effects on proteolytic enzymes, have been reported. Some of them may be linked to the antifolate properties of methotrexate. Overall, the drug appears to act in rheumatoid arthritis as an anti-inflammatory agent with subtle immunomodulating properties. Direct inhibitory effects on rapidly proliferating cells in the synovium have also been suggested. Methotrexate is usually given orally. Marked interindividual variation in its bioavailability has been found. Food intake has no significant effect on the pharmacokinetics of oral methotrexate. Methotrexate undergoes significant metabolism. The functionally important metabolites are the polyglutamated derivatives of methotrexate, which are selectively retained in the cells. Less than 10% of a dose of methotrexate is oxidised to 7-hydroxy-methotrexate, irrespective of the route of administration. This metabolite is extensively (91 to 93%) bound to plasma proteins, in contrast to the parent drug (35 to 50% bound). Methotrexate is mainly excreted by the kidneys. It undergoes tubular secretion and may thereby compete with various organic acid compounds. Early placebo-controlled trials demonstrated that weekly low dosage methotrexate produced early symptomatic improvement in most rheumatoid arthritis patients. Two meta-analyses showed that methotrexate is among the most efficacious of slow-acting antirheumatic agents, together with parenteral gold (sodium aurothiomalate), penicillamine and sulfasalazine. Furthermore, in the short term context of clinical trials, methotrexate has one of the best efficacy/toxicity ratios. There is little evidence that methotrexate, or any available slow-acting antirheumatic agent, is a true disease-modifying drug. However, the probability that a patient will continue methotrexate therapy over time appears quite favourable compared with any other slow-acting antirheumatic drug. Combination therapy with slow-acting drugs has been advised for the management of rheumatoid arthritis, but the evidence currently available does not support general use of combination therapy including methotrexate. Almost all investigations indicated that toxic effects, rather than lack of response, were the major reason for discontinuing methotrexate therapy.(ABSTRACT TRUNCATED AT 400 WORDS)

Renal effects of aspirin and low dose methotrexate in rheumatoid arthritis

OBJECTIVES

The aim of this investigation was to study the glomerular and tubular effects of low doses (15 mg) of methotrexate in patients with rheumatoid arthritis with and without combined treatment with aspirin (2 g single dose).

METHODS

Renal function was measured by the plasma clearance of EDTA labelled with chromium-51 (51Cr-EDTA) and mercaptoacetyltriglycine labelled with technetium-99m (99mTc-MAG-3).

RESULTS

Clearance of 51Cr-EDTA was reduced from 98 (6) to 87 (5) ml/min (mean (SEM)) for patients receiving methotrexate only and further reduced to 76 (5) ml/min for patients receiving methotrexate and aspirin. This effect was reversible as 51Cr-EDTA increased to 85 (6) ml/min during continued treatment with methotrexate alone. Clearance of 99mTc-MAG-3 also decreased from 366 (18) to 315 (17) ml/min in patients receiving methotrexate alone and further to 295 (17) ml/min during treatment with aspirin and methotrexate. Continued treatment with methotrexate alone resulted in a further decrease in the 99mTc-MAG-3 clearance to 253 (17) ml/min.

CONCLUSIONS

The study shows that treatment with low doses of methotrexate particularly when combined with aspirin affects glomerular and tubular function. These effects may be of clinical importance and renal function should therefore be monitored with more sensitive methods than serum creatinine as this may not reflect these changes.