Folate supplementation in methotrexate-treated rheumatoid arthritis patients

Three decades of low-dose methotrexate in rheumatoid arthritis: can we predict toxicity?

Methotrexate (MTX) is the anchor disease-modifying antirheumatic drug (DMARD) in rheumatoid arthritis (RA) treatment. It is used in monotherapy and/or in combination with other synthetic or biological DMARDs, and is known to have the best cost-effectiveness and efficacy/toxicity ratios. However, toxicity is still a concern, with a significant proportion of patients interrupting long-term treatment due to the occurrence of MTX-related adverse drug reactions (ADRs), which are the main cause of drug withdrawal. Despite the extensive accumulated experience in the last three decades, it is still impossible in routine clinical practice to identify patients prone to develop MTX toxicity. While clinical and biological variables, including folate supplementation, partially help to minimize MTX-related ADRs, the advent of pharmacogenomics could provide further insight into risk stratification and help to optimize drug monitoring and long-term retention. In this paper, we aimed to review and summarize current data on low-dose MTX-associated toxicity, its prevention and predictors, keeping in mind practical RA clinical care.

Genetic risk factors for drug-induced liver injury in rheumatoid arthritis patients using low-dose methotrexate

Low-dose methotrexate (MTX) is part of the mainstay of rheumatoid arthritis treatment. Hepatotoxicity is among the most feared side effects of low-dose MTX and is associated with increased morbidity. At present, histological evaluation of liver biopsies is the gold standard to retrospectively diagnose MTX-induced liver damage. Genetic markers present an interesting opportunity to preemptively identify patients at risk for MTX-induced hepatotoxicity. Here, we will review the literature on candidate genetic markers for the risk of MTX-induced hepatotoxicity. These candidate genetic markers include polymorphisms in the gene encoding the enzyme MTHFR.

Folic acid and folinic acid for reducing side effects in patients receiving methotrexate for rheumatoid arthritis

BACKGROUND

Methotrexate (MTX) is a disease modifying antirheumatic drug (DMARD) used as a first line agent for treating rheumatoid arthritis (RA). Pharmacologically, it is classified as an antimetabolite due to its antagonistic effect on folic acid metabolism. Many patients treated with MTX experience mucosal, gastrointestinal, hepatic or haematologic side effects. Supplementation with folic or folinic acid during treatment with MTX may ameliorate these side effects.

OBJECTIVES

To identify trials of supplementation with folic acid or folinic acid during MTX therapy for rheumatoid arthritis and to assess the benefits and harms of folic acid and folinic acid (a) in reducing the mucosal, gastrointestinal (GI), hepatic and haematologic side effects of MTX, and (b) whether or not folic or folinic acid supplementation has any effect on MTX benefit.

SEARCH METHODS

We originally performed MEDLINE searches, from January 1966 to June 1999. During the update of this review, we searched additional databases and used a sensitive search strategy designed to retrieve all trials on folic acid or folinic acid for rheumatoid arthritis from 1999 up to 2 March 2012.

SELECTION CRITERIA

We selected all double-blind, randomised, placebo-controlled clinical trials (RCTs) in which adult patients with rheumatoid arthritis were treated with MTX (at a dose equal to or less than 25 mg/week) concurrently with folate supplementation. In this update of the review we only included trials using 'low dose' folic or folinic acid (a starting dose of ≤ 7 mg weekly).

DATA COLLECTION AND ANALYSIS

Data were extracted from the trials, and the trials were independently assessed for risk of bias using a predetermined set of criteria.

MAIN RESULTS

Six trials with 624 patients were eligible for inclusion. Most studies had low or unclear risk of bias for key domains. The quality of the evidence was rated as 'moderate' for each outcome as assessed by GRADE, with the exception of haematologic side effects which were rated as 'low'. There was no significant heterogeneity between trials, including where folic acid and folinic acid studies were pooled.For patients supplemented with any form of exogenous folate (either folic or folinic acid) whilst on MTX therapy for rheumatoid arthritis, a 26% relative (9% absolute) risk reduction was seen for the incidence of GI side effects such as nausea, vomiting or abdominal pain (RR 0.74, 95% CI 0.59 to 0.92; P = 0.008). Folic and folinic acid also appear to be protective against abnormal serum transaminase elevation caused by MTX, with a 76.9% relative (16% absolute) risk reduction (RR 0.23, 95% CI 0.15 to 0.34; P < 0.00001), as well as reducing patient withdrawal from MTX for any reason (60.8% relative (15.2% absolute) risk reduction, RR 0.39, 95% CI 0.28 to 0.53; P < 0.00001).We analysed the effect of folic or folinic acid on the incidence of stomatitis / mouth sores, and whilst showing a trend towards reduction in risk, the results were not statistically significant (RR 0.72, 95% CI 0.49 to 1.06)It was not possible to draw meaningful conclusions on the effect of folic or folinic acid on haematologic side effects of methotrexate due to small numbers of events and poor reporting of this outcome in included trials.It does not appear that supplementation with either folic or folinic acid has a statistically significant effect on the efficacy of MTX in treating RA (as measured by RA disease activity parameters such as tender and swollen joint counts, or physician's global assessment scores).

AUTHORS' CONCLUSIONS

The results support a protective effect of supplementation with either folic or folinic acid for patients with rheumatoid arthritis during treatment with MTX.There was a significant reduction shown in the incidence of GI side effects, hepatic dysfunction (asmeasured by elevated serum transaminase levels) as well as a significant reduction in discontinuation of MTX treatment for any reason. A trend towards a reduction in stomatitis was demonstrated however this did not reach statistical significance.This updated review with its focus on lower doses of folic acid and folinic acid and updated assessment of risk of bias aimed to give a more precise and more clinically relevant estimate of the benefit of folate supplementation for patients with rheumatoid arthritis receiving methotrexate.

Methotrexate and oral ulceration

Methotrexate is well established in the drug treatment of various neoplastic diseases. More recently it has become increasingly used as a once-weekly, low-dose treatment of disorders such as psoriasis and rheumatoid arthritis. Clinical trials have shown its effectiveness in these conditions and it is likely that dentists will encounter patients taking this drug in general dental practice. Oral ulceration can occur as a side effect of methotrexate therapy. This may be due to lack of folic acid supplementation or overdosage due to confusion regarding its once-weekly regime. Illustrations of these problems, which have initially presented in a dental setting, are given. Important drug interactions of methotrexate relevant to dentistry are discussed.

Folate supplementation during methotrexate treatment of patients with rheumatoid arthritis. An update and proposals for guidelines

The efficacy of weekly low-dose methotrexate treatment of rheumatoid arthritis is well documented. Efficacy and adverse effects are both dose dependent. and adverse effects rather than lack of efficacy are the main reason for discontinuing therapy. Several adverse effects are related to folate deficiencies, largely due to the antifolate properties of methotrexate. In order to reduce adverse effects without compromising drug efficacy, numerous clinical investigations have been performed using supplementation with folic or folinic acid during methotrexate therapy of patients with rheumatoid arthritis, addressing both the timing of folate supplementation and the weekly folate-to-methotrexate ratio. Based on these studies, an individually adjusted supply of folic acid rather than folinic acid is proposed. For many patients, however, a properly balanced diet is sufficient to avoid folate deficiency.

Do patients with rheumatoid arthritis established on methotrexate and folic acid 5 mg daily need to continue folic acid supplements long term?

BACKGROUND

It is postulated that some aspects of methotrexate toxicity may be related to its action as an anti-folate. Folic acid (FA) is often given as an adjunct to methotrexate therapy, but there is no conclusive proof that it decreases the toxicity of methotrexate and there is a theoretical risk that it may decrease the efficacy of methotrexate.

OBJECTIVES

To look at the effect of stopping FA supplementation in UK rheumatoid arthritis (RA) patients established on methotrexate <20 mg weekly and FA 5 mg daily, to report all toxicity (including absolute changes in haematological and liver enzyme indices) and to report changes in the efficacy of methotrexate.

METHODS

In a prospective, randomized, double-blind, placebo-controlled study, 75 patients who were established on methotrexate <20 mg weekly and FA 5 mg daily were asked to stop their FA and were randomized to one of two groups: placebo or FA 5 mg daily. Patients were evaluated for treatment toxicity and efficacy before entry and then at intervals of 3 months for 1 yr.

RESULTS

Overall, 25 (33%) patients concluded the study early, eight (21%) in the group remaining on FA and 17 (46%) in the placebo group (P = 0.02). Two patients in the placebo group discontinued because of neutropenia. At 9 months there was an increased incidence of nausea in the placebo group (45 vs. 7%, P = 0.001). The placebo group had significantly lower disease activity on a few of the variables measured, but these were probably not of clinical significance.

CONCLUSIONS

It is important to continue FA supplementation over the long term in patients on methotrexate and FA in order to prevent them discontinuing treatment because of mouth ulcers or nausea and vomiting. Our data suggest that FA supplementation is also helpful in preventing neutropenia, with very little loss of efficacy of methotrexate.

Folic acid and folinic acid for reducing side effects in patients receiving methotrexate for rheumatoid arthritis

OBJECTIVES

To assess the effects of folic acid and folinic acid in reducing the mucosal and gastrointestinal (GI) and haematologic side effects of low-dose of Methotrexate (MTX) in patients with Rheumatoid Arthritis (RA) and to determine whether or not folate supplementation alters MTX efficacy.

SEARCH STRATEGY

We searched the Cochrane Controlled Clinical Trial's Register (CCTR), the Cochrane Musculoskeletal Group Specialized Register and Medline up to and including June 1999, using the search strategy developed by the Cochrane Collaboration (Dickersin 1994). We also handsearched the following: (i) bibliographic references; (ii) current contents of the last 6 months; (iii) abstracts of the rheumatology meetings; and (iv) all issues of four journals; Journal of Rheumatology, Arthritis & Rheumatism, Clinical and Experimental Rheumatology, and British Journal of Rheumatology. All languages were included. Principal investigators were also contacted in order to look for unpublished literature.

SELECTION CRITERIA

We selected all double-blind, randomized, placebo-controlled, clinical trials (RCTs), in which adult RA patients were treated with a low dose of MTX (<20 mg / week) concurrently with folate supplementation.

DATA COLLECTION AND ANALYSIS

Two observers extracted the data and assessed the quality of the trials. (BS, Z0) The overall treatment effect across trials was calculated using a fixed effect model. Disease activity was evaluated using standardized mean differences to ensure comparability across outcome measures. Results are presented with 95% Confidence Inervals (95% CI). Subgroup analyses were conducted evaluating different doses and sensitivity analysis looking at the quality of the trials. Publication bias was assessed with an inverted funnel plot technique. Heterogeneity of the trials was measured using a standard chi square test. Costs per month in different countries were compared.

MAIN RESULTS

Of the 12 trials retrieved, 7 met the inclusion criteria. The total sample included 307 patients, of which 147 were treated with folate supplementation, 80 patients with folinic acid and 67 patients with folic acid. A 79% reduction in mucosal and GI side effects was observed for folic acid [OR = 0.21 (95% CI 0.10 to 0.44)]. For folinic acid, a clinically but non-statistically significant reduction of 43% was found [OR = 0. 57 (95% CI 0.28 to 1.15)]. No major differences were observed between low and high doses of folic or folinic acid. Haematologic side effects could not be analyzed, since details of each haematologic side effect by patients were not provided. No consistent differences in disease activity parameters were observed when comparing placebo and folic or folinic acid at low or high doses, although patients on high dose folinic acid had an increase in the number of tender joints, but not swollen joints. Large differences in costs across countries were found, but folinic acid was more expensive in all.

REVIEWER'S CONCLUSIONS

The results support the protective effect of folate supplementation in reducing MTX side effects related to the oral and GI systems. We could not determine if folic was different from folinic acid. Therefore, for folinic acid to be considered cost-effective it must be found more effective than folic acid at reducing MTX side effects.

Potentiated decrease of plasma folate levels caused by the coadministration of folic acid in rats treated with methotrexate

The decrease of plasma 5-methyltetrahydrofolic acid (5-MF) levels, postulated as an indicator of folate status, was studied following the administration of both methotrexate (MTX) alone and MTX with folic acid (FA) using rats as our experimental model. Blood and urine samples were serially collected over a 9 hr period after the administration of MTX, MTX with FA and from a control group to examine the plasma kinetics and the renal clearance of 5-MF. The pharmacokinetics of MTX and the plasma protein binding of 5-MF were also examined. The concentrations of these analytes were assayed using high performance liquid chromatography (HPLC). MTX administration produced decreased plasma 5-MF levels. This observed decrease was potentiated by oral FA administration, suggesting that the folate status was more severely altered by the coadministration of FA. The renal clearance of 5-MF also increased dose-dependently with FA (0.05-5 mg/kg) coadministration. The plasma protein binding of 5-MF was not affected by the FA administration, which indicates that the fraction of 5-MF that was filtered through the glomerular apparatus appeared to be unchanged. In addition, the pharmacokinetic profiles of MTX also appeared not to be affected by the addition of FA. We conclude that the inhibition of reabsorption of 5-MF in the renal tube by concurrent administration of MTX and FA must be one of the causal factors for the demonstrated decrease in the plasma 5-MF levels in rats.

Side effects of immunosuppressant therapies used in neurology

This article provides an overview of the clinically relevant complications of the main immunosuppressants currently used in the treatment of neurologic disorders with suspected or established immune etiology. The most serious complications are discussed in detail, including pathophysiology and preventative measures. An intimate knowledge of these complications proves helpful in the day to day practice of the neurologist supervising immunotherapy.

Methotrexate use in rheumatoid arthritis

To overstate the importance of methotrexate in the contemporary management of rheumatoid arthritis would be difficult. It has achieved this distinction because of its efficacy and tolerability. This article reviews the data on the efficacy and toxicity of methotrexate, discusses caveats for clinical use, examines the use of methotrexate in combination therapy, and speculates on the future use of methotrexate in rheumatoid arthritis.

The use of folates concomitantly with low-dose pulse methotrexate

Toxicities related to low-dose weekly methotrexate are largely due to its antifolate properties. Preexisting folate deficiency is associated with methotrexate toxicity in some patients. At the onset of methotrexate therapy and throughout therapy, the physician should be vigilant regarding one or more nutrient deficiencies. A multivitamin and, where appropriate, specific daily folic acid supplements should be employed. The only regimen known presently (through controlled trials) to treat side effects is the low-dose folinic acid (leucovorin) protocol outlined herein. Folic acid may be helpful to treat mild gastrointestinal symptoms. Folinic acid supplementation should be considered prophylactically in those requiring methotrexate who are at increased risk of hepatic disease. Other possible factors besides methotrexate should always be considered with the onset of new patient complaints or laboratory abnormalities. Claims that folic acid therapy is safer and more convenient than folinic acid seem unwarranted when one reviews the literature carefully. Cost differences between folic acid supplementation and folinic acid supplementation have been exaggerated.

The remarkable spectrum of methotrexate toxicities

This article outlines a general scheme for categorizing medication-related adverse events. This is followed by a review of the less well-recognized adverse events attributed to low-dose methotrexate therapy. Known and suspected risk factors are described and causative mechanisms are suggested. Ultimately, this article aims at increasing the readers awareness of uncommon or underreported methotrexate-associated adverse events so that prescribing and monitoring practices can be tailored to enhance the safe use of this valuable antirheumatic agent.

Folic acid fortification of grain: an economic analysis

OBJECTIVES

The purpose of this study was to compare the economic costs and benefits of fortifying grain with folic acid to prevent neural tube defects.

METHODS

A cost-benefit analysis based on the US population, using the human capital approach to estimate the costs associated with preventable neural tube defects, was conducted.

RESULTS

Under a range of assumptions about discount rates, baseline folate intake, the effectiveness of folate in preventing neural tube defects, the threshold dose that minimizes risk, and the cost of surveillance, fortification would likely yield a net economic benefit. The best estimate of this benefit is $94 million with low-level (140 micrograms [mcg] per 100 g grain) fortification and $252 million with high-level (350 mcg/100 g) fortification. The benefit-to-cost ratio is estimated at 4.3:1 for low-level and 6.1:1 for high-level fortification.

CONCLUSIONS

By averting costly birth defects, folic acid fortification of grain in the United States may yield a substantial economic benefit. We may have underestimated net benefits because of unmeasured costs of neural tube defects and unmeasured benefits of higher folate intake. We may have overestimated net benefits if the cost of neurologic sequelae related to delayed diagnosis of vitamin B12 deficiency exceeds our projection.

A risk-benefit assessment of slow-acting antirheumatic drugs in rheumatoid arthritis

There is no ideal slow-acting antirheumatic drug. Therapy of rheumatoid arthritis (RA) is currently being modified, with strong recommendations to abandon the traditional pyramidal approach. The call is for a more aggressive, earlier approach to suppress inflammation. Combination therapy rather than the use of a single agent is advocated by some. Improved methods for assessing disease activity as well as measurement of outcome have been developed. Markers of poor prognosis have helped to define patients for earlier treatment. Comparison of toxicity among such a diverse group of drugs is probably best achieved with a toxicity index measuring the number of episodes expressed in terms of patient-years of exposure. Toxicity remains the commonest reason for discontinuing an agent, while remission beyond 36 months on therapy is uncommon, except with methotrexate. The profile of toxicity is clearly defined for individual agents, but combination therapy may reveal an entirely different set of toxic manifestations. There is an urgent need to develop a set of risk factors to predict toxicity in an individual patient. Juvenile chronic arthritis behaves differently from adult RA. Drug toxicity profiles are similar, but less common. Outcome is more difficult to measure, with the major impact of disease and therapy being on growth retardation.

A clinical and biochemical assessment of methotrexate in rheumatoid arthritis

Low-dose methotrexate has gained widespread acceptance as a second-line agent in rheumatoid arthritis (RA). The Leeds Human Model Screening System (LHMSS) is a validated screening mechanism allowing the rapid evaluation of compounds for their potential as anti-rheumatic agents, the results of which have been confirmed in longer term studies. We have evaluated methotrexate in patients with RA using the LHMSS at a maintenance dose of 10mg/week. Significant change occurred in four out of eleven variables over a 24-week period (p < 0.01). This degree of change is greater than that seen with nonsteroidal anti-inflammatory agents but less than with other recognised second-line agents such as D-penicillamine, suggesting that methotrexate may have less potential as a second-line agent than D-penicillamine.

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)

Concurrent acute megaloblastic anaemia and pneumonitis: a severe side-effect of low-dose methotrexate therapy during rheumatoid arthritis

In a patient suffering from rheumatoid arthritis, we report the first simultaneous occurrence of two side effects of low-dose methotrexate: an acute megaloblastic anaemia and a pneumonitis. A combination of methotrexate suspension, folinic acid and corticosteroids led to recovery. The correlation between the haematologic and pneumologic toxicity is discussed.

Impact of omeprazole on the plasma clearance of methotrexate

Omeprazole inhibits the gastric hydrogen pump and is an effective treatment for peptic ulcers. Methotrexate is a chemotherapeutic agent that inhibits dihydrofolate reductase and is eliminated by a hydrogen-ion-dependent mechanism in the kidney. We present evidence that omeprazole inhibits methotrexate clearance and may result in potentially toxic methotrexate levels.