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Concept: Folinic acid


Cerebral folate deficiency (CFD) syndrome is a neurodevelopmental disorder typically caused by folate receptor autoantibodies (FRAs) that interfere with folate transport across the blood-brain barrier. Autism spectrum disorders (ASDs) and improvements in ASD symptoms with leucovorin (folinic acid) treatment have been reported in some children with CFD. In children with ASD, the prevalence of FRAs and the response to leucovorin in FRA-positive children has not been systematically investigated. In this study, serum FRA concentrations were measured in 93 children with ASD and a high prevalence (75.3%) of FRAs was found. In 16 children, the concentration of blocking FRA significantly correlated with cerebrospinal fluid 5-methyltetrahydrofolate concentrations, which were below the normative mean in every case. Children with FRAs were treated with oral leucovorin calcium (2 mg kg(-1) per day; maximum 50 mg per day). Treatment response was measured and compared with a wait-list control group. Compared with controls, significantly higher improvement ratings were observed in treated children over a mean period of 4 months in verbal communication, receptive and expressive language, attention and stereotypical behavior. Approximately one-third of treated children demonstrated moderate to much improvement. The incidence of adverse effects was low. This study suggests that FRAs may be important in ASD and that FRA-positive children with ASD may benefit from leucovorin calcium treatment. Given these results, empirical treatment with leucovorin calcium may be a reasonable and non-invasive approach in FRA-positive children with ASD. Additional studies of folate receptor autoimmunity and leucovorin calcium treatment in children with ASD are warranted.

Concepts: Autism, Folic acid, Asperger syndrome, Autism spectrum, Neurodevelopmental disorder, Pyrimethamine, Folinic acid, Folates


A 19-year-old male with 22q11.2 deletion syndrome presented with a 4-year history of cognitive decline and symptoms suggestive of atypical psychosis. Potential for elevated homocysteine and NMDA-receptor antibodies in the pathogenesis of his symptoms was investigated. He had elevated blood homocysteine level (18.7 μmol/l), low-normal vitamin B12 and folate levels and was positive for NMDA-receptor antibodies. Treatment with daily folinic acid (0.8 mg) and vitamin B12 (1 mg) led to dramatic improvement in his cognitive and behavioural presentation. Subsequent plasma exchange resulted in a further, significant clinical improvement. Homocysteine levels and NMDA-R antibodies should be investigated as potential causes of behavioural and cognitive symptoms in patients with 22q11.2 deletion syndrome.

Concepts: Immune system, Vitamin, Folic acid, Vitamin B12, B vitamins, Homocysteine, Methionine, Folinic acid


Folate is required for metabolic processes and neural development. Insuring its adequate levels for pregnant women through supplementation of grain-based foods with synthetic folic acid (FA) in order to prevent neural tube defects has been an ongoing public health initiative. However, because women are advised to take multivitamins containing FA before and throughout pregnancy, the supplementation together with natural dietary folates has led to a demographic with high and rising serum levels of unmetabolized FA. This raises concerns about the detrimental effects of high serum synthetic FA, including a rise in risk for autism spectrum disorder (ASD). Some recent studies have reported a protective effect of FA fortification against ASD, but others have concluded there is an increased risk for ASD and other negative neurocognitive development outcomes. These issues are accompanied by further health questions concerning high, unmetabolized FA levels in serum. In this review, we outline the reasons excess FA supplementation is a concern and review the history and effects of supplementation. We then examine the effects of FA on neuronal development from tissue culture experiments, review recent advances in understanding of metabolic functional blocks in causing ASD and treatment for these with alternative forms such as folinic acid, and finally summarize the conflicting epidemiological findings regarding ASD. Based on the evidence evaluated, we conclude that caution regarding over supplementing is warranted.

Concepts: Pregnancy, Autism, Folic acid, Autism spectrum, Spina bifida, Neural tube defect, Pyrimethamine, Folinic acid


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.

Concepts: Statistics, Statistical significance, Rheumatoid arthritis, Folic acid, Methotrexate, Effect size, Pyrimethamine, Folinic acid


Autism spectrum disorder (ASD) has been linked to abnormalities in folate metabolism. Polymorphisms in folate genes may act in complex polygenic ways to increase the risk of developing ASD. Autoantibodies that block folate transport into the brain have been associated with ASD and children with ASD and these autoantibodies respond to high doses of a reduced form of folate known as folinic acid (leucovorin calcium). Some of the same abnormalities are also found in mothers of children with ASD and supplementing folate during preconception and gestational periods reduces the risk to the offspring from developing ASD. These data suggest that folate pathway abnormalities may be a major metabolic disturbance underlying ASD that can be leveraged as biomarkers to improve symptoms and prevent ASD.

Concepts: Protein, Metabolism, Autism, Folic acid, Autism spectrum, Pyrimethamine, Folinic acid, Folates


Hereditary folate malabsorption is a rare autosomal recessive disorder caused by impaired active folate transport across membranes and into the central nervous system due to loss-of-function mutations in proton-coupled folate transporter (PCFT). Newborns with this condition have initially normal folate stores, but as they are unable to absorb dietary folate and use rapidly their stores because of their growth demands, symptoms appear in the early infancy. Significant neurological morbidity usually follows the initial non-specific clinical presentation and delayed initiation of treatment. High dose oral and parenteral folinic acid treatment have been previously reported in literature to improve the clinical outcome without achieving optimal cerebrospinal fluid (CSF) folate levels though. The active isomer of 5-formyltetrahydrofolate, also known as levofolinic acid, is available for administration. We report our experience in achieving normal (age dependent) CSF 5-Methyltetrahydrofolate (5-MTHF) levels following daily intramuscular administration of levofolinic acid in three patients with HFM. Follow-up assessment with repeated lumbar punctures has shown a stabilization of 5-MTHF levels within normal range. Clinical features and brain MRI findings had as well either improvement or stabilization. To the best of our knowledge, we provide as well for the first time data in regard to the im levofolinate treatment dosage.

Concepts: Central nervous system, Nervous system, Brain, Neurology, Folic acid, Cerebrospinal fluid, Pyrimethamine, Folinic acid


Blood serum proteins play a critical role in the transport, biodistribution, and efficacy of systemically-delivered therapeutics. Here, we have investigated the concentration- and ligand-dependent aggregation of folate binding protein (FBP), focusing in particular on folic acid, an important vitamin and targeting agent; methotrexate, an antifolate drug used to treat cancer and rheumatoid arthritis; and leucovorin which is used to decrease methotrexate toxicity. We employed atomic force microscopy to characterize, on a particle-by-particle basis, the volumes of the FBP nanoparticles that form upon ligand binding. We measured the distribution of FBP nanoparticle volumes as a function of ligand concentration over physiologically- and therapeutically-relevant ranges. At physiologically-relevant concentrations, significant differences in particle volume distributions exist that we hypothesize are consistent with different trafficking mechanisms for folic acid and methotrexate. In addition, we hypothesize leucovorin is trafficked and delivered like folic acid at therapeutically-relevant concentrations. We propose that changes in dosing procedures could improve the delivery and therapeutic index for methotrexate and other folic acid-targeted drug conjugates and imaging agents. Specifically, we suggest pre-binding the drugs to FBP may provide a better formulation for drug delivery of methotrexate for both cancer and rheumatoid arthritis. This would be analogous to pre-binding paclitaxel to albumin, which is already used in the clinic.

Concepts: Protein, Blood, Rheumatoid arthritis, Albumin, Nanotechnology, Folic acid, Methotrexate, Folinic acid


5-Fluorouracil (5-FU) chemotherapy is associated with severe and unpredictable toxicity in a significant proportion of patients. 5,10-Methylenetetrahydrofolate and 5-fluorodeoxyuridine monophosphate bind to thymidylate synthase and together inhibit its function, resulting in cytotoxicity. We hypothesized that susceptibility to 5-FU toxicity might be related to individual differences in the serum components of folate metabolism affecting intracellular 5,10-methylenetetrahydrofolate levels.

Concepts: Cancer, Folic acid, Fluorouracil, Capecitabine, Thymidylate synthase, Thymidylate synthase inhibitor, Pyrimethamine, Folinic acid


Folate-producing bifidobacteria have been studied extensively but appropriate methods for detailed quantitation of intra- and extracellular pteroylmono- and pteroylpolyglutamate patterns are lacking. Therefore, B. adolescentis DSM 20083(T) was cultivated in folate-free medium (FFM) for 24h to develop and validate stable isotope dilution assays (SIDAs) coupled with LC-MS/MS for the determination of 5-formyltetrahydrofolic acid (5-HCO-H4folate), 10-formylfolic acid (10-HCO-PteGlu), tetrahydrofolic acid (H4folate), folic acid (PteGlu) and 5-methyltetrahydrofolic acid (5-CH3-H4folate) including its di-, tri-, and tetraglutamic vitamers (5-CH3-H4PteGlu2-4). The respective monoglutamylated isotopologues labelled with deuterium were used as internal standards for quantitation. Limits of detection and quantitation (LOD/LOQ) were sufficiently low to quantify 48.2nmol L(-1) 5-CH3-H4folate (5.7/17nmolL(-1)) and 71.0nmolL(-1) 5-HCO-H4folate (10/30nmolL(-1)) as major folate vitamers extracellularly and 124nmolL(-1) 5-CH3-H4folate (3.4/10nmolL(-1)), 213nmolL(-1) 5-HCO-H4folate (4.8/14nmolL(-1)), and 61.4nmolL(-1) H4folate (2.3/7.0nmolL(-1)) intracellularly after deconjugation. The major portion of native 5-CH3-H4folate vitamer was ascribed to its tetraglutamate ( > 95%). Concentrations of mono-, di-, tri-, and pentaglutamylated folates were below LOD or LOQ. Intra-assay precision coefficients of variation (CVs) ranged from 7% (at a concentration of 53.9nmolL(-1) for 5-CH3-H4PteGlu4), 15% (25.5nmolL(-1) 5-CH3-H4folate) to 18% (78.5nmolL(-1) 5-HCO-H4folate), extracellularly, and from 6% (60.7nmolL(-1) 5-CH3-H4PteGlu4), 7% (202nmolL(-1) 5-HCO-H4folate), 10% (67.1nmolL(-1) H4folate) to 11% (127nmolL(-1) 5-CH3-H4folate), intracellularly. Inter-assay precision CVs ranged from 2% (54.7nmolL(-1) 5-CH3-H4PteGlu4), 3% (71nmolL(-1) 5-HCO-H4folate) to 11% (48.2nmolL(-1) 5-CH3-H4folate), extracellularly, and from 1% (61.4nmolL(-1) H4folate), 5% (213nmolL(-1) 5-HCO-H4folate), 6% (63.5nmolL(-1) 5-CH3-H4PteGlu4) to 10% (124nmolL(-1) 5-CH3-H4folate), intracellularly, thus showing excellent reproducibility. Recoveries for all analytes under study ranged between 81 and 113%. These newly developed methods enable reproducible, precise and sensitive quantitation of eight bacterially synthesized folate vitamers in two totally different matrices, including both monoglutamates and polyglutamates. Furthermore, we here present the first assay using solely monoglutamylated [(2)H4]-5-CH3-H4folate to quantify native polyglutamate patterns of this vitamer in bacteria which might replace time-consuming determination of monoglutamates in the future.

Concepts: Vitamin, Folic acid, Folate deficiency, Reproducibility, Dihydrofolic acid, Pyrimethamine, Folinic acid, Folates


The standard of care for second-line therapy in patients with advanced pancreatic cancer after gemcitabine-based therapy is not clearly defined. The CONKO-003 phase III study reported a survival benefit with second-line fluorouracil (FU) and oxaliplatin using the oxaliplatin, folinic acid, and FU (OFF) regimen.(1) PANCREOX was a phase III multicenter trial to evaluate the benefit of FU and oxaliplatin administered as modified FOLFOX6 (mFOLFOX6; infusional fluorouracil, leucovorin, and oxaliplatin) versus infusional FU/leucovorin (LV) in this setting.

Concepts: Cancer, Chemotherapy, Folic acid, Pancreatic cancer, Pyrimethamine, Folinic acid