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PubMed1991

Local infectious complications following large joint replacement in rheumatoid arthritis patients treated with methotrexate versus those not treated with methotrexate.

We performed a 10-year retrospective analysis of the frequency of local postoperative infectious complications in methotrexate (MTX)-treated rheumatoid arthritis patients who underwent total joint arthroplasty. Sixty patients, who had a total of 92 joint arthroplasties, were receiving MTX. A comparison group of 61 patients with a combined total of 110 total joint arthroplasties were not receiving MTX. The 2 groups were compared for the occurrence of local postoperative infectious complications and poor wound healing. Eight patients in the MTX group experienced a total of 8 complications (8.7% of procedures). In comparison, 5 patients in the non-MTX group experienced a total of 6 complications (5.5% of procedures), a difference that was not statistically significant (chi 2 = 0.816, P = 0.366). Statistical analysis of many other variables revealed none that could be identified as risk factors for postoperative complications. These results suggest that treatment in the perioperative period with weekly low-dose pulse MTX does not increase the risk of local postoperative infectious complications or poor wound healing in rheumatoid arthritis patients who undergo total joint arthroplasty.

Adrenal Cortex Hormones↗

PubMed1997

Combination treatment of severe rheumatoid arthritis with cyclosporine and methotrexate for forty-eight weeks: an open-label extension study. The Methotrexate-Cyclosporine Combination Study Group.

OBJECTIVE: To determine whether the clinical benefit and favorable safety profile previously noted with the combination of cyclosporine (CSA) and methotrexate (MTX) given for 24 weeks in patients with rheumatoid arthritis (RA) would be maintained for a further 24 weeks, and whether the addition of CSA in patients who had previously been randomized to receive placebo + MTX would result in clinical benefit. METHODS: Eligible subjects from the initial study (weeks 0-24), in which the addition of placebo or CSA to MTX therapy was compared in patients with RA that was partially responsive to MTX, were enrolled. Patients who had received CSA + MTX continued this regimen for a further 24 weeks (weeks 24-48) (group 1; n = 48), and patients who had initially received placebo + MTX now received CSA + MTX for 24 weeks (weeks 24-48) (group 2; n = 44), in an open-label extension study. The primary outcome measures were the number of tender joints, number of swollen joints, physician and patient global assessments, pain, functional disability as measured by the modified Health Assessment Questionnaire, and erythrocyte sedimentation rate. RESULTS: Of the 92 patients enrolled, 80 (87%) completed the extension study. In patients in group 1, the clinically and statistically significant improvement in response outcomes previously noted at week 24, ranging from 25% to 50%, was maintained through week 48. In patients in group 2, the addition of CSA resulted in significant clinical improvement. By week 48, most outcome measures in group 2 patients were similar to those in group 1 patients. CSA treatment resulted in a small increase in serum creatinine levels, but only 1 patient was withdrawn from the study for this reason. CONCLUSION: The clinical improvement previously observed in patients treated with the CSA + MTX combination for 24 weeks was maintained for 24 subsequent weeks, without serious adverse effects, and was also observed in the patients whose treatment was switched from placebo + MTX to CSA + MTX.

Adult↗

PubMed2004

Dose escalation of parenteral methotrexate in active rheumatoid arthritis that has been unresponsive to conventional doses of methotrexate: a randomized, controlled trial.

OBJECTIVE: To examine whether dose escalation of intramuscular (IM) methotrexate (MTX) up to 45 mg/week improves disease control in patients who have active rheumatoid arthritis (RA) despite receiving conventional doses (15 mg/week) of IM MTX, and to obtain preliminary data on patient tolerability and adverse effects of higher doses of IM MTX. METHODS: Patients >18 years of age who had active RA, defined as a European League Against Rheumatism (EULAR) Disease Activity Score in 28 joints (DAS28) of >3.2, and who had received 15-20 mg/week of oral MTX for at least 2 months were switched (week 0) to 15 mg/week of IM MTX for 6 weeks. Patients whose DAS28 remained >3.2 at both week 4 and week 6 were randomized, in a double-blind manner, either to continue to receive 15 mg/week IM MTX with monthly placebo escalation or to receive escalating doses of IM MTX monthly up to 45 mg/week. The dose of MTX or placebo was escalated every 4 weeks if the DAS28 was >2.5. Safety assessments and determination of the DAS28 were performed every 2 weeks and monthly, respectively. Disease activity parameters from the American College of Rheumatology (ACR) core disease activity set and health status as recorded on the Medical Outcomes Study Short-Form 12 were determined at baseline (week 0) and final assessment (week 22). The primary outcome was the percentage of patients in each group achieving a target DAS28 of <3.2. Secondary outcomes comprised the percentage of patients whose DAS28 improved by >1.2, the percentage of patients achieving a 20% improvement in the ACR core disease activity measures (ACR20), and the percentage of patients achieving a good response, a moderate response, or no response in accordance with the EULAR response criteria. RESULTS: Sixty-four patients were eligible for entry and were switched from oral MTX to 15 mg/week IM MTX. At baseline, the mean +/- SD DAS28 was 5.6 +/- 0.88; after 6 weeks of IM MTX, the DAS28 had improved by a mean of 0.42 (95% confidence interval [95% CI] 0.15-0.69). At 6 weeks, 54 patients still had a DAS28 of >3.2 and were therefore eligible for randomization. By 22 weeks, 1 patient (3.7%) in each group achieved the primary outcome of a DAS28 <3.2 (95% CI for the difference between the groups -15% to +15%). Five patients (18.5%) in each group showed an improvement of >1.2 in the DAS28 (95% CI for the difference between the groups -18% to +18%). One patient (3.7%) in each group achieved an ACR20 response, but none achieved a good response as defined by the EULAR response criteria. One patient in each group had a serious adverse reaction; minor adverse reactions were more frequently reported in the dose escalation group. CONCLUSION: Switching from oral to parenteral MTX 15 mg/week results in a minor improvement in disease control. For patients with active RA receiving 15 mg/week IM MTX, increasing the dose up to 45 mg/week does not improve disease control. Higher doses of IM MTX were generally well tolerated and not associated with an increase in serious adverse reactions to the drug.

Arthritis, Rheumatoid↗

PubMed2004

A randomized trial of parenteral methotrexate comparing an intermediate dose with a higher dose in children with juvenile idiopathic arthritis who failed to respond to standard doses of methotrexate.

OBJECTIVE: To compare the safety and efficacy of parenteral methotrexate (MTX) at an intermediate dosage (15 mg/m(2)/week) versus a higher dosage (30 mg/m(2)/week) in patients with polyarticular-course juvenile idiopathic arthritis (JIA) who failed to improve while receiving standard dosages of MTX (8-12.5 mg/m(2)/week). METHODS: In the screening phase, 595 patients who were newly started on a standard dose of MTX were followed up for 6 months. Subsequently, the nonresponders, defined according to the American College of Rheumatology (ACR) pediatric 30% improvement criteria (pediatric 30), were randomized to receive an intermediate dose or higher dose of parenteral MTX for an additional 6 months. Improvement in the screening and randomization phase was defined by the ACR pediatric 30 response, as well as by the 50% and 70% response levels (ACR pediatric 50 and ACR pediatric 70, respectively). RESULTS: In the screening phase, after receiving standard doses of MTX, 430 patients (72%) improved according to the ACR pediatric 30, while 360 (61%) met the ACR pediatric 50 and 225 (38%) met the ACR pediatric 70; among these patients, 69 (12%) also met the definition of complete disease control. Of the 133 nonresponders, 80 were randomized to receive an intermediate dose or higher dose of MTX. In the randomization phase, the ACR pediatric 30 response rate was 25 of 40 children (62.5%) in the intermediate-dose group versus 23 of 40 children (57.5%) in the higher-dose group. An ACR pediatric 50 response rate was attained by 23 patients (57.5%) receiving an intermediate dose versus 22 (55%) in the higher-dose group. An ACR pediatric 70 response rate was seen in 18 children (45%) receiving an intermediate dose versus 19 (47.5%) receiving a higher dose. Five children (12.5%) in the intermediate-dose group versus 4 (10%) receiving the higher dose of MTX also met the definition of complete disease control. None of the intergroup differences in response rate were significant. There were no significant differences in the frequency of adverse events or laboratory abnormalities between the 2 randomized groups. CONCLUSION: This study shows that the plateau of efficacy of MTX in JIA is reached with parenteral administration of 15 mg/m(2)/week and that a further increase in dosage is not associated with any additional therapeutic benefit. MTX should be administered for up to 9-12 months to appreciate its full therapeutic effect.

Antirheumatic Agents↗

PubMed2004

Polyglutamation of methotrexate with common polymorphisms in reduced folate carrier, aminoimidazole carboxamide ribonucleotide transformylase, and thymidylate synthase are associated with methotrexate effects in rheumatoid arthritis.

OBJECTIVE: Methotrexate (MTX) enters cells through the reduced folate carrier (RFC-1) and exerts part of its effects through polyglutamation to MTX polyglutamates (MTXPGs) and inhibition of 5-aminoimidazole-4-carboxamide ribonucleotide transformylase (ATIC) and thymidylate synthase (TS). We investigated the contribution of common genetic polymorphisms in RFC-1 (G80A), ATIC (C347G), and TS (28-bp tandem repeats located in the TS enhancer region [TSER*2/*3]) and of MTXPGs to the effect of MTX in patients with rheumatoid arthritis. METHODS: The study was cross-sectional. All patients received MTX for at least 3 months. The numbers of tender and swollen joints, the Visual Analog Scale (VAS) scores for the physician's global assessment of disease activity, and the modified Health Assessment Questionnaire scores were collected. Using the VAS score for the physician's assessment of patient's response to MTX, the population of patients was dichotomized into responders to MTX (VAS score < or =2 cm) and nonresponders to MTX (VAS score >2 cm). A pharmacogenetic index was calculated as the sum of homozygous variant genotypes (RFC-1 AA + ATIC 347GG + TSER *2/*2) carried by the patients. MTXPG concentrations were measured in red blood cells (RBCs) by high-performance liquid chromatography. RESULTS: The dose of MTX was not associated with the effects of MTX (P > 0.05). In contrast, increased RBC long-chain MTXPG concentrations (median 40 nmoles/liter; range <5-131 nmoles/liter) and an increased pharmacogenetic index were associated with a lower number of tender and swollen joints (P < 0.05) and a lower score for the physician's global assessment of disease activity (P < or = 0.001). Patients with RBC MTXPG levels of >60 nmoles/liter and carriers of a homozygous variant genotype were 14.0-fold (95% confidence interval [95% CI] 3.6-53.8) and 3.7-fold (95% CI 1.7-9.1), respectively, more likely to have a good response to MTX (P <or = 0.01). CONCLUSION: These data suggest that measuring RBC MTXPG levels and/or the common polymorphisms in the folate-purine-pyrimidine pathway may help in monitoring MTX therapy.

Adult↗

PubMed2006

Treatment of early seropositive rheumatoid arthritis: doxycycline plus methotrexate versus methotrexate alone.

OBJECTIVE: To compare the efficacy of doxycycline plus methotrexate (MTX) versus MTX alone in the treatment of early seropositive rheumatoid arthritis (RA), and to attempt to differentiate the antibacterial and antimetalloproteinase effects of doxycycline. METHODS: Sixty-six patients with seropositive RA of <1 year's duration who had not been previously treated with disease-modifying antirheumatic drugs were randomized to receive 100 mg of doxycycline twice daily with MTX (high-dose doxycycline group), 20 mg of doxycycline twice daily with MTX (low-dose doxycycline group), or placebo with MTX (placebo group), in a 2-year double-blind study. Treatment was started with an MTX dosage of 7.5 mg/week, which was titrated every 3 months until remission was reached (maximum dosage of 17.5 mg/week). The primary end point was an American College of Rheumatology 50% improvement (ACR50) response at 2 years. RESULTS: ACR50 responses were observed in 41.6% of patients in the high-dose doxycycline group, 38.9% of those in the low-dose doxycycline group, and 12.5% of patients in the placebo group. Results of chi-square analysis of the ACR50 response in the high-dose doxycycline group versus that in the placebo group were significantly different (P = 0.02). Trend analysis revealed that the ACR20 response and the ACR50 response were significantly different between groups (P = 0.04 and P = 0.03, respectively). MTX doses at 2 years were not different among groups. Four patients in the high-dose doxycycline group, 2 patients in the low-dose doxycycline group, and 2 patients in the placebo group were withdrawn because of toxic reactions. CONCLUSION: In patients with early seropositive RA, initial therapy with MTX plus doxycycline was superior (based on an ACR50 response) to treatment with MTX alone. The therapeutic responses to low-dose and high-dose doxycycline were similar, suggesting that the antimetalloproteinase effects were more important than the antibacterial effects. Further studies to evaluate the mechanism of action of tetracyclines in RA are indicated.

Adult↗

PubMed1994

The pharmacokinetics of methotrexate after intravenous administration of methotrexate-loaded proliposomes to rats.

The pharmacokinetics and tissue distribution of methotrexate (MTX) were investigated after intravenous (i.v.) injection of free MTX (treatment I), MTX-loaded proliposomes (treatment II), and empty proliposomes mixed manually with free MTX (treatment III), 8 mg kg-1, to rats using an HPLC assay. After i.v. infusion in 1 min, the plasma concentration of MTX (Cp), the area under the plasma concentration-time curve (AUC, 639 versus 913 micrograms min mL-1), the terminal half-life (t1/2, 48.8 versus 397 min), the mean residence time (MRT, 8.40 versus 325 min), and the apparent volume of distribution at steady state (Vss, 98.1 versus 2800 mL kg-1) were significantly higher; however, the total body clearance (CL, 12.5 versus 8.76 mL min-1 kg-1), renal clearance (CLR, 4.49 versus 2.78 mL min-1 kg-1), non-renal clearance (CLNR, 7.50 versus 5.99 mL min-1 kg-1), and the amount of MTX excreted in urine (Xu, 808 versus 685 micrograms, p < 0.0948) were significantly lower from treatment II than from treatment I. This could be due to the fact that some of the MTX-loaded liposomes (formed immediately after hydration of MTX-loaded proliposomes) are entrapped in tissues and the rest are present in the plasma (higher MRT and Vss from treatment II), and MTX is slowly released from MTX-loaded liposomes (higher t1/2 from treatment II). In the present HPLC assay, the concentrations of MTX represent the sum of free MTX and MTX loaded in liposomes (higher Cp and AUC, slower CL from treatment II). After i.v. infusion in 1 min, some pharmacokinetic parameters, such as t1/2, MRT, and Vss, were significantly different between treatments I and III; however, the differences seemed to be smaller than those between treatments I and II. After 30 min from i.v. infusion, the tissue to plasma (T/P) ratios of MTX in kidney and stomach from treatment II were significantly lower than those from treatment I. This suggested that the i.v. administration of MTX-loaded proliposomes might have fewer side effects in the organs than that of free MTX. The mean amount of MTX loaded in MTX-loaded proliposomes was 2.54 mg/g proliposomes and the MTX was released slowly from hydrated MTX-loaded proliposomes when incubated with phosphate-buffered saline (PBS), rat plasma, or rat liver homogenate.

Animals↗

PubMed1995

Pharmacokinetics of methotrexate after intravenous and intramuscular injection of methotrexate-bearing positively charged liposomes to rats.

The pharmacokinetics and tissue distribution of methotrexate (MTX) were investigated after intravenous (IV) and intramuscular (IM) injection of free MTX (treatment I), freshly prepared MTX-bearing positively charged liposomes (large unilamellar vesicles), PLUVs (treatment II), and empty PLUVs mixed manually with free MTX (treatment III), 4 mg kg-1 as free MTX to rats, using HPLC assay. After 1 min IV infusion, the plasma concentrations of MTX (Cp), the area under the plasma concentration-time curve (AUC, 173 against 314 micrograms mL min-1), the terminal half-life (t1/2, 24.0 against 412 min), the mean residence time (MRT, 13.0 against 324 min), and the apparent volume of distribution at steady state (VSS, 289 against 3370 mL kg-1) were significantly larger, but the total body clearance (CL, 23.1 against 12.8 mL min-1 kg-1), the renal clearance (CLR, 8.38 against 3.09 mL min-1 kg-1), the non-renal clearance (CLNR, 14.6 against 9.56 mL min-1 kg-1), and the amount of MTX excreted in urine (Xu, 415 against 275 micrograms) were significantly lower in treatment II than in treatment I. This could be due to the fact that some of the MTX-bearing PLUVs were entrapped in tissues and the rest were present in plasma (larger MRT and Vss in treatment II), and MTX is slowly released from MTX-bearing PLUVs (longer t1/2 in treatment II). In the present HPLC assay, the concentrations of MTX represent the sum of free MTX and MTX in MTX-bearing PLUVs (larger Cp and AUC and slower CL in treatment II). Saturable formation of 7-hydroxymethotrexate from MTX was reported in rabbit blood and nonlinear disposition of MTX was also reported in rats and rabbits (lower Xu and CLR in treatment II). After 1 min IV infusion, some pharmacokinetic parameters of MTX, such as AUC, CL, CLR, CLNR, and Xu, were significantly different between treatments I and III, but nonetheless the differences were smaller than those between treatments I and II. After both IV and IM administration, the amount of MTX remaining per gram of tissue or organ in the kidney, stomach, small intestine, and large intestine was significantly smaller in treatment II than in treatment I.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗

PubMed2004

Methotrexate loaded poly(L-lactic acid) microspheres for intra-articular delivery of methotrexate to the joint.

A controlled release delivery system that localizes methotrexate (MTX) in the synovial joint is needed to treat inflammation in rheumatoid arthritis (RA). The purpose of this work was to develop and characterize MTX loaded poly(l-lactic acid) (PLLA) microspheres and evaluate in vivo tolerability and MTX plasma concentrations following intra-articular injection into healthy rabbits. MTX loaded PLLA (2 kg/mole) microspheres were prepared using the solvent evaporation method and characterized in terms of size, molecular weight, thermal properties, and release rates into phosphate buffered saline (PBS) (pH 7.4) at 37 degrees C. Biocompatibility was evaluated by observing the swelling of the joints of the rabbits and histological analysis following the injection of the microspheres. MTX concentrations in the plasma and urine samples of rabbits were evaluated by high-performance liquid chromatography (HPLC). MTX loaded microspheres showed a rapid burst phase followed by a slow release phase. MTX loaded and control microspheres were biocompatible and plasma concentrations of MTX were tenfold higher in rabbits injected intra-articularly with free MTX than MTX microspheres. MTX microspheres may retain the drug in the joint by reducing clearance from the joint into the blood.

Animals↗

PubMed2005

Pharmacokinetic study of methotrexate following intra-articular injection of methotrexate loaded poly(L-lactic acid) microspheres in rabbits.

The pharmacokinetics and tissue distribution of methotrexate (MTX) were investigated following intra-articular injection of either MTX solution or controlled release MTX loaded microspheres in healthy rabbit joints. MTX solution or MTX loaded microspheres (size 30-100 mum) (10 mg MTX) was injected into the right knee joint cavity of rabbits. Blood samples were taken at predetermined times from the jugular vein. Urine samples were also collected over time periods up to 24 h. The major organs and synovial tissues were removed for analysis 6 and 24 h post-injection (n = 4). MTX and 7-OH-MTX concentrations in the plasma and major organs were determined by HPLC. The MTX plasma area under the concentration-time curve (AUC) for rabbits injected with MTX solution was seven fold higher than that of the rabbits injected with MTX microspheres, while t(1/2) and mean residence time (MRT) were not significantly different between two treatment groups. Four fold more MTX was excreted in the urine from rabbits injected with MTX solution compared to those injected with MTX loaded microspheres 24 h following intra-articular injection. The concentration of MTX in the synovial tissues following intra-articular injection was significantly higher in the rabbits injected with microspheres than in the rabbits injected with MTX solution. MTX solution was rapidly cleared from the joint cavity while MTX encapsulated microspheres retained MTX in the joint cavity.

Alanine Transaminase↗

PubMed1989

Oral mucositis and salivary methotrexate concentration in intermediate-dose methotrexate therapy for children with acute lymphoblastic leukemia.

The relationship between salivary methotrexate (MTX) concentration and severity of oral mucositis after administration of MTX was investigated in six children with acute lymphoblastic leukemia. They received two administrations of MTX at 500 mg/m2 with one third given bolusly and the remainder by 24-hour continuous infusion. No significant difference among patients or administration session was observed in serum MTX concentration. Detectable concentrations of salivary MTX (greater than 0.01 microM) were observed during nine of the ten infusions. A concentration of 0.1 microM or more, apparently lasting at least 12 hours, was observed during one infusion and followed by severe mucositis. During two of the ten infusions for different patients, concentrations of 0.04 to 0.07 microM and 0.02 to 0.04 microM, apparently lasting at least 12 and 18 hours, respectively, were observed, followed by moderate mucositis. During the other seven infusions, either much shorter or no increase in salivary MTX concentration was observed, with only mild or no subsequent mucositis. Analysis by Kendall's rank method showed a statistical correlation between concentration at 6 hours of infusion and severity of oral mucositis. The findings suggest that the early secretion of MTX into saliva has a significant role in the development of oral mucositis in leukemic children.

Child↗

PubMed1994

Methotrexate content in squamous cell carcinoma of the head and neck after low-dose methotrexate.

Eleven patients with squamous carcinoma of the head and neck who were scheduled for surgical resection or endoscopic biopsy of tumor received 15 mg/m2 of methotrexate (MTX). Samples of tumor, normal mucosa, and plasma were obtained at surgery or endoscopy, 18-24 hours after the last MTX dose. Tissue content and plasma concentration of MTX and folate were measured using sequential radioligand-binding assays. Median MTX content was 50.0 pmol/g wet weight in tumor, 19.0 in normal mucosa, and < 0.5 nM (pmol/ml) in plasma. Since dihydrofolate reductase (DHFR) content of human tumors has previously been shown to be less than 5 pmol enzyme/g wet weight, tumor MTX content exceeded expected DHFR content in all but one patient. These data support the concept that low doses of MTX saturate tumor DHFR and that, in this regard, dose escalation may have limited value.

Administration, Oral↗

PubMed1994

Plasma and urine levels of methotrexate and 7-hydroxymethotrexate in children with ALL during maintenance therapy with weekly oral methotrexate.

A new high-performance liquid chromatographic assay was used to determine methotrexate (MTX) and its main metabolite, 7-hydroxymethotrexate (7-OH-MTX), in the plasma (n = 17) and urine (n = 14) of children (age 3-12 years) on maintenance therapy for acute lymphocytic leukemia (n = 14) or non-Hodgkin's lymphoma (n = 3). Each child received oral doses of weekly MTX (4.0-29 mg/m2) and daily 6-mercaptopurine (40-111 mg/m2). Plasma samples were collected daily from two children during the 1-week dose interval. A limited sampling strategy was designed, whereby 2 days of blood sampling were used in the other 15 patients. Morning urine samples were collected daily for 1 week following MTX intake from 14 of the children. MTX was detectable in all plasma and urine samples for the entire dose interval. The main metabolite, 7-OH-MTX, could be detected in plasma and urine from all patients on the first day after dose intake but only in a few patients during the whole dose interval. Interpatient variability of MTX and 7-OH-MTX levels was high at all points during the week. Significant correlation were found between the urinary MTX levels on days 2 and 7 and plasma MTX levels on day 2 after intake. No significant correlation was found between drug levels in plasma or urine and liver function tests in the children showing signs of mild liver injury. This assay provides a tool for further studies on the role of pharmacokinetics for the clinical effects of weekly oral low-dose MTX given alone or in combination with 6-mercaptopurine.

Administration, Oral↗

PubMed2004

Correlation of cerebrospinal fluid beta-glucuronidase activity with plasma methotrexate concentrations in leukemic children receiving high-dose methotrexate.

BACKGROUND: The activity of lysosomal enzymes is increased in body fluids during inflammation, in which cellular malfunction and cellular death occurs. Because chemotherapy also causes cell malfunction and death, for identifying a neurologic effect, we studied the activity of beta-glucuronidase in the cerebrospinal fluid (CSF) of leukemic children during treatment. PROCEDURE: The beta-glucuronidase activity in CSF was determined in 13 patients with B-precursor acute lymphoblastic leukemia (ALL) treated with the medium risk arm of ALL Berlin-Frankfurt-Munster (BFM) 95 protocol. Plasma methotrexate (MTX) levels were determined at 24 and 48 hr after the infusion of high-dose (5 g/m(2)/24 hr) MTX (MCA phase). RESULTS: The mean (SD) beta-glucuronidase activity prior to the onset of chemotherapy was 19.9 (5.6) nmoles/4-methylumbelliferone/ml/hr. No significant changes in activity were noted during the phases of the protocol except of the MCA3. The activity was 24.4 (6.8) on MCA2, 28.4 (9.3) on MCA3, and 24.1 (9.5) on MCA4. The beta-glucuronidase activity was positively correlated with the plasma MTX levels at both 24 hr (r = 0.483, P = 0.006) and 48 hr (r = 0.676, P < 0.0001). No progressive changes were noted during the different phases of the protocol. The greatest beta-glucuronidase activity was measured in two patients with neurotoxicity. CONCLUSIONS: The beta-glucuronidase activity is increased in the CSF of leukemic children receiving high-dose MTX and particularly in neurotoxicity. It is positively correlated with plasma MTX levels. No cumulative effect of the chemotherapy was observed. The increased beta-glucuronidase activity is most likely due to enzyme leakage through the cell membranes caused mainly by a toxic effect of MTX on the cells of the central nervous system (CNS).

Biomarkers↗

PubMed2004

High-dose methotrexate therapy of childhood acute lymphoblastic leukemia: lack of relation between serum methotrexate concentration and creatinine clearance.

BACKGROUND: The objectives of this study were: (1) to analyze the relation of serum methotrexate (MTX) concentration with creatinine clearance, (2) to compare the leucovorin rescue dose administered to the patients based on creatinine clearance, with the one calculated according to serum MTX levels, and (3) to determine MTX-related toxicity. PROCEDURE: Thirty children with high-risk non-B acute lymphoblastic leukemia (ALL) treated according to the national protocol (PINDA 92) based on ALL BFM 90, were randomized to receive consolidation with four doses of either 1 or 2 g/m(2) MTX as a 24-hr infusion, at 2-week intervals (group M1 and M2, respectively). Serum MTX concentrations were measured at 24, 42, and 48 hr after beginning the infusion and were analyzed retrospectively. The creatinine clearance was calculated after 12-hr intravenous hydration prior to each MTX dose. Leucovorin dosage was adjusted according to creatinine clearance. RESULTS: Serum MTX concentrations at 24, 42, and 48 hr after starting the infusion were not related to creatinine clearance in both treatment groups. Leucovorin rescue administered according to creatinine clearance was excessive in 43% in group M1 and in 51% in group M2, as compared to the dose calculated according to serum MTX levels. No serious clinical complications were observed. CONCLUSIONS: These results suggest that creatinine clearance is not a good parameter to calculate leucovorin rescue. MTX-related toxicity in this group of patients receiving a dose of 1 or 2 g/m(2) and rescued with leucovorin without monitoring serum MTX levels was acceptable.

Adolescent↗

PubMed1985

Conjugation of methotrexate to IgG antibodies and their F(ab)2 fragments and the effect of conjugated methotrexate on tumor growth in vivo.

Methotrexate (MTX) was first conjugated to antibovine serum albumin IgG (antiBSA) or its F(ab)2 fragment to define conditions for retention of drug and antibody activity. With identical drug: protein molar ratios, incorporation in the F(ab)2 fragment was lower than in intact antiBSA, an observation consistent with analysis of the number of lysine residues (22 in F(ab)2 compared to 40 in antiBSA). In either case, up to approximately 10 mol MTX could be incorporated per mol protein, with recovery of 70% of the protein. At an incorporation ratio of 6 mol MTX per mol protein, MTX-antiBSA retained 100% of antibody activity and MTX-F(ab)2-antiBSA retained 75%. MTX-antiBSA and MTX-F(ab)2antiBSA were equally potent in vitro inhibitors of dihydrofolate reductase. Conjugates prepared from antiEL4 IgG (AELG) and from F(ab)2AELG significantly increased survival in EL4 lymphoma-bearing mice compared with mice receiving equal amounts (5 mg MTX/kg) of free MTX, MTX linked to the F(ab)2 fragment of normal rabbit IgG, or a simple mixture of MTX and F(ab)2AELG. MTX-AELG at this dose level produced longer survival than MTX-F(ab)2AELG (0.005 less than P less than 0.01).

Animals↗

PubMed1984

Methotrexate-vindesine association in the treatment of head and neck cancer influence of vindesine on methotrexate's pharmacokinetic behavior.

Determination of methotrexate (MTX) kinetics after an IV bolus (50 mg/m2) allows prediction of the steady-state plasma level of this drug during a constant infusion. This prediction allows high-dose MTX (HD-MTX) therapy without major toxicity. Patients with head and neck carcinoma received HD-MTX and vindesine (VDS) infusions concomitantly. The therapeutic survey of these patients showed that the predicted plasma level of MTX was not achieved in the presence of VDS. Moreover, the computed dose of MTX had to be increased by a larger amount if the MTX plasma clearance after the identification IV push was low (less than 9 l/h). In the presence of VDS, the creatinine clearance is lower than when MTX is infused alone, and MTX renal elimination is identical (MTX or MTX + VDS infusions). Thus it seems that the decrease of the MTX plasma level during MTX-VDS infusion could be due to an increase of cellular incorporation.

Adult↗

PubMed1986

Inhibitory effect of bile salts on the enterohepatic circulation of methotrexate in the unanesthetized rat: inhibition of methotrexate intestinal absorption.

The effect of conjugated and unconjugated bile salts on the intestinal absorption of methotrexate (MTX) in the unanesthetized rat was investigated using a recycling perfusion technique. We initially determined the general characteristics of MTX absorption in vivo. Absorption of low (0.5 microM) and high (6 microM) concentrations of MTX was linear with time for 60 min perfusion and occurred at rates of 0.2 and 1.65 nmol/100 cm dry length/min, respectively. Absorption of 0.5 microM MTX was pH-dependent and increased with decreasing perfusate pH. Absorption of MTX involves two processes: (1) a saturable process with a Kt of 0.98 microM, and (2) a nonsaturable diffusion process. The unconjugated deoxycholate and the conjugated taurocholate inhibited the intestinal absorption of 1 microM MTX in a concentration-dependent manner. The inhibitory effect of bile salts was reversible, and was not due to damage to the intestinal mucosa. The structural analogues folic acid and 5-methyltetrahydrofolate and the organic anions rose bengal and sulfobormophthalein were also inhibitory to MTX absorption. This study demonstrates that a variety of organic anions inhibit MTX intestinal absorption. The possible therapeutic importance of this observation is discussed.

Animals↗