Comparison of everolimus QMS immunoassay on Architect ci4100 and liquid chromatography/mass spectrometry: lack of agreement in organ-transplanted patients.

BACKGROUND: Liquid chromatography with mass spectrometry (LC-MS/MS) is the method of choice for the determination of everolimus whole blood concentrations but is not always available. Therefore, immunoassays have been developed for clinical monitoring of everolimus. In previous studies, the Quantitative Microsphere System (QMS) immunoassay had a positive bias compared with LC-MS/MS, but was judged acceptable, although clinical agreement (eg, 95% limits of agreement) was not reported. The objective of this study was to assess whether the agreement between the QMS assay and an LC-MS/MS method was clinically acceptable for use interchangeably in therapeutic everolimus monitoring. METHODS: Whole blood samples from organ-transplanted patients on everolimus therapy were analyzed by both QMS (on Architect ci4100 analyzer) and LC-MS/MS. Paired results were compared using paired Student t test, Bland-Altman plots, and Deming regression analysis. The proportions of falsely supratherapeutic and subtherapeutic results on the QMS assay compared with the LC-MS/MS were calculated. RESULTS: Among 250 samples (169 patients), mean everolimus concentrations determined by LC-MS/MS and QMS assays were 4.8 ± 2.1 ng/mL and 6.3 ± 2.1 ng/mL, respectively (P < 0.001), with 95% lines of agreement between -2.1 and 5.2 ng/mL, a range corresponding to 152% of the mean concentration. When stratified by the type of transplant, a similar positive bias was found in each subgroup (all P < 0.014). Sixty-nine percent of the samples yielding supratherapeutic concentrations (>8 ng/mL) on the QMS assay were within the therapeutic range on the LC-MS/MS. CONCLUSIONS: The everolimus QMS immunoassay, using the Architect ci4100 analyzer, had a significant positive bias compared with LC-MS/MS, with a wide range between the limits of agreement. The lack of agreement may result in inadequate everolimus dose adjustments, suggesting that the QMS assay cannot be used interchangeably with the LC-MS/MS method for therapeutic everolimus monitoring in organ-transplanted patients.

Busulfan use in hematopoietic stem cell transplantation: pharmacology, dose adjustment, safety and efficacy in adults and children.

Busulphan (1, 4-bis [methanesulfonyl-y] butane) is a bi-functional alkylating agent that, in combination with cyclophosphamide, has been commonly used in conditioning regimens before hematological stem cell transplantation (HSCT) for nearly 20 years. Busulfan has a very narrow therapeutic index, and acute toxicity may be related to absorption and disposition of the drug and metabolites. Precise delivery of the oral formulation is compromised by erratic gastrointestinal absorption, particularly in infants and small children. An intravenous busulfan formula was approved nearly 40 years after the approval of the oral formulation. Busulfan levels expressed as the area under the concentration-time curve (AUC) higher than 1500 microM* minute were reported to increase the risk of developing veno-occlusive disease (VOD), while low levels may result in engraftment failure or disease relapse. VOD occurs in 11-40% of patients undergoing HSCT and is associated with death in 3.3% of patients. Measurement of individual plasma busulfan levels during oral or intravenous dosing to obtain an AUC is likely to provide the necessary elements to monitor the drug disposition, ensuring efficacy and preventing toxicity of patients undergoing HSCT. It is also important to consider the busulfan drug-drug interactions and adverse drug reactions that can develop during the therapeutic process. Busulfan therapeutic drug monitoring and dose-adjustment should be performed in specialized laboratories staffed by well-trained personnel.

Pharmacokinetics of high-dose diluted lidocaine in local anesthesia for facelift procedures.

The maximal recommended local anesthetic dose of lidocaine is 7 mg/kg; higher doses are used in tumescent liposuction. The objective of this study was to characterize the pharmacokinetics of high-dose diluted lidocaine administered together with epinephrine for local anesthesia in facelift procedures. This was a prospective study of six female patients undergoing elective facelift surgery. The local anesthetic solution consisted of 0.33% lidocaine, 0.07% sodium bicarbonate, and 1:600,000 epinephrine in normal saline. Plasma lidocaine levels were determined in the course of 24 hours and were subjected to pharmacokinetic analysis. Patients' age was 58.5 +/- 8 years and weight 68.5 +/- 18.7 kg. Mean lidocaine dose was 21.6 +/- 3.6 mg/kg (range, 17.5-26.3 mg/kg) infiltrated subcutaneously over 20 minutes or less. No lidocaine-related adverse effects were recorded. Major bleeding was not observed. Postoperative analgesia was required only at 11.8 +/- 4.6 hours after surgery. Pharmacokinetic analysis was peak concentration 1.41 +/- 0.4 microg/mL, time to reach peak concentration 9.3 +/- 1.6 hours, terminal half-life 6.2 +/- 1.5 hours, area under the curve from time zero to last data point 1379.8 +/- 470 microg/min/mL, and area under the curve from time zero to infinity 1530.6 +/- 471.6 microg/min/mL. Plasma lidocaine concentrations formed almost a plateau between 2 and 12 hours (ie, at approximately 1.2 microg/mL) after infiltration. It is concluded that local anesthesia with diluted lidocaine at a dose 3.1 times higher than the currently recommended dose (7 mg/kg) administered with epinephrine yielded a peak plasma lidocaine level that was 72% below the level considered safe (5 microg/mL).

Anti-cyclic citrullinated protein antibodies as a predictor of response to anti-tumor necrosis factor-alpha therapy in patients with rheumatoid arthritis.

OBJECTIVE: . The treatment of rheumatoid arthritis (RA) has changed dramatically with the introduction of anti-tumor necrosis factor (TNF) agents. Unfortunately, a subset of patients have partial or no response. No measurements were found to predict the efficacy of this therapy. Anti-cyclic citrullinated protein antibodies (anti-CCP) are highly specific and sensitive for RA, and their titer correlates with erosive disease. We investigated the correlation between the efficacy of infliximab therapy and the titer of anti-CCP. METHODS: Thirty consecutive seropositive patients with RA were treated with infusion of 3 mg/kg infliximab on Weeks 0, 2, 6, and 14. Clinical assessment and blood withdrawal were done before each treatment, i.e., at the minimal concentration of the drug. Disease activity was assessed by DAS28 score and by interleukin 6 (IL-6) level. Anti-CCP titer was measured by a commercial ELISA at Week 0 and Week 14. RESULTS: At baseline, 24 patients were positive for anti-CCP antibodies. In most patients there was a significant correlation between clinical response to therapy and anti-CCP titer. The results were especially noteworthy in those patients who showed a sustained and significant decrease in IL-6 levels through the entire period. CONCLUSION: Anti-CCP titer and IL-6 levels might be early predictors of the efficacy of anti-TNF therapy in patients with RA.

Monitoring of occupational exposure to methylene chloride: sampling protocol and stability of urine samples.

A sampling protocol for biomonitoring of the volatile solvent methylene chloride (MeCl(2)) by analysis of urine from exposed workers was established. Storage temperature, sample volume in headspace vial (HSV), and time to sealing HSV on determination of MeCl(2) in urine were evaluated. MeCl(2) was analyzed by a solid-phase microextraction technique combined with gas chromatography. Volume of urine in HSV has no effect on MeCl(2) analysis. Delays of 30 and 60 min from collection of urine until sealing the HSV caused 14.47 +/- 6.98% and 26.17 +/- 9.57% decreases from baseline concentration, respectively. MeCl(2) concentration in spiked urine samples stored in sealed HSVs decreased on day 2 and then remained stable for 2 weeks. Refrigeration did not improve recovery although it seems to be associated with less variability. MeCl(2) in urine samples of seven exposed workers was in the range of 0.02-0.06 mg/L. Sampling of MeCl(2)-containing urine should include collection of urine in closed plastic bottles, transfer to HSV within 15 min, sealing and clamping of HSV within 15 s, and storage of HSV in refrigeration until analysis, but no longer than 2 weeks. Standard samples should be prepared on the day of test sample collection and handled under the same conditions.

A simple approximation for busulfan dose adjustment in adult patients undergoing bone marrow transplantation.

Busulfan is an alkylating agent used in preparative regimens before bone marrow transplantation (BMT). Busulfan concentrations in plasma, expressed as the area under the concentration-time curve (AUC), were reported to correlate with treatment outcome. Because busulfan is administered in 16 doses of 1 mg/kg every 6 hours for 4 days, the opportunities to "correct" the dose as a consequence of the measured AUC are limited to the 16-dosage protocol. In the present research busulfan pharmacokinetics were prospectively evaluated in 27 adult patients treated according to the above protocol by measuring the first, second, and fifth dose AUC. The pharmacokinetic analysis was based on a noncompartment model for extravascular absorption, but calculations according to a 1-compartment model gave similar results. A simple mathematical approximation allowed prediction of the AUC of the second dose from that of the first and the busulfan concentration at trough. Fifteen patients had the dose adjusted at the fourth dose to obtain an AUC within the "therapeutic window" of 950-1500 microM-min. This procedure was then validated by the measurement of the fifth dose AUC. It appears that this simple pocket calculator method allows a rapid evaluation of the need and the extent of dose adjustment and proved to be a valuable tool to improve busulfan administration in pre BMT treatment.

Lamotrigine for intractable sciatica: correlation between dose, plasma concentration and analgesia.

An open trial was conducted to study the potential efficacy of the antiepileptic agent lamotrigine in relieving the sciatic pain and the relationship between lamotrigine dosage, plasma concentration and the clinical response. Subsequent to a 1 week washout period from previous analgesics, lamotrigine dose was titrated on a weekly basis from 25 to 400mg/day and was maintained at that dose for additional 4 weeks. Spontaneous pain, the Short Form McGill Pain Questionnaire (SFMPQ), the Straight Leg Raise (SLR) test, and range of motion of the lumbar spine (leaning foreword, to the affected side) were used to assess lamotrigine efficacy. Lamotrigine plasma concentration was tested at the end of each week during the titration period and at the end of the study. Fourteen patients were enrolled in the study. All outcome measurers improved compared to baseline during the titration period, but reached a statistically significant level of improvement only at the 400mg dose. A linear correlation was found between mean lamotrigine dose, mean plasma concentration and mean weekly spontaneous pain, mean SLR and mean bending the affected side, but not with the SFMPQ score. Study results suggest lamotrigine is a potentially effective and safe compound for the treatment of painful lumbar radiculopathy, and that it is likely to act in a dose- and plasma concentration-dependent fashion.

N-Acetylcysteine enhances the action of anti-inflammatory drugs as suppressors of prostaglandin production in monocytes.

The anti-inflammatory effect of non-steroidal anti-inflammatory drugs (NSAIDs) is associated with inhibition of cyclooxygenase (COX), the rate-limiting enzyme responsible for the synthesis of prostaglandins. Since oxygen free radicals can act as second cellular messengers, especially to modulate the metabolism of arachidonic acid and the prostaglandin tract, it seems plausible that antioxidants might affect the production of prostaglandin by activated cells. This research is focused on the effect of the antioxidant N-acetylcysteine (NAC) on the inhibition of prostaglandin E(2) formation in activated monocytes by specific and non-specific COX inhibitors. We found that lipopolysaccharide-induced prostaglandin E(2) formation was significantly reduced by rofecoxib and by diclofenac, two NSAIDs. Addition of NAC to each of these drugs enhanced the effect of the NSAIDs. These results suggest that one might expect either a potentiation of the anti-inflammatory effect of COX inhibitors by their simultaneous administration with NAC, or obtaining the same anti-inflammatory at lower drug levels.