Intranasal vitamin B12 administration in elderly patients: A randomized controlled comparison of two dosage regimens.

AIM: Vitamin B12 deficiency is common in the elderly population. Standard treatment via intramuscular injections, however, has several disadvantages. Safer and more convenient dosage forms such as intranasal are therefore being explored. This study compares the effects of two intranasal vitamin B12 dosage regimens in elderly vitamin B12-deficient patients. METHODS: Sixty patients ≥65 years were randomly assigned to either a loading dose (daily administration for 14 days followed by weekly administration) or a no loading dose (administration every 3 days) regimen for 90 days. Each dose contained 1000 µg cobalamin. Total vitamin B12, holotranscoblamin (holoTC), methylmalonic acid (MMA) and total homocysteine (tHcy) levels in serum were measured on days 0, 7, 14, 30, 60 and 90. RESULTS: Both dosage regimens resulted in a rapid increase of vitamin B12 and holoTC concentrations and normalization of initial high, MMA and tHcy concentrations. The loading dose regimen resulted in the fastest and greatest increase to a median vitamin B12 of 1090 pmol/L (reference 350-650 pmol/L) concentration after 14 days. Following weekly administration, B12 rapidly decreased to a median concentration of 530 pmol/L after 90 days. The no loading dose regimen resulted in a steady increase to a median vitamin B12 of 717 pmol/L after 90 days. CONCLUSIONS: Intranasal vitamin B12 administration is an effective and suitable way to replenish and sustain vitamin B12 levels in elderly patients.

Fixed-dose enoxaparin after bariatric surgery: the influence of body weight on peak anti-Xa levels.

INTRODUCTION: There is lack of data on the pharmacodynamics of low-molecular-weight heparins in obese patients. BACKGROUND: The aims of this study are to investigate the correlation between anti-factor Xa (anti-Xa) levels and body weight with fixed-dose enoxaparin after bariatric surgery and to investigate the percentage of patients that reach the desired prophylactic range for anti-Xa levels. METHODS: Blood for anti-Xa peak levels measurement was drawn 3-5 h after administration of enoxaparin at the planned visit 8-16 days after surgery. Patients were included in three categories: <110 kg (group 1), 110-150 kg (group 2), and >150 kg (group 3). RESULTS: Fifty-one patients were included (43.9 ± 9.9 years, 75% women). Mean anti-Xa level was 0.37 ± 0.14 IU/ml. This level was the highest in group 1 (0.47 ± 0.13 IU/ml) and lowest in group 3 (0.23 ± 0.07). No subprophylactic (<0.2 IU/ml) anti-Xa levels were detected in group 1, whereas this was observed in 38% in patients in group 3. Supraprophylactic levels (>0.5 IU/ml) were most often present in group 1 (36%). With multivariable regression analysis, body weight (ß -0.720 (95 % confidence interval -.717; -.993), p < 0.001) was an independent predictor of anti-Xa levels, whereas lean body was not independently associated. This was confirmed in a non-linear mixed effects analysis of the data. CONCLUSIONS: Patients with excessive body weight may not be adequately treated with fixed-dose enoxaparin thromboprophylaxis while patients with lower body weight may have an increased bleeding risk. Body weight is a better predictor of anti-Xa levels compared to lean body weight.

Dendritic cells require multidrug resistance protein 1 (ABCC1) transporter activity for differentiation.

Dendritic cells (DC) express the ATP-binding cassette (ABC) transporters P-glycoprotein (ABCB1) and multidrug resistance protein 1 (MRP1; ABCC1). Functionally, both these transporters have been described to be required for efficient DC and T cell migration. In this study, we report that MRP1 activity is also crucial for differentiation of DC. Inhibition of MRP1, but not P-glycoprotein, transporter activity with specific antagonists during in vitro DC differentiation interfered with early DC development. Impaired interstitial and Langerhans DC differentiation was characterized by 1) morphological changes, reflected by dropped side scatter levels in flow cytometric analysis and 2) phenotypic changes illustrated by maintained expression of the monocytic marker CD14, lower expression levels of CD40, CD86, HLA-DR, and a significant decrease in the amount of cells expressing CD1a, CD1c, and Langerin. Defective DC differentiation also resulted in their reduced ability to stimulate allogeneic T cells. We identified the endogenous CD1 ligands sulfatide and monosialoganglioside GM1 as MRP1 substrates, but exogenous addition of these substrates could not restore the defects caused by blocking MRP1 activity during DC differentiation. Although leukotriene C(4) was reported to restore migration of murine Mrp1-deficient DC, the effects of MRP1 inhibition on DC differentiation appeared to be independent of the leukotriene pathway. Though MRP1 transporter activity is important for DC differentiation, the relevant MRP1 substrate, which is required for DC differentiation, remains to be identified. Altogether, MRP1 seems to fulfill an important physiological role in DC development and DC functions.

Multidrug-resistant tumor cells remain sensitive to a recombinant interleukin-4-Pseudomonas exotoxin, except when overexpressing the multidrug resistance protein MRP1.

Tumor cells may become resistant to conventional anticancer drugs through the occurrence of transmembrane transporter proteins such as P-glycoprotein (ABCB1), breast cancer resistance protein (ABCG2), or members of the multidrug resistance-associated protein family (MRP1-MRP5; ABCC1-ABCC5). In this report, we studied whether tumor cells that are cytostatic drug resistant because of overexpression of one of the above mentioned proteins are sensitive to a new anticancer agent, interleukin-4 toxin (IL-4 toxin). IL-4 toxin is a fusion protein composed of circularly permuted IL-4 and a truncated form of Pseudomonas exotoxin (PE) [IL-4(38-37)-PE38KDEL]. Ninety-six-h cytotoxicity assays and 10-day clonogenic assays showed that drug-selected multidrug resistant (MDR) tumor cells that overexpress P-glycoprotein or breast cancer resistance proteins are still sensitive to IL-4 toxin. Also, tumor cells transfected with cDNA for MRP2-5 showed no resistance, or marginal resistance, only to the toxin as compared with the parent cells. In contrast, MRP1-overexpressing cells, both drug selected and MRP1 transfected, are clearly resistant to IL-4 toxin with resistance factors of 4.3 to 8.4. MRP1-overexpressing cells were not resistant to PE itself. IL-4 toxin resistance in MRP1-overexpressing cells could be reversed by the MRP1 inhibitors probenecid or MK571 and were not affected by glutathione depletion by DL-buthionine-S,R-sulfoximine. In a transport assay using plasma membrane vesicles prepared from MRP1-overexpressing cells, IL-4 toxin and IL-4, but not PE, inhibited the translocation of the known MRP1 substrate 17beta-estradiol 17-(beta-D-glucuronide) (E(2)17betaG). These data suggest that MRP1-overexpressing cells are resistant to IL-4 toxin because of extrusion of this agent by MRP1. Still, the results of this study demonstrate that IL-4 toxin effectively kills most MDR tumor cells and, therefore, represents a promising anticancer drug.