Peak Drug Levels Research Articles

Letter: dry blood spots for anti‐TNF treatment monitoring in IBD

As nicely reviewed by Chaparro et al.,1 therapeutic drug monitoring (TDM) of anti-tumour necrosis factor (TNF)-alpha monoclonal antibodies with drug level determinations at regular intervals holds the potential for predicting treatment failure and sustained response in inflammatory bowel disease patients. The currently ongoing TAXIT trial will show whether the long-term adjustment of the treatment based on infliximab levels is superior to the empiric approach.2 An easy system of blood sampling, combined with an accessible analysis method, would allow peak and intermediate drug level determinations. Using population pharmacometric analyses, an ideal trough level (window) could be predicted which would allow for dose-to-target adaptations to increase the efficacy and safety of anti-TNF treatment. We propose here an easy method via capillary puncture and dry blood spot (DBS) that avoids impracticalities associated with conventional venous sampling (e.g. extra hospital visits, processing of blood, shipment of serum, etc.) and which costs less.3 The advantages of DBS have already been recognised for use in preclinical and clinical pharmacokinetic studies with many small molecules.4 Ideally, an extraction method should be developed to elute the biopharmaceutical from the sampling paper after which the eluent can be analysed using an established method (e.g. ELISA) (Figure 1).5 To exploit the full potential of DBS, stability at different conditions should be tested and the extraction and detection method should be insensitive to the volume spotted (above a certain threshold). It is not required to have 100% recovery of the analyte for TDM (if a recalculation factor is used) as long as the extent of recovery is consistent, precise and reproducible within a concentration range (e.g. a range from 0.3 to 100 μg/mL would seem appropriate for infliximab).3 Within this range, the accuracy should lie within the predefined limits of 80–120% and the precision should not exceed 15%, except for the lower limit of quantification where it should not exceed more than 20%. In addition, blood from patients with different haematocrit levels should be investigated, as well as the impact of anti-drug antibodies on the detection of drug. To rule out errors associated with this new technique, a thorough validation is needed but we believe that it constitutes a major advantage of intermediate sampling (in between scheduled hospital visits) which is patient-friendly and would allow immediate intervention at the next dosing. Declaration of personal interests: N.V.C., S.B. and P.D. have no conflict of interests. M.F. has served as a speaker for Abbott, Janssen, MSD, Ferring, Chiesi and Tillots and as a consultant for Abbott, Janssen and MSD. P.R. has served as a speaker and a consultant for Centocor, Merck and Abbott and has received research funding from UCB, Centocor, Merck and Abbott. S.V. has served as a speaker for UCB, Abbott, MSD, Ferring, Centocor and Chiesi and has received research funding from Abbott, Centocor, MSD and UCB. A.G. has served as a speaker for Pfizer and MSD and has received research funding from Pfizer. Declaration of funding interests: This study was funded in part by the Fund for Scientific Research-Flanders, grant number G.0617.12.

Effects of ranolazine on exercise tolerance and angina frequency in patients with severe chronic angina receiving maximally-tolerated background therapy: analysis from the Combination Assessment of Ranolazine In Stable Angina (CARISA) randomized trial

Ranolazine has been previously shown to improve exercise capacity and symptoms in patients with severe chronic angina treated with standard doses of beta-blockers and calcium-channel blockers, without a significant effect on heart rate or blood pressure. The purpose of this study was to assess whether the benefit of ranolazine extends to the subgroup of angina patients treated with maximally-tolerated doses of beta-blockers or calcium blockers. In this post-hoc analysis, 258 patients from the Combination Assessment of Ranolazine In Stable Angina (CARISA) trial were considered as treated with maximally-tolerated doses of beta-blockers or calcium-channel blockers (systolic blood pressure (SBP) ≤ 100 mm Hg, and/or a resting heart rate ≤ 60 beats per minute, and/or an ECG PR interval ≥ 200 msec). Change from baseline in total exercise duration after 12 weeks compared to placebo were 34.5 (95% CI 0.8; 68.1) sec (p = 0.045) with ranolazine (750/1000 mg bid) at trough drug levels and 46.3 (13.5; 79.1) (p = 0.006) at peak drug levels. The number of angina attacks per week compared to baseline were reduced compared to placebo (-2.3 ± 0.3 vs -0.9 ± 0.6 (p < 0.001)). The effects of ranolazine 750 mg bid and 1000 mg bid were similar and the beneficial effects of ranolazine in this subgroup of maximally-treated patients were consistent with those not on maximally-tolerated doses of the background therapy. Ranolazine is effective for the symptomatic treatment of patients with stable angina on background therapy with maximally-tolerated doses of first line anti-anginal therapies.

The efficacy and safety of high-dose arbekacin sulfate therapy (once-daily treatment) in patients with MRSA infection

The efficacy and safety of once-daily high-dose arbekacin sulfate therapy for methicillin-resistant Staphylococcus aureus (MRSA) infection were evaluated, with analysis of their relationship to blood drug levels. The study was conducted in patients with pneumonia or sepsis, the cause of which was suspected to be MRSA, who were admitted to the Nagasaki University Hospital or its affiliated hospitals between January 2009 and December 2010. The initial drug dose was set at a level expected to yield the goal peak of 20 μg/ml and a trough level of less than 2 μg/ml, using the Habekacin Therapeutic Drug Monitoring analysis software. Thirteen patients were enrolled: 10 patients had pneumonia and 3 patients had sepsis. Patient mean age was 72.0 years; mean initial drug dose was 269.2 mg. Clinical efficacy at completion of treatment and bacterial eradication-reduction were achieved in 66.7% (6/9) and 62.5% (5/8) of patients, respectively. Incidence of adverse reactions was 38.5% (5/13). In analysis of efficacy in relationship to serum drug levels, the peak drug level was 22.7 ± 5.50 μg/ml, on average, and 15 μg/ml or higher in all 6 responders. Also, in patients with renal dysfunction, it seemed to be essential to ensure a certain peak drug level and to control the trough level appropriately. Although the number of patients was limited, once-daily high-dose arbekacin sulfate therapy may be highly effective, without posing any major safety problems. Further larger-scale studies are needed.

Pharmacokinetics bases of adverse drug-drug interactions

A drug reactions (ADRs) are a leading cause of morbidity and mortality. A major contributing factor to ADRs is Drug-Drug Interactions (DDIs), which often results from pharmacodynamic (PD) and pharmacokinetics (PK) changes due to co-administration of one or more therapeutic agents. Clearly, the chances of such interactions are higher in therapeutic areas requiring administration of a cocktail therapy such as that in cancer, HIV, epilepsy and CNS disorders.The PD interactions typically occur at the receptor site and may be additive, synergistic or antagonistic in nature. The PK bases for DDIs often entail changes in the activity and expression of drug metabolizing enzymes and/or transporters leading to altered ADME (absorption, distribution, metabolism and excretion) characteristics. Changes in PK parameters such as bioavailability, systemic clearance (resulting from altered hepatic, renal or biliary clearance) manifest in altered systemic exposure (peak drug levels or Cmax and the overall area under the plasma concentration-time curve or AUC). While a few DDIs are utilized for therapeutic benefit (best example is the use of ritonavir for enhancing systemic exposure of co-administered anti-retroviral drugs), most DDIs are deleterious, which require careful changes in dosing regimen and/or therapeutic monitoring, especially for narrow therapeutic index drugs. This seminar will discuss the mechanistic bases for DDIs mediated by PK alterations (induction and inhibition of enzymes and transporters), and the current status of in vitro and in vivo/clinical approaches for assessment of such interactions. Clinically relevant examples leading to adverse toxicities and measures to circumvent such toxicities will be underscored.

Comparison of the Pharmacokinetic and Pharmacodynamic Behavior of Branded and Generic Enoxaparin in Non-Human Primates

Abstract 1254 Introduction:Low molecular weight heparins (LMWHs) have been shown to be safe and effective in the prevention and treatment of venous thrombosis and in the treatment of patients with pulmonary embolism or acute coronary syndrome. Commercially available LMWHs are distinct agents in terms of their molecular weight profile and in vitro potency. Molecular weight influences the pharmacokinetics (PK) and pharmacodynamics (PD) of heparin oligosaccharides. Although there continues to be interest in developing biosimilar versions of LMWHs, defining biosimilarity for LMWHs is challenging because chemical means of measuring plasma heparin levels do not exist, potency measures typically only measure AT-dependent activities, bioequivalence in terms of one activity does not ensure identical pharmacokinetic behavior in terms of other biological activities and identification and quantification of the various oligosaccharide components in a LMWH preparation is difficult. In vitro studies have shown that biosimilar LMWHs can differ considerably from the branded product as well as from each other. In the current study, the PD behavior of branded and biosimilar enoxaparin was compared in a cross-over study following a single subcutaneous dose to non-human primates. Methods:Lovenox (lot #514956, sanofi-aventis, Paris, France) and Fibrinox (lot#0002, Sandoz S.A., Buenos Aires, Argentina) were obtained in pre-filled syringes at a concentration of 100 mg/ml. Upon anesthesia, the non-human primates (Macaca mulatta) were weighed and a baseline blood sample was collected. A site on the abdomen was shaved and cleansed prior to the subcutaneous administration of LMWH. Blood samples were collected at 1, 4, 6 and 28 hours post-administration and were centrifuged to make platelet poor plasma which was stored in aliquots at −70°C until analysis. Primates were randomly dosed with one of the two test agents. After a minimum of one week wash-out, the same primates were dosed with the other test agent. Plasma samples were evaluated using clot-based and amidolytic assays. LMWH concentrations in the blood samples were determined by extrapolation from in vitro concentration-response curves and used to calculate values for PK parameters. p-values < 0.05 determined by two-way repeated measures analysis of variance were considered to be statistically significant. Results:LMWH levels determined by circulating anti-Xa activity following Fibrinox and Lovenox administration were not observed to be significantly different. Circulating anti-IIa levels, however, were significantly higher in Lovenox-treated animals at 1, 4 and 6 hours post-administration. Using the Heptest assay, higher circulating drug levels were measured in Fibrinox-treated animals at 4 and 6 hours. A high degree of variability was observed in the absorption and elimination of the LMWHs. Statistically significant differences in pharmacokinetic behavior was not observed when circulating drug concentrations were determined using anti-Xa activity or Heptest prolongation. Using drug concentrations determined from anti-IIa activity, the AUC following Lovenox treatment was significantly larger than following Fibrinox treatment. Plotting mean drug levels based on anti-IIa activity versus mean drug levels based on anti-Xa activity at the various sample times indicated a hysteretic relationship which was distinct for Fibrinox and Lovenox-treated primates. Clear differentiation of the two LMWHs was also observed when drug levels measured by anti-IIa activity were plotted against those determined using the prolongation of the Heptest. Conclusions:Potency of LMWHs can be expressed in terms of a number of AT-dependent and AT-independent activities, which may not be proportional. The PK/PD behavior of LMWHs is different when drug levels are determined using distinct biologic activities. The measured concentration of a drug and its corresponding effect can be asynchronous, that is, peak drug levels may not occur at the same time as peak effect levels. In this study, plotting drug concentrations determined by one functional parameter against those derived from a different parameter provided clear visual evidence that the two LMWHs tested exhibit distinct pharmacodynamic behavior. In vivo behavior is an important consideration for defining pharmacoequivalence of complex biologic drugs. Disclosures:No relevant conflicts of interest to declare.

Oral Administration of Low-Dose Decitabine and Tetrahydrouridine In Combination Increases Fetal Hemoglobin to Therapeutic Levels In the Absence of Cytotoxicity and Reduces Inter-Individual Drug Bioavailability In Baboons

Abstract 2147Increased fetal hemoglobin (HbF) levels alleviate the symptoms and improve survival of patients with sickle cell disease and β-thalassemia. Because therapeutic options remain limited for a large group of patients refractory to hydroxyurea (HU) therapy, alternative therapeutic agents to increase HbF are urgently needed. Decitabine (DAC) increases HbF to therapeutic levels in sickle cell disease patients refractory to HU. Oral administration of DAC would ease administration, increase compliance, and lower costs. Previous studies showed that oral administration of high doses of DAC increased HbF levels in baboons (Lavelle et al Am J Hematol 82:981, 2007). The oral bioavailability of DAC is limited by the degradative action of cytidine deaminase (CDA), and patients with CDA polymorphisms associated with reduced CDA activity may exhibit increased risk of cytotocity. We hypothesized that oral administration of low-dose DAC in combination with the CDA inhibitor THU would improve the DAC concentration-time profile while avoiding high peak drug levels likely to cause DNA damage and cytotoxicity and reduce risks of cytotoxicity in patients with CDA polymorphisms. Pharmacokinetics (PK) analysis in six baboons following oral administration of high-dose DAC alone showed that a dose (10mg/kg) previously shown sufficient to induce maximal (62.3–72%) HbF levels in 3 of 5 baboons when administered daily for ten days was associated with a mean AUC value of 355min*ng/ml. PK analysis following administration of varying doses of DAC in combination with THU showed that this AUC of 355min*ng/ml was attained with a 0.5 mg/kg DAC dose administered orally in combination with THU. The effect of oral low-dose DAC in combination with THU on HbF was then evaluated in four baboons. Initially, a single baboon (7482) was treated at 0.5mg/kg/d 3X/week for 3 weeks followed by 2X/week for an additional 5 weeks. Three additional baboons (7484, 7472, and 7470) were treated with either 0.25 or 0.5mg/kg/d 2X/week for eight weeks. Results (Table 1) showed significant increases in HbF associated with modest decreases in ANC and increases in platelets in all animals.AnimalDecitabine dose (mg/kg/d)SchedulePre-treatment HbF (%)Maximal HbF (%)ΔHbFANC nadirPlt max(x103)74820.53Xwk/3wks 2Xwk/5wks3.523.820.32580100474840.52Xwk/8wks4.223.118.91680102974720.252Xwk/8wks12.830.117.3146060074700.252Xwk/8wks9.929.319.42130895Decreased DNA methylation in the 5’ γ-globin gene region was observed in post-treatment BM samples by quantitative MassARRAY DNA methylation analysis. PK analysis showed that DAC bioavailability following oral administration of high-dose DAC alone differed 33 fold between 7470 and 7484 but only 1.3 fold following oral administration of low-dose DAC in combination with THU. Thus co-administration of low-dose DAC with THU reduced inter-individual variability of drug bioavailability and this was consistent with the similar HbF responses observed in these animals. Importantly, the ability of oral low dose DAC-THU to increase HbF to similar levels in the absence of cytotoxicity in two baboons differing in DAC bioavailability following oral administration of high-dose DAC alone predicts that oral low-dose DAC-THU in combination will reduce risks of cytotoxicity in patients with differences in DAC bioavailability due to CDA polymorphisms. These experiments have determined a dose and schedule of oral low-dose DAC in combination with THU that effectively increases HbF to therapeutic levels in the absence of cytotoxic effects in baboons and thus provide critical information important for the design of a future clinical trial of this drug combination in patients with sickle cell disease refractory to hydroxyurea therapy. Disclosures:No relevant conflicts of interest to declare.

Comparison of pharmacokinetics of the limus‐eluting stents in Japanese patients

The aim of this study was to compare the pharmacokinetics of the four limus-eluting stents used in Japanese patients. There are presently no reports comparing human pharmacokinetics among drug-eluting stents (DESs). We retrospectively analyzed data from pharmacokinetic studies of patients implanted with an 18-mm DES: Cypher stent (sirolimus, n = 10), Endeavor stent (zotarolimus, n = 7), Xience V stent (everolimus, n = 6), and Nobori stent (biolimus A9, n = 10), in multicenter trials of Japan. Total drug doses of the Cypher stent, Endeavor stent, Xience V stent, and Nobori stent were 150, 180, 88, and 293 μg, respectively. Drug concentrations were measured in serial whole blood samples after implantation and the pharmacokinetics were analyzed. Mean peak drug levels were 0.86 ng mL(-1) for Cypher, 1.80 ng mL(-1) for Endeavor, 0.50 ng mL(-1) for Xience V, and 0.09 ng mL(-1) for Nobori. After adjustment for the loaded dose, mean peak drug levels of the Cypher and Xience V stents were similar (0.0057 ng mL(-1) μg(-1) each) while the Endeavor (0.0100 ng mL(-1) μg(-1)) was higher, and the Nobori (0.0003 ng mL(-1) μg(-1)) was lower, compared with the Cypher and Xience V stents. The other pharmacokinetic parameters of four DESs differed according to characteristics of the coated drug. The systemic exposure of biolimus A9 was much lower than that of the other DESs studied. In Japanese patients, systemic exposure was low, regardless of the type of limus drug eluted from the stents; but specific pharmacokinetic activities were varied according to the drug characteristics, concentration, and DES design.

Epigenetic regulation by decitabine of melanoma differentiation in vitro and in vivo.

Apoptosis genes, such as TP53 and p16/CDKN2A, that mediate responses to cytotoxic chemotherapy, are frequently nonfunctional in melanoma. Differentiation may be an alternative to apoptosis for inducing melanoma cell cycle exit. Epigenetic mechanisms regulate differentiation, and DNA methylation alterations are associated with the abnormal differentiation of melanoma cells. The effects of the deoxycytidine analogue decitabine (5-aza-2'-deoxycytidine), which depletes DNA methyl transferase 1 (DNMT1), on melanoma differentiation were examined. Treatment of human and murine melanoma cells in vitro with concentrations of decitabine that did not cause apoptosis inhibited proliferation accompanied by cellular differentiation. A decrease in promoter methylation, and increase in expression of the melanocyte late-differentiation driver SOX9, was followed by increases in cyclin-dependent kinase inhibitors (CDKN) p27/CDKN1B and p21/CDKN1A that mediate cell cycle exit with differentiation. Effects were independent of the TP53, p16/CDKN2A and also the BRAF status of the melanoma cells. Resistance, when observed, was pharmacologic, characterized by diminished ability of decitabine to deplete DNMT1. Treatment of murine melanoma models in vivo with intermittent, low-dose decitabine, administered sub-cutaneously to limit high peak drug levels that cause cytotoxicity and increase exposure time for DNMT1 depletion, and with tetrahydrouridine to decrease decitabine metabolism and further increase exposure time, inhibited tumor growth and increased molecular and tumor stromal factors implicated in melanocyte differentiation. Modification of decitabine dose, schedule and formulation for differentiation rather than cytotoxic objectives inhibits the growth of melanoma cells in vitro and in vivo.

Reversal of long-term methamphetamine sensitization by combination of pergolide with ondansetron or ketanserin, but not mirtazapine

Psychostimulant abuse represents a psychiatric disorder and societal concern that has been largely unamenable to therapeutic interventions. We have previously demonstrated that the 5-HT 3 antagonist ondansetron or non-selective 5-HT 2A/2C antagonist ketanserin administered 3.5 h following daily pergolide, a non-selective DA agonist, reverses previously established cocaine sensitization. The present study was conducted to evaluate whether the same treatments or delayed pairing of pergolide with the antidepressant mirtazapine can also reverse consolidated methamphetamine (METH) behavioral sensitization. Sprague-Dawley rats received METH infusion via osmotic minipumps (25 mg/kg/day, s.c.) for 7 days, with accompanying daily injections of escalating METH doses (0–6 mg/kg, s.c.). This regimen takes into account the faster elimination of METH in rats, and is designed to replicate plasma METH concentrations with superimposed peak drug levels as observed during METH binging episodes in humans. Following a 7-day METH withdrawal, ondansetron (0.2 mg/kg, s.c.), ketanserin (1.0 mg/kg, s.c.), or mirtazapine (10 mg/kg, i.p.) was administered 3.5 h after pergolide injections (0.1 mg/kg, s.c., qd) for 7 days. Behavioral sensitization as a model of METH abuse was assessed 14 days after the combination treatment cessation (i.e., day 28 of METH withdrawal) through an acute challenge with METH (0.5 mg/kg, i.p.). Pergolide combined with ondansetron or ketanserin reversed METH behavioral sensitization, but pergolide–mirtazapine combination was ineffective. The role of reactivation of addiction “circuit” by a non-selective DA agonist, and subsequent reconsolidation blockade through 5-HT 3 or 5-HT 2 antagonism in reversal of METH sensitization and treatment of METH addiction is discussed.

Tetrahydrouridine Co-Administration Improves Oral Bioavailability and Dampens Inter-Individual Variability of Decitabine Pharmacokinetics In Baboons

AbstractAbstract 2081The cytosine analogue decitabine binds and depletes the chromatin modifying enzyme DNA methyl-transferase 1 (DNMT1), thereby modifying cellular epigenetics and differentiation. An oral formulation of decitabine would potentially increase the time-above-threshold concentration for depleting DNMT1 while avoiding high peak drug levels that cause DNA damage/cytotoxicity, facilitating outpatient epigenetic-differentiation therapy. The enzyme cytidine deaminase (CDA) is the major barrier to oral absorption and furthermore, causes significant inter-individual variability in decitabine pharmacokinetics. Since there is a narrow therapeutic window for depleting DNMT1 without causing cytotoxicity, decreasing inter-individual variability and improving the predictability of dose-pharmacokinetic relationships is important to the objective of non-cytotoxic epigenetic/differentiation therapy. Therefore, we examined if combining the CDA inhibitor tetrahydrouridine (THU) with decitabine could facilitate oral administration and furthermore, decrease inter-individual variability in decitabine pharmacokinetics. Drugs were administered under ketamine/xylazine anesthesia to normal female baboons by intravenous or subcutaneous injection or oral gavage. Blood samples for pharmacokinetic (PK) analysis were drawn at 7 time-points during anesthesia. Decitabine levels were measured using LC-MS/MS. The AUClast (the area under the curve from the time of dosing to the last measurable concentration) was calculated by the linear trapezoidal method. Oral bioavailability was estimated by the ratio of AUCoral to AUCIV, following adjustment of the AUC values for the different doses administered. Minimum doses of THU (400 mg/m2, oral gavage) and decitabine (100 mg/m2, oral gavage), and optimal timing between THU and decitabine administration (60 minutes), that achieved peak levels of decitabine associated with depletion of DNMT1 without cytotoxicity in normal hematopoietic cells (0.2 – 0.5 μM) were determined. Even with AUClast being calculated over a longer period of time for the decitabine alone group (240 versus 180 minutes), the increase in AUClast in the THU group was significant per mg/kg of decitabine administered (p=0.02, Wilcoxon test) (Table 1). Oral decitabine administered 60 minutes after THU produced area under the curve (AUClast) similar to that produced by decitabine alone at double the dose, with a decrease in the inter-individual variability in pharmacokinetics observed with decitabine alone (Table 1).Table 1:The largest increases in AUClast produced by co-administration of THU occurred in baboons which had the lowest AUClast with decitabine alone, thereby decreasing inter-individual variability in decitabine pharmacokineticsAUClast (min*ng/mL)Baboon NumberWeight (kg)Decitabine 10 mg/kg aloneDecitabine 5 mg/kg aloneTHU 20 mg/kg 60 mins before Decitabine 5 mg/kgPA748212.349.98Not doneNot donePA748411.5190.35252.735621.05PA725619.8299.02Not done760.27PA747210.7327.25Not done444.825PA725414.4463Not done2587PA725519.9807.8Not done533.47PA725812.62863.6Not done2284.48PA74709.66278.781219.987515.32Mean±SD1604 ± 22622821 ± 2749Median±IQR463 ± 25652284 ± 5088Median±IQR per mg of decitabine160 ± 226457 ± 1017Fold-variation~30-fold~14-foldCoefficient of Variation14197This is the first report of oral THU in combination with oral decitabine. The significant increase in decitabine bioavailability produced by preceding THU administration may actually be larger than reported here, since AUClast estimates for THU-decitabine were calculated over 180 minutes while AUClast estimates for decitabine alone were calculated over 240 minutes to accommodate the period of allowable anaesthesia. Furthermore, the concentration-time profiles suggested that decitabine levels may have continued to increase beyond the last sampling time in some animals, moreso in the THU-decitabine group. Preceding administration of THU could facilitate oral administration of decitabine and concurrently address other limitations of decitabine therapy, including the problem of inter-individual variability, to advance towards the objective of accessible non-cytotoxic epigenetic-differentiation therapy. Disclosures:Off Label Use: FDA approved decitabine for use in MDS, therefore, its use in thalassemia is off-label. Furthermore, the dose, schedule and route of administration used is also not on the label. Decitabine was used in a study to augment production of fetal hemoglobin in an NIH sponsored trial.

Sequential phase II Southwest Oncology Group studies (S0112 and S0301) of daunorubicin and cytarabine by continuous infusion, without and with ciclosporin, in older patients with previously untreated acute myeloid leukaemia

Attempts to overcome multi-drug resistance in acute myeloid leukaemia (AML) have been limited by toxicities. To investigate the effect of reducing peak drug levels, we performed sequential phase II studies using continuous infusion daunorubicin and cytarabine without (AD) and then with ciclosporin (ADC) in older patients with AML. Untreated patients (age 56+ years) received daunorubicin (45 mg/m2 per day for 3 d) and cytarabine (200 mg/m2 per day for 7 d), both by continuous infusion, without (S0112, 60 patients) and then with (S0301, 50 patients) the addition of ciclosporin. Complete response (CR) rates were 38% on S0112 and 44% on S0301. Fatal induction toxicities occurred in 17% and 12% respectively, arising primarily from infection and haemorrhage. Median overall and relapse-free survival was 7 and 8 months for AD respectively, and 6 and 14 months for ADC. Patients with phenotypic or functional P-glycoprotein had somewhat higher CR rates with ADC than AD, although confidence intervals overlapped. In these sequential trials, continuous infusion AD produced CR rates comparable to those with bolus daunorubicin. The addition of ciclosporin did not cause undue toxicities, produced a similar CR rate, and possibly improved relapse-free survival. Further correlate analyses did not identify a subpopulation specifically benefitting from the addition of ciclosporin.

Tolterodine extended-release for overactive bladder

Overactive bladder (OAB) is a common problem. Affected individuals suffer decreased quality of life and productivity. The mainstay of pharmacological treatment of OAB is antimuscarinic agents. Tolterodine was the first antimuscarinic drug designed specifically for treating OAB. Compared with the immediate-release (IR) drug, once-daily tolterodine extended-release (ER) releases the drug in a steady but constant manner lowering peak and trough drug levels. This translates to more constant serum concentrations and theoretically better patient tolerability. The dry mouth rate for the ER formulation has been reported to be lower than for the IR formulation. Recent literature strongly supports the efficacy and safety of tolterodine ER in carefully selected older men with OAB symptoms. Tolterodine ER is well tolerated and withdrawal rates are similar to those in placebo. Fesoterodine is a new antimuscarinic that shares the same active metabolite as tolterodine and may provide less pharmacokinetic variability. We support tolterodine ER for treating for OAB. It has proven efficacy and tolerability.

Acute Kidney Injury in Patients Receiving Subcutaneous Deferoxamine Therapy.

Iron chelation is an important modality in treating patients with iron overload syndromes to minimize end-organ damage. The greatest experience has been in young patients with thalassemia, but there is growing use of chelation therapy in patients with acquired transfusion-dependent disorders such as myelodysplastic syndrome. Deferoxamine is a clinically proven and effective therapy for long term chelation, but the standard mode of administration by subcutaneous pump-driven infusion is burdensome for patients and leads to poor adherence. Intermittent bolus injection (1g in 10ml of water injected subcutaneously twice daily) has been advocated as an alternative protocol that may facilitate compliance. Acute kidney injury has been described previously in patients receiving high dose intravenous deferoxamine, but not in patients receiving subcutaneous therapy, and nephrotoxicity is not listed as an adverse effect in the product monograph. Here we report a series of three patients who developed acute kidney injury when receiving subcutaneous deferoxamine by intermittent bolus injection.CASES: All three patients were elderly adults. The first was a 64 year old man who developed iron overload secondary to hemoglobin H disease, the second was a 78 year old woman with transfusion-dependent myelodysplastic syndrome (refractory anemia with ring sideroblasts), and the third was an 83 year old man with transfusion-dependent smoldering multiple myeloma. These patients had preexisting mild renal impairment: the first was a kidney transplant recipient taking cyclosporine, the second had a prior nephrectomy for renal carcinoma, and the third had longstanding renal impairment from renovascular disease. All three patients had resolution of their acute kidney injury on discontinuation of therapy and have had stable creatinine values subsequently. Rechallenge with deferoxamine led again to a reversible rise in creatinine in the first patient. The most striking effect was in the second patient: her creatinine level rose from a baseline of 154μmol/l to 280μmol/l one month after starting deferoxamine, and fell to 138μmol/l two weeks after discontinuing the drug.DISCUSSION: We conclude that renal dysfunction can be an important side effect of deferoxamine chelation. The toxicity appears to be reversible on discontinuation of therapy. Older patients and patients with pre-existing renal impairment may be more susceptible to this effect, and subcutaneous bolus dosing may increase the risk, possibly due to higher peak drug levels. Careful monitoring of creatinine values and minimization of other nephrotoxic agents is appropriate and prudent when managing iron overload syndromes with deferoxamine chelation therapy.

Comparación de dos pautas de dosificación de gentamicina en el recién nacido

Gentamicin is widely used in full-term neonates as empirical therapy for early-onset suspected or proven sepsis. Several dosing schedules for gentamicin have been recommended for this neonatal population.To compare gentamicin serum levels, efficacy and toxicity of two dosing schedules in term and preterm newborns.The study included 200 newborns who were started on gentamicin therapy. Group A (N=100) was prescribed a multiple-daily dosing regimen and Group B (N=100) on a once-daily dosing regimen. Newborns in Group A received gentamicin at 2.5-3.5 mg/kg/dose q12-18 h depending on postnatal age and serum creatinine levels, and newborns in Group B received 4-5 mg/kg/dose q24-48 h depending on postconceptional and postnatal age. All peak and trough serum drug levels, demographic data, and markers of potential nephrotoxicity and ototoxicity were compared.Peak serum gentamicin levels were significantly higher (8.2+/-0.22 microg/ml vs. 5.9+/-0.13 microg/ml; p <or= 0.001) and trough levels were significantly lower (0.9+/-0.06 microg/ml vs. 1.7+/-0.08 microg/ml; p <or= 0.001) in Group B than in Group A. There was no significant difference between the groups either in the clinical failure rate or in the nephrotoxicity or ototoxicity outcomes.Once-daily dosing regimen of gentamicin in preterm and term newborns is safe and effective, with a reduced risk of serum drug concentrations falling outside the therapeutic range.

Ocular penetration and pharmacokinetics of topical voriconazole in rabbit eyes

To investigate the penetration of topical 1% voriconazole into the cornea and aqueous humor in New Zealand white rabbits. It was a experimental study. Forty-eight healthy rabbits were randomly divided into groups A (21 cases), B (21 cases) and C (6 cases). Blank samples from group C were used to determine the essential parameters for the validation of analytical procedures. A single 50 microl drop of 1% voriconazole was administered in group A (non-debrided cornea) and group B (debrided cornea). The aqueous humor and the cornea were obtained at 2, 5, 10, 15, 30, 60 and 90 min after application. All samples were analyzed by high-performance liquid chromatography (HPLC). The HPLC system consisted of Waters 1525 pump, Phenomenex Luna C18 (250.0 mm x 4.6 mm, 5.0 microm) column, Phenomenex C18 (4.0 mm x 3.0 mm, 5.0 microm) analytical steel column and a Waters Empower data workstation. The UV detector was set to 255.0 nm. Methanol-0.04 mol/L ammonium hydroxide (62:38, V/V) was used as mobile phase and the flow rate was 0.8 ml/min. External standard was used in this assay. The pharmacokinetic parameters were calculated with nonlinear least square method by the computer. Calibration curves were linear over the range 0.1-15.0 mg/L. The concentration at 0.1 mg/L was the lowest quantified limit. The recovery of voriconazole from aqueous humor samples ranged from 91.06% to 94.80%, and ranged from 79.84% to 83.20% in the cornea samples. After single dose application, the drug concentration in aqueous humor peaked at 10 min in both group A [ (5.172 +/- 1.012) mg/L] and group B [(6.118 +/- 1.123) mg/L], and the parameters t(1/2 ke) in groups A and B were 6.859 min and 13.176 min, respectively. However, peak drug levels were achieved immediately at 2 min in the cornea [group A: (9.958 +/- 3.481) microg/g and group B: (158.476 +/- 10.462) microg/g]. The parameter t(1/2 beta) in nondebrided cornea was 94.938 min and 46.367 min in debrided corneas. Topical voriconazole exhibits excellent penetration into the cornea, and effective high drug levels are achieved in both the cornea and aqueous humor after single dose application. It can be a prominent agent for the treatment of fungal keratitis in the future.

Phase I Trial of HuLuc63 in Multiple Myeloma.

Background: HuLuc63 is a humanized monoclonal antibody directed against CS1 that has demonstrated potent in vivo and in vitro activity against myeloma cells in pre-clinical models. CS1 is a cell surface glycoprotein expressed at high levels on myeloma cells, plasma cells and to a lesser extent on a subset of CD8 + lymphocytes and natural killer (NK) cells. A Phase I study was initiated to evaluate the maximum tolerated dose (MTD) of HuLuc63 in a population of relapsed refractory multiple myeloma patients who have been exposed to at least two prior therapies. In a traditional phase 1 design, six potential dosing cohorts are planned with 3 to 6 patients enrolled per cohort to evaluate safety, pharmacokinetics (PK), biologic activity and clinical response. Each course of HuLuc63 is given IV at the same dose every 2 weeks for a total of 4 doses at a level of 0.5, 1, 2.5, 5, 10, 20 mg/kg. An additional 4 doses may be administered if the patient has demonstrated at least stable disease during the initial course of therapy. To date, a total of 7 patients have been treated at 2 dose levels; 3 in the 0.5 mg/kg cohort and 4 in the 1.0 mg/kg cohort. Median patient age is 64 years and the median number of prior therapies is five. An additional patient was enrolled in the 1.0 mg/kg cohort as a patient in that cohort had a 2-week delay in receiving his second dose due to worsening pain at the site of a pre-existing lytic bone lesion. No dose-limiting toxicities have occurred. Infusions were well tolerated, with grade 1 and 2 toxicities occurring during or after the first dose including chills (2 patients), flushing, pyrexia, rigors, dyspnea and fatigue. Patients who reported first dose reactions were pretreated with acetaminophen and diphenhydramine prior to subsequent doses and only one patient reported fatigue after the second dose. Four serious adverse events have occurred in 2 patients which were considered unrelated to HuLuc63. These include migraine headache (twice in the same patient), congestive heart failure and hypercalcemia. Two patients discontinued therapy prematurely due to progressive disease but all other patients have received 4 doses of HuLuc63. No clinical responses have been observed. In xenograft mouse models, a consistent drug level of 10 mcg / mL was required to show minimal biologic activity. Preliminary PK data reveals that peak serum drug levels for the 0.5 mg/kg dosing cohort reached 10 mcg / mL, which was sufficient to achieve CS 1 saturation of at least 70% on the antigen rich NK cell subset. Drug levels dropped below 1 mcg/mL by day 7, however, coinciding with a decrease in saturation. This indicates that the higher doses to be used in subsequent cohorts may achieve and surpass sustained concentrations in patients above this level. Thus far, HuLuc63 appears to be well tolerated in patients with multiple myeloma. Enrollment is continuing to determine the MTD.

Safety, Tolerability, Pharmacokinetics, and Aβ Levels After Short-term Administration of R-flurbiprofen in Healthy Elderly Individuals

To evaluate the safety and tolerability and pharmacokinetic properties of R-flurbiprofen (Tarenflurbil) in normal elderly individuals and to determine the effect of the drug on amyloid beta 42 (Abeta42) levels, we conducted a double-blind, placebo-controlled study of 48 healthy subjects aged 55 to 80. Three successive cohorts were randomized to doses of 400, 800, or 1600 mg/d, or placebo, given as 2 divided doses for 21 days. Blood and cerebrospinal fluid were collected for pharmacokinetic studies and measurement of Abeta levels at baseline and on day 21. R-flurbiprofen was well-tolerated at all 3 doses. The compound penetrated the blood-brain barrier in a dose-dependent manner. From baseline to 21 days, comparisons between study groups revealed no significant differences in changes of cerebrospinal fluid Abeta42 levels and no significant differences in changes of plasma Abeta42 levels at the time of trough drug level at 21 days of treatment. Further analysis of drug concentration-response for plasma samples showed that at the time of peak plasma concentration, higher plasma drug concentration was related to lower Abeta42 plasma levels (P=0.016). R-flurbiprofen had an excellent safety profile and showed dose-dependent central nervous system penetration. Exploratory analyses of plasma Abeta and peak drug levels suggested a short-term effect in plasma that warrants independent verification. The safety, tolerability, and pharmacokinetic profile of R-flurbiprofen in these older individuals support the ongoing studies of this compound in patients with Alzheimer disease.

Pharmacokinetic and safety study of subcutaneously administered weekly ING-1, a human engineered™ monoclonal antibody targeting human EpCAM, in patients with advanced solid tumors

ING-1 is a high-affinity, human engineeredtrade mark monoclonal antibody that recognizes a 40 kilodalton epithelial cell adhesion molecule (EpCAM) glycoprotein that is expressed in high levels on most adenocarcinomas and is an attractive target for immunotherapy. ING-1 was administered subcutaneously weekly at doses between 0.1 and 2 mg/kg/week. Pharmacokinetic samples were drawn during weeks 1 and 6. Fourteen patients with advanced refractory cancer received a median of 6 (range 1-9) doses of ING-1. At 1 mg/kg, a 62-year-old man with colon cancer developed reversible grade 3 pancreatitis after the third dose. His plasma ING-1 levels were similar to the other two patients dosed at 1 mg/kg. Two patients dosed at 0.6 mg/kg experienced stable disease at 6 weeks. Peak drug levels increased with dose and time, suggesting drug accumulation with repeated dosing. Low human anti-human antibody response was noted in three of the 13 patients assessed and was directed towards the variable region of ING-1. Weekly ING-1 administered subcutaneously was well tolerated at 0.6 mg/kg/week and further experience at this dose is warranted to demonstrate safety. The risk of pancreatitis and the marginal anti-tumor effect may preclude further monotherapy studies; however, combination studies with chemotherapy are warranted.

Cardiac Evaluation, Toxicity and Monitoring in the Treatment of Breast Cancer

Multiple chemotherapeutic drugs are used in the treatment of breast cancer, many of which have the potential to produce cardiotoxicity. The anthracyclines are highly efficacious against breast cancer, but pose a particularly high risk for cardiotoxicity. The incidence of anthracycline-induced cardiomyopathy increases in a dose-related fashion and with prior cardiac radiation exposure. The exact mechanism of toxicity is unknown, but the maximum tolerated cumulative dose can be increased by reducing peak drug levels and with concurrent administration of dexrazoxane. Because anthracycline-induced cardiomyopathy is largely irreversible and cumulative, prevention is the preferred strategy. Monitoring by assessment of left ventricular function by the most reproducible method available as patients approach potentially toxic doses can substantially reduce toxicity. The long-term outcome of anthracycline-induced cardiomyopathy is better than previously reported because of advances in therapy. Recommendations for cardiac monitoring depend on the baseline cardiac function. In patients with baseline left ventricular ejection fraction (LVEF) >50%, periodic assessment of LV function will depend on other cardiac risk factors present and cumulative dosing of the cardiotoxic drugs. A decrease in LVEF of more than 10% or an absolute decrease to less than 30% is an indication for doxorubin discontinuation. Doxorubin-based chemotherapy should not be initiated in patients with a baseline LVEF of less than 30%.

A Phase II, Open Label Study of AT-101 in Combination with Rituximab in Patients with Relapsed or Refractory Chronic Lymphocytic Leukemia.

Chronic lymphocytic leukemia (CLL) cells express high-levels of Bcl-2 and related anti-apoptotic proteins that collectively can enhance leukemia-cell survival and drug-resistance. AT-101 is an orally active BH3-mimetic that can inhibit the anti-apoptotic activity of Bcl-2-family-member proteins (e.g. Bcl-2, Bcl-XL, Mcl-1) and induce CLL cells to undergo apoptosis. Furthermore, we found that AT-101 also can enhance the cytotoxicity of rituximab for CLL cells in vitro. As such we conducted a phase 2 trial to evaluate the safety and activity of AT-101 when used together with rituximab to treat 12 patients who had relapsed/refractory CLL. Patients received AT-101, at 30 mg/d, for 21 or 28 days during each of three 28-day cycles. Rituximab was administered at 375 mg/m2 for 12 doses (total dose = 4,500 mg/m2) on days 1, 3, 5, 8, 15, 22, 29, 31, 33, 40, 57, 59, 61. The first dose of rituximab was given over two days to minimize infusion-related adverse events. The patients' median age was 61.5 years (range 43–81). Nine patients were high risk and 3 were intermediate risk based on the modified Rai classification and had received a median of 2 prior regimens (range 1–8). Six patients had leukemia cells that expressed ZAP-70 and/or unmutated immunoglobulin variable region genes and 4 patients had either 11q deletions or complex cytogenetics. Six patients interrupted treatment due to adverse events, most of which were transient and without residual complications. Grade 1–2 gastrointestinal effects (e.g., nausea, vomiting) occurred in 11 patients, 2 of whom had grade 3/4 ileus. Six patients experienced treatment-associated fatigue (grade 1–2 in 5 and grade 3 in one). Other than ileus and fatigue the only grade 3/4 event noted was neutropenia. One patient without neutropenia died while undergoing treatment from community-acquired bacterial pneumonia[j1]. Pharmacokinetic studies demonstrated that the average Cmax of AT-101 was 565 ng/ml (280 – 805 ng/ml) at a Tmax of 3.1 hours (1.7 – 5.6 hrs.). Correlative science studies performed on leukemia cells isolated at various times after treatment demonstrated leukemia-cell apoptosis in vivo, with maximum levels seen at times when we observed peak drug levels of AT-101. Eight patients had completed the study and had full response evaluation at the time of this abstract's submission. The overall response rate was 38% [CRu (2); PR (1); SD (3); PD (2)]. Four of eight patients (50%) had significant reductions in leukemia cell counts and splenomegaly and 5 of 8 (63%) had reductions in lymphadenopathy. AT-101 in combination with Rituximab has apparent activity in patients with relapsed-refractory high-risk CLL. Additional enrollment is planned using alternate AT-101 schedules in an attempt to increase peak plasma concentrations (and potentially activity) and reduce GI toxicity.