Long-term safety data from the cladribine tablets clinical development program in multiple sclerosis.

BACKGROUND: Long-term safety data are of particular interest for any newly approved treatment in multiple sclerosis such as cladribine tablets 10 mg (MAVENCLAD®; 3.5 mg/kg cumulative dose over 2 years, referred to as cladribine tablets 3.5 mg/kg), which is approved in Europe and the USA. Here we provide the final report on the integrated analysis of the safety profile of cladribine tablets 3.5 mg/kg from the clinical development program, including final data from the PREMIERE registry. METHODS: Safety data for cladribine tablets 3.5 mg/kg from three previously reported Phase III studies (CLARITY, CLARITY Extension and ORACLE-MS), as well as the prospective, observational PREMIERE registry (which ran from November 2009 to October 2018; consisting of patients who had participated in at least one of the Phase III trials) were combined to provide the Monotherapy Oral cohort. Serious adverse events (SAEs) and predefined SAEs of special interest were recorded. Observation-adjusted incidence rates per 100 patient-years (Adj-AE per 100 PY) were used to assess adverse events (AEs). Standardized incidence ratios for malignancies were calculated in relation to a matched GLOBOCAN reference population, and risk differences (cladribine tablets versus placebo) were estimated. RESULTS: The Monotherapy Oral cohort comprised 923 patients who received cladribine tablets 3.5 mg/kg and 641 patients who received placebo. Overall, the reported number of SAEs was higher in the cladribine tablets 3.5 mg/kg group (133/923 [14.4%] patients with at least 1 SAE), versus the placebo group (68/641 [10.6%] patients with at least 1 SAE). Four patients in the cladribine tablets 3.5 mg/kg group had lymphopenia classified as a serious event (resulting in an Adj-AE of 0.10 per 100 PY) and 2 patients had serious herpes zoster (resulting in an Adj-AE of 0.05 per 100 PY). There were no cases in the corresponding placebo groups. There was no difference between the cladribine tablets 3.5 mg/kg group and placebo in the overall incidence of infections. However herpetic infection AEs occurred more frequently in the cladribine tablets 3.5 mg/kg group (driven primarily by herpes zoster, followed by oral herpes and herpes simplex). Overall, there was a numerical imbalance in malignancy incidence between cladribine tablets 3.5 mg/kg and placebo, with an Adj-AE of 0.26 and 0.12 per 100 PY, respectively; however the difference was not statistically significant. The rate of malignancies observed with cladribine tablets 3.5 mg/kg in the final integrated safety analysis was not different from the expected rate in the matched GLOBOCAN reference population (standardized incidence ratio, 0.88; 95% CI, 0.44-1.69). CONCLUSION: Additional patient-years of observation do not significantly alter the conclusions of earlier interim analyses, and no new major safety findings were identified in this consolidated analysis of safety data of cladribine tablets 3.5 mg/kg monotherapy in patients with relapsing-remitting multiple sclerosis.

Cetuximab and irinotecan/5-fluorouracil/folinic acid is a safe combination for the first-line treatment of patients with epidermal growth factor receptor expressing metastatic colorectal carcinoma.

BACKGROUND: To investigate the safety/tolerability of the EGFR-antibody cetuximab when added to irinotecan/5-fluorouracil (5-FU)/folinic acid (FA) for first-line treatment in patients with metastatic colorectal cancer (mCRC). PATIENTS AND METHODS: Twenty-one patients with untreated, metastatic, EGFR-expressing CRC received cetuximab 400 mg/m(2) as an initial dose, and thereafter 250 mg/m(2) weekly. In addition, patients received infusional 5-FU (24 h) in two dose levels (1500 mg/m(2), low 5-FU group, n = 6 or 2000 mg/m(2), high 5-FU group, n = 15), plus FA at 500 mg/m(2) and irinotecan at 80 mg/m(2), weekly x6 q50d. RESULTS: Twenty patients were assessable for tolerability after the first cycle. There were no dose limiting toxicities (DLTs) in the low 5-FU group and three DLTs (20%) in the high 5-FU group (two patients with diarrhea grade 3 and one patient with diarrhea grade 4). In the low 5-FU group all six patients received >80% of the planned dose. In the high 5-FU group, seven of 14 patients (50%) received < or =80% of the planned chemotherapy dose during the first cycle due to dosage reductions whilst treatment delays occurred in 10/14 patients. During the whole study period, the common grade 3/4 adverse events were acne-like rash (38%) and diarrhea (29%). Chemotherapy did not affect the pharmacokinetics of cetuximab determined at weeks 1 and 4. Fourteen patients (67%, 95% CI 47% to 87%) had a confirmed response, and six (29%) had stable disease. Median time to progression was 9.9 months [lower 95% confidence limit (CL) 7.9, upper 95% CL not reached]. Median survival time was 33 months (lower CL 20, upper CL not reached). Four patients received secondary surgery with curative intent, and a fifth was potentially eligible for surgery but declined. CONCLUSIONS: Addition of cetuximab to weekly infusional 5-FU/FA plus irinotecan is safe and first data suggest a promising activity. The 5-FU dose of 1500 mg/m(2) is recommended for further studies.

The single-dose pharmacokinetics of the novel CCK1 receptor antagonist, dexloxiglumide, are not influenced by age and gender.

OBJECTIVE: The effects of age and gender on the single-dose pharmacokinetics of dexloxiglumide, a selective cholecystokinin (CCK1-subtype) receptor antagonist, were assessed in healthy young and elderly male and female subjects. METHODS: In total, 24 males and 24 females (12 young and 12 elderly subjects per gender group) received a single oral dose of 200 mg dexloxiglumide under fasted conditions. Mean (range) ages were 23.8 (18 - 32) and 71.3 (66 - 88) years for young and elderly subjects, respectively. Analysis of covariance (ANCOVA) with age group and gender as factors and body weight as a covariate was performed on the dexloxiglumide pharmacokinetic parameters of peak plasma concentration (C(max)) and the area under the plasma concentration-time curve (AUC). The p values obtained from ANCOVA were considered for the assessment of age and gender effects. RESULTS: A small (approximately 18%) but statistically significant (p < or = 0.036) increase in the area under the plasma concentration-time curve from 0 to time of last quantifiable concentration (AUC(0-t) and the area under the plasma concentration-time curve from 0 to infinity (AUC(0-infinity)) in elderly compared to young subjects was noted. Given the lack of age effects on the other pharmacokinetic parameters of dexloxiglumide, this limited difference is unlikely to be clinically relevant. Without the adjustment for body weights, female subjects exhibited mean C(max) and AUC values approximately 26% and 36% higher than male subjects; however, these exposure differences did not reach statistical significance (p > 0.05) following ANCOVA analysis with body weight as a covariate. Likewise, there were no statistically significant differences (p > 0.05) observed for any other pharmacokinetic parameters between young and elderly and between male and female groups. CONCLUSIONS: Dose adjustments based on age and gender are not necessary. Dexloxiglumide administration was safe and well tolerated in these subjects.

Deposition and pharmacokinetics of flunisolide delivered from pressurized inhalers containing non-CFC and CFC propellants.

Our objective was to assess the deposition and pharmacokinetics of a novel formulation of flunisolide (Aerobid, Forest Laboratories) in hydrofluoroalkane (HFA) 134a delivered by pressurized metered dose inhaler (pMDI). The design was a two-way crossover investigation in 12 healthy male subjects comparing HFA-134a flunisolide by pMDI versus pMDI plus 50 mL spacer device. Four of these subjects also took part in a two-way crossover investigation comparing chlorofluorocarbon (CFC) flunisolide pMDI versus pMDI plus Aerochamber holding chamber. The imaging technique of gamma scintigraphy was used to quantify total and regional lung deposition of flunisolide. Plasma levels of flunisolide and its major metabolite (6beta-OH flunisolide) were also determined. The spacer and Aerochamber reduced oropharyngeal deposition dramatically for both the HFA and CFC products (mean 59.8 to 14.9% (p < 0.01) of ex-valve (metered) dose for HFA product; 66.3 to 12.3% (p < 0.01) of ex-valve dose for CFC product) owing to deposition of part of the dose on the walls of the add-on devices themselves. Lung deposition averaged 22.6 and 40.4% (p < 0.01) of the ex-valve dose for the HFA formulation used with pMDI alone and with pMDI plus spacer. Mean lung deposition of the CFC formulation delivered via the Aerochamber (mean 23.4%) was higher than that for the CFC pMDI alone (mean 17.0%), but this difference was not statistically significant. Lung deposition expressed as percentage ex-device (delivered) dose averaged 68.3% for HFA pMDI plus spacer and 19.7% for CFC pMDI. Plasma levels of flunisolide were higher for the pMDI plus spacer than for pMDI alone, reflecting higher lung deposition via the spacer, but plasma levels of the 6beta-OH flunisolide metabolite were higher for the pMDI alone as a consequence of higher oropharyngeal deposition. When delivered via the spacer, pulmonary targeting of the flunisolide HFA formulation was improved compared with the CFC formulation, which should benefit patients by providing satisfactory asthma therapy from a much-reduced delivered dose of flunisolide.

Flunisolide HFA vs flunisolide CFC: pharmacokinetic comparison in healthy volunteers.

Two preparations of flunisolide, an inhaled corticosteroid, were compared in a parallel, multiple-dose study of 31 healthy volunteers. The new flunisolide preparation substitutes hydrofluoroalkane (HFA) for chlorofluorocarbon (CFC) as a propellant and incorporates a spacer into its pressurized metered-dose inhaler (pMDI). In this study, subjects were randomly assigned to receive flunisolide CFC 1000 microg bid; flunisolide HFA 170 microg bid; or flunisolide HFA 340 microg bid. Dosing was continued for 13.5 days. Plasma samples were analyzed after the first dose on day 1 and again after 13.5 days of treatment. No significant differences in day 1 dose-adjusted peak plasma concentrations (C(max)) were observed. Dose proportionality in C(max) and area under the concentration--time curves (AUC) was observed for the flunisolide HFA 170 and 340 microg bid groups on days 1 and 14. Day 1 mean dose-adjusted AUC was significantly greater in the flunisolide CFC 1000 microg bid group than in either flunisolide HFA group, indicating greater systemic availability of flunisolide CFC. Oral clearance and volume of distribution were significantly higher for flunisolide CFC than for flunisolide HFA. This may be due to greater oropharyngeal deposition by the flunisolide CFC formulation. Another indicator of greater flunisolide CFC oropharyngeal deposition was observed in C(max) and AUC(0--tlast) values for 6beta-OH flunisolide, the first-pass metabolite of flunisolide. The values of these pharmacokinetic parameters were significantly higher in the flunisolide CFC group than in the 340 microg bid flunisolide HFA group on days 1 and 14. However, this was not the case for cortisol values where flunisolide HFA accounted for less oropharyngeal deposition and more targeted delivery without adverse events. The study demonstrated that flunisolide HFA administered through a pMDI with built-in spacer was safe and well tolerated in healthy volunteers.

Lack of interaction between citalopram and the CYP3A4 substrate triazolam.

STUDY OBJECTIVES: To determine the effect of the selective serotonin reuptake inhibitor citalopram on plasma levels of triazolam, and to determine the effect of a single dose of triazolam on steady-state levels of citalopram and its major metabolites. DESIGN: Open-label, multidose study. SETTING: Clinical Studies, Ltd., Fort Lauderdale, Florida. PARTICIPANTS: Eighteen healthy male and female volunteers. INTERVENTIONS: Subjects received triazolam 0.25 mg alone and another 0.25-mg dose after 4 weeks of citalopram 20 mg/day for 1 week, followed by 3 weeks of citalopram 40 mg/day MEASUREMENTS AND MAIN RESULTS: Pharmacokinetic parameters were determined after single-dose administration of triazolam alone, after administration of citalopram alone at steady state, and after coadministration of the drugs. The pharmacokinetics of triazolam and its metabolite alpha-hydroxytriazolam were unchanged by citalopram coadministration. Triazolam appeared to be absorbed slightly more quickly during coadministration. Citalopram kinetics were unaffected by coadministration. CONCLUSION: No pharmacokinetic interaction between the drugs was observed, suggesting that triazolam and other cytochrome P450 3A4 substrates can be coadministered safely with citalopram.

hKCNMB3 and hKCNMB4, cloning and characterization of two members of the large-conductance calcium-activated potassium channel beta subunit family.

We cloned two beta subunits of large-conductance calcium-activated potassium (BK) channels, hKCNMB3 (BKbeta1) and hKCNMB4 (BKbeta4). Profiling mRNA expression showed that hKCNMB3 expression is enriched in testis and hKCNMB4 expression is very prominent in brain. We coexpressed BK channel alpha (BKalpha) and BKbeta4 subunits in vitro in CHO cells. We compared BKalpha/beta4 mediated currents with those of smooth muscle BKalpha/beta1 channels. BKbeta4 slowed activation kinetics more significantly, led to a steeper apparent calcium sensitivity, and shifted the voltage range of BK current activation to more negative potentials than BKbeta1. BKalpha/beta4 channels were not blocked by 100 nM charybdotoxin or iberiotoxin, and were activated by 17beta-estradiol.

Determination of free interstitial concentrations of piperacillin-tazobactam combinations by microdialysis.

The investigation of tissue penetration and distribution of antibiotics is of great importance, since infections occur mostly in the tissues. The aim of this study was to investigate the pharmacokinetics of piperacillin and tazobactam, alone and in combination, by measuring total plasma and free interstitial concentrations, and to examine the relationship between free levels of both drugs in blood and those in the extracellular space. Piperacillin and tazobactam were administered, alone and in combination, to anaesthetized rats as a single iv bolus dose. Total plasma concentrations and free extracellular concentrations were quantified by HPLC. In-vivo microdialysis sampling was used to study the free tissue distribution patterns of both drugs. The pharmacokinetics of piperacillin and tazobactam in plasma were consistent with a two-compartment body model. Piperacillin pharmacokinetics were not influenced by co-administration of tazobactam. Tazobactam's volumes of distribution and clearance were decreased by the co-administration of piperacillin and the area under the curve was significantly increased. Comparisons between calculated free concentrations in the peripheral compartment for both drugs and measured free extracellular concentrations revealed excellent agreement. For piperacillin and tazobactam, alone and in combination, predictions of the concentration-time profiles of free drug in the peripheral compartment can be made on the basis of plasma data.

Pharmacokinetic-pharmacodynamic modelling of the in vitro antiinfective effect of piperacillin-tazobactam combinations.

PURPOSE: The aim of the study was to investigate the in vitro antiinfective effect of piperacillin-tazobactam (PIP-TZB) combinations on Escherichia coli in simulations of free concentration time profiles of both drugs, similar to those obtained in human tissue after i.v. bolus administrations. METHODS: An in vitro dilution model was used to expose E. coli ATCC 35218 (beta-lactamase producer) to various piperacillin-tazobactam concentration profiles obtained after i.v. bolus multiple dose, using different dose ratio combinations (1:4, 1:8, 1:16) and dosing regimens, ranging from once-a-day to 4 times a day. The antimicrobial effect was evaluated by determination of the number of bacteria over time. The concentration of PIP in the model was determined by HPLC. RESULTS: A modified Emax model was used to describe the pharmacodynamic effect. The model was linked with the piperacillin concentrations determined experimentally to provide a pharmacokinetic-pharmacodynamic (PK-PD) model. The EC50 for piperacillin alone averaged 5.66 +/- 0.29 micrograms/ml. The EC50 for all doses of piperacillin combined with 0.5 g of tazobactam were dose-dependent and averaged 1.70 +/- 0.56, 3.95 +/- 1.02, and 6.14 +/- 1.24 micrograms/ml for PIP 2, 4, and 8 g, respectively. By increasing the dose of TZB in combination with a fixed dose of PIP, a decreased EC50 was observed. CONCLUSIONS: The PK-PD model allowed a detailed evaluation of the dosing regimens investigated. The results suggested that for these combinations, 3 times a day administration is as effective as 4 times a day. Pharmacodynamic activity of the combinations can be prolonged by sufficiently high inhibitor concentrations.

Characterization of complexes of oligonucleotides with polyamidoamine starburst dendrimers and effects on intracellular delivery.

This study evaluates polyamidoamine PAMAM "starburst" dendrimers (generation 3, Mr 6909) as a potential delivery vehicle for oligonucleotides. Complexes between dendrimer and phosphorothioate oligonucleotides were observed by agarose gel electrophoresis and were positive, negative, or neutral in charge depending on stoichiometry. Complexes were stable in 50% serum to variations in pH (3, 5, and 10) and ionic strength (0-500 mM). Ultrafiltration and gel filtration characterization indicated that the dendrimer:oligonucleotide complexes were primarily < 100 kD, although some larger complexes were formed at oligonucleotide excess. Use of dendrimers resulted in a 50-fold enhancement in cell uptake of oligonucleotide as determined by flow cytometry, and enhanced cytosolic and nuclear availability, as shown by confocal microscopy. These data support the further evaluation of dendrimers for oligonucleotide delivery in cell culture and in vivo.

Comparative pharmacokinetics, tissue distribution, and tumor accumulation of phosphorothioate, phosphorodithioate, and methylphosphonate oligonucleotides in nude mice.

The goals of this study were to systematically compare the pharmacokinetics and tissue distribution of phosphorothioate (PS), methylphosphonate (MP), and phosphorodithioate (PS2) oligonucleotide analogs; 15-mers of sequence d-TAC GCC AAC AGC TCC (5'-3') complementary to the AUG region of K-ras were radiolabeled with carbon-14. Oligomers were administered as a single dose in the tail vein of nude mice harboring a K-ras-dependent human pancreatic tumor (CFPAC1). The kinetics of PS, PS2, and MP oligomer availability in the bloodstream was followed. Concentration versus time profiles for all oligomers were biphasic, indicative of a two-compartment model. A rapid distribution phase with t1/2 alpha values of 1 minute or less and an elimination phase with average t1/2 beta values of 24-35 minutes were observed. Volumes of distribution (Vd) were 3.2, 4.8, and 6.3 ml for PS2, MP, and PS, respectively, in comparison to 3.6 ml for sucrose, a fluid-phase marker. Relative tissue drug levels obtained at 1 and 24 hours after administration were kidney > liver > spleen > tumor > muscle. Total kidney and liver oligonucleotide accumulation was approximately 7%-15% of the initial dose, with tumor accumulating 2%-3%. Intact compound was recovered from all tissues, including tumor, as assessed by high-pressure reversed-phase HPLC coupled to radiometric detection. Integrity of the oligonucleotides ranged from 73% in blood to 43%-46% in kidney and liver. Kidney and liver appear to be the primary sites of metabolism. These results demonstrate widespread tissue availability of these compounds and suggest their development as potential antitumor agents.

Hepatic distribution and clearance of antisense oligonucleotides in the isolated perfused rat liver.

PURPOSE: This study was conducted to investigate the impact of backbone modifications on the hepatobiliary disposition of oligonucleotides. METHODS: The disposition of backbone-modified antisense oligonucleotides [phosphorothioate (PS) and methylphosphonate (MP)] of the same base-length and sequence (5'-TAC-GCC-AAC-AGC-TCC-3'), complementary to the codon 12 activating mutation of Ki-ras, was investigated in the isolated perfused rat liver. Livers were perfused for 2 hr: perfusate and bile concentrations were analyzed by HPLC. Hepatocellular distribution was examined by measuring the amount of radiolabeled PS oligonucleotide associated with hepatocytes and Kupffer cells. Protein binding of the PS and MP oligonucleotides was determined in rat serum by ultrafiltration. RESULTS: MP oligonucleotide perfusate concentrations remained constant during the 2-hour perfusion. In contrast, PS oligonucleotide was eliminated slowly by the isolated perfused liver [CI = 1.05 +/- 0.21 mL/min; extraction ratio = 0.06 +/- 0.01]. Uptake of PS oligonucleotide by Kupffer cells appeared to exceed uptake by hepatocytes, based on standard cell separation techniques as well as confocal microscopy. The degree of protein binding in rat serum was greater for the PS oligonucleotide (79.9 +/- 2.2%) than for the MP oligonucleotide (53.0 +/- 4.7%). CONCLUSIONS: Backbone modifications significantly-influence the hepatic clearance of oligonucleotides. Uncharged MP oligonucleotides are not extracted by the isolated perfused rat liver, whereas the charged PS oligonucleotide is processed more readily.

Determination of free extracellular concentrations of piperacillin by microdialysis.

The tissue penetration and distribution of antibiotics is of great importance, since most of the infections occur in the tissue. At the infection site, the free, unbound fraction of the antibiotic is responsible for the antiinfective effect. These free extracellular concentrations can be measured by microdialysis. It was the aim of the study to correlate free levels of the beta-lactam antibiotic piperacillin in blood with those in tissue. In vivo microdialysis sampling was used to study the tissue distribution patterns of piperacillin in anesthetized rats after single dose iv administration of the drug. The pharmacokinetics of piperacillin in plasma were consistent with a two-compartment body model. Comparisons between calculated free concentrations in the peripheral compartment and measured free extracellular concentrations revealed excellent agreement. Microdialysis is a suitable method to evaluate unbound drug concentrations in the tissues. In case of piperacillin, predictions of the concentration time profiles of free drug in the peripheral compartment can be made on the basis of plasma data.

Pharmacokinetic-pharmacodynamic modeling of the antibiotic effect of piperacillin in vitro.

PURPOSE: It was the aim of the present study to investigate the in vitro antimicrobial effects of the beta-lactam antibiotic piperacillin on Escherichia coli using concentration-time profiles similar to those encountered in vivo. METHODS: An in vitro dilution model was used to expose E. coli to various piperacillin concentration profiles. The antimicrobial effect was evaluated by determination of the number of bacteria over time. RESULTS: A modified Emax-model was found appropriate to describe the pharmacodynamic effect. This model was linked with the respective piperacillin concentrations to provide a suitable pharmacokinetic-pharmacodynamic (PK-PD) model. The average growth half-life in absence of piperacillin was 28 min and the maximum kill half-life was 25 min. The EC50 for the various dosing regimens averaged 5.2 micrograms/mL and was independent of dose. These parameters were used the simulate the bacterial effects of commonly administered doses or dosing regimens in humans. CONCLUSIONS: Based on the in vitro data a more frequent administration of piperacillin will be more efficacious. The proposed PK-PD-model allows a more detailed evaluation of dosing regimens than the use of minimum inhibitory concentrations.