Updated efficacy results from the JAVELIN Renal 101 trial: first-line avelumab plus axitinib versus sunitinib in patients with advanced renal cell carcinoma

BACKGROUND

The phase 3 JAVELIN Renal 101 trial (NCT02684006) demonstrated significantly improved progression-free survival (PFS) with first-line avelumab plus axitinib versus sunitinib in advanced renal cell carcinoma (aRCC). We report updated efficacy data from the second interim analysis.

PATIENTS AND METHODS

Treatment-naive patients with aRCC were randomized (1 : 1) to receive avelumab (10 mg/kg) intravenously every 2 weeks plus axitinib (5 mg) orally twice daily or sunitinib (50 mg) orally once daily for 4 weeks (6-week cycle). The two independent primary end points were PFS and overall survival (OS) among patients with programmed death ligand 1-positive (PD-L1+) tumors. Key secondary end points were OS and PFS in the overall population.

RESULTS

Of 886 patients, 442 were randomized to the avelumab plus axitinib arm and 444 to the sunitinib arm; 270 and 290 had PD-L1+ tumors, respectively. After a minimum follow-up of 13 months (data cut-off 28 January 2019), PFS was significantly longer in the avelumab plus axitinib arm than in the sunitinib arm {PD-L1+ population: hazard ratio (HR) 0.62 [95% confidence interval (CI) 0.490-0.777]}; one-sided P < 0.0001; median 13.8 (95% CI 10.1-20.7) versus 7.0 months (95% CI 5.7-9.6); overall population: HR 0.69 (95% CI 0.574-0.825); one-sided P < 0.0001; median 13.3 (95% CI 11.1-15.3) versus 8.0 months (95% CI 6.7-9.8)]. OS data were immature [PD-L1+ population: HR 0.828 (95% CI 0.596-1.151); one-sided P = 0.1301; overall population: HR 0.796 (95% CI 0.616-1.027); one-sided P = 0.0392].

CONCLUSION

Among patients with previously untreated aRCC, treatment with avelumab plus axitinib continued to result in a statistically significant improvement in PFS versus sunitinib; OS data were still immature.

CLINICAL TRIAL NUMBER

NCT02684006.

Economic and survival burden of dysphagia among inpatients in the United States

The inpatient burden of dysphagia has primarily been evaluated in patients with stroke. It is unclear whether dysphagia, irrespective of cause, is associated with worse clinical outcomes and higher costs compared to inpatients with similar demographic, hospital, and clinical characteristics without dysphagia. The aim of this study is to assess how a dysphagia diagnosis affects length of hospital stay (LOS), costs, discharge disposition, and in-hospital mortality among adult US inpatients. Annual and overall dysphagia prevalence, LOS, hospital charges, inpatient care costs, discharge disposition, and in-hospital mortality were measured using the AHRQ Healthcare Cost and Utilization Project (HCUP) National Inpatient Sample (2009-2013). Patients aged 45 years or older with ≤180 days of stay in hospital with and without dysphagia were included. Multivariable survey regression methods with propensity weighting were used to assess associations between dysphagia and different outcomes. Overall, 2.7 of 88 million (3.0%) adult US inpatients had a dysphagia diagnosis (50.2% male, 72.4% white, 74.6% age 65-90 years) and prevalence increased from 408,035 (2.5% of admissions) in 2009 to 656,655 (3.3%) in 2013. After inverse probability of treatment weighting adjustment, mean hospital LOS in patients with dysphagia was 8.8 days (95% CI 8.66-8.90) compared to 5.0 days (95% CI 4.97-5.05) in the non-dysphagia group (P < 0.001). Total inpatient costs were a mean $6,243 higher among those with dysphagia diagnoses ($19,244 vs. 13,001, P < 0.001). Patients with dysphagia were 33.2% more likely to be transferred to post-acute care facility (71.9% vs. 38.7%, P < 0.001) with an adjusted OR of 2.8 (95% CI 2.73-2.81, P < 0.001). Compared to non-cases, adult patients with dysphagia were 1.7 times more likely to die in the hospital (95% CI 1.67-1.74). Dysphagia affects 3.0% of all adult US inpatients (aged 45-90 years) and is associated with a significantly longer hospital length of stay, higher inpatient costs, a higher likelihood of discharge to post-acute care facility, and inpatient mortality when compared to those with similar patient, hospital size, and clinical characteristics without dysphagia. Dysphagia has a substantial health and cost burden on the US healthcare system.

Quantitative Evaluations of Time-Course and Treatment Effects of Systemic Agents for Psoriasis: A Model-Based Meta-Analysis

Aggregate data model‐based meta‐analysis is a regression approach to compare the dose–response and/or time‐course across different treatments using summary level data from the literature. Literature search and systematic review following the Cochrane approach yielded 912 sources for investigational and approved treatments for psoriasis. In addition, data for tofacitinib were obtained from an internal database. Tofacitinib is an oral Janus kinase inhibitor. Two mathematical models were developed for Psoriasis Area and Severity Index (PASI) response in moderate to severe psoriasis patients to quantify the time to maximum effect for PASI75 and to evaluate the dose–response relationship for PASI responders (PASI50, PASI75, PASI90, PASI100) at Week 12. Body weight exhibited an inverse effect on the placebo component of both models, suggesting that body weight affects the overall PASI response regardless of drug. This analysis provides a quantitative framework for efficacy comparisons across psoriasis treatments.

Evaluating Dosage Optimality for Tofacitinib, an Oral Janus Kinase Inhibitor, in Plaque Psoriasis, and the Influence of Body Weight

Tofacitinib is an oral Janus kinase inhibitor. An integrated analysis was conducted to evaluate dosage optimality for tofacitinib in patients with moderate‐to‐severe plaque psoriasis and the impact of body weight on optimality in this patient population. Data were pooled from one phase IIb trial (2, 5, and 15 mg twice daily (b.i.d.)) and four phase III trials (5 and 10 mg b.i.d.). A longitudinal exposure–response model for Psoriasis Area and Severity Index (PASI) improvement (percent change from baseline) was established. Body weight influenced potency; heavier subjects require higher doses to achieve comparable benefit to lighter subjects. Disease severity, sex, and prior biologic usage were also predictive of response. The 10 and 5 mg doses were predicted to achieve 81% and 65%, respectively, of the maximum effect based on a 75% improvement in PASI. The greater efficacy of 10 mg over 5 mg was clinically meaningful.

Model-Informed Development and Registration of a Once-Daily Regimen of Extended-Release Tofacitinib

Extended‐release (XR) formulations enable less frequent dosing vs. conventional (e.g., immediate release (IR)) formulations. Regulatory registration of such formulations typically requires pharmacokinetic (PK) and clinical efficacy data. Here we illustrate a model‐informed, exposure–response (E‐R) approach to translate controlled trial data from one formulation to another without a phase III trial, using a tofacitinib case study. Tofacitinib is an oral Janus kinase (JAK) inhibitor for the treatment of rheumatoid arthritis (RA). E‐R analyses were conducted using validated clinical endpoints from phase II dose–response and nonclinical dose fractionation studies of the IR formulation. Consistent with the delay in clinical response dynamics relative to PK, average concentration was established as the relevant PK parameter for tofacitinib efficacy and supported pharmacodynamic similarity. These evaluations, alongside demonstrated equivalence in total systemic exposure between IR and XR formulations, provided the basis for the regulatory approval of tofacitinib XR once daily by the US Food and Drug Administration.

The JAK inhibitor tofacitinib suppresses synovial JAK1-STAT signalling in rheumatoid arthritis

Objective

Tofacitinib is an oral Janus kinase (JAK) inhibitor for the treatment of rheumatoid arthritis (RA). The pathways affected by tofacitinib and the effects on gene expression in situ are unknown. Therefore, tofacitinib effects on synovial pathobiology were investigated.

Methods

A randomised, double-blind, phase II serial synovial biopsy study (A3921073; NCT00976599) in patients with RA with an inadequate methotrexate response. Patients on background methotrexate received tofacitinib 10 mg twice daily or placebo for 28 days. Synovial biopsies were performed on Days -7 and 28 and analysed by immunoassay or quantitative PCR. Clinical response was determined by disease activity score and European League Against Rheumatism (EULAR) response on Day 28 in A3921073, and at Month 3 in a long-term extension study (A3921024; NCT00413699).

Results

Tofacitinib exposure led to EULAR moderate to good responses (11/14 patients), while placebo was ineffective (1/14 patients) on Day 28. Tofacitinib treatment significantly reduced synovial mRNA expression of matrix metalloproteinase (MMP)-1 and MMP-3 (p<0.05) and chemokines CCL2, CXCL10 and CXCL13 (p<0.05). No overall changes were observed in synovial inflammation score or the presence of T cells, B cells or macrophages. Changes in synovial phosphorylation of signal transducer and activator of transcription 1 (STAT1) and STAT3 strongly correlated with 4-month clinical responses (p<0.002). Tofacitinib significantly decreased plasma CXCL10 (p<0.005) at Day 28 compared with placebo.

Conclusions

Tofacitinib reduces metalloproteinase and interferon-regulated gene expression in rheumatoid synovium, and clinical improvement correlates with reductions in STAT1 and STAT3 phosphorylation. JAK1-mediated interferon and interleukin-6 signalling likely play a key role in the synovial response.

Trial registration number

NCT00976599.

Dose Response and Pharmacokinetics of Tofacitinib (CP-690,550), an Oral Janus Kinase Inhibitor, in the Treatment of Chronic Plaque Psoriasis

Longitudinal nonlinear mixed effects modeling was used to characterize the dose–response profile of tofacitinib using data from a placebo-controlled dose-ranging study, where tofacitinib 2, 5, and 15 mg twice daily (b.i.d.) were evaluated for plaque psoriasis treatment. Bayesian estimation was applied with prior information derived from the literature: nonclinical and clinical data in psoriasis, as well as other indications. The probability to achieve a certain target effect associated with a given dose was calculated from the posterior samples. On the basis of these probabilities along with safety considerations, tofacitinib 5 and 10 mg b.i.d. were selected for further testing in confirmatory phase III clinical trials. Pharmacokinetics in patients with psoriasis was characterized using a population-based modeling approach, and body weight was identified as an important covariate. A subgroup analysis suggested reduced efficacy of tofacitinib with increasing body weight; however, it is unclear whether this trend could be explained by systemic exposure alone.

Efficacy and safety of tofacitinib, an oral Janus kinase inhibitor, in the treatment of psoriasis: a Phase 2b randomized placebo-controlled dose-ranging study

BACKGROUND

Tofacitinib is a novel, oral Janus kinase inhibitor under investigation as a potential treatment for plaque psoriasis.

OBJECTIVES

This Phase 2b, 12-week, dose-ranging study (A3921047, NCT00678210) aimed to characterize the exposure-response, efficacy and safety of tofacitinib vs. placebo in patients with moderate-to-severe chronic plaque psoriasis.

METHODS

One hundred and ninety-seven patients were randomized. The primary endpoint was the proportion of patients achieving a ≥ 75% reduction in the Psoriasis Area and Severity Index (PASI 75) score at week 12.

RESULTS

At week 12, PASI 75 response rates were significantly higher for all tofacitinib twice-daily groups: 25·0% (2 mg; P < 0·001), 40·8% (5 mg; P < 0·0001) and 66·7% (15 mg; P < 0·0001), compared with placebo (2·0%). Significant increases in the proportion of PASI 75 responses were seen by week 4 and were maintained at week 12. Exposure-response over the 0-15 mg tofacitinib twice-daily dose range was successfully characterized. PASI 50, PASI 90 and Physician's Global Assessment response rates were also higher for tofacitinib vs. placebo. The most frequently reported adverse events (AEs) were infections and infestations: 22·4% (2 mg twice daily), 20·4% (5 mg twice daily), 36·7% (15 mg twice daily) and 32·0% (placebo). Discontinuations due to AEs were 6·0%, 2·0%, 4·1% and 6·1% of patients in the placebo, and 2, 5 and 15 mg twice-daily tofacitinib groups, respectively. Dose-dependent increases from baseline in mean serum high-density lipoprotein, low-density lipoprotein and total cholesterol, and decreases in haemoglobin and neutrophils were observed.

CONCLUSION

Short-term treatment with oral tofacitinib results in significant clinical improvement in patients with moderate-to-severe plaque psoriasis and is generally well tolerated.

Randomized phase 2b trial of tofacitinib (CP-690,550) in de novo kidney transplant patients: efficacy, renal function and safety at 1 year

In this Phase 2b study, 331 low-to-moderate risk de novo kidney transplant patients (approximately 60% deceased donors) were randomized to a more intensive (MI) or less intensive (LI) regimen of tofacitinib (CP-690, 550), an oral Janus kinase inhibitor or cyclosporine (CsA). All patients received basiliximab induction, mycophenolic acid and corticosteroids. Primary endpoints were: incidence of biopsy-proven acute rejection (BPAR) with a serum creatinine increase of ≥0.3 mg/dL and ≥20% (clinical BPAR) at Month 6 and measured GFR at Month 12. Similar 6-month incidences of clinical BPAR (11%, 7% and 9%) were observed for MI, LI and CsA. Measured GFRs were higher (p < 0.01) at Month 12 for MI and LI versus CsA (65 mL/min, 65 mL/min vs. 54 mL/min). Fewer (p < 0.05) patients in MI or LI developed chronic allograft nephropathy at Month 12 compared with CsA (25%, 24% vs. 48%). Serious infections developed in 45%, 37% and 25% of patients in MI, LI and CsA, respectively. Anemia, neutropenia and posttransplant lymphoproliferative disorder occurred more frequently in MI and LI compared with CsA. Tofacitinib was equivalent to CsA in preventing acute rejection, was associated with improved renal function and less chronic allograft histological injury, but had side-effects at the doses evaluated.

Phase 1 dose-escalation study of CP-690 550 in stable renal allograft recipients: preliminary findings of safety, tolerability, effects on lymphocyte subsets and pharmacokinetics

CP-690 550 inhibits Janus kinase 3 with nanomolar potency. In this dose-escalation study, we assessed the safety, tolerability, effects on lymphocyte subsets, and pharmacokinetics of CP-690 550 when coadministered with mycophenolate mofetil in stable renal allograft recipients for 28 days. Twenty-eight patients were enrolled. Six patients received CP-690 550 5 mg twice daily (BID), 6 patients received 15 mg BID, 10 patients received 30 mg BID, and 6 patients received placebo. The most frequent adverse events were infections and gastrointestinal (abdominal pain, diarrhea, dyspepsia, and vomiting). CP-690 550 15 mg BID and 30 mg BID were associated with a mean decrease in hemoglobin from baseline of 11% and a mean decrease in absolute natural killer cell counts of 50%. CP-690 550 30 mg BID was also associated with a mean increase in absolute CD19(+) B-lymphocytes of 130%. There were no changes in the number of neutrophils, total lymphocytes, platelets, or CD4(+) or CD8(+) T cells; clinical chemistry; vital signs; or electrocardiograms from the pretreatment baseline. Administration of CP-690 550 without a concomitant calcineurin inhibitor resulted in CP-690 550 exposures consistent with previous studies in nontransplant subjects. Additional dose-ranging studies are warranted to evaluate the safety and efficacy of CP-690 550 in renal transplant recipients over longer treatment duration.

Altered relationship of blood pressure to adiposity in hypertension

BACKGROUND

Blood pressure levels and the prevalence of hypertension are related to adiposity. We evaluated the relationship of adiposity to blood pressure in normotensive and untreated hypertensive African Americans-an ethnic group with a high prevalence of hypertension and obesity.

METHODS

Outpatient measurements were obtained in 1,858 normotensive and 1,998 hypertensive subjects (44% untreated) residing in Milwaukee. The blood pressure-adiposity relationship was also analyzed in non-Hispanic black (n = 908) and non-Hispanic white (n = 2182) National Health and Nutrition Examination Survey (NHANES) participants.

RESULTS

In Milwaukee subjects, body mass index (BMI), waist/hip ratio, waist/height ratio, and percent body fat were higher in hypertensives (P < 0.0001). Combining normotensive and untreated hypertensive subjects, each of the anthropometric indices was correlated with systolic and diastolic blood pressure (P <0.0001). In separate analyses, correlations of the indices with blood pressure were observed in normotensive subjects (P < 0.0001), but generally not in hypertensive subjects. Further, separating all subjects into quartiles based on systolic blood pressure, indices of adiposity correlated with blood pressure only in subjects in the lowest blood pressure quartile (blood pressure <120/78 mm Hg). Similarly, among NHANES participants, blood pressure correlated with anthropometric indices in normotensive (P < 0.0005), but not in untreated hypertensive blacks or whites.

CONCLUSIONS

Although indices of adiposity were greater in hypertensive than in normotensive subjects, blood pressures were significantly correlated with measures of adiposity in normotensive, but not in untreated hypertensive subjects. We hypothesize that the blood pressure-adiposity relationship in hypertensives is modulated by a combination of environmental and genetic factors.

Interpretation of absorption rate data for inhaled fluticasone propionate obtained in compartmental pharmacokinetic modeling

OBJECTIVE

Reports characterizing the pharmacokinetics of inhaled fluticasone propionate (FP) using compartmental approaches have suggested that the absorption of FP into the systemic circulation is rapid with a half-life of approximately 10 min. We believe that this is a classical case of misassignment of the pharmacokinetic parameter estimates, a problem often encountered while modeling pharmacokinetic data. The objective of this study was to illustrate and analyze this problem using actual blood level data of FP obtained in 14 healthy subjects.

MATERIALS AND METHODS

Serum concentration-time data of FP were obtained from a double-blind, randomized study involving single and multiple twice-daily inhalations of 500 microg via a dry powder device, Diskus. The profiles were fitted using one- and two-compartment pharmacokinetic models with first order absorption. Various permutations of the resulting exponential rate constants were analyzed to determine the combination that was most consistent with the underlying physical process.

RESULTS

The two-compartment body model with first order absorption gave excellent fits for the observed FP concentrations after both single and multiple dosing. Even though peak levels were reached relatively early (30 - 90 min) after inhalation, the combination that most appropriately described the underlying process was alpha > Ka > beta, i.e. slow absorption, rapid distribution and slower elimination kinetics. The absorption, distribution and elimination half-lives resulted to be 3.8 h, 9.9 min and 13.6 h, respectively, consistent with the high lipophilicity and sustained dissolution characteristics observed in vitro.

CONCLUSIONS

Analysis of FP pharmacokinetics after inhalation represents a classical case of potential misassignment of the exponential rate constants, which if ignored, could lead to erroneous interpretations regarding the underlying process. The study also elucidates the pitfall of using t(max) to calculate absorption rate.

238U series isotopes and 232Th in carbonates and black shales from the Lesser Himalaya: implications to dissolved uranium abundances in Ganga-Indus source waters

238U and (232)Th concentrations and the extent of (238)U-(234)U-(230)Th radioactive equilibrium have been measured in a suite of Precambrian carbonates and black shales from the Lesser Himalaya. These measurements were made to determine their abundances in these deposits, their contributions to dissolved uranium budget of the headwaters of the Ganga and the Indus in the Himalaya and to assess the impact of weathering on (238)U-(234)U-(230)Th radioactive equilibrium in them. (238)U concentrations in Precambrian carbonates range from 0.06 to 2.07 microg g(-1). The 'mean' U/Ca in these carbonates is 2.9 ng U mg(-1) Ca. This ratio, coupled with the assumption that all Ca in the Ganga-Indus headwaters is of carbonate origin and that U and Ca behave conservatively in rivers after their release from carbonates, provides an upper limit on the U contribution from these carbonates, to be a few percent of dissolved uranium in rivers. There are, however, a few streams with low uranium concentrations, for which the carbonate contribution could be much higher. These results suggest that Precambrian carbonates make only minor contributions to the uranium budget of the Ganga-Indus headwaters in the Himalaya on a basin wide scale, however, they could be important for particular streams. Similar estimates of silicate contribution to uranium budget of these rivers using U/Na in silicates and Na* (Na corrected for cyclic and halite contributions) in river waters show that silicates can contribute significantly (approximately 40% on average) to their U balance. If, however, much of the uranium in these silicates is associated with weathering resistant minerals, then the estimated silicate uranium component would be upper limits. Uranium concentration in black shales averages about 37 microg g(-1). Based on this concentration, supply of U from at least approximately 50 mg of black shales per liter of river water is needed to balance the average river water U concentration, 1.7 microg L(-1) in the Ganga-Indus headwaters. Data on the abundance and distribution of black shales in their drainage basin are needed to test if this requirement can be met. (234)U/(238)U activity ratios in both carbonates and black shales are at or near equilibrium, thus preferential mobilization of (234)U from these deposits, if any, is within analytical uncertainties. (230)Th is equivalent to or in excess of (238)U in most of the carbonates. (230)Th/(238)U>1 indicates that during weathering, uranium is lost preferentially over Th. (232)Th concentrations in carbonates are generally quite low, <0.5 microg g(-1), though with a wide range, 0.01-4.8 microg g(-1). The variation in its concentrations seem to be regulated by aluminosilicate content of the carbonates as evident from the strong positive correlation between (232)Th and Al.

Single-dose and steady-state pharmacokinetic and pharmacodynamic evaluation of therapeutically clinically equivalent doses of inhaled fluticasone propionate and budesonide, given as Diskus or Turbohaler dry-powder inhalers to healthy subjects

Direct comparisons of the pharmacokinetic (PK) and systemic pharmacodynamic (PD) properties of inhaled corticosteroids after single and multiple dosing in the same subjects are scarce. The objective of this study was to compare thePK/PDproperties of clinically equivalent, single, and multiple doses of dry-powder formulations of inhaled fluticasone propionate (FP 200 and 500 microg via Diskus) and budesonide (BUD, 400 and 1,000 microg via Turbohaler). Fourteen healthy subjects completed a double-blind, double-dummy, randomized, placebo-controlled, five-way crossover study consisting of a single dose administered at 8 a.m. on day 1 followed by 4 days of twice-daily dosing at 8 a.m. and 8 p.m. on days 2 to 5. Serum concentrations of FP and BUD were measured using validated liquid chromatography/ mass spectrometry assays. The 24-hour cumulative cortisol suppression (CCS) in serum was monitored as the pharmacodynamic surrogate marker. Peak serum concentrations following single and multiple dosing were observed 10 to 30 minutes after inhalation for BUD and 30 to 90 minutes afterinhalation of FP with no influence of dose ordosingregimen. After a single dose of 1000 microg BUD and 500 microg FP the median estimates of terminal half-life and mean residence time were 3.5 and 3.9 hours for BUD and 10.1 and 12.0 hours for FP, respectively. Using previously reported intravenous data, the mean absorption times (MAT) were calculated to be around 2 hours and 7 hours for BUD and FP respectively. On average, the area under the curve (A UC) at steady state (day 5) was up to 30% higher for BUD compared to that over a 12-hour period following the first dose on day 1, whereas A UC estimates were 50% to 80% higherforFP at steady state, indicating accumulation. However, the steady-state Cmax values were seven to eight times and AUC values three to four times higher for BUD than for FP. Comparison of active treatment data with placebo showed that CCS after a single dose was not pronounced for any of the doses/drugs studied. On day 5, both doses of BUD caused statistically significant suppression (CCS of 19% for the 400 microg dose and 36% for the 1,000 microg dose). For FP only the high dose had a statistically significant effect on serum cortisol (CCS of 14% for the 200 microg dose and 27% for the 500 microg dose). Compared to BUD, FP has slower pulmonary absorption and slower elimination kinetics. However, following inhalation of therapeutically equipotent, multiple twice-daily doses in healthy subjects, the systemic effects of FP delivered via Diskus on AUC24 serum cortisol were relatively low and similar to those of BUD delivered via Turbohaler.

Adenosine as an adjunct to inducing rapid asystole during cardioplegic arrest

A study was undertaken in 68 patients to assess the beneficial effect of adenosine as an adjunct to K(+)-enriched cardioplegia to induce rapid asystole. In the study group (n = 22), adenosine was given in the dose of 3 mg bolus into the aortic root immediately after aortic cross clamp along with K(+)-enriched cardioplegia. In the control group (n = 46) K(+)-enriched cardioplegia solution was used without adenosine. Important parameters monitored were: time to asystole in seconds and recovery of normal sinus rhythm following release of aortic cross clamp. In addition, standard haemodynamic parameters were measured. The results showed a marked reduction in the time to achieve asystole in the study group (3.53 +/- 1.18 seconds) as compared to the control group (18.19 +/- 11.80 seconds) (p < 0.001). Restoration of sinus rhythm was achieved in the study group at 43.53 +/- 33.60 seconds while in the control group it was achieved at 161.90 +/- 11.36 seconds (p < 0.001). The haemodynamic parameters measured 10 minutes after the termination of cardiopulmonary bypass were not different in the two groups. When measured one hour after the termination of cardiopulmonary bypass, haemodynamic parameters in the study group revealed a statistically significant improvement in inotropicity. No side effects or complications were encountered in the study group. We conclude that adenosine given as an adjunct to K(+)-enriched cardioplegia helps to achieve rapid asystole and faster recovery of sinus rhythm with no adverse effects and may aid in better myocardial preservation.

Optimized therapeutic ratio of inhaled corticosteroids using retrometabolism

During recent years, the treatment of pulmonary diseases could be significantly improved due to the introduction of modern retrometabolism-based corticosteroids with improved therapeutic ratio. It is the goal of all inhaled corticosteroids to produce long lasting therapeutic effects at the pulmonary target site and to minimize systemic side effects by rapid clearance of the absorbed drug and low oral bioavailability. The development of PK/PD models allows predictions of drug effects based on the administered dose. For example, the cumulative suppression of endogenous cortisol release (CCS) as one of the major systemic side effects of inhaled corticosteroid therapy can be described with an integrated Emax based PK/PD model. In order to assess the predictive power of this model, a study was conducted to compare the PK/PD-based predictions with CCS data obtained from actual clinical trials for flunisolide, fluticasone propionate, budesonide and triamcinolone acetonide. CCS was predicted for different single doses from different inhaler devices for each drug and a good correlation was observed. Thus, the presented PK/PD model proved to be a valid tool for predicting CCS of inhaled corticosteroids. By fully understanding the underlying mechanisms it will be possible to further improve their therapeutic index.

A sensitive LC-MS/MS method for the quantification of fluticasone propionate in human plasma

A sensitive and selective LC-(APCI) MS/MS method capable of quantifying fluticasone propionate (FP) at levels down to 10 pg ml(-1) in human plasma is reported. The method was validated over a linear range from 10 to 1000 pg ml(-1) using a previously published solid-phase extraction procedure with a 13C3-labeled internal standard. The inter and intra batch precision (coefficient of variation) and accuracy (% bias) of the quality controls samples (20, 25, 50, 100, 200, 500 and 1000 pg ml(-1)) were less than 15 and 11%, respectively. The method is robust, rapid (analysis time of 2 min), selective and hence is ideally suited for pharmacokinetic investigations involving inhalation of therapeutic doses of FP.

Clinical and pharmacological aspects of accidental triamcinolone acetonide overdosage: a case study

Local administration of corticosteroids for rheumatic diseases have had a long history of effective and well-tolerated use. We report here the pharmacodynamics and pharmacokinetics of an accidental triamcinolone acetonide (TCA) overdose. The presented patient was treated with 200 mg TCA and developed Cushing's syndrome 6 weeks later (cortisol and ACTH concentrations were below limits of detection, TCA concentrations were > 3 micrograms/l). Because of her severe symptoms, mifepristone was administered for a period of 19 days. Cortisol concentrations became detectable 2 days after initiation of mifepristone treatment and persisted, being detectable for a period of at least a week after cessation of the drug. Twenty days after cessation, cortisol concentrations were undetectable again. Cushing's syndrome persisted more than 6 months while TCA concentrations remained detectable for at least 80 days. Based on plasma TCA concentrations in our patient, we calculated a terminal half-life of TCA of 33 days as opposed to 5 days observed after intra-articular administration of a therapeutic dose of 40 mg TCA. We conclude that after an accidental overdose in this patient, body TCA disappearance was strongly prolonged due to a very slow (absorption) half-life of the drug in comparison to a therapeutic dose. This finding is explained by a 'flap-flop phenomenon' where drug absorption is the rate-limiting step of overall drug disposition. Caution is, therefore, needed to prevent undesired accumulation of TCA that may lead to protracted Cushing's syndrome.

Enhanced transgene expression in rat brain cell cultures with a disulfide-containing cationic lipid

The transfection efficiency of a disulfide-containing cationic lipid, 1',2' dioleoyl-sn-glycero-3'-succinyl-2-hydroxyethyl disulfide ornithine conjugate (DOGSDSO) and its non-disulfide analog (DOGSHDO) were compared in neuronal, astroglial and microglial cultures from newborn rat cerebral cortex. We hypothesized that the relatively high intracellular concentrations of reductive substances in the cytoplasm may help to cleave the reversible disulfide bond in DOGSDSO, thus increasing free DNA and decreasing toxicity due to rapid degradation of the lipid. We have demonstrated through mass spectrometric analysis that a reductive compound, e.g. dithiothreitol (DTT) could degrade the disulfide lipid. DOGSDSO was more efficient at transfecting each type of brain cell than were the non-disulfide DOGSHDO and DOTAP (1,2-dioleoyl-3-trimethyl-ammonium-propane) liposomes. These results demonstrate that disulfide-containing cationic liposomes facilitate gene transfection in cultured rat brain cells.

Effects of intranasal challenge with group A beta haemolytic streptococcus M type 49 in Swiss albino mice

Mice are susceptible to natural infections with streptococci and therefore can serve as suitable animal models to study experimental streptococcal infections. In an earlier study, we had shown the development of pharyngeal colonization, antibody response and histopathological changes in the heart following intranasal (IN) challenge with a rheumatogenic serotype of group A beta haemolytic streptococcus, the M type 18. To determine if nonpharyngitis associated serotypes can also elicit similar responses, 30 Swiss albino mice were challenged intranasally with 2 x 10(7) colony forming units of a skin associated serotype of group A beta haemolytic streptococcus, the M type 49. Pharyngeal colonization varied from 64% (n = 30) in the first week to 69% (n = 16) during the fourth week after IN challenge. Eleven (36.7%) of the 30 animals studied showed antibody response to DNase B (ADNB) with peak titers varying from 150 to 1200 units. Wide variations were seen in ADNB titers in individual mice. Histopathological evidence for cardiac lesions were seen in three animals. The changes were mild and varied from mild to chronic endocardial inflammation to calcification. The study shows that Swiss albino mice are also susceptible to IN challenge with skin associated strains of GABHS and therefore can serve as useful models to study the effects of experimental infection with diverse serotypes of GABHS.

Pharmacokinetic-pharmacodynamic profile of systemic nitric oxide-synthase inhibition with L-NMMA in humans

AIMS

It has been demonstrated that inhibition of endothelium derived nitric oxide with NG-monomethyl-L-arginine (L-NMMA) results in a different cardiac and peripheral vascular response. The purpose of this study was to investigate the pharmacokinetic-pharmacodynamic profile of L-NMMA and pharmacokinetic interactions with L-arginine in healthy subjects.

METHODS

Plasma pharmacokinetics were analysed from two different studies: In study 1, 3 mg kg-1 L-NMMA was administered i.v. over 5 min and systemic haemodynamics, cardiac output (CO), fundus pulsation amplitude (FPA), and NO-exhalation (exhNO) were measured at baseline and 15, 65, 95, 155, and 305 min after start of drug administration (n=7). In study 2, 17 mg kg-1 min-1 of the physiologic substrate for nitric oxide synthase, L-arginine, was coinfused i.v. over 30 min with a primed constant infusion of 50 microg kg-1 min-1 L-NMMA (n=8).

RESULTS

Bolus infusion of L-NMMA resulted in a maximum plasma concentration of 12. 9+/-3.4 microg ml-1 (mean+/-s.d.) with elimination half-life of 63. 5+/-14.5 min and clearance of 12.2+/-3.5 ml min-1 kg-1 and caused a small hypertensive response, decreased CO by 13%, FPA by 26%, exhNO by 46% and increased systemic vascular resistance by 16% (P<0.05 each) 15 min after start of drug administration. Although only limited data points were available in the L-NMMA plasma concentration range between 0 and 4 microg ml-1, drug effects over time were in good agreement with an Emax model (r2>0.98 each), which also suggested that concentrations producing half-maximum effects were higher for FPA than for CO and exhNO. The coinfusion with L-arginine caused a nearly two-fold increase in plasma L-NMMA levels, indicating a pharmacokinetic interaction.

CONCLUSIONS

In the absence of a systemic hypertensive response, L-NMMA significantly decreased CO, exhNO, and FPA. The concentration calculated to produce a half maximal effect was equivalent for exhNO and CO, but markedly higher for FPA. Furthermore, measurement of FPA is susceptible to changes in L-NMMA levels at small plasma concentrations.