OP0290 EMAPALUMAB (ANTI-INTERFERON-GAMMA MONOCLONAL ANTIBODY) IN PATIENTS WITH MACROPHAGE ACTIVATION SYNDROME (MAS) COMPLICATING SYSTEMIC JUVENILE IDIOPATHIC ARTHRITIS (SJIA)

Background:

MAS is a severe complication of rheumatic diseases and occurs most frequently in patients with sJIA. Data from animal models and from observational studies in patients suggest that interferon gamma (IFNy) is a driver of the hyperinflammation and hypercytokinemia observed in MAS.

Objectives:

To assess the pharmacokinetics, efficacy, and safety of intravenous (IV) infusions of emapalumab, a fully human anti-IFNγ monoclonal antibody, in patients with MAS in the context of sJIA.

Methods:

This ongoing, pilot, open-label, single-arm study (NCT03311854) includes patients with MAS (2016 ACR/EULAR criteria) on a background of confirmed, or high presumption of, sJIA, and with inadequate response to high-dose IV glucocorticoids. Emapalumab is initiated at 6 mg/kg (1 dose) and continued at 3 mg/kg twice weekly for a total of 4 weeks, or less upon achievement of complete response (CR). CR is defined as an absence of MAS clinical signs plus white blood cell and platelet counts above the lower limit of normal, LDH, AST and ALT <1.5 x upper limit of normal, fibrinogen >100 mg/dL, and ferritin decreased by ≥80% or to <2,000 ng/mL.

Results:

We report preliminary data from the first 9 patients (median age [range] 11.6 [2.1-25.3] years) enrolled (7 in Europe and 2 in the USA). All patients had failed high-dose methylprednisolone, of which there were prior treatment failures from cyclosporin A (n=4) and from anakinra (n=4). Treatment with emapalumab resulted in rapid IFNγ neutralization, as demonstrated by the decrease in CXCL9 levels (Figure 1), and subsequent deactivation of T cells, as indicated by the decrease in sIL-2R levels. CR was achieved in all patients after a median of 23 (12-56) days. A progressive improvement in all clinical and laboratory parameters of MAS was observed (Table 1 and Figure 2). Glucocorticoids were tapered in all patients (median % tapering -92%; range -45% to -98% at Week 8). Emapalumab infusions were well tolerated by all patients, with no discontinuation. CMV reactivation was reported in 1 patient as a serious event possibly related to emapalumab and resolved with antiviral treatment.

Table 1.

Time to response for key clinical and laboratory parameters.

ParametersMedian baseline value (range)Median days of treatment (range)D-dimers to <1000 mg/L12,480 (550-89,552)15 (1-49)sIL-2R to <2000 ng/L4596 (1664-20,954)21 (6-37)Ferritin <500 mg/L29,240 (716-192,584)21 (9-42)Physician visual analog scale of MAS activity ≤19.0 (2-10)19 (9-56)All MAS laboratory parameters within range of CRNA21 (15-55)All MAS parameters within range of CRNA23 (12-56)Glucocorticoid tapering at ≤1 mg/kg prednisolone equivalent*NA42 (16-50)

*Data incomplete for 1 patient

Figure 1.

Rapid neutralization of IFNy. Each line represents an individual patient (n=9).

Figure 2.

Ferritin levels and platelet counts over time.

Conclusion:

Emapalumab administration led to rapid neutralization of IFNy and was efficacious in controlling MAS with a favorable safety profile. These results support the pathogenic role of IFNγ in MAS/sJIA and the therapeutic value of IFNγ neutralization in MAS patients who have failed standard of care.

Disclosure of Interests:

Fabrizio De Benedetti Grant/research support from: AbbVie, Pfizer, Novartis, Novimmune, Sobi, Sanofi, Roche, Speakers bureau: AbbVie, Novartis, Roche, Sobi, Paul Brogan Grant/research support from: Sobi, Novartis, Roche, Chemocentryx, Consultant of: Roche, Sobi, Speakers bureau: Sobi, Roche, Novartis, UCB, Claudia Bracaglia: None declared, Manuela Pardeo: None declared, Giulia Marucci: None declared, Emanuela Sacco: None declared, Despina Eleftheriou Speakers bureau: Sobi, Charalampia Papadopoulou: None declared, Alexei Grom Grant/research support from: Novartis, AB2Bio, Consultant of: Novartis, Pierre Quartier Consultant of: AbbVie, Chugai-Roche, Lilly, Novartis, Sanofi, Sobi, Speakers bureau: AbbVie, BMS, Chugai-Roche, Novartis, Pfizer, Sobi, Rayfel Schneider Grant/research support from: Roche, Novartis, Sobi, Pfizer, Consultant of: Sobi, Novartis, Novimmune, Philippe Jacqmin Consultant of: Sobi, Rikke Frederiksen Employee of: Sobi, Maria Ballabio Employee of: Sobi, Cristina De Min Employee of: Sobi

Evidence of NI-0101 pharmacological activity, an anti-TLR4 antibody, in a randomized phase I dose escalation study in healthy volunteers receiving LPS

Toll-like receptor-4 (TLR4) pathways are major contributors to pathological inflammatory responses induced by tissue damage. NI-0101 is the first monoclonal antibody (mAb) blocking TLR4 signaling. This activity is independent of the ligand type and concentration, therefore, potentially blocking any TLR4 ligands. A phase I single ascending dose study was conducted in 73 healthy volunteers to evaluate NI-0101 tolerability, preliminary safety, pharmacokinetics (PKs), and pharmacodynamics (PDs), in absence and in presence of a systemic challenge with lipopolysaccharide (LPS), a TLR4 ligand. NI-0101 was well tolerated without safety concern. The PK profile was characterized by a half-life of ∼10 days at high concentrations and by a rapid elimination at low concentrations due to expected target-mediated drug disposition. NI-0101 prevented cytokine release following ex vivo and in vivo LPS administration and prevented the C-reactive protein (CRP) increase and the occurrence of flu-like symptoms expected following the in vivo administration of LPS.

Modeling Alzheimer's Disease Progression Using Disease Onset Time and Disease Trajectory Concepts Applied to CDR-SOB Scores From ADNI

Disease-onset time (DOT) and disease trajectory concepts were applied to derive an Alzheimer's disease (AD) progression population model using the clinical dementia rating scale—sum of boxes (CDR-SOB) from the AD neuroimaging initiative (ADNI) database. The model enabled the estimation of a DOT and a disease trajectory for each patient. The model also allowed distinguishing fast and slow-progressing subpopulations according to the functional assessment questionnaire, normalized hippocampal volume, and CDR-SOB score at study entry. On the basis of these prognostic factors, 81% of the mild cognitive impairment (MCI) subjects could correctly be assigned to slow or fast progressers, and 77% of MCI to AD conversions could be predicted whereas the model described correctly 84% of the conversions. Finally, synchronization of the biomarker-time profiles on estimated individual DOT virtually expanded the population observation period from 3 to 8 years. DOT-disease trajectory model is a powerful approach that could be applied to many progressive diseases.

Assessment of Maraviroc Exposure-Response Relationship at 48 Weeks in Treatment-Experienced HIV-1-Infected Patients in the MOTIVATE Studies

Efficacy exposure–response relationships of the CCR5 antagonist maraviroc were evaluated across two phase III clinical trials. This post-hoc analysis used 48-week efficacy data from 841 treatment-experienced patients infected with CCR5-tropic human immunodeficiency virus type 1 (HIV-1), identified by the enhanced sensitivity Trofile assay. Probability of treatment success (viral RNA <50 copies/ml) was modeled using generalized additive logistic regression, testing exposure, clinical, and virologic variables. Prognostic factors for treatment success (in decreasing order of Akaike information criterion (AIC) change) were: maraviroc treatment, high-weighted overall susceptibility to background treatment, absence of an undetectable maraviroc concentration, high baseline CD4 count (BCD4), low viral load (VL), race (other than black), absence of non-R5 baseline tropism (BTRP), and absence of fosamprenavir (FPV). No concentration–response relationship was found with treatment (maraviroc vs. placebo) and presence/absence of undetectable maraviroc concentration (adherence marker) in the model. The maraviroc doses studied (300 or 150 mg with potent CYP3A4 inhibitors once (q.d.)/twice daily (b.i.d.)) deliver concentrations near the top of the concentration–response curve.

A comprehensive hepatitis C viral kinetic model explaining cure

We propose a model that characterizes and links the complexity and diversity of clinically observed hepatitis C viral kinetics to sustained virologic response (SVR)-the primary clinical end point of hepatitis C treatment, defined as an undetectable viral load at 24 weeks after completion of treatment)-in patients with chronic hepatitis C (CHC) who have received treatment with peginterferon alpha-2a +/- ribavirin. The new attributes of our hepatitis C viral kinetic model are (i) the implementation of a cure/viral eradication boundary, (ii) employment of all hepatitis C virus (HCV) RNA measurements, including those below the lower limit of quantification (LLOQ), and (iii) implementation of a population modeling approach. The model demonstrated excellent positive (99.3%) and negative (97.1%) predictive values for SVR as well as high sensitivity (96.6%) and specificity (99.4%). The proposed viral kinetic model provides a framework for mechanistic exploration of treatment outcome and permits evaluation of alternative CHC treatment options with the ultimate aim of developing and testing hypotheses for personalizing treatments in this disease.

Modelling response time profiles in the absence of drug concentrations: definition and performance evaluation of the K-PD model

The plasma concentration-time profile of a drug is essential to explain the relationship between the administered dose and the kinetics of drug action. However, in some cases such as in pre-clinical pharmacology or phase-III clinical studies where it is not always possible to collect all the required PK information, this relationship can be difficult to establish. In these circumstances several authors have proposed simple models that can analyse and simulate the kinetics of the drug action in the absence of PK data. The present work further develops and evaluates the performance of such an approach. A virtual compartment representing the biophase in which the concentration is in equilibrium with the observed effect is used to extract the (pharmaco)kinetic component from the pharmacodynamic data alone. Parameters of this model are the elimination rate constant from the virtual compartment (KDE), which describes the equilibrium between the rate of dose administration and the observed effect, and the second parameter, named EDK(50) which is the apparent in vivo potency of the drug at steady state, analogous to the product of EC(50), the pharmacodynamic potency, and clearance, the PK "potency" at steady state. Using population simulation and subsequent (blinded) analysis to evaluate this approach, it is demonstrated that the proposed model usually performs well and can be used for predictive simulations in drug development. However, there are several important limitations to this approach. For example, the investigated doses should extend from those producing responses well below the EC(50) to those producing ones close to the maximum response, optimally reach steady state response and followed until the response returns to baseline. It is shown that large inter-individual variability on PK-PD parameters will produce biases as well as large imprecision on parameter estimates. It is also clear that extrapolations to dosage routes or schedules other than those used to estimate the parameters should be undertaken with great caution (e.g., in case of non-linearity or complex drug distribution). Consequently, it is advised to apply this approach only when the underlying structural PD and PK are well understood. In any case, K-PD model should definitively not be substituted for the gold standard PK-PD model when correct full model can and should be identified.

A combined specific target site binding and pharmacokinetic model to explore the non-linear disposition of draflazine

The capacity-limited high-affinity target site binding of draflazine to the nucleoside transporters located on the erythrocytes is a source of nonlinearity in the pharmacokinetics of the drug. An attractive feature of draflazine is that the specific target site binding characteristics can be determined easily by simultaneously measuring plasma and whole blood concentrations of the drug. Measured drug concentrations following various infusion rates and infusion durations were used to develop a model in which the interrelated blood-plasma distribution, elimination, and specific target site binding of draflazine were incorporated simultaneously. The estimated binding (dissociation) constant Kd was 0.57 ng/ml plasma and the maximal specific erythrocyte binding capacity (BmaxRBC) was 163 ng/ml RBC. The maximal specific binding capacity to the tissues (Bmaxtissue) was estimated to be about 1 mg. The estimated volume of the central compartment (Vplasma + tissue fluids) was 12.9 L and the total intrinsic CL was 645 ml/min. After validation, the model was used to further investigate the impact of the specific high-affinity target site binding of draflazine on its disposition in plasma. The time required to reach steady-state plasma concentrations of draflazine decreased with an increasing infusion rate. Time profiles of the plasma concentrations were not always representative for the time profiles of the specific target site (RBC) occupancy of draflazine, but the t1/2,z in plasma paralleled that of the drug at target sites. The apparent Vd and the t1/2,z decreased with increasing single doses whereas the total CL remained constant. The recovery of draflazine was also dose dependent and increased with increasing doses. Finally, the total CL and apparent Vd of the first dose were greater than those of the second dose of draflazine.

Physiological red blood cell kinetic model to explain the apparent discrepancy between adenosine breakdown inhibition and nucleoside transporter occupancy of draflazine

A physiological red blood cell (RBC) kinetic model is proposed for the adenosine (ADO) transport into erythrocytes and its subsequent intracellular deamination into inactive inosine (INO) and further breakdown into hypoxanthine (HYPO). The model and its parameters were based on previous studies investigating the kinetics of the biochemical mechanism of uptake and metabolism of ADO in human erythrocytes. Application of the model for simulations of the breakdown of ADO in a RBC suspension revealed that the predicted adenosine breakdown inhibition (ABI) of draflazine corresponded well with the ABI measured ex vivo. The model definitely explained the apparent discrepancy between the ex vivo measured ABI and the nucleoside transporter occupancy of draflazine. Intracellular deamination of ADO rather than its transport by the nucleoside transporter is the rate-limiting step in the overall catabolism of ADO. Consequently, at least 90% occupancy of the transporter by draflazine is required to inhibit adenosine breakdown ex vivo substantially. Simulations on basis of the validated model were performed to evaluate the ABI for different experimental conditions and to mimic the clinical situation. The latter may be very helpful for the design of optimal dosing schemes of draflazine. It was demonstrated that the short half-life of released ADO was prolonged substantially in a dose-related manner after a continuous infusion of draflazine. Finally, the previously found different sigmoidal Emax relationships between the measured ABI and the concentrations of draflazine in plasma and whole blood could be explained by the ADO transport and breakdown RBC kinetic model and the capacity-limited specific RBC binding characteristics of draflazine.

Repeated-dose pharmacokinetics of an oral solution of itraconazole in infants and children

The safety, tolerability, and pharmacokinetics of an oral solution of itraconazole and its active metabolite hydroxyitraconazole were investigated in an open multicenter study of 26 infants and children aged 6 months to 12 years with documented mucosal fungal infections or at risk for the development of invasive fungal disease. The most frequent underlying illness was acute lymphoblastic leukemia, except in the patients aged 6 months to 2 years, of whom six were liver transplant recipients. The patients were treated with itraconazole at a dosage of 5 mg/kg of body weight once daily for 2 weeks. Blood samples were taken after the first dose, during treatment, and up to 8 days after the last itraconazole dose. On day 1, the mean peak concentrations in plasma after the first and last doses (Cmax) and areas under the concentration-time curve from 0 to 24 h (AUC0-24) for itraconazole and hydroxyitraconazole were lower in the children aged 6 months to 2 years than in children aged 2 to 12 years but were comparable on day 14. The mean AUC0-24-based accumulation factors of itraconazole and hydroxyitraconazole from day 1 to 14 ranged from 3.3 to 8.6 and 2.3 to 11.4, respectively. After 14 days of treatment, Cmax, AUC0-24, and the half-life, respectively, were (mean +/- standard deviation) 571+/-416 ng/ml, 6,930+/-5,830 ng.h/ml, and 47+/-55 h in the children aged 6 months to 2 years; 534+/-431 ng/ml, 7,330+/-5,420 ng.h/ml, and 30.6+/-25.3 h in the children aged 2 to 5 years; and 631+/-358 ng/ml, 8,770+/-5,050 ng.h/ml, and 28.3+/-9.6 h in the children aged 5 to 12 years. There was a tendency to have more frequent low minimum concentrations of the drugs in plasma for both itraconazole and hydroxyitraconazole for the children aged 6 months to 2 years. The oral bioavailability of the solubilizer hydroxypropyl-beta-cyclodextrin was less than 1% in the majority of the patients. In conclusion, an itraconazole oral solution given at 5 mg/kg/day provides potentially therapeutic concentrations in plasma, which are, however, substantially lower than those attained in adult cancer patients, and is well tolerated and safe in infants and children.

Population analysis of the non-linear red blood cell partitioning of draflazine following various infusion durations

OBJECTIVE

The pharmacokinetics and non-linear red blood cell partitioning of the nucleoside transport inhibitor draflazine were investigated in 19 healthy male and female subjects (age range 22-55 years) after a 15-min i.v. infusion of 1 mg, immediately followed by infusions of variable rates (0.25, 0.5 and 1 mg.h-1) and variable duration (2-24 h).

METHODS

The parameters describing the capacity-limited specific binding of draflazine to the nucleoside transporters located on erythrocytes were determined by NONMEM analysis. The red blood cell nucleoside transporter occupancy of draflazine (RBC occupancy) was evaluated as a pharmacodynamic endpoint.

RESULTS

The population typical value for the dissociation constant Kd (%CV) was 0.648 (12) ng.ml-1 plasma, expressing the very high affinity of draflazine for the erythrocytes. The typical value of the specific maximal binding capacity Bmax (%CV) was 155 (2) ng.ml-1 RBC. The interindividual variability (%CV) was moderate for Kd (38.9%) and low for Bmax (7.8%). As a consequence, the variability in RBC occupancy of draflazine was relatively low, allowing the justification of only one infusion scheme for all subjects. The specific binding of draflazine to the red blood cells was a source of non-linearity in draflazine pharmacokinetics. Steady-state plasma concentrations of draflazine virtually increased dose-proportionally and steady state was reached at about 18 h after the start of the continuous infusion. The t1/2 beta averaged 11.0-30.5 h and the mean CL from the plasma was 327 to 465 ml.min-1. The disposition of draflazine in whole blood was different from that in plasma. The mean t1/2 beta was 30.2 to 42.2 h and the blood CL averaged 17.4-35.6 ml.min-1.

CONCLUSION

Although the pharmacokinetics of draflazine were non-linear, the data of the present study demonstrate that draflazine might be administered as a continuous infusion over a longer time period (e.g., 24 h). During a 15-min i.v. infusion of 1 mg, followed by an infusion of 1 mg.h-1, the RBC occupancy of draflazine was 96% or more. As the favored RBC occupancy should be almost complete, this dose regimen could be justified in patients.

Population analysis of the non linear red blood cell partitioning and the concentration-effect relationship of draflazine following various infusion rates

AIMS

To investigate the impact of the specific red blood cell binding on the pharmacokinetics and pharmacodynamics of the nucleoside transport inhibitor draflazine after i.v. administration at various infusion rates. It was also aimed to relate the red blood cell (RBC) occupancy of draflazine to the ex vivo measured adenosine breakdown inhibition (ABI).

METHODS

Draflazine was administered to healthy volunteers as a 15-min i.v. infusion of 0.25, 0.5, 1, 1.5 and 2.5 mg immediately followed by an infusion of the same dose over 1 h. Plasma and whole blood concentrations were measured up to 120 h post dose, and were related to the ex vivo measured ABI, serving as a pharmacodynamic endpoint. The capacity-limited specific binding of draflazine to the nucleoside transporter located on the erythrocytes was evaluated by a population approach.

RESULTS

The estimate of the population parameter typical value (%CV) of the binding constant Kd and the maximal specific binding capacity (Bmax) was 0.385 (3.5) ng ml-1 plasma and 158 (2.1) ng ml-1 RBC, respectively. The non-specific binding was low. The specific binding to the erythrocytes was a source of non-linearity in the pharmacokinetics of draflazine. The total plasma clearance of draflazine slightly decreased with increasing doses, whereas the total clearance in whole blood increased with increasing doses. The sigmoidal Emax equation was used to relate the plasma and whole blood concentration of draflazine to the ex vivo determined ABI. In plasma, typical values (%CV) of Emax, IC50 and Hill factor were 81.4 (1.9)%, 3.76 (9.3) ng ml-1 and 1.06 (3.4), respectively. The relationship in whole blood was much steeper with population parameter typical values (%CV) of Emax, IC50 and Hill factor of 88.2 (2.0)%, 65.7 (2.8) ng ml-1 and 4.47 (5.5), respectively. The RBC occupancy of draflazine did not coincide with the ex vivo measured ABI. The observed relationship between RBC occupancy and ABI was not directly proportional but similar for all studied infusion schemes.

CONCLUSIONS

The findings of this study show that the occupancy of the nucleoside transporter by draflazine should be at least 90% in order to inhibit substantially adenosine breakdown in vivo. On the basis of these findings it is suggested that a 15 min infusion of 1 mg draflazine followed by an infusion of 1 mg h-1 could be appropriate in patients undergoing a coronary artery bypass grafting.

The implications of non-linear red blood cell partitioning for the pharmacokinetics and pharmacodynamics of the nucleoside transport inhibitor draflazine

1. Draflazine, a nucleoside transport inhibitor, was administered as a 15 min i.v. infusion of 2.5 mg to eight healthy male subjects. Plasma and whole blood concentrations were measured up to 32 h post-dose, and were related to adenosine breakdown inhibition (ABI) measured ex vivo, which served as a pharmacodynamic endpoint. 2. The red blood cell/plasma distribution of draflazine was non-linear and characterized as a capacity-limited specific binding to the nucleoside transporter on the red blood cells. The binding (dissociation) constant Kd was 0.87 ng ml-1 plasma and the maximal specific binding capacity (Bmax) was 164 ng ml-1 RBC, which corresponds to about 14,000 specific binding sites per erythrocyte. Non-specific binding amounted to less than 15% of the total binding. 3. The pharmacokinetics of draflazine in blood were determined in each subject and characterized by a two-compartment pharmacokinetic model. The pharmacokinetic parameters (mean +/- s.d.) were: clearance 22.0 +/- 8.0 ml mm-1, volume of distribution at steady-state 39.8 +/- 4.7 l and terminal half-life 24.0 +/- 9.4 h. Concentrations in plasma were much lower, and could only be determined accurately in pooled plasma samples with a red blood cell binding assay. The pharmacokinetic parameters in pooled plasma were: clearance 551 ml min-1, volume of distribution at steady-state 349 l and terminal half-life 10.7 h. 4. A non-linear relationship was observed between the plasma or blood concentration of draflazine and the ABI determined ex vivo. This relationship was characterized by the sigmoidal Emax pharmacodynamic model. Based on concentrations in pooled plasma, values of the pharmacodynamic parameters were Emax 100%, IC50 10.5 ng ml-1 and Hill factor 0.9. When using whole blood concentrations, the relationship was much steeper with values (mean +/- s.d.) Emax 92.4 +/- 5.6%, IC50 76.0 +/- 15.3 ng ml-1 and Hill factor 3.5 +/- 0.9. 5. Binding to the nucleoside transporter on red blood cells is an important determinant of the pharmacokinetics of draflazine and a high degree of occupancy of the transporter by draflazine is required to inhibit adenosine breakdown ex vivo. It is suggested that red blood cell nucleoside transporter occupancy may serve as a useful pharmacodynamic endpoint in dose ranging studies with draflazine.

Antifungal pulse therapy for onychomycosis. A pharmacokinetic and pharmacodynamic investigation of monthly cycles of 1-week pulse therapy with itraconazole

BACKGROUND AND DESIGN

In the treatment of onychomycosis, oral therapies have generally been given as a continuous-dosing regimen. For example, the suggested dose of itraconazole for the treatment of onychomycosis has thus far been 200 mg/d for 3 months. Based on the advances in our understanding of the pharmacokinetics of itraconazole, we investigated the efficacy and nail kinetics of intermittent pulse-dosing therapy with oral itraconazole in patients who were suffering from onychomycosis. Fifty patients with confirmed onychomycosis of the toenails, predominantly Trichophyton rubrum, were recruited and randomly assigned to three (n = 25) or four (n = 25) pulses of 1-week itraconazole therapy (200 mg twice daily for each month). Clinical and mycological evaluation of the infected toenails, and determination of the drug levels in the distal nail ends of the fingernails and toenails, were performed at the end of each month up to month 6 and then every 2 months up to 1 year.

RESULTS

In the three-pulse treatment group, the mean concentration of itraconazole in the distal ends of the toenails ranged from 67 (month 1) to 471 (month 6) ng/g, and in the distal ends of the fingernails, it ranged from 103 (month 1) to 424 (month 6) ng/g. At month 11, the drug was still present in the distal ends of the toenails at an average concentration of 186 ng/g. The highest individual concentrations of 1064 and 1166 ng/g were reached at month 6 for toenails and fingernails, respectively. At end-point follow-up, toenails in 84% of the patients were clinically cured with a negative potassium hydroxide preparation and culture in 72% and 80% of the patients, respectively. In the four-pulse treatment group, the mean concentration of itraconazole in the distal ends of the toenails ranged from 32 (month 1) to 623 (month 8) ng/g, and in the distal ends of the fingernails, it ranged from 42 (month 1) to 380 (month 6) ng/g. The highest individual concentrations of 1549 and 946 ng/g were reached at month 7 for toenails and at month 9 for fingernails, respectively. At month 12, the drug was still present in the distal ends of the toenails at an average concentration of 196 ng/g. At end-point follow-up, toenails in 76% of the patients were clinically cured with a negative potassium hydroxide preparation and culture in 72% and 80% of the patients, respectively. There were no significant intergroup differences between the three- and four-pulse treatment groups for the primary efficacy parameters. The drug was well tolerated with no significant side effects in either patient group.

CONCLUSIONS

Following pulse therapy with itraconazole (400 mg/d given for 1 week each month for 3 to 4 months), the drug has been detected in the distal ends of nails after the first pulse, and it has reached therapeutic concentrations with further therapy. After stopping the last pulse, the drug remains in the nail plate at levels above 300 ng/g for several months. Clinical cure rates between 76% and 84% and negative mycological examination findings between 72% and 80%, respectively, were observed in toenail onychomycosis. The data suggest that pulse therapy with itraconazole is an effective and safe treatment option for onychomycosis.

Paradoxical response to itraconazole treatment in a patient with onychomycosis caused by Microsporum gypseum

A Columbian patient presented with a rare type of onychomycosis caused by Microsporum gypseum. Oral treatment with itraconazole formulation (Funazol) available in Columbia failed to improve the nail alteration. The fungitoxic effect of itraconazole was assessed on the M. gypseum strain cultured from the nail of the patient by using the method of culture of fungi on cyanoacrylate skin surface strippings (CSSS). In addition, a comparative evaluation of the oral bioavailability of itraconazole was made in volunteers after intake of Funazol and Sporanox. In the ex vivo bioassay on CSSS, topical itraconazole proved to be highly active against M. gypseum. After oral intake, however, the itraconazole bioavailability of Funazol relative to Sporanox averaged only 3.5%. Antifungal pulse therapy with Sporanox, 400 mg daily for 1 week per month for 4 months, cured the patient. This study shows that itraconazole is hardly or not absorbed from the oral formulation Funazol. Both the oral bioavailability and consequently therapeutic efficacy of the genuine drug (Sporanox) are highly superior.

A study of lactate metabolism without tracer during passive and active postexercise recovery in humans

Tracers have been used extensively to study lactate metabolism in humans during rest and exercise. Nevertheless, quantification of in vivo lactate kinetics as measured by lactate tracers remains controversial and new data are necessary to clarify the issue. The present study has developed a simple kinetic model which does not require labelled molecules and which yields proportional and quantitative information on lactate metabolism in humans during postexercise recovery performed at different levels of intensity. Five subjects took part in six experiments each of which began with the same strenuous exercise (StrEx; 1 min, 385 W, 110 rpm). The StrEx of each session was followed by a different intensity of recovery: passive recovery (PR) and active recoveries (AR) with power outputs of 60, 90, 120, 150 and 180 W, respectively. Blood lactate concentration was measured prior to and immediately after StrEX and regularly during the 1st h of recovery. Oxygen uptake (VO2) was measured every 30 s during the whole session. The results showed that the disappearance rate constant (ke) increases abruptly from PR [0.080 (SEM 0.004) min-1] to moderate AR [60 W: 0.189 (SEM 0.039) min-1] and decreases slowly during more intense AR [180 W: 0.125 (SEM 0.027) min-1]. The lactate apparent clearance (Cl.F-1) was calculated from the area under the lactate concentration-time curve. The Cl.F-1 increased 1.81 (SEM 0.17) fold from PR to moderate AR (60 W) and only 1.31 (SEM 0.14) from PR to the most intense AR (180 W). Using the model, the apparent lactate production (F"K0) was also calculated. The F"K0 increased regularly following a slightly curvilinear function of VO2 and was 2.61 (SEM 0.53) fold greater during the most intense AR (180 W) than during PR. Because of the lack of data concerning the size of apparent lactate distribution volume (Vd), the apparent turnover rate (Rbl) has been presented here related to Vd. The Rbl.Vd-1 increased also following a slightly curvilinear function of VO2. The Rbl.Vd-1 was 85.90 (SEM 14.42) mumol.min-1.l-1 during PR and reached 314.09 (SEM 153.95) mumol.min-1.l-1 during the most intense AR (180 W). In conclusion the model presented here does not require labelled molecules and firstly makes it possible to follow the proportional change of apparent lactate clearance and apparent lactate production during active postexercise recovery in comparison with passive recovery conditions and secondly to estimate the blood lactate turnover.

Irreversible binding to proteins after single and repeated daily oral administration of 4-(2,2-diphenylethyl) imidazole (SC-46264) to the Cynomolgus monkey

SC-46264 is an antagonist of the alpha 2-adrenergic receptor. Distribution and excretion of [14C]-SC-46264 were studied after single and repeated daily oral administrations to the Cynomolgus monkey at a 1.5 mg/kg dose. After a single oral administration, more than 95% of the administered dose was recovered within 48 h in the urine (+/- 60%) and faeces (+/- 40%). Approximately 1.7% remained in the gastro-intestinal (GI) tract and 2% in the animal body. However, the radioactivity remaining in the animal body decreased very slowly from 2 to 1% between 48 and 144 h. An accumulation of very small amounts of radioactivity could be suspected in the plasma, the liver, the thyroid, the adrenals and the kidneys. In a 2 week daily oral administration of [14C]-SC-46264, the amount of total radioactivity remaining in the animal body 24, 48 and 216 h after the last administration was approximately 21, 11 and 5% of the daily administered dose, respectively. It confirmed the accumulation of [14C]-SC-46264 related compound in the plasma, the liver, the thyroid, the adrenals and the kidneys. The minimum plasma concentrations of total radioactivity observed before each administration increased during the treatment and apparently did not yet reach an equilibrium after 14 days. In these plasma samples obtained throughout the study, an increasing fraction of the total radioactivity could not be extracted and was recovered with precipitable material. These observations lead to the hypothesis of an irreversible binding of some material to the proteins.(ABSTRACT TRUNCATED AT 250 WORDS)

Safety, pharmacokinetics and efficacy of once-a-day netilmicin and amikacin versus their conventional schedules in patients suffering from pelvic inflammatory disease

The safety, pharmacokinetics and efficacy of one daily injection (qd) of amikacin (AK) and netilmicin (NT) was compared with the recommended schedules (cs), i.e. twice-daily or thrice-daily, respectively. Women (17-43 years, n = 78) suffering from pelvic inflammatory disease were randomly assigned to qd or cs of either AK (14 mg/kg per day) or NT (6.6 mg/kg per day). Biometric parameters were similar in the 4 groups and all patients received ampicillin (4 g/day) and tinidazole (0.8 g/day). The Repeated Measures Analysis of Variance was used to distinguish the effects of the schedules and of the drugs choice on critical parameters. Efficacy was similar in the 4 groups and not influenced by the schedule of administration. No significant differences in nephro- and oto-toxicity were observed as assessed by serum creatinine and losses of hearing at low frequencies, but early phospholipiduria and auditory losses at high frequencies were significantly reduced with the qd administration compared to cs and by AK compared to NT. These data suggest that the qd schedule of AK and of NT is as efficacious as their cs schedules, and causes less renal and auditory alterations.

Comparison of sublingual and oral prazepam in normal subjects. II. Pharmacokinetic and pharmacodynamic data

The pharmacokinetic profiles of oral and sublingual administrations of prazepam 20 mg to 5 normal volunteers were compared in order to explain the clinical observation that sublingual prazepam appears to exhibit sedative properties when compared to the same dose of oral prazepam. Blood samples for pharmacokinetic evaluation were collected just before drug intake and 7.5, 15, 22.5, 30, 45, 60, 90 min, 2, 3, 5, 6, 7, 8, 9, 10 and 24 h after drug intake. The study was performed in double-blind and crossover conditions. Serum levels of prazepam and its major metabolite N-desmethyl-diazepam were measured by HPLC. No prazepam was detected at a concentration higher than 20 ng/ml (limit of detection) whereas N-desmethyl-diazepam reached concentrations around 140 ng/ml. To correlate this observation with the clinical data, the affinity of prazepam and N-desmethyl-diazepam was compared measuring their ability to displace 50% of 3H-flunitrazepam bound to benzodiazepine receptors contained in synaptosomal preparation obtained from rat brain. N-desmethyl-diazepam was 17-fold more potent than prazepam. This data suggests that prazepam is a pro-drug which is transformed to the active compound N-desmethyl-diazepam and that the difference in clinical observation with both administrations could be correlated to N-desmethyl-diazepam concentration-time curves. Nevertheless, the comparison of the area under the N-desmethyl-diazepam serum concentration-time curves, the maximum concentrations, the times when the maximum concentrations were observed and the times needed to detect a significant level after oral and sublingual administration did not show statistical difference.(ABSTRACT TRUNCATED AT 250 WORDS)

The quantification of gamma-aminobutyric acid in the cerebrospinal fluid by a radioreceptorassay

The development of a radioreceptor assay designed to measure gamma-aminobutyric acid (GABA) in CSF is described. The method is based on the presence of high affinity and selective GABA binding sites obtained from rat brain membrane preparations treated with 0.05% Triton X-100. The optimum protein concentration in the incubation medium, the duration of incubation to reach equilibrium, the temperature and the optimum pH are discussed. The standard curve permits measurements in the range 35 to 2250 nmol/l GABA. The imprecision of the method calculated from three different concentrations: 1125, 562 and 281 nmol/l shows coefficients of variation for 'within' and 'between' assays, between 5.2% and 9.3% and between 7.4% and 12.4%, respectively. The percentage of recovery is 102 +/- 3.3% (n = 4). This radioreceptorassay has a sensitivity of 14 nmol/l. The method is easy, rapid and not expensive. It enables analysis of small volumes of CSF (200 microliters). Several samples (greater than 20) can be analysed in the same run in about one hour.

Benzodiazepine receptors are involved in tabernanthine-induced tremor: in vitro and in vivo evidence

Tabernanthine, an indol alkaloid, is structurally related to carbolines (harmane, harmaline) which, in vitro, displace specific flunitrazepam binding to brain benzodiazepine receptors. In vivo, both tabernanthine and carbolines cause a fine general tremor, suggesting that a possible interaction with benzodiazepine receptors could be involved in the activity of tabernanthine. This hypothesis was validated by the in vitro and in vivo antagonism of benzodiazepine by tabernanthine. In vitro, tabernanthine inhibited specific flunitrazepam binding in a competitive manner with an affinity (IC50 150 microM) in the same range as harmane. Tabernanthine appeared as a benzodiazepine receptor inverse agonist in a discriminant in vitro binding assay. In vivo, the time course of tremorigenic activity was related to the tabernanthine concentration in brain (half-life = 2 h). Moreover, tabernanthine-induced tremor was inhibited reversibly by flunitrazepam or by Ro-15 1788 (an antagonist of benzodiazepine-receptors). These results suggest that part of the action of tabernanthine may be mediated by an interaction at the benzodiazepine receptor level.

Comparison of sublingual and oral prazepam in normal subjects. I. Clinical data

Five normal volunteers received at a 2-week interval a single dose of sublingual or oral prazepam in double-blind and cross-over conditions. All subjects completed a battery of 15 visual analogue scales before drug intake and 7.5, 15, 22.5, 30, 45, 60, 90 min, 2, 3, 5, 6, 7, 8, 9, 10 and 24 h following intake whereas a computerized assessment of vigilance (reaction time) was performed before intake, 15, 30, 60 min, 2, 3, 6, 8, 10 h following intake. Subjects rated themselves significantly more feeble, clumsy, lethargic, and incompetent following sublingual as compared to oral prazepam while a trend in the same direction was noted for the adjectives muzzy and mentally slow. In contrast, reaction time did not exhibit significantly different changes over time between the two forms. These results suggest a subjectively more rapid onset of activity following sublingual compared to oral prazepam.

Selective affinity of one enantiomer of suriclone demonstrated by a binding assay with benzodiazepine receptors

The binding of racemic 3H-suriclone on the BZD receptor was performed in special conditions in order to discriminate between the affinity of the two enantiomers: a rebinding method was used. In the first incubation 40% of 3H-suriclone was specifically bound to the BZD receptor. In the second incubation performed with the supernatant coming from the first incubation, less than 1% of the radiolabelled suriclone was specifically bound to the BZD receptor. These results suggest that most probably only one of the two enantiomers of suriclone may bind the BZD receptor. It appears that this enantiomer has the greatest affinity constant ever found for a BZD receptor agonist (Kd = 20 pM at 37 degrees C in presence of GABA and 70 pM in absence of GABA).

Classification of benzodiazepine receptor agonists, inverse agonists and antagonists using bicuculline in an in vitro test

The mechanism by which a substance that binds to the benzodiazepine receptor acts as an agonist, an inverse agonist (e.g. methyl-beta-carboline-3-carboxylate (beta-CCM] or an antagonist (e.g. Ro 15-1788) was investigated. For this purpose, we studied the influence of bicuculline, an antagonist of gamma-aminobutyric acid (GABA), on the binding of these substances in crude synaptosomal preparation (P2 fraction) containing high levels of endogenous GABA. Displacement curves were performed, using 3H-flunitrazepam in the absence and in the presence of a high concentration (7.10(-5) M) of bicuculline. The ratios of IC50 values with and without bicuculline were significantly higher than 1 for all benzodiazepine agonists investigated (e.g. 1.91 +/- 0.11 (n = 3) for diazepam), about 1 for Ro 15-1788 (0.94 +/- 0.06 (n = 4)) and lower than 1 for beta-CCE (0.55 +/- 0.05 (n = 4)). Statistically significant differences were also observed among benzodiazepine agonists e.g. between flunitrazepam (a sedative-hypnotic drug) and clonazepam (an anticonvulsant drug) or lorazepam (an anxiolytic drug). These data indicate that the ratios of IC50 values with and without bicuculline might provide the basis for an in vitro, pharmacologically relevant, classification of drugs acting on the benzodiazepine receptor. This procedure does not require extensive washing of the membrane preparation, in contrast to the method in which the ratios of IC50 values were determined with and without addition of GABA.