Population pharmacokinetics of recombinant factor VIIa in volunteers anticoagulated with acenocoumarol

This study establishes a population PK model for FVII clotting activity (FVII:C) after injection of recombinant activated factor VII (rFVIIa) to healthy volunteers. Twenty eight volunteers, anticoagulated with acenocoumarol, received one or two rFVIIa injections, with dose ranging from 5 to 320 microg/kg. The FVII:C kinetic was fitted to a 2 compartment model, with continuous "endogenous perfusion" mimicking endogenous activity. Estimated clearance was 2.4 1/h (20% inter-individual variability and 9% inter-period variability). The volume of distribution at steady-state appeared to be significantly dose dependent: 78 ml/kg for doses < or = 20 microg/kg and 88 ml/kg for doses > 20 microg/kg respectively, with 16% inter-individual variability. The dose producing 50% of the maximum drop of INR was estimated to be 2.2 microg/kg. The model will be used to better define the dosage regimen for future clinical developments.

Expressional control of the 'constitutive' isoforms of nitric oxide synthase (NOS I and NOS III)

Nitric oxide synthase (NOS) exists in three established isoforms. NOS I (NOS1, ncNOS) was originally discovered in neurons. This enzyme and splice variants thereof have since been found in many other cells and tissues. NOS II (NOS2, iNOS) was first identified in murine macrophages, but can also be induced in many other cell types. NOS III (NOS3, ecNOS) is expressed mainly in endothelial cells. Whereas NOS II is a transcriptionally regulated enzyme, NOS I and NOS III are considered constitutively expressed proteins. However, evidence generated in recent years indicates that these two isoforms are also subject to expressional regulation. In view of the important biological functions of these isoforms, changes in their expression may have physiological and pathophysiological consequences. This review recapitulates compounds and conditions that modulate the expression of NOS I and NOS III, summarizes transcriptional and posttranscriptional effects that underlie these changes, and-where known-describes the molecular mechanisms leading to changes in transcription, RNA stability, or translation of these enzymes.

[PHOLY: a pilot study of drug utilization in civil hospitals in Lyon. Results]

As shown in many studies, up-to-date knowledge is not reflected in prescribing behaviours. The aim of pilot study PHOLY (Prescription aux Hospices civils de LYon) was to study methodological and technical conditions of a drug utilization study in a large university medical centre and to evaluate the discrepancy between drug prescribing and up-to-date knowledge. Data of 1115 in-patients of Hospices Civils de Lyon were collected. We have shown the feasibility of such a study in spite of many difficulties (52.15 per cent of questionnaires received, missing data...). Reference treatments such as ACE inhibitors in heart failure treatment or betablockers for high blood pressure represent respectively only 14.6 per cent and 6.7 per cent of the prescriptions in these indications. Within the framework of quality of care improvement, the study of the appropriateness of the treatments enables identification of domains where better therapeutic information is necessary.

[PHOLY: A pilot study of drug utilization in civil hospices in Lyon - methodology and difficulties]

PHOLY is a study of drug Prescription in Hospices civils of LYon by a transverse and descriptive survey. It aims at studying the methodology of such an investigation in a large university medical centre, elaborating a methodology for continuous assessment of prescribing, comparing prescriptions with scientific knowledge and identifying specific therapies. We collected 1525 questionnaires from 4333 hospitalized patients in 11 hospitals (prescriptions and indications). The main difficulties we encountered concerned communications (4 letters), fewer questionnaires collected than expected (1525/3018), many missing data, and the lack of a specific budget, thus allowing only partial data exploitation and control. This study revealed many problems such as relevant information for physicians, training and management of investigators, control, data capture and analysis. However, a prescription study may be possible with limited means.

Revisiting the effect compartment through timing errors in drug administration

The variations in the pharmacological effects induced by timing errors in drug intake are compared for two drugs, one acting by way of an effect compartment and the other directly from the central compartment. A simulation was performed for two drugs having the same concentration-effect relationship at the receptor site, the same mean effect at equilibrium and identical concentrations in the central compartment. In this article. Patrice Nony, Michel Cucherat and Jean-Pierre Boissel discuss how, for the same variability of concentrations in the central compartment, the variations in mean effects are different. When there is a large variability in the interval separating two consecutive doses, the model that includes an effect compartment dampens the pharmacokinetic variability present in the central compartment. Such an approach may be useful for the prescription recommendations of drugs, especially those with narrow therapeutic indices.

Standardization of terminology in meta-analysis: a proposal for working definitions

In this paper we present a brief overview of the growing concern to standardize definitions and terminology in meta-analysis. This tool has become inescapable in both drug research and therapeutic evaluation. The performed and published meta-analyses are increasing, as well as the variation in the meaning of the terms used in meta-analysis. In the second part of the paper we propose glossary of the most common terms used in reports of meta-analyses. The glossary has been written by only one group of scientists, the definitions are therefore proposed to the scientific community as working definitions, to be subject to reactions from leaders in meta-analysis.

A mathematical model for the determination of the optimum value of the treatment threshold for a continuous risk factor

Hypercholesterolemia or hypertension are continuous risk factors for coronary heart disease. When a preventive action is carried out against such a risk factor, it is necessary to specify a risk factor level value, named the treatment threshold, above which a subject should be treated. But a non-arbitrary determination of this threshold value is impossible from the epidemiological data. A method for the non-arbitrary determination of the treatment threshold value is presented, based upon mathematical modelling of the clinical and economics consequences of the prevention policy in the whole population. In a cost-effectiveness approach, the model was used to estimate the cost per coronary event prevented according to the threshold value for blood cholesterol. It was found that a minimum in this outcome proposed as the optimum treatment threshold. It is possible, from a public health point of view, to determine an optimum, non-arbitrary treatment threshold value in the prevention of coronary heart disease with cholesterol-lowering interventions. The model proposed here could be useful in decision making processes.

Effect of antihypertensive treatment in patients having already suffered from stroke. Gathering the evidence. The INDANA (INdividual Data ANalysis of Antihypertensive intervention trials) Project Collaborators

BACKGROUND AND PURPOSE

Drug treatment of high blood pressure has been shown to reduce the associated cardiovascular risk. Stroke represents the type of event more strongly linked with high blood pressure, responsible for a high rate of death or invalidity, and with the highest proportion of events that can be avoided by treatment. Hypertensive patients with a history of cerebrovascular accident are at particularly high risk of recurrence. Specific trials of blood pressure lowering drugs in stroke survivors showed inconclusive results in the past.

METHODS

We performed a meta-analysis using all available randomized controlled clinical trials assessing the effect of blood pressure lowering drugs on clinical outcomes (recurrence of stroke, coronary events, cause-specific, and overall mortality) in patients with prior stroke or transient ischemic attack.

RESULTS

We identified 9 trials, including a total of 6752 patients: 2 trials included 551 hypertensive stroke survivors; 6 trials of hypertensive patients included a small proportion of stroke survivors (536 patients); 1 trial included stroke survivors, whether hypertensive or not (5665 patients). The recurrence of stroke, fatal and nonfatal, was significantly reduced in active groups compared with control groups consistently across the different sources of data (relative risk of 0.72, 95% confidence interval: 0.61 to 0.85). There was no evidence that this intervention induced serious adverse effect.

CONCLUSIONS

Blood pressure lowering drug interventions reduced the risk of stroke recurrence in stroke survivors. Available data did not allow to verify whether such benefit depends on initial blood pressure level. More data are needed before considering antihypertensive therapy in normotensive patients at high cerebrovascular risk.

[Local drug delivery and gene therapy]

One of the most important problems in clinical cardiology is still unresolved, i.e., the development of a restenosis following coronary balloon angioplasty. Our knowledge about the sequelae of pathophysiologic events occurring during neointima formation is still far from complete (Figure 1) and numerous therapeutic trials using systemic administration of drugs with different mechanisms of action have failed. Possible innovative strategies are the local administration of high doses of drugs into the coronary arteries and local gene therapeutic interventions to inhibit neointima formation by reducing the proliferation of vascular smooth muscle cells. Numerous catheter devices were developed (Figure 2) in order to enable the local application of high doses of a drug or DNA. Additionally, galenic techniques are being developed to guarantee a steady release of locally administered drugs, e.g. from drug containing liposomes or microcarriers (Figure 3). There are already several animal models in which the development of a neointima was reduced by injecting antisense oligonucleotides directed towards the RNA encoding cell cycle regulatory proteins or peptides. Alternatively, the transfer of cDNA encoding proteins or protein products which inhibit the cellular proliferation and migration are being tested in vitro and in vivo with the help of reporter genes (Figure 4). Although, gene transfer techniques are believed to offer great therapeutic options for the future, the clinical data available today regarding this method are very limited and are derived from studies in patients with peripheral arterial disease. Thus, it is still questionable if gene transfer techniques will ever be able to become an integral part of our standard treatment for patients with vascular diseases.

Prognostic value of bisoprolol-induced hemodynamic effects in heart failure during the Cardiac Insufficiency BIsoprolol Study (CIBIS)

BACKGROUND

To further evaluate the mechanism of beta-blocker-induced benefits in heart failure, the relationships between bisoprolol-induced hemodynamic effects and survival were studied during the Cardiac Insufficiency BIsoprolol Study (CIBIS).

METHODS AND RESULTS

In 557 patients studied, bisoprolol significantly reduced heart rate (-16.3+/-15.3 versus -1.6+/-13.4 bpm, respectively; P<.001) compared with placebo at 2 months after inclusion in the study. Heart rate change over time had the highest predictive value for survival (P<.01). Left ventricular fractional shortening (LVFS) significantly increased in the bisoprolol group compared with the placebo group 5 months after inclusion (+0.04+/-0.06 versus -0.001+/-0.05, respectively; P<.001; n=160). LVFS change over time was also significantly correlated with further survival (P<.02 by Cox analysis). Using a nonparametric approach, we demonstrated a significant interaction between study treatment group and LVFS over time. Patients who demonstrated improvement of LVFS over time (82% and 51% of patients in the bisoprolol and the placebo groups, respectively; P<.02) were at lower risk, but the hazard did not further decrease with a further increase of fractional shortening, and there was no significant difference between study treatment groups. Finally, it could be demonstrated that each of the three factors (heart rate change over time, LVFS change over time, and bisoprolol treatment) made a specific contribution to mortality rate.

CONCLUSIONS

Preservation of left ventricular function appears to play a key role in the bisoprolol-induced beneficial effects on prognosis in heart failure. Short-term beta-blocker-induced cardiac effects could provide a means to identify those patients who will experience improved survival over the long term.

[Diagnostic contribution of abnormal delayed-type hypersensitivity to Candida albicans. Characterization test by activation of cells sensitized to successive dilutions of Candida]

By measuring the activation of different cell models (lymphocytes and lymphocytic subsets) in the presence of Candida albicans with flow cytometry reading, it is possible to show that successive dilutions of Candida albicans can lead to lymphocyte activation in abnormally-sensitized subjects. In a first trial, 10 subjects were tested in duplicate. The decrease of activity of the dilutions does not appear to be regular in relation to the progression of the dilutions. The activity of the dilutions wanes relatively rapidly with the first dilutions, then recurs later very distinctly, at the 6th dilution, then ebbs, then reappears in similar manner at the 9th, the 14th, and finally, the 19th dilution. Cell reactivity appears to differ depending on the subject. It can be represented through the calculated slope of the regression line, for each series of data. It therefore appears feasible to determine a threshold of reactivity and a scale of sensitivity, to make it possible to specify the degree of abnormal reactivity existing at a given time for a given subject. The constancy of the activity of the different dilutions tested, on 10 cultures of a single cell suspension, is especially well demonstrated in the second trial, showing unusually small standard deviations. Thus, the question arises as to the exact nature of the observed phenomenon and of its analysis from a physical-chemical point of view, with regard to the pharmacological effect of successive dilutions of Candida albicans.

[Target population for hypertensive therapy]

The efficacy of treatment may be demonstrated globally but, in some patients, treatment can be either inappropriate or harmful because of undesirable secondary effects. Ideally, treatment should be limited to patients who respond, but this is impossible with the published data from clinical trials. This could become possible by creating a data base containing all published results and carrying out meta analyses on individual parameters. Using the most powerful methods of analysis this could allow identification of patients responding to treatment by taking into account not only the benefits but also the risks of a given treatment (the principle is to identify and estimate factors--demographical, sociological, generic, which interfere with the size of the effect). In order to identify responders to antihypertensive treatment, a meta analysis of individual data was started, the INDANA project. With a common data base of all the preventive trials of antihypertensive therapy, this study should contribute to improved identification of responders and therefore to individualization of treatment of hypertension.

[The Hypertension Cochrane Review Group. Presentation and user's guide]

Cochrane collaboration has been developing since 1992 as an international network aiming at performing systematic reviews of available data on therapeutic effectiveness. The fundamental principles of this organisation are trying to avoid duplication of efforts, seeking the best reliability, using reproducible and quantitative synthesis techniques, offering constantly updated results. All health domains are progressively covered. The production unit in one domain is the review group. The Hypertension Cochrane Review Group (HTN CRG) has been officially registered on May 15th 1996. Information and products from the group are available through its news letter, through the Cochrane Library CD-ROM, regularly updated, and on the Internet (http://merece.uthscsa.edu/htncrg). The Hypertension Cochrane Review Group includes an editorial board (with an administrator and three editors), the authors of systematic reviews, internal and external reviewers. The geographic link is the San Antonio Cochrane Centre (Texas, USA). Invitations to participate have been sent to people interested in hypertension and who where known to the Cochrane collaboration, and to authors of previous reviews in hypertension. It is possible to collaborate with the HTN CRG through: performing a systematic review; reviewing protocols and systematic reviews; hand-searching medical journals; being a member of the editorial team. The first protocol for a systematic review edited by the group concerns antihypertensive treatment in the elderly, and is available in the 1996 and subsequent editions of the Cochrane Library. The group welcomes other reviews from domains awaiting registration, and collaborates with related domains review groups such as Diabetes CRG, or Stroke CRG. The group contributes to the effort of hand-searching medical literature, Pr Plouin being responsible for the Archives des Maladies du Coeur et des Vaisseaux. The second edition in 1996 of the Cochrane Library included 114 systematic reviews and 131 protocols, being the only media with similar objectives.

EasyMA: a program for the meta-analysis of clinical trials

Meta-analysis of clinical trial data is an increasingly important method in clinical research, particularly in the field of therapeutic evaluation. This method uses some specific statistical techniques which are not all available on standard packages and therefore require specific developments. This paper describes a program designed to help medical researchers perform meta-analyses of clinical trial data with dichotomous outcomes. This program includes the various statistical methods of meta-analysis and enables cumulative meta-analysis and sub-groups to be performed. A robustness index can be determined and the results obtained in table and graphic formats. Data-editing and data-manipulating facilities are also possible. Much care has been taken to make the user interface as user-friendly as possible, so that the program is within the reach of all medical researchers.

[Clinical evaluation: from intermediate to surrogate criteria]

The development and evaluation of new drugs often rely on surrogacy. An intermediate outcome becomes a surrogate outcome if it fulfils certain criteria, it should be easier to measure compared with the clinical outcome, a statistical relationship should exist between the clinical outcome and the surrogate outcome, a relation should exist allowing prediction of the degree of clinical effect based on the measured effect on the surrogate outcome. Development and authorization of drugs today often rely on so-called surrogate outcomes. Is this use sound? The validity of such outcomes has been reviewed in different therapeutic areas: hypertension, venous thromboembolism, AIDS, osteoporosis, hepatitis C. Based on this review, a pragmatic strategy is proposed which allows for the validation and proper use of surrogate outcomes.

[Diagnosis of delayed type hypersensitivity to Candida albicans. Evaluation of lymphocyte activation by flow cytometry (171 observations)]

Abnormal delayed-type hypersensitivy to Candida albicans, since it results in an excessive reaction of the immune system, is very difficult to diagnose. This study shows that the syndromic reaction observed after intradermal injection of an extract of Candida albicans, in patients suspected of abnormal delayed-type hypersensitivy to this antigen, is associated with the presence of specific circulating T cells, detectable through cell culture in the presence of Candida albicans. There is a very significant correlation between the clinical symptoms, the cutaneous tests, and the lymphocyte activation tests. This abnormal reactivity essentially involves the CD8 cells.

Effect of antihypertensive drug treatment on cardiovascular outcomes in women and men. A meta-analysis of individual patient data from randomized, controlled trials. The INDANA Investigators

BACKGROUND

Trials of drug therapy for hypertension have shown that such therapy has a clear overall benefit in preventing cardiovascular disease. Although these trials have included slightly more women than men, it is still not clear whether treatment benefit is similar for both sexes.

OBJECTIVE

To quantify the average treatment effect in both sexes and to determine whether available data show significant differences in treatment effect between women and men.

DESIGN

Subgroup meta-analysis of individual patient data according to sex. Analysis was based on seven trials from the INDANA (INdividual Data ANalysis of Antihypertensive intervention trials) database and was adjusted for possible confounders.

PATIENTS

20,802 women and 19,975 men recruited between 1972 and 1990.

INTERVENTIONS

Primarily beta-blockers and thiazide diuretics.

RESULTS

In women, treatment effect was statistically significant for stroke (fatal strokes and all strokes) and for major cardiovascular events. In men, it was statistically significant for all categories of events (total and specific mortality, all coronary events, all strokes, and major cardiovascular events). The odds ratios for any category of event did not differ significantly between men and women. In absolute terms, the benefit in women was seen primarily for strokes; in men, treatment prevented as many coronary events as strokes. Graphical analyses suggest that these results could be completely explained by the difference in untreated risk.

CONCLUSIONS

In terms of relative risk, treatment benefit did not differ between women and men. The absolute risk reduction attributable to treatment seemed to depend on untreated risk. These findings underline the need to predict accurately the untreated cardiovascular risk of an individual person in order to rationalize and individualize antihypertensive treatment.

The Eurevie Study: contrasting effect of piretanide and thiazides in mild to moderate hypertension

This study compares the loop diuretic piretanide 6 mg in a slow-release formulation (PIR) with hydrochlorothiazide 25 mg (HCT) and the fixed combination altizide 15 mg-spironolactone 25 mg (ALT-SP) in hypertension. 1105 mild to moderate hypertensive patients entered a three-week placebo wash-out period; 899 were randomized in a 6-month, double-blind, parallel group treatment phase; 800 completed the study. Primary end-points; serum potassium concentration and quality of life at one month; secondary end-points: ionic, renal and metabolic variables; blood pressure (BP) measurements. HCT and ALT-SP were compared only to PIR using Dunnett's or chi 2 tests.

RESULTS

No difference was found for the overall quality of life. No change of serum potassium concentration at one month was found in PIR while small decreases were detected with ALT-SP (-0.1 mM) and HCT (-0.26 mM). Serum creatinine concentration increased significantly in ALT-SP when compared to PIR. All the drugs were effective in reducing BP: HCT had a higher rate of responders than PIR with similar mean BP falls and ALT-SP induced greater falls in blood pressure.

CONCLUSION

PIR proves to be a potent antihypertensive drug without significant effect on serum electrolytes, plasma glucose and lipids. HCT was slightly more potent but induced a fall in serum potassium concentration with a significant risk of hypokalaemia. The addition of SP to ALT led to a more potent diuretic with a higher level of serum potassium and plasma creatinine disturbances.

Persistent reduction of mortality for five years after one year of acebutolol treatment initiated during acute myocardial infarction. The APSI Investigators. Acebutolol et Prévention Secondaire de l'Infarctus

The APSI trial was a randomized placebo-controlled trial designed to assess the efficacy of 1 year of treatment by acebutolol in high-risk patients who had survived an acute myocardial infarction. At 1 year there was a statistically significant 48% relative reduction in total mortality (p = 0.019) in favor of acebutolol. In 1995 a long-term mortality survey was undertaken through an administrative inquiry and contacts with investigators. The vital status of 586 of the 607 (96.5%) patients enrolled was known at the cutoff date and all these patients were followed up for at least 5 years. During follow-up (in-trial and post-trial period), 74 deaths (24.8%) occurred in the acebutolol group and 96 (31.1%) in the placebo group (p = 0.10). No difference between the 2 groups was observed for the number of deaths that occurred after the end of the trial: 55 deaths (19.6%) among the 281 survivors in the acebutolol group and 59 deaths (21.7%) (p = 0.70) among the 272 survivors in the placebo group. The annual hazard rate (annual death rate), calculated year by year using the actuarial method, was significantly different (p < 0.01) only for the first year and was not significantly different thereafter. Thus, the initial benefit obtained in 1 year of treatment by acebutolol lasts for 5 years.

Pre-hospital and hospital time delays in thrombolytic treatment in patients with suspected acute myocardial infarction. Analysis of data from the EMIP study. European Myocardial Infarction Project

OBJECTIVES

To compare the components of the time delay involved in pre-hospital and hospital thrombolytic therapy in patients presenting with suspected acute myocardial infarction.

MATERIAL AND METHODS

From October 1988 to January 1992 a total of 198 mobile emergency units in 15 European countries and Canada randomized 5469 patients to receive either pre-hospital thrombolytic treatment, followed by placebo in hospital (pre-hospital group), or pre-hospital (hospital group) in the European Myocardial Infarction Project trial. We performed a post hoc analysis of these data to correlate components of the interval between symptom onset and treatment with baseline patient characteristics.

RESULTS

The delay between onset of symptoms and calling for an ambulance was significantly longer for female patients (P = 0.0001), older patients (> 65 years old; P = 0.0001), those who had experienced pain within the previous 24 h (P = 0.0001), and those with pulmonary oedema (P = 0.04). This delay was significantly shorter in patients with previous myocardial infarction (P = 0.02), those with ventricular fibrillation (P = 0.0001), and those in shock (P = 0.0001). The delay between the two injections was significantly longer for older patients (> 65 years old; P = 0.02), those with previous myocardial infarction (P = 0.03), and those in shock (P = 0.003).

CONCLUSIONS

Action undertaken to reduce delays between symptom onset and treatment should focus on modifiable factors such as patients who are likely to be late callers i.e. women and those over 65 years of age.

[The Cochrane Collaboration, support of therapeutic information]

Today, prescribers need to distinguish between the clinical practices based on randomized clinical trialing information and those based on animal physiological data or theory. Now the information on therapeutics is becoming more dense, more complex and less available to the clinicians. Information sources are numerous and varied, including data whose quality differs. These data are unhierarchised in terms of methodological quality and clinical relevance. It will be optimal if each prescriber could himself collect and analyse scientific information. In fact this situation cannot be effective in private physician's practices. An international collaboration, the Cochrane Collaboration, including volunteers, university researchers, and clinical investigators has the following objective: to prepare, maintain and disseminate systematic reviews of the effects of health care. The Cochrane Collaboration is thus the most adapted intermediairy between scientifically actualized data and clinical practitioners.

[Critical analysis of individual data in meta-analysis. Apropos of an experience in the domain of drug treatment in arterial hypertension]

Reliable syntheses are more and more needed by physicians. In the therapeutic field, this need is illustrated by the growing number of syntheses using meta-analysis tools. Some of these syntheses are based on individual patient data, and this offers three kinds of advantages: the favourable consequences of a collaborative approach, the enhancement of data reliability, and a more complete extraction of useful information thanks to wider analysis potential. Most often, achieving the first two advantages does not require the individual patient data to be available, and a wider analysis potential seems to be the major rationale of such an approach. For instance, the assessment of the variation of treatment effect with along time is more accurate, but may also raise doubts about the validity of some hypotheses, for example, those underlying classical analysis techniques, or at the basis of even acknowledged pathophysiological theory. Ultimately, the concepts of identifying responders (here defined in terms of quantity or quality of life) and identifying the therapy target population are concretely applied in a way that will affect classical medical practice. Tomorrow, drugs will not be prescribed to a hypertensive individual because of the blood pressure level, but considering the size of the predicted therapeutic benefit.