Chrono-Pharmacological Study of Once Daily Curative Dose of a Low Molecular Weight Heparin (200IU antiXa/kg of Dalteparin) in Ten Healthy Volunteers

Low molecular weight heparin (LMWH) is currently prescribed for the treatment of deep vein thrombosis at the dose of 100 IU antiXa/kg twice daily or at a dose of 175 IU antiXa/kg once daily with a similar efficacy. We decided to study the chrono-pharmacology of curative dose of LMWH once daily administrated according to the one previously described with unfractionated heparin (UFH).

Ten healthy volunteers participated in an open three-period crossover study according to three 24 h cycles, separated by a wash-out interval lasting 7 days: one control cycle without injection, two cycles with subcutaneous injection of 200 IU antiXa/kg of Dalteparin (Fragmin®) at 8 a.m. or at 8 p.m. Parameters of heparin activity were analysed as maximal values and area under the curve.

Activated partial thromboplastin time (APTT), thrombin time (TT), prothrombin time (PT) and tissue factor pathway inhibitor (TFPI) were higher after 8 p.m. injection than after 8 a.m. injection (p <0.05) while no chrono-pharmacological variation of anti factor Xa (AXa) activity was observed. Thus the biological anticoagulant effect of 200 IU antiXa/kg of Dalteparin seems to be higher after an evening injection than after a morning injection.

A chrono-therapeutic approach with LMWH, as prescribed once daily, deserves further investigation since our results suggest that a preferential injection time may optimise the clinical efficacy of these LMWH.

Aging and Venous Thromboembolism Influence the Pharmacodynamics of the Anti-Factor Xa and Anti-thrombin Activities of a Low Molecular Weight Heparin (Nadroparin)

Venous thromboembolism may be efficiently treated by one single daily administration of a high dose of low molecular weight heparin (LMWH). The present study investigates if the physiological deterioration of renal function associated with normal aging or the presence of an acute venous thromboembolism influences the pharmacodynamic pattern of the anti-factor Xa and anti-thrombin activities. Three groups of 12 subjects were investigated. The first 2 groups were composed of healthy volunteers differing by age (25 ± 4 and 65 ± 3 yrs) and creati-nine clearance (114 ± 15 and 62 ± 6 ml · min –1). The third group was composed of patients hospitalized for deep vein thrombosis, having a mean age of 65 ± 11 yrs and creatinine clearance of 76 ± 8 ml · min –1. Nadroparin was administered subcutaneously once daily at the dose of 180 anti-factor Xa IU.kg–1 for 6 to 10 days. Serial sampling on day 1 and on the last day of administration (day n) allowed the pharmacodynamic parameters of the anti-factor Xa and anti-thrombin activities to be compared at the begining and at the end of the treatment. The main findings were the following: (1) After repeated administration, a significant accumulation of the anti-factor Xa activity was observed in the healthy elderly and in the patients but not in the healthy young subjects (accumulation factor: 1.3). There was no evidence of accumulation of anti-thrombin activity; (2) There were significant correlations between the clearance of creatinine and the clearance of the anti-factor Xa activity but not with that of the anti-thrombin activity; (3) In the patients, the clearance of the anti-factor Xa and of the anti-thrombin activities were 1.4 and 2 times higher respectively than those calculated in the healthy elderly; (4) The mean ratio of the of anti-factor Xa and anti-thrombin clearances was close to 2 in the healthy subjects but equal to 5.4 in the patients. These results suggest that the mechanisms involved in the clearance of polysaccharide chains which support the anti-thrombin activity are different from those of the anti-factor Xa activity and that the enhanced binding properties of plasma proteins to unfractionated heparin reported in patients presenting an acute venous thromboembolism also exists for LMWH, predominantly for the anti-thrombin activity.

A chronopharmacodynamic study on standard heparin, a low molecular weight heparin (nadroparin) and danaproid: establishing and comparing the daily variations of these drugs in rats

The effects of dosing time on the anticoagulant activity of unfractionated heparin, low molecular weight heparin (nadroparin) and danaproid were investigated. The chronopharmacological comparisons of the drugs were done on the anti-Xa, anti-IIa activities and activated partial thromboplastin time assays. Several dosing times were considered and an analysis based on a population approach was adopted. Under unfractionated heparin, the pharmacological activities did not exhibit significant daily variations. In contrast, significant daily profiles were observed in all the biological assays performed with low molecular weight heparin. Anti-Xa and anti-IIa activities showed some fluctuations over a 24-hour period with a peak at noon. As for the variations of the activated partial thromboplastin time, two peaks were noted early in the morning and at the beginning of nightfall. As for danaproid, only a daytime maximum of anti-Xa activity could be found.

[Bepridil: importance of serum level in treatment surveillance]

OBJECTIVE

Despite precise recommendations for prescription and monitoring, tosades de pointes is still observed with bepridil. The purpose of this study was to demonstrate the contribution of bepridil serum assay in therapeutic supervision.

PATIENTS AND METHODS

Seventy-five patients over 70 years of age were included. Prolongation of the QT interval was observed in 23 patients.

RESULTS

The potential prognostic factors for increased QT interval as demonstrated by univariate logistic regression were hypokaliemia, bradycardia, renal failure and bepridil serum level. After multivariate logistic regression, the persisting causal factors for increased QT interval were hypokaliemia, bradycardia and bepridil serum level.

CONCLUSION

Prolongation of the QT interval remains dependent on several variables. Bepridil determination during treatment is insufficient alone.

Establishing the dose-dependent daily variations of a low molecular weight heparin (Fraxiparine) through a population approach analysis in the rat

The effects of dose and dosing time on the anticoagulant activity of a low molecular weight heparin (Fraxiparine) were studied in rats. Three doses were administered at four evenly spaced dosing times. Rats were kept under a light-dark cycle of 24h, and all the main external factors were constant. The bleeding time, the anti-Xa activity of the drug, and the activated partial thromboplastin time (APTT) were measured. A population approach analysis to assess daily variations was used. With standard methods, interindividual variability may mask potential time-related effects, while the population approach analysis overcomes this difficulty. Bleeding time was at its peak at 04:00 and at its trough at 22:00, suggesting that platelet activity was time of day dependent. For the pharmacological activity of the drug, we compared several pharmacokinetic models derived from a monocompartmental model. The model that describes the anti-Xa pharmacological activity best is expressed through parameters that depend on animal weight and drug level. The model for APTT is of a sinusoidal type for which the clearance depends on the dosing time. The most inter esting result is that the amplitude of this daily variation is linearly dependent on drug level.

Inter-study variability in population pharmacokinetic meta-analysis: when and how to estimate it?

Population pharmacokinetic analysis is being increasingly applied to individual data collected in different studies and pooled in a single database. However, individual pharmacokinetic parameters may change randomly from one study to another. In this article, we show by simulation that neglecting inter-study variability (ISV) does not introduce any bias for the fixed parameters or for the residual variability but may result in an overestimation of inter-individual (IIV) variability, depending on the magnitude of the ISV. Two random study-effect (RSE) estimation methods were investigated: (i) estimation, in a single step, of the three-nested random effects (inter-study, inter-individual and residual variability); (ii) estimation of residual variability and a mixture of ISV and IIV in the first step, then separation of ISV from IIV in the second. The one-stage RSE model performed well for population parameter assessment, whereas, the two-stage model yielded good estimates of IIV only with a rich sampling design. Finally, irrespective of the method used, ISV estimates were valid only when a large number of studies was pooled. The analysis of one real data set illustrated the use of an ISV model. It showed that the fixed parameter estimates were not modified, whether an RSE model was used or not, probably because of the homogeneity of the experimental designs of the studies, and suggest no study-effect in this example.

Prevention of venous thromboembolism in internal medicine with unfractionated or low-molecular-weight heparins: a meta-analysis of randomised clinical trials

BACKGROUND

The prevention of venous thromboembolic disease is less studied in medical patients than in surgery.

METHODS

We performed a meta-analysis of randomised trials studying prophylactic unfractionated heparin (UFH) or low-molecular-weight heparin (LMWH) in internal medicine, excluding acute myocardial infarction or ischaemic stroke. Deep-vein thrombosis (DVT) systematically detected at the end of the treatment period, clinical pulmonary embolism (PE), death and major bleeding were recorded.

RESULTS

Seven trials comparing a prophylactic heparin treatment to a control (15,095 patients) were selected. A significant decrease in DVT and in clinical PE were observed with heparins as compared to control (risk reductions = 56% and 58% respectively, p <0.001 in both cases), without significant difference in the incidence of major bleedings or deaths. Nine trials comparing LMWH to UFH (4,669 patients) were also included. No significant effect was observed on either DVT, clinical PE or mortality. However LMWH reduced by 52% the risk of major haemorrhage (p = 0.049).

CONCLUSIONS

This meta-analysis, based on the pooling of data available for several heparins, shows that heparins are beneficial in the prevention of venous thromboembolism in internal medicine.

Decision analysis for use of platelet aggregation test, carbon 14-serotonin release assay, and heparin-platelet factor 4 enzyme-linked immunosorbent assay for diagnosis of heparin-induced thrombocytopenia

The value of the platelet aggregation test, carbon 14-labeled serotonin release assay (SRA), and heparin-platelet factor 4 enzyme-linked immunosorbent assay (H-PF4 ELISA) for the diagnosis of heparin-induced thrombocytopenia was evaluated by studying blood samples from 100 patients with suspected heparin-induced thrombocytopenia, and categorized into 4 clinical groups: unlikely (n = 22), possible (34), probable (36), and definite (8) thrombocytopenia. Results of the platelet aggregation test were positive in 40 of 44 patients with probable or definite heparin-induced thrombocytopenia (sensitivity 91%) and in 5 of 22 unlikely to have heparin-induced thrombocytopenia (specificity 77%). The SRA exhibited sensitivity of 88% and negative predictive value of 81%, close to those values for the platelet aggregation test; specificity and positive predictive value were 100%. The sensitivity of the heparin-PF4 ELISA was 97%, with specificity 86%, and a positive correlation was recorded between the level of antibodies to H-PF4 and clinical score (P = 0.66). When ELISA was used with the platelet aggregation test or SRA, positive predictive value and specificity were 100% when both tests yielded positive results, and negative predictive value was 100% when both tests yielded negative results. A biologic flow chart was designed that presented a choice based on the results of the platelet aggregation test or SRA in association with ELISA, and enabled more accurate and specific identification of heparin-induced thrombocytopenia.

Pharmacokinetic and pharmacodynamic variations of acenocoumarol orally administrated either once or twice daily in patients with deep venous thrombosis

The literature suggests that variations in anticoagulant effect occur when acenocoumarol is administrated in a daily dose. We assessed the anticoagulant effects of acenocoumarol with INR, factors VII and X and protein C in 12 randomly selected hospitalised patients with deep-vein thrombosis, six of them receiving a daily dose of acenocoumarol, the other six receiving twice daily doses. When the drug effect had been at a steady-state for at least 72 h, five blood samples were drawn per patient over a period of 24 h. No nycthemeral significant variations were noted for INR, factor X and protein C in the two groups (P > 0.10). Nycthemeral significant variation in factor VII when acenocoumarol was administered once daily was noted (P = 0.02), but the clinical relevance of factor VII variation at steady-state is uncertain. In spite of the short pharmacokinetic half-life of acenocoumarol, a stable nycthemeral pharmacodynamic activity was observed after once daily administration; twice-daily administration of acenocoumarol does not appear to be justified.

[Evaluation of the risk of venous thromboembolism in the medical patients]

The venous thromboembolic risk seems to be demonstrated in medical patients since the incidence of symptomatic and asymptomatic deep vein thrombosis (DVT) without any prophylactic methods is respectively about 50 per cent in stroke, 25 per cent in acute myocardial infarction (AMI) and 15 per cent in internal medicine. A synthesis of clinical trials performed in medical patients shows that prophylactic doses of heparins (unfractionated heparin or low molecular weight heparins) reduce the incidence of DVT by 40 to 60 per cent compared with the lack of any antithrombotic agents but without any significant effect on total mortality. Other antithrombotic agents such as antiplatelet agents seem to reduce the incidence of DVT by about 40 per cent associated with a significant decrease in total mortality of stroke or AMI. But the recommendations made on the basis of these results have to be extremely cautious since the number of medical patients included in clinical trials is quite limited compared with the surgical area. Moreover, each of these recommendations is not sufficiently proven. Thus more clinical trials have to be carried out with a placebo control group in internal medicine and an aspirin control group for stroke and AMI.

Aging and venous thromboembolism influence the pharmacodynamics of the anti-factor Xa and anti-thrombin activities of a low molecular weight heparin (nadroparin)

Venous thromboembolism may be efficiently treated by one single daily administration of a high dose of low molecular weight heparin (LMWH). The present study investigates if the physiological deterioration of renal function associated with normal aging or the presence of an acute venous thromboembolism influences the pharmacodynamic pattern of the anti-factor Xa and anti-thrombin activities. Three groups of 12 subjects were investigated. The first 2 groups were composed of healthy volunteers differing by age (25 +/- 4 and 65 +/- 3 yrs) and creatinine clearance (114 +/- 15 and 62 +/- 6 ml x min(-1)). The third group was composed of patients hospitalized for deep vein thrombosis, having a mean age of 65 +/- 11 yrs and creatinine clearance of 76 +/- 8 ml x min(-1). Nadroparin was administered subcutaneously once daily at the dose of 180 anti-factor Xa IU.kg(-1) for 6 to 10 days. Serial sampling on day 1 and on the last day of administration (day n) allowed the pharmacodynamic parameters of the anti-factor Xa and anti-thrombin activities to be compared at the beginning and at the end of the treatment. The main findings were the following: (1) After repeated administration, a significant accumulation of the anti-factor Xa activity was observed in the healthy elderly and in the patients but not in the healthy young subjects (accumulation factor: 1.3). There was no evidence of accumulation of anti-thrombin activity; (2) There were significant correlations between the clearance of creatinine and the clearance of the anti-factor Xa activity but not with that of the anti-thrombin activity; (3) In the patients, the clearance of the anti-factor Xa and of the anti-thrombin activities were 1.4 and 2 times higher respectively than those calculated in the healthy elderly; (4) The mean ratio of the of anti-factor Xa and anti-thrombin clearances was close to 2 in the healthy subjects but equal to 5.4 in the patients. These results suggest that the mechanisms involved in the clearance of polysaccharide chains which support the anti-thrombin activity are different from those of the anti-factor Xa activity and that the enhanced binding properties of plasma proteins to unfractionated heparin reported in patients presenting an acute venous thromboembolism also exists for LMWH, predominantly for the anti-thrombin activity.

[Heparins and curative treatment of venous thromboembolic disease: meta-analysis]

Heparin treatment of venous thromboembolic disease has been validated since 1960. Nevertheless no study was sufficient to determine an optimal therapeutic schedule between sub-cutaneous (SC) unfractionated heparin (UFH), intravenous (IV) UFH and low molecular weight heparin (LMWH). One meta-analysis showed a significant risk reduction of recurrent thromboembolic events (OR = 0.58, CI 95 per cent [0.34-0.99]) and a non-significant risk reduction of haemorrhagic events (OR = 0.78 [0.40-1.52]) with UFH SC compared to UFH IV, but homogeneity testing was significant (p < 0.001). Some discrepancy was shown between the results of the three metaanalyses which compared LMWH to UFH according to the selection criteria of clinical trials used. With an exhaustive selection, LMWH involved a non-significant risk reduction of recurrent thromboembolic events (OR = 0.66 [0.41-1.07], p = 0.09), and a non-significant risk reduction of haemorrhagic events (OR = 0.65 [0.36-1.16], p = 0.15). So no definitive conclusion could be drawn but it seems that UFH can be recommended whatever the administration route or LMWH for deep vein thrombosis treatment.

Evolution of blood coagulation and fibrinolysis parameters after abrupt versus gradual withdrawal of acenocoumarol in patients with venous thromboembolism: a double-blind randomized study

A double-blind randomized trial was conducted to research a hypercoagulable state rebound after abrupt versus gradual withdrawal of acenocoumarol, 20 patients were included: 10 in the abrupt withdrawal group (AW) and 10 in the gradual withdrawal group (GW). Between days 1 and 15,F1 + 2 was higher in group AW (P < 0.002). A significant increase of D-dimer with time was found (P < 0.001) without difference between the two groups, tPA and PAI-1 levels remained stable throughout without difference between the two groups. No rebound phenomenon was observed. Four thrombotic recurrences were observed: group AW: 1, group GW: 3 (P = 0.29). There is neither clinical nor biological support for a gradual anticoagulation withdrawal.

[Search for the "optimal" dose of antithrombotic agents]

The determination of the "optimal" dose is an essential step in the development of a molecule. In the case of anti-thrombotic agents, the search for this "optimal" dose is based on dose-effect relationships on biological criteria in phase I, and, often, radiological criteria in phase II trials. The main objective of these dose studies is not to directly evaluate the benefit-risk ratio of the molecule under development, but to find the dose which will be tested in phase II to estimate the benefit-risk ratio. Errors of choice of dosage observed at the end of phase III trials may be due to problems of extrapolability of the results of the dose studies due to too strict a selection of subjects included and therefore not representative of the target population of the new treatment or to the use of intermediary criteria for the evaluation of the antithrombotic effect. However, these dosage errors are still mainly due to an inadequate search for the "optimal" dose despite the fact that the ethnical and economic consequences are not negligible.

Effects of long travels in sitting position in elderly volunteers on biological markers of coagulation activation and fibrinolysis

OBJECTIVE

To evaluate whether long travel in sitting position is associated with an increase of coagulation activation and/or a decrease of fibrinolytic activity.

DESIGN

Comparison of blood coagulation and fibrinolysis parameters before and after two pleasure trips by bus organized in winter period (600 km in 8 hours) and in summer period (1200 km in 16 hours).

SUBJECTS

31 and 23 healthy elder volunteers for the winter and the summer trip respectively. Nine other elder volunteers were selected as a control group for the winter study.

MAIN OUTCOME MEASURES

prothrombin fragment 1 + 2 (F1 + 2), thrombin-antithrombin III (TAT), D-dimers (D-D), factor VII activated, plasminogen activator inhibitor (PAI), tissue-type plasminogen activator (t-PA), plasma albumin.

RESULTS

A significant difference before and after the travel was only observed for TAT in the summer period. However all values of TAT were in the normal range. No volunteer presented with thromboembolic disease during the month following the travel.

CONCLUSION

In the condition of our study, long travel in sitting position does not lead to an enhanced procoagulant state for elderly with varicose veins. These results suggest that there is no biological support to propose heparin prophylactic therapy for the elderly with varicose veins wishing to travel by bus.

Chrono-pharmacological study of once daily curative dose of a low molecular weight heparin (200 IU antiXa/kg of Dalteparin) in ten healthy volunteers

Low molecular weight heparin (LMWH) is currently prescribed for the treatment of deep vein thrombosis at the dose of 100 IU antiXa/kg twice daily or at a dose of 175 IU antiXa/kg once daily with a similar efficacy. We decided to study the chrono-pharmacology of curative dose of LMWH once daily administrated according to the one previously described with unfractionated heparin (UFH). Ten healthy volunteers participated in an open three-period crossover study according to three 24 h cycles, separated by a wash-out interval lasting 7 days: one control cycle without injection, two cycles with subcutaneous injection of 200 IU antiXa/kg of Dalteparin (Fragmin) at 8 a.m. or at 8 p.m. Parameters of heparin activity were analysed as maximal values and area under the curve. Activated partial thromboplastin time (APTT), thrombin time (TT), prothrombin time (PT) and tissue factor pathway inhibitor (TFPI) were higher after 8 p.m. injection than after 8 a.m. injection (p < 0.05) while no chrono-pharmacological variation of anti factor Xa (AXa) activity was observed. Thus the biological anticoagulant effect of 200 IU antiXa/kg of Dalteparin seems to be higher after an evening injection than after a morning injection. A chrono-therapeutic approach with LMWH, as prescribed once daily, deserves further investigation since our results suggest that a preferential injection time may optimise the clinical efficacy of these LMWH.

Influence of confounding factors on designs for dose-effect relationship estimates

Three types of designs can be used to estimate the drug dose-effect relationship during phase II clinical trials: parallel-dose designs (parallel); cross-over designs (X), and dose-escalation designs ([symbol: see text]). Despite the use of non-linear mixed effect models, the potential influence of confounding factors on [symbol: see text] designs has not been previously fully elucidated; we undertook simulations to investigate this for all three experimental designs. We found that: (i) monotonic spontaneous evolution of the effect (EV) did not affect the maximum effect estimation (Emax) and the dose giving 50 per cent of this (ED50); (ii) EV similar to a regression to the mean gave rise to biases for [symbol: see text] designs; (iii) the introduction of a pharmacodynamic carry-over generates important biases and imprecision for [symbol: see text] designs, even when the carry-over is adjusted for; (iv) the introduction of non-responders resulted in bias and imprecision for both Emax and ED50 in all three designs.

Fibrinolysis and elastic compression: no fibrinolytic effect of elastic compression in healthy volunteers

The local and systemic fibrinolytic response to the placing of elastic compression in healthy volunteers was studied to determine whether this method of preventing venous thromboembolism has any profibrinolytic effect, as previously demonstrated with intermittent pneumatic compression. Variations in the major parameters of fibrinolysis (euglobulin lysis time, t-PA antigen, PAI-1 antigen, PAI-1 activity) were studied in an open randomized cross-over study in 21 healthy volunteers, in which three types of treatment were tested for periods of 24 h each (without elastic compression, elastic compression of an upper limb, elastic compression of the lower limbs). Four blood samples were taken from the upper limb during each period (at 08:00 h, 10:00 h, 18:00 h, 08:00 h on the following day). The placing of elastic compression did not cause any statistically significant change in the four parameters tested between the three types of treatment. In contrast, circadian rhythm was confirmed for all the fibrinolytic factors studied with a minimal fibrinolytic activity in the morning and a maximal activity in the evening. Elastic compression does not seem to have any profibrinolytic effect in healthy volunteers but other studies are needed in patients before a definitive conclusion can be reached.

[Aging and procedural memory. Study of a series of tests on microcomputers]

The authors have assessed perceptual motor tasks involving the learning of the mouse control by locking at a Macinthosh computer screen during three consecutive sessions. Tests were performed by 102 control subjects aged between 16 and 85 years. Concerning age, there was a significant time difference (ANOVA) but improvement was the same for all subjects. Educational level and IQP results didn't influence procedural performance. Men were faster in three tasks. We can argue that implicit learning abilities appear before explicit memory and within the adult life span there appears to be little significant deterioration in implicit memory abilitie.

Acceptability and efficacy of two associations of paracetamol with a central analgesic (dextropropoxyphene or codeine): comparison in osteoarthritis

A double-blind randomized parallel group trial was undertaken to compare the acceptability and efficacy of 2 forms of analgesic treatment, DI-Antalvic (Houde Laboratories, Puteaux, France) (30 mg dextropropoxyphene and 400 mg paracetamol per capsule) and Efferalgan-Codeine (UPSA Laboratories, Rueil Malmaison, France) (30 mg codeine and 500 mg paracetamol per tablet) prescribed for 1 week at doses of 6 capsules/day and 6 tablets/day, respectively, in 141 outpatients with active osteoarthritis of the knee or hip. The principal aim of the trial was concerned with acceptability, with efficacy as its secondary aim. The principal trial criterion was defined as overall assessment of acceptability by the patient at the end of the trial (success or failure) or by treatment dropouts because of an adverse effect (failure). Comparability of the groups was confirmed before any treatment regarding the physical characteristics of the patients, characteristics of osteoarthritis, and the initial level of pain and functional consequences of pain. Results show that the analgesic efficacy of the treatment was similar, but that the acceptability of Efferalgan-Codeine was significantly worse than that of DI-Antalvic: 53% failure with Efferalgan-Codeine versus 29% failure with DI-Antalvic (P = .005). Other trials of the same type would seem necessary (comparison of lower doses, other types of pain) before being able to generally extrapolate such findings.

[Chronopharmacology of fractionated heparin (nadroparin) administrated by subcutaneous route at prophylactic doses in healthy volunteers]

This study evaluated the effect of injection time on pharmacodynamic of a single subcutaneous bolus of nadroparine (7500 anti-Xa IC U) evaluated by anti-Xa activity (Hepaclot and Heptest) and by activated partial thromboplastin time (APTT by auto PTT reagent). 10 healthy male volunteers were studied at 4 different 24 hours periods with 4 different injection times (6 am, 12 am, 6 pm, 12 pm) and with a one week wash-out period between each period. No chronopharmacological variation of the anti-Xa activity evaluated by Hepaclot was found. However the anti-Xa activity evaluated by Heptest was higher at the sixth hour after 12 am injection (p = 0.0022). No difference on APTT values was observed whatever the injection time. So the injection time of nadroparine has a weak influence on anti-Xa activity and no effect on APTT; Before to conclude on the lack of chronopharmacological effect of nadroparine, it seems necessary to evaluate such a possibility with higher dosage, with sick and older subjects.