Effect of a ginkgolide mixture (BN 52063) in antagonising skin and platelet responses to platelet activating factor in man

Antagonism of the effects of platelet activating factor (PAF) by the ginkgolide mixture BN 52063 was assessed in a double-blind, placebo-controlled, crossover study in 6 normal subjects. Weal and flare responses to 400 ng PAF, examined 2 h after ingestion of BN 52063 (80 mg, 120 mg) were inhibited in a dose-related manner. After 120 mg the flare area was reduced by a mean 62.4% (p less than 0.005) and the weal volume by a mean 60% (p less than 0.05). Both doses of BN 52063 significantly inhibited PAF-induced platelet aggregation in platelet-rich plasma (p less than 0.001). In vitro, BN 52063 inhibited PAF-induced but not ADP-induced platelet aggregation. Thus BN 52063 seems to be an antagonist of PAF in man.

Platelet activating factor (PAF). A review of its effects, antagonists and possible future clinical implications (Part I)

This review is an attempt to summarise recent data on platelet activating factor (PAF) and PAF antagonists from 1988 to the present. This period saw a burst in research activity focused predominantly on the effect of PAF in various organs. The effect of PAF and its antagonists was further intensively studied in vitro on isolated platelets, leucocytes, macrophages and endothelial cells. From these and earlier data, based on the catastrophe theory of Thom and Zeeman, a new concept on the interaction between PAF and various cytokines could be recognised as an important mechanism of action of the phospholipid mediator, suggesting the existence of an autocatalytic feedback network through which PAF can influence cellular function under certain pathophysiological conditions. This mechanism can be regarded as the culmination of our recent knowledge on the role of PAF, and may influence the possible clinical implications of PAF antagonists in the near future. It is recognised that PAF is released in shock and ischaemic states, and that PAF antagonists can protect the heart and brain against ischaemic injury. Therefore, in contrast to the previous period, which was predominantly devoted to the elucidation of the role of PAF in immediate hypersensitivity reactions, studies performed on cerebral, myocardial and intestinal ischaemia as well as in various shock conditions have concentrated on entirely new aspects of the effect of PAF antagonists, emphasising the significance of the inflammatory process and cell-to-cell interactions in these pathophysiological states. This has led to a re-evaluation of the experimental data previously accumulated. At the same time, these new trends in PAF and PAF antagonist research have explored further possibilities for the application of PAF antagonists in clinical practice. Attention has been focused on the physiological role of PAF as a signal molecule, especially between the neuroendocrine system and related sensory organs. The recognition of the significance of PAF in mammalian reproduction is fascinating and may lead to new clinical applications of PAF antagonists. It appears probable that, like eicosanoids, PAF is involved in a great variety of membrane-dependent processes that play a fundamental role in the maintenance of homeostasis. PAF research has provided several potent natural and synthetic antagonists which may facilitate the clinical application of these drugs in the near future.

Confirmatory platelet-activating factor receptor antagonist trial in patients with severe gram-negative bacterial sepsis: a phase III, randomized, double-blind, placebo-controlled, multicenter trial. BN 52021 Sepsis Investigator Group

OBJECTIVE

To determine the efficacy and safety of using natural platelet-activating factor receptor antagonist (PAFra), BN 52021, to treat patients with severe Gram-negative bacterial sepsis.

DESIGN

A prospective, randomized, double-blind, placebo-controlled, multicenter clinical trial.

SETTING

Fifty-nine academic medical center intensive care units in Europe.

PATIENTS

Six hundred nine patients with severe sepsis, suspected to be related to Gram-negative bacterial infection, who received PAFra or placebo.

INTERVENTIONS

Patients were randomized to receive either a dose of PAFra (120 mg iv) every 12 hrs over a 4-day period or placebo over a 4-day period.

MEASUREMENTS AND MAIN RESULTS

The patients were well matched at study entry for severity of illness and for risk factors known to influence the outcome of sepsis. Among all randomized patients, the 28-day, all-cause mortality rate was 49% (152/308) in the placebo group, and 47% (140/300) in the PAFra group (p=.50). When analyzed on the basis of the previously defined target population, the 28-day, all-cause mortality rate was 50% (115/232) in the placebo group and 44% (94/212) in the PAFra group, yielding a 12% reduction in mortality rate (p=.29). In patients with documented infection involving other organisms, there was no difference between treated and placebo groups. When the outcomes of organ dysfunctions were examined in the overall population and in the documented Gram-negative bacterial infection population, the number of patients who resolved hepatic dysfunction tended to be higher in the treated group than in the placebo group (p=.06). The number of adverse events reported were not different between the two groups.

CONCLUSIONS

A 4-day administration of the studied PAFra (BN 52021) failed to demonstrate a statistically significant reduction in the mortality rate of patients with severe sepsis suspected to be related to Gram-negative bacterial infection. If PAFra treatment has any therapeutic activity in severe Gram-negative bacterial sepsis, the incremental benefits are small and will be difficult to demonstrate in a patient population as defined by this clinical trial.

Effect of BN 52063, a specific PAF-acether antagonist, on bronchial provocation test to allergens in asthmatic patients. A preliminary study

Platelet Activating Factor, PAF-acether, elicits acute and more prolonged inflammatory responses in both experimental animals and man, and is recognised as a possible mediator of asthma. The effect of a specific PAF-acether antagonist, BN 52063, on the early asthmatic response to inhaled allergen was assessed in a randomised, double-blind, crossover study in eight atopic asthmatics, who received three days treatment with BN 52063 or placebo, separated by a one week washout. On the third day of treatment, subjects were challenged with nebulised house dust mite or pollen allergen. BN 52063 significantly antagonised early bronchoconstriction and showed a tendency to inhibit residual bronchial hyperreactivity, assessed six hours after allergen challenge by a provocation test to acetylcholine. No side effects were reported during active treatment. This is the first study in man demonstrating the efficacy of a specific PAF-acether antagonist on the immediate response to inhaled allergen challenge in asthmatics. The findings support the possible role of specific PAF-acether antagonists in the treatment of asthma.

Detection of hazardous weight-loss substances in adulterated slimming formulations using ultra-high-pressure liquid chromatography with diode-array detection

The presence on the market of illegal products for slimming purposes or the treatment of overweight is a public health issue. These products may contain illicit chemicals in order to improve their effectiveness. Some of these weight-loss compounds are responsible for adverse events, including fatal outcomes. A general strategy for the analysis of any suspect formulation begins with a large screening for the general search of a wide range of compounds. A methodology for the qualitative and quantitative determination of 34 compounds in slimming preparations (such as dietary supplements or medicinal products) was used for the control of slimming formulations from the market, including over the Internet. The fast liquid chromatography system (ultra-high-pressure liquid chromatography) used a gradient of solvent (phosphate buffer and acetonitrile), a C18 endcapped column and a diode array detector. This system allows dual identification based on retention time and UV spectra. The analytical method is simple, fast and selective since 34 weight-loss compounds can be detected in a 15-min run time. Thus, 32 commercial slimming formulations were analysed using this method, allowing the detection and quantification of hazardous active substances: caffeine, clenbuterol, nicotinamide, phenolphthalein, rimonabant, sibutramine, didesmethylsibutramine, synephrine and yohimbine.

Inhibition of PAF-acether induced weal and flare reaction in man by a specific PAF antagonist

It has been suggested that PAF-acether may be an important mediator in asthma and a PAF antagonist may therefore have a potentially important role. PAF-acether has been shown to induce a dual inflammatory response in the skin of man and we investigated the effect of BN 52063, a PAF antagonist, on this response. At a dose of 80 mg, BN 52063 orally inhibited the inflammatory response to a sub-cutaneous injection of PAF-acether 400 ng. A late cutaneous response was not observed in any of the subjects. BN 52063 was also demonstrated to be well tolerated at doses of 20, 40, 80 and 120 mg with no significant side effects.

Double blind placebo controlled multicentre study of ginkgolide B in treatment of acute exacerbations of multiple sclerosis. The Ginkgolide Study Group in multiple sclerosis

After an open labelled pilot study of ginkgolide B, a potent inhibitor of platelet activating factor, in the treatment of acute exacerbations of multiple sclerosis, a randomised double blind placebo controlled study was undertaken. One hundred and four patients were enrolled in the study: for seven days 43 received placebo, 29 received 240 mg/day ginkgolide B and 32 received 360 mg/day ginkgolide B. There was no statistical difference between the three groups for changes in Rankin, Kurtzke expanded disability status scale (EDSS), and Hauser ambulation index (AI) scores. Although there was a trend in favour of groups treated with ginkgolide for a change of Rankin and AI scores, it is concluded that ginkgolide B is not an effective treatment of exacerbations of multiple sclerosis.

Platelet activating factor-induced clinical and histopathologic responses in atopic skin and their modification by the platelet activating factor antagonist BN52063

The clinical and histopathologic responses to intradermal platelet-activating factor (PAF-acether) in atopic subjects, without evidence of atopic dermatitis are documented. An immediate acute wheal and flare reaction was observed in all volunteers. Histopathologically, the reaction was characterized by a predominantly neutrophilic response, which was seen at 30 minutes and was maximal at 4 hours. Eosinophils were observed in the infiltrate as early as 30 minutes after injection, and were maximal by 12 hours. The specific PAF-acether antagonist BN52063 antagonized the acute flare response to intradermal PAF-acether but had little effect on cellular recruitment at the site of injection.

Effects of the platelet activating factor antagonists BN 52021 and BN 50730 on antigen-induced bronchial hyperresponsiveness and eosinophil infiltration in lung from sensitized guinea-pigs

The involvement of platelet activating factor (PAF) in antigen-induced bronchial hyperresponsiveness was investigated by the use of the PAF antagonists BN 52021 and BN 50730, in a guinea-pig model where sensitization and challenge were performed by aerosol. Male Hartley guinea-pigs were sensitized by two aerosol exposures at 48 hr intervals to a 0.9% NaCl solution (saline) containing 2 mg/ml ovalbumin for 30 min. Fifteen to 20 days later, guinea-pigs were challenged by exposure to five successive aerosols of increasing concentrations of ovalbumin (OA) or respectively, 10 microg/ml, 100 microg/ml, 1 mg/ml, 5 mg/ml and 10 mg/ml for 15 min each, or saline alone. Three to four hr and 18-24 hr after the aerosol challenge the guinea-pigs were prepared for recording of bronchopulmonary response and aerosol administrations were then generated with an ultrasonic nebulizer. The bronchopulmonary responses induced by successive 1-min aerosol bursts of acetylcholine (ACh) was assessed. As compared with saline-challenged guinea-pigs, an enhanced bronchopulmonary response to aerosol administration of cumulative doses of ACh was observed, 3-4 hr and 18-24 hr post-ovalbumin challenge. When the sensitized guinea-pigs were pretreated 1 hr before ovalbumin exposure with BN 52021 or BN 50730 (25 mg/kg, per os), a significant inhibition of the increase in the bronchopulmonary response to ACh was observed, both at 3-4 hr and 18-24 hr. Furthermore, when guinea-pigs were treated 3-4 hr after the ovalbumin exposure with BN 52021 or BN 50730, a significant inhibition of the hyperresponsiveness to ACh was recorded at 18-24 hr. A marked accumulation of eosinophils in the peribronchial regions was observed on histological preparations of lung specimens collected 4 hr or 24 hr after ovalbumin exposure. Pretreatment of the guinea-pigs by BN 50730 or BN 52021 did not modify the eosinophil accumulation in the peribronchial area. No significant difference in the number of eosinophils collected in the bronchoalveolar lavage fluid is observed, 24 hr post-ovalbumin challenge, under the pretreatment with BN 52021 or BN 50730. Pretreatment of guinea-pigs by BN 50730 or BN 52021 significantly reduced the PAF-induced (100 microg/ml) increase in eosinophil number in the peribronchial area. By contrast, they did not inhibit the eosinophilia induced by aerosol administration of LTB4 (5 microg/ml). These results suggest that the bronchial hyperresponsiveness observed in this study is associated with eosinophil accumulation in the lung. The potent inhibition of the bronchial hyperresponsiveness by the two unrelated antagonists of PAF suggests that the lipid mediator is involved in its triggering and duration, but not in the eosinophil infiltration.

Antisense approach for the treatment of cytomegalovirus infection

Human cytomegalovirus (HCMV) is the most common viral opportunistic infection in patients suffering with acquired immunodeficiency virus (AIDS). HCMV is a systemic infection that may infect several sites in the body, including the retina, gastrointestinal tract, lungs, liver, and central nervous system. Retinitis is the most frequent manifestation of HCMV infection, occurring in 15-40% of all patients. HCMV is progressive and destroys the retina, eventually leading to blindness. Although, there are several drugs available to treat this disease, they are often of limited efficacy and have significant side-effects. Antisense oligonucleotides represent a novel alternative to the currently available drugs. Due to their high affinity and specificity to target the HCMV RNAs, interest in antisense technology to treat HCMV infections has been intense during the past few years. Two antisense drugs are currently in clinical trials, ISIS 2922 (Formivirsen) and GEM 132.

Tanakan inhibits platelet-activating-factor-induced platelet aggregation in healthy male volunteers

An open study to investigate the PAF-acether antagonist activity of Tanakan in healthy male volunteers examined the effect of a single 15-ml oral dose on ex vivo platelet aggregation induced by adrenaline, adenosine diphosphate (ADP), collagen or PAF-acether. Aggregometry was performed on platelet-rich plasma samples from blood taken 1 h before dosing with Tanakan and 2, 4 and 8 h after intake of Tanakan. Following dosing with Tanakan there was a reduction in platelet aggregation at all doses of PAF, with 1 microM ADP and adrenaline, the most significant decreases occurred with 75 nM PAF-acether 4 h after intake (p less than 0.05) and 300 nM PAF-acether 4 h (p less than 0.01) and 8 after intake (p less than 0.05). There were no concomitant changes in coagulation, skin bleeding time, haematological and biochemical laboratory tests, blood pressure or pulse. The results provide a possible explanation for the clinical efficacy of Tanakan in the treatment of peripheral vascular disease; they also confirm that a single oral dose of 15 ml Tanakan is well tolerated.

Treatment of carrageenan induced arthritis by the platelet activating factor antagonist BN 50730

OBJECTIVE

To evaluate the role of platelet activating factor (PAF) in the early stage of arthritis.

METHODS

Arthritis was induced in rabbits by weekly intra-articular injections of carrageenan. A PAF receptor antagonist, BN 50730, was used as a preventive or curative agent.

RESULTS

BN 50730 was able partially to prevent the development of arthritis, and was also active on established arthritis. The joint arthritis scores of BN treated animals were significantly lower than those of the non-treated animals. The blood concentrations of PAF, PAF bound to lipoproteins (lipo-PAF), and its precursor, lyso-PAF, were not correlated with clinical variations.

CONCLUSIONS

The present data demonstrate a therapeutic action of a PAF antagonist in experimental arthritis and suggest a critical role for PAF during the early stage of arthritis.

[Antisense oligonucleotides: a new therapeutic approach]

The use of antisense oligonucleotides as therapeutic agents has generated considerable enthusiasm in the research and medical community. Oligonucleotides inhibit gene expression by binding to their target nucleic acid with high specificity and selectivity. The field of antisense technology has progressed enormously. Major progress has been accomplished in the synthesis and manufacturing of modified oligonucleotides. Numerous studies have demonstrated the ability of antisense oligonucleotides to modulate gene expression, in such diverse fields as infectious diseases, cancer, and inflammation. More than a dozen of clinical trials using antisense oligonucleotides have been initiated during the last three years or so. The insights gained through these ongoing clinical trials has opened the pathway to the design of more advanced chemistries which have improved safety profile and efficacy.

[Development of an antihypertensive agent. Methodology and cost]

This schematic analysis demonstrates the great increase in the cost and time required to develop a new molecule, factors which therefore limit the development of new therapeutic methods. The patent period is shorter so that the period of commercialisation of a product by a single drug company is more and more limited. Therefore the situation may occur where the costs of development will no longer be covered. (In addition, the costs of research not leading to a marketable product have not been taken into account).

Determination of the optimal dose of the antihypertensive drug cicletanine hydrochloride in man

The optimal antihypertensive dose of cicletanine (BN 1270) was investigated in 3 short-term and 3 long-term therapeutic trials using doses of 12.5 to 200 mg. There was a dose-response effect such that in double-blind studies of 1 month's duration, 50 mg/d was the minimum effective dose in mild to moderate hypertensive patients, while a higher dose, 200 mg/d, was more effective in patients with severe hypertension. Despite a quicker reduction in blood pressure by 100 mg cicletanine compared with 50 mg, a similar antihypertensive effect resulted after 3 months' treatment. In patients with mild to moderate hypertension the average decrease in blood pressure over this period was 43.7/38.0 mmHg. A daily dose of 50 mg, which may be increased, particularly at the beginning of treatment, is therefore the optimal recommended dose for these patients. Furthermore, the similar efficacy of the 50 mg and 100 mg doses was confirmed in the long-term trial in the elderly. In all studies, at all doses, cicletanine had a gradual antihypertensive effect, avoiding the risks associated with a sudden fall in blood pressure. The different rates of effect of the 50 mg and 100 mg doses are thought to be due to different mechanisms of action: since 50 mg has no natriuretic effect and 100 mg has a slight natriuretic effect, which is even more pronounced at higher doses.

[Treatment of growth hormone deficiencies with growth hormone releasing hormone. Current status and perspectives]

Results of clinical trials performed with human hypothalamic growth hormone releasing factor (GRF) are conflicting, but rather disappointing for most of them. Pulsatile administration of GRF has been found to increase growth hormone secretion as well as growth velocity, but is not convenient for practical use. All other routes and rhythms of administration lead only to sub-optimal results, and generally does not seem to procure an appropriate GRF bio-availability. Improvements are possible, particularly the development of agonists and new galenic forms with sustained release. Therapeutic approach with hexapeptides, or hexapeptides analogs, looks promising, but could be more complementary than competitive.