Synthesis and free radical scavenging properties of the enantiomers of erdosteine.

The synthesis of enantiomers R and S of erdosteine, a derivative of homocysteine-gamma-thiolactone, and the NMR studies for the determination of the enantiomeric excess with chiral shift reagent on the more soluble ethyl esters, are described. Pharmacological data relative to the free radical scavenging properties of the R and S enantiomers are reported. In particular, it has been documented that the S isomer is more effective than R isomer in protecting mice against lethal doses of paraquat (substance able to form free radicals when administered by i.p. route).

Pharmacokinetics of dipyridamole-beta-cyclodextrin complex in healthy volunteers after single and multiple doses.

Dipyridamole is a well known anti-aggregating agent characterized by poor water solubility as well as scant and variable bioavailability. Recently, the compound was complexed with beta-cyclodextrin forming a molecular encapsulation resulting in better oral absorption and stronger biological activities in animals. In the present study, a randomized double blind cross-over comparison between dipyridamole-beta-cyclodextrin complex (dip-beta-CD) and dipyridamole was performed in 12 healthy subjects after single (75mg) and multiple oral treatments (75mg TID). Dip-beta-CD showed better bioavailability and less interindividual variability than dipyridamole either after single or multiple doses. In particular, dip-beta-CD had a greater AUC and Cmax, and a smaller Tmax even at the steady state. In addition, 100% of the subjects receiving a single dose of dip-beta-CD, as compared to 66.7% of those treated with dipyridamole, had plasma levels superior to 1 microgram/ml (which is the supposed anti-aggregating threshold level). In contrast, 0 and 33.03% of the subjects showed plasma levels superior to 2.5 micrograms/ml (which might cause the appearance of side-effects) on the 7th day of the multiple treatment with dip-beta-CD and dipyridamole, respectively. In fact, the subjects presenting higher levels after uncomplexed dipyridamole also complained of headache and/or dizziness on occasion. No adverse side effects were reported for dip-beta-CD.

Lack of gastric adverse effects of erdosteine in rats and men.

Erdosteine is a thiol derivative endowed with mucolytic, mucomodulator and free radical scavenging properties. Studies were performed in rats and men with the aim to assess its safety on gastric mucous barrier. Two experiments were performed in rats by comparing the effects of erdosteine, homocysteine thiolactone (HTL), carbocysteine, tiopronin and placebo on a) macroscopic appearance of G. I. ulcer, total HCl, pH and volume of gastric juice 4 and 6 hours after, respectively, pylorus ligation in Shay rats and drug oral treatment, and on b) macroscopic appearance of G. I. ulcer in fasting rats for 50 hours, during which the animals received 4 oral doses of each compound. In both conditions erdosteine was completely inactive in the dose-range of 500-1000 mg/kg p.o. while HTL, carbocysteine and tiopronin were ulcerogenic already at the dose of 500 mg/kg p.o. Accordingly, 15 human beings, undergoing gastroscopy, well tolerated erdosteine at the oral dose of 300 mg TID for 9-13 days. In this open study the patients neither revealed worsening of their pre-existing gastric complains, nor indicated new subjective symptoms, nor manifested macroscopic and histological alterations concerning the parietal tonus, the status of epithelial mucosa and of gastric content (including: volume, total acidity and total, bound and free sialic acid).

Activity of erdosteine on mucociliary transport in patients affected by chronic bronchitis.

The influence of erdosteine (a mucomodulator endowed with mucolytic and antioxidant properties) on human mucociliary transport (MCT) was investigated in a double-blind placebo controlled study. Sixteen former smokers affected by chronic bronchitis, preselected for their mucociliary responsiveness to an inhaled beta 2-agonist, were divided into two groups (matched by number, sex, age and FEV1%) and orally treated with placebo or erdosteine (300 mg t.i.d.) for 8 days. Their MCT was assessed by the bronchofiberscopy technique just before starting the treatment and at the end of the treatment. The pretreatment mucus transport velocity in these patients was significantly decreased with respect to healthy subjects. The erdosteine treatment induced a significant improvement of MCT while placebo was inactive (mean % variation +/- SE against their baseline values being +60.4 +/- 18.4 and -3.0 +/- 5.9, respectively). This peculiar activity of erdosteine on mucus transport may be of clinical usefulness in chronic bronchitic patients and it can be added to beta 2-agonist to restore the decreased MCT.

Enhancement of specific biological activity of dipyridamole by complexation with beta-cyclodextrin.

Dipyridamole forms an inclusion complex with beta-cyclodextrin (dip-beta-CD) which shows better solubility and bioavailability than the uncomplexed compound. The present studies have demonstrated that dip-beta-CD is more effective than dipyridamole either as base or HCl (dispersed or not in lactose) on some important cardiovascular parameters when orally administered to conscious animals. In particular, dip-beta-CD causes a stronger and prompter coronary and carotid vasodilatation in dogs, at doses which weakly influence the systemic arterial pressure and the heart rate. In addition, platelets collected from treated rabbits at various intervals appear to be protected from sodium adenosine diphosphate-induced aggregation in vitro more effectively and rapidly by dip-beta-CD than by dipyridamole. Studies on tail bleeding time have confirmed that dip-beta-CD is more active than dipyridamole when given orally to mice. These biological findings are fully in agreement with other oral bioavailability studies in dogs and men indicating that dip-beta-CD gives quicker and higher blood levels with smaller interindividual variability than dipyridamole.

Effects of erdosteine on sputum biochemical and rheologic properties: pharmacokinetics in chronic obstructive lung disease.

Erdosteine is a new thioderivative endowed with mucokinetic, mucolytic, and free-radical-scavenging properties. This study evaluated (in a double-blind design vs. placebo) its efficacy on biochemical and rheologic properties of sputum and on some indices of respiratory function in chronic patients with chronic bronchitis (10 per group), while receiving basic treatment with a controlled-release theophylline preparation. The pharmacokinetics of erdosteine and theophylline were also studied. We found that a 2 week treatment with erdosteine (300 mg 3 times daily) was able to reduce significantly (p less than 0.05) the sputum apparent viscosity, fucose content, and macromolecular dry weight (MDW) with no statistically significant influence on sputum elasticity, DNA, albumin, total proteins, total IgA, lactoferrin, and lysozyme content. The treatment caused a significant increase in the following ratios: total IgA/albumin, lactoferrin/albumin, and lysozyme/albumin. The pharmacokinetics of erdosteine, its metabolites, and theophylline were the same after 1 or 14 days of treatment, evidence both of absence of an enzymatic induction and of an accumulation process. Further confirmation that there was no interference between erdosteine and theophylline was obtained from the data available on the group of patients receiving only theophylline, since its plasma levels and related pharmacokinetic parameters were identical to those obtained in patients receiving both drugs. In conclusion, 2 weeks of therapy with erdosteine reduced the marker of mucus glycoproteins (fucose) in patients with chronic bronchitis but did not interfere with the pharmacokinetics of xanthine derivatives. We also suggest that the significant increment in the IgA/albumin ratio might be related to a sum of other local effects such as reduction of the inflammatory process and enhancement of the humoral defense mechanism.

5-Piperazinylalkyl-2(3H)-oxazolones with neuroleptic activity.

A series of new 4-aryl-5-[omega-(4-aryl-1-piperazinyl)alkyl]-2(3H)- oxazolones was synthesized and tested for neuroleptic activity in mice and rats. Several compounds exhibited interesting neuroleptic activity with very low liability to the extrapyramidal side effects. In particular the activity of 4-(4-fluorophenyl)-5-[2-[4-(3,5-dichlorophenyl)-1- piperazinyl]ethyl]-2(3H)-oxazolone (14) was greater than that of butropipazone and fluanisone, while of the same order of that of chlorpromazine; however, the product showed a longer lasting activity and minor ability to produce catalepsy as compared with the reference drugs.

Pharmacokinetics of dipyridamole-beta-cyclodextrin complex in dogs.

Plasma concentrations and urinary and fecal excretion of intact dipyridamole were followed in dogs after oral administration of dipyridamole-beta-cyclodextrin complex (dip-beta-CD) (capsules containing 37.5 and 75 mg of active principle), of commercial dipyridamole and of dipyridamole. HCl (tablets and capsules of 75 mg of active principle, respectively), according to a crossover design. Dip-beta-CD afforded significantly shorter lag-times, higher Cmax, smaller interindividual variations of plasma concentrations and greater urinary excretion than the other two preparations, as a consequence of a better bioavailability of the former one. This amelioration seems to be due not only to an increased wettability and water solubility of the product, but also to a finer molecular dispersion in the gastrointestinal fluids which favors the contact of dipyridamole with a greater absorption surface.

Erdosteine protection from cigarette smoke-induced loss of alpha 1-antitrypsin activity in rat lungs.

Acute inhalation of cigarette smoke induced alpha 1-antitrypsin inactivation in rat lungs. The elastase inhibitory capacity of the protein could be prevented by oral treatment with erdosteine (a mucoregulator endowed with free radical scavenging properties). A partial dose-dependent protection was observed with 500 and 1,000 mg/kg. The mechanism of its action might be related either to the inhibition of alpha 1-antitrypsin oxidation manifested by two SH groups liberated in vivo or to the anti-inflammatory and mucoregulator properties present in the substance.

Erdosteine protection against cigarette smoking-induced functional antiprotease deficiency in human bronchiolo-alveolar structures.

Cigarette smoke reduces the elastase inhibitory capacity (EIC) of alpha 1-antitrypsin by an oxidative process and thus may promote the pathogenetic bases for the development of pulmonary emphysema. The present study was performed with the aim to evaluate the protective activity of erdosteine, a novel thiol derivative endowed with reducing properties, against the functional inactivation of alpha 1-AT induced by smoke. For the purpose, a double-blind study was carried out on 24 healthy smokers divided into two groups orally treated with placebo or erdosteine 900 mg/day for one month. The antigenic and functional alpha 1-AT was measured in bronchoalveolar (BAL) fluids and sera before and shortly after the last treatment. The findings indicate that the loss of EIC of alpha 1-AT in BAL fluids can be partially prevented by pharmacological treatment. In this regard, it is reasonable to hypothesize that the reestablishment of the oxidant-antioxidant balance in favor of the antioxidants would be useful as a therapeutic strategy to arrest or at least delay the emphysematous process.

In vitro protection by erdosteine against oxidative inactivation of alpha-1-antitrypsin by cigarette smoke.

Direct exposure in vitro of the protein alpha 1-antitrypsin (alpha 1-AT; human neutrophil elastase inhibitor, alpha 1-proteinase inhibitor) to gas phase cigarette smoke causes a loss of elastase-inhibitory capacity (EIC). This effect appears to be related to the formation of reactive oxygen species in the smoke that inactivate alpha 1-AT by oxidizing the methionine terminal amino acid. Reducing agents such as glutathione and ascorbic acid prevent this inactivation. In the present investigation erdosteine, a novel thiol derivative, which contains two blocked SH groups with potential reducing properties, was tested in vitro for its capacity to protect human alpha 1-AT. For the purpose, the compound, previously hydrolyzed with bicarbonate-carbonate buffer or with microsomal enzymes was put in contact with alpha 1-AT and exposed to gas phase cigarette smoke. The EIC of alpha 1-AT was then measured by incubating the samples with leukocyte elastase and, subsequently, by titrating the residual elastolytic activity against a synthetic substrate. Under these conditions erdosteine effectively protected alpha 1-AT against the smoke injury and, after alkaline hydrolysis, it appeared to be as active as glutathione and ascorbic acid (EC50 being respectively 6.4, 7.2 and 6.2 mM). This evidence suggests that the erdosteine SH groups, which can become free, may have an important role in the mechanism of action, by blocking highly reactive oxygen-free radicals. Erdosteine may have a therapeutic application in preventing oxidative lung damage induced by cigarette smoke.

Human pharmacokinetics of erythromycin propionate-N-acetylcysteinate: comparative evaluation with erythromycin stearate and N-acetylcysteine.

The pharmacokinetic pattern of erythromycin propionate-N-acetylcysteinate (EPAC) (erythromycin stinoprate I.N.N.), a new derivative, was studied on 12 healthy volunteers after single and multiple oral treatments. Microbiological and/or HPLC analytical methods were used to titer either erythromycin as base, propionate and total or N-acetylcysteine (NAC). In the acute experiment, a comparative evaluation was performed with erythromycin stearate (ES) and with N-acetylcysteine, according to a randomized-multi-crossover design. EPAC showed a better bioavailability than ES with longer-lasting serum levels of active antibiotic. NAC concentrations in the serum after EPAC were practically identical to those found after an oral administration of NAC alone. The multiple treatment study, performed in the same 12 volunteers with only EPAC, indicated that the pharmacokinetic pattern is somewhat different from that observed after a single dose, since higher concentrations were present at the steady state conditions.

Influence of erdosteine, a mucolytic agent, on amoxycillin penetration into sputum in patients with an infective exacerbation of chronic bronchitis.

Twenty four patients with acute infective exacerbations of chronic bronchitis received amoxycillin alone or in combination with erdosteine (a mucolytic agent) for a week in a double blind, placebo controlled study. Clinical assessment scores, body temperature, serum and sputum amoxycillin concentrations, and sputum culture results were recorded in each group. Erdosteine significantly increased antibiotic concentrations in sputum but not in serum. The combined treatment also caused a more rapid decrease in sputum viscosity and in body temperature and faster sterilisation of the sputum. These results show that erdosteine increases amoxycillin concentration in sputum in patients with acute exacerbations of chronic bronchitis. This effect may be due to a reduction in the viscosity of the bronchial secretions produced by erdosteine.

Serum, sputum and bronchial concentrations of erythromycin in chronic bronchitis after single and multiple treatments with either propionate-N-acetylcysteinate or stearate erythromycin.

Serum and bronchial concentrations of erythromycin were determined in 30 chronic bronchitic patients during an exacerbation phase of bacterial infections. The levels were measured after single and multiple oral treatments with erythromycin-propionate-N-acetylcysteinate (EPAC) or erythromycin stearate (ES) in a double-blind design. EPAC showed higher and longer-lasting erythromycin levels in serum, sputum and pure bronchial mucus than ES. It is believed that EPAC is better absorbed because of its greater stability in the gastrointestinal juices. Higher concentrations in bronchial secretions not always depend on the blood levels. It seems to be possible that the N-acetylcysteine moiety in the molecule of EPAC drug can facilitate antibiotic penetration because of its mucolytic activity. The clinical response (disappearance of fever, clearance of bacterial pathogens from sputum, reduction of quantity and viscosity of sputum) also occurred faster in the EPAC than in the ES group.

Synthesis and antiarrhythmic activity of new 3-[2-(omega-aminoalkoxy)phenoxy]-4-phenyl-3-buten-2-ones and related compounds.

A number of the title compounds (1) and a few related hydroquinone derivatives (2) have been synthesized and tested for antiarrhythmic activity in vivo (protection against CaCl2-induced ventricular fibrillation in anesthetized rat) and in vitro (ability to reduce the maximum driven frequency of an electrical stimulus in isolated rabbit atria). The effects induced by modification of the enol ether moiety in the parent compound 1a were also examined. Many of the compounds exhibited antiarrhythmic properties stronger than quinidine and procainamide, associated with a more favorable LD50/ED50 ratio. Compounds 1a (LR-18,460, 3-[2-[2-(diethylamino)ethoxy]phenoxy]-4-phenyl-3-buten-2-one) and 1h (LR-18,795, 3-[2-[3-(dimethylamino)propoxy]phenoxy]-4-phenyl-3-buten-2-one) were submitted to further antiarrhythmic testing, which confirmed their effectiveness and superiority to quinidine in all the experiments. After safety evaluation studies, both were selected for clinical investigation.

N-phenylpiperazine derivatives with hypocholesterolemic activity.

A series of new 4-(4-phenyl-1-piperazinyl)-1-(4-fluorophenyl)-2-(acyloxy)-1-butanones and 4-aryl-5-[omega-(4-aryl-1-piperazinyl)alkyl]-1,3-dioxol-2-ones were synthesized and tested preliminarily for hypolipemic activity. Plasma cholesterol-lowering activity in normal rats was found especially in several dioxolones, two of the most active compounds (6 and 8) being more potent than clofibrate. 4-(4-Chlorophenyl)-5-[2-(4-phenyl-1-piperazinyl)ethyl]-1,3-dioxol- 2-one (8, LR-19,731) has been selected for clinical trials.

Drug latentiation of isoxsuprine: synthesis and preliminary pharmacological activities of four monoesters.

Four new esters (1 b-e) involving the phenolic group of isoxsuprine have been prepared. Preliminary pharmacological evaluation showed that the pivaloyl ester (1 e) (LR693) lowers blood pressure values more gradually than isoxsuprine with a longer-lasting effect. This compound was selected for further assessment as a long-acting peripheral vasodilator.

Synthesis and pharmacological activity of some 2,3-dihydro-1,4-benzodioxin and 1,3-benzodioxol derivatives, as cyclic analogs of isoxsuprine.

A few analogs of the isoxsuprine drug with the phenoxyethyl group incorporated into the heterocyclic 2,3-dihydro-1,4-benzodioxin or 1,3-benzodioxol ring have been synthesized. Among these compounds, the benzodioxol derivative (I e) has been found to possess hypotensive activity in rats in the same range as isoxsuprine, with no alpha-adrenolytic and central sedative properties. Cardiovascular studies in dogs have shown that (I e) is less potent than isoxsuprine, although its activity is longer-lasting at an equally hypotensive dose.

Therapeutic properties of dihydroxy-dibutylether on sub-acute liver damage induced by several hepatotoxic agents in rats.

The data presently reported show that repeated exposure of rats to allyl alcohol, ethionine or alpha-naphthyl isothiocyanate (ANIT) impaired some plasmatic parameters mainly by means of different mechanisms which involve the liver function. In particular, four administrations of allyl alcohol, given every other day, increased glutamate oxaloacetate transaminase (GOT) for at least 48 hours from the last dose; ethionine reduced the bromsulphthalein (BSP) clearance even after 48 hours from the 1st, 2nd, or 3rd administration given on the 1st, 5th, or 12th day; ANIT, administered daily for seven days, increased glutamate pyruvate transaminase (GPT), alkaline phosphatase (AP), bilirubin, triglycerides (TG) and cholesterol (CH) while it decreased the body-weight and retarded growth for at least six to seven days after intoxication. Twice daily administrations of dihydroxy-dibutylether (DHBE), a strong choleretic agent, brought to normality the parameters impaired by the three hepatointoxicating agents even when the intoxication was already established. In fact, DHBE reduced the plasma GOT levels increased by allyl alcohol, improved the BSP clearance impaired by ethionine and tended to normalize the parameters modified by ANIT by lowering GPT, AP, CH, TG and bilirubin plasma levels and by enhancing body growth. The curative activity of DHBE does not seem to be related only to a membrane stabilizing action since silymarin, a known cell membrane stabilizer, does not significantly influence the parameters described above in all the experimental conditions. Even the choleretic activity of DHBE alone might not be sufficient to explain its hepatoprotective action since fenipentol (a known choleretic agent) is inactive at least after ANIT intoxication.