Improvement of aqueous solubility of fenretinide and other hydrophobic anti-tumor drugs by complexation with amphiphilic dextrins.

This study relates to the preparation of a series of amphiphilic dextrins and their evaluation as complexing agents for anti-tumor hydrophobic drugs such as fenretinide, paclitaxel, etoposide, and camptothecin. The amphiphilic dextrins were obtained by conjugation of low molecular weight dextrin (average molecular weight 1670, average polymerization degree 9.33 glucose monomer) with hydrocarbon chains at substitution degree of about 0.1 mole hydrocarbon chain per mole of glucose monomer, as confirmed by 1H-NMR spectra. The conjugates were highly soluble in water and dissolved with formation of nano-aggregates endowed with hydrophobic inner cores able to host hydrophobic drugs by complexation. Complexation raised hydrophobic drugs aqueous solubility; the best results were obtained with fenretinide. Solid complexes with fenretinide were prepared by using three different approaches: the kneading method, the co-solubilisation method, and the co-precipitation method. Kneading method provided the complexes endowed with the best functional properties. Thermogravimetric analysis on solid samples suggested a notable thermal stability up to 300 degrees C for both the conjugated dextrins and the solid complexes. In differential scanning calorimetry profiles no significant differences were observed among amphiphilic dextrins and complexed drug, indicating that the guest molecule exists in an amorphous state in the solid matrices. Particle size analysis confirmed the dimensional suitability of the complexes for parenteral administration. Moreover, sustained drug release, in vitro, has been observed from all the complexes analyzed. Regarding the biological effects, the cytotoxicity of complexed fenretinide towards HTLA-230 neuroblastoma cell line was always higher than the free drug, suggesting that complexation increased drug bioavailability. These findings, taken together, indicated that these biodegradable, self-assembling dextrin conjugates may be regarded as new potential complexing agents for hydrophobic drugs and, in particular, for fenretinide, to increase drug solubility, bioavailability, and thus therapeutic efficacy.

Micellar complexes of all-trans retinoic acid with polyvinylalcohol-nicotinoyl esters as new parenteral formulations in neuroblastoma.

All-trans-retinoic acid (ATRA) is now included in many antitumor therapeutic schemes for the treatment of acute promyelocytic leukemia, Kaposi's sarcoma, head and neck squamous cell carcinoma, ovarian carcinoma, bladder cancer, and neuroblastoma. Unfortunately, its poor aqueous solubility hampers its parenteral formulation, whereas oral administration of ATRA is associated with progressively diminishing drug levels in plasma, which is related to induction of retinoic acid-binding proteins and increased drug catabolism by cytochrome P450-mediated reactions. An ATRA formulation, obtained by complexation of the drug into polymeric micelles, might be suitable for parenteral administration overcoming these unwanted effects. To this purpose, amphiphilic polymers were prepared by polyvinylalcohol (PVA) partial esterification with nicotinoyl moieties and their functional properties evaluated with regard to ATRA complexation. The physicochemical characteristics of the polymers and the complexes were analyzed by 1H-NMR, Dynamic Light Scattering (DLS), Capillary Electophoresis (CE), and were correlated with the complex ability to improve the drug solubilization and release the free drug in an aqueous environment. Subsequently, the best complex, providing the highest ATRA solubilization and release, was evaluated in vitro to test its cytotoxicity towards neuroblastoma cell lines. The PVA substitution degree calculated from 1H-NMR was found to be 5.0%, 8.2%, 15.3% (nicotinoyl moiety:PVA monomer molar ratio), while capillary electrophoresis analysis on the complexes revealed that the drug loadings were 0.95%, 1.20%, 4.76% (ATRA:polymer w:w) for PVA substitution degrees of 5.0%, 8.2%, and 15.3%, respectively. Complexation strongly increased ATRA aqueous solubility, which reached 1.20 +/- 0.25 mg/mL. The DLS measurements of the polymers and the complexes in aqueous solutions revealed mean sizes always below 400 nm, low polydispersity (min 0.202 +/- 0.013, max 0.450 +/- 0.032), and size almost unaffected by concentration. Drug fractional release did not exceed 8% after 48 h. The cytotoxicity studies against neuroblastoma cell lines outlined a significant growth inhibition effect of complexed ATRA with respect to free ATRA. These data suggest that the systems analyzed may be suitable carriers for parenteral administration of ATRA and other hydrophobic antitumor drugs, where the carriers are required to improve drug aqueous solubility and delay drug release almost after their accumulation in solid tumors.

Fenretinide-polyvinylalcohol conjugates: new systems allowing fenretinide intravenous administration.

N-(4-hydroxyphenyl)retinamide (fenretinide, 4-HPR) has been shown to be active toward many tumors without appreciable side effects. However its in vitro activity does not match a correspondent efficacy in vivo. The main reason is that the drug's hydrophobicity hinders its bioavailability in the body fluids. Even if the drug is previously dissolved in organic solvents, such as ethanol or DMSO, the subsequent dilution in body fluids trigger its precipitation in fine aggregates characterized by very low dissolution efficiency, never reaching amounts suitable for therapeutic response. To date no intravenous formulation of 4-HPR exists on the market. The 4-HPR linkage to a hydrophilic polymer by a covalent bond easily hydrolyzable in aqueous environment is expected to increase the drug's aqueous solubility, providing the free drug after hydrolysis of the covalent bond. This may be a useful tool for the preparation of aqueous intravenous formulations of 4-HPR. For this purpose, we linked 4-HPR to polyvinylalcohol (PVA) by a carbonate bond at different drug/hydroxy vinyl monomer molar ratios. We demonstrated that conjugation increased 4-HPR aqueous solubility and strongly inhibited neuroblastoma cell proliferation. In addition, in an in vivo neuroblastoma metastatic model, we obtained a significant antitumor effect as a consequence of the improved drug bioavailability.

Enhancement of oleyl alcohol anti tumor activity through complexation in polyvinylalcohol amphiphilic derivatives.

Oleyl alcohol was complexed with new amphiphilic polyvinylalcohol derivatives with the aim of increasing its aqueous solubility, thus improving bioavailability and favoring its antitumor activity. Water-soluble amphiphilic polymers were prepared by polyvinyl alcohol (PVA) substitution with oleyl chains through a succinyl spacer at 2% and 3% substitution degree. The complexes were obtained by spray-drying hydroalcoholic solutions of the substituted polymers and free oleyl alcohol at different weight ratios (3:1; 5:1; 10:1 w/w). The main physicochemical characteristics of the complexes were analyzed and correlated to the cytotoxic activity of oleyl alcohol toward tumor cell lines. The complexes strongly increased the aqueous solubility of oleyl alcohol and provided oleyl alcohol release in the presence of extractive conditions (simulating in vivo absorption). The complexes obtained by 10:1 polymer:fatty alcohol weight ratio offered higher release rates than the 5:1 and 3:1 ratios, respectively. Complexation also increased oleyl alcohol cytotoxicity toward tumor cells due to increased availability of the active molecule in the aqueous phase. Pure polymers were found to be biocompatible and no toxic effect was detected up to the highest concentration used in the present study (500 mu g/ml). The complexation of oleyl alcohol with the polymers analyzed here efficiently increased the availability of the fatty alcohol in aqueous environment. The enhanced cytotoxicity toward tumor cells of the complexed oleyl alcohol and the polymer biocompatibility make these amphiphilic PVA derivatives interesting candidates for soluble pharmaceutical formulations containing hydrophobic drugs whose therapeutic potential is often underestimated due to unsuitable levels of their aqueous solubilization.

Amphiphilic poly(vinyl alcohol) derivatives as complexing agents for fenretinide.

Poly(vinyl alcohol) (PVA) substituted with oleyl chains and tetraethyleneglycol monoethyl ether chains (TEGMEE) at 1.5% and 1% degrees of substitution respectively (mol of substituent to mol of hydroxyvinyl monomer) has previously been shown to self-assemble in water, providing aggregates selectively cytotoxic toward tumor cells vs normal cells. These polymers have also been shown to increase the long-term survival of nude mice injected with both human and murine neuroblastoma cell lines. In the present work, we changed the substitution degree of the oleyl chains on the poly(vinyl alcohol) backbone and maintained constant at 1% the degree of TEGMEE substitution. We evaluated the main physicochemical characteristics of the final polymers, their cytotoxicity toward tumor cells, and their complexing ability for hydrophobic molecules. The aim was to investigate the possibility of improving intrinsic antitumor efficacy of the polymer by changing the degree of oleyl chain substitution and further increase activity by complexation with antitumor drugs. The polymers were prepared at oleyl chain substitution degrees ranging from 0.5 to 3% (mol of substituent to mol of hydroxyvinyl monomer). The most active was again the 1.5% substituted polymer. It was further characterized by exhibiting the highest complexing ability toward hydrophobic molecules allowing the formation of a complex with fenretinide (HPR). The polymer-HPR complex was stable in aqueous environment and released the free drug prevalently in the presence of fluid hydrophobic phases. It was cytotoxic toward tumor cells with minimal activity toward normal cells. Antitumor activity exceeded that of the separate complex components resulting from the concomitant effect of the polymer and the HPR solubilized by complexation.

Preparation and evaluation of polyvinyl alcohol-co-oleylvinyl ether derivatives as tumor-specific cytotoxic systems.

A series of poly(vinyl alcohol) amphiphilic derivatives have been prepared to obtain polymeric aggregates in aqueous phase holding thermodynamic instability. The aim was to evaluate their ability to interact with tumor cells eliciting selective cytotoxicity. The poly(vinyl alcohol) derivatives were prepared by partial substitution of poly(vinyl alcohol) (MW 10 kDa) with both oleyl chains and poly(ethylene glycol) monoethyl ethers (PEGMEE) of different molecular weights. The substitution degree was 1.5% for the oleyl chains and 1% for the PEGMEE chains (moles of substituent per 100 mol of hydroxyvinyl monomer). The polyvinyl derivatives obtained easily dissolved in water. Dynamic and static light scattering measurements on the polymer aqueous solutions indicated the formation of polymeric aggregates characterized by low polydispersity (0.232-0.299) and mean size (218-382 nm) in the range suitable for intravenous administration. Moreover, they were characterized by different packing densities and thermodynamic instabilities driving the polymers to interact with hydrophobic membranes. Among the analyzed polymers, the poly(vinyl alcohol)-co-oleylvinyl ether substituted with triethylene glycol monoethyl ether (P10(4)) provided in solution the highest affinity for hydrophobic membranes. P10(4), moreover, was the most cytotoxic toward the tumor cell lines analyzed (neuroblastoma: SH-SY5Y, IMR-32, HTLA-230. melanoma: MZ2-MEL, RPMI7932.), while it did not appreciably alter the viability of the normal resting lymphocytes. The peculiar behavior of the P10(4) aggregates has been correlated to their high thermodynamic instability in solution due to the high packing density that triggers the polymeric aggregates to interact with hydrophobic membranes such as the tumor cell membranes, thus eliciting cytotoxicity.

Modified doxorubicin for improved encapsulation in PVA polymeric micelles.

Polyvinylalcohol, partially substituted with lipophilic acyl chains, generates polymeric micelles in aqueous phase, containing a hydrophobic core able to encapsulate lipophilic drugs. Two types of polymers were obtained by conjugation of polyvinylalcohol with oleoyl or linoleoyl chains as pendant groups. The polymers, at a substitution degree of approximately 1%, are soluble in water and form polymeric micelles whose size increases with polymer concentration. Doxorubicin was hydrophobized, by linking an oleoyl chain via amide bond, to make the drug more similar to the substituted polymers and promote its encapsulation into the inner core of the micelles. The properties of the drug-polymer systems were evaluated in solution by dynamic light scattering technique and correlated to the physicochemical characteristics of the drug and the substituted polymers. Solubilization tests revealed that the similarity of the chain, in both the polymer and the drug, promotes better drug encapsulation in the oleoyl than linoleoyl derivative. The drug-polymer systems are stable in phosphate buffer saline (pH 7.4) at 37 degrees C, and the release of the drug is activated by the presence of the proteolytic enzyme pronase-E. The enzyme activated drug release and the size of the polymeric micelles, compatible with the pore dimensions of the tumor vessels, make these systems interesting for targeting lipophilic drugs to solid tumors, where the proteolytic enzyme concentration strongly raises with respect to the other body compartments.

Modified polyvinylalcohol for encapsulation of all-trans-retinoic acid in polymeric micelles.

All-trans-retinoic acid (ATRA) is now included in many antitumor therapeutic schemes for the treatment of acute promyelocytic leukaemia, Kaposi's sarcoma, head and neck squamous cell carcinoma, ovarian carcinoma, bladder cancer and neuroblastoma. Unfortunately its poor aqueous solubility hampers its parenteral formulation. To date, there is no parenteral formulation of ATRA commercially available and oral administration of ATRA is associated with progressively diminishing ATRA levels in plasma, which is related to induction of retinoic acid-binding protein and increased drug catabolism by cytochrome P-450-mediated reaction. An ATRA formulation, obtained by complexation of the drug into polymeric micelles, might be suitable for parenteral administration overcoming these unwanted effects. To this purpose we prepared an amphiphilic polymer by polyvinylalcohol (PVA) substitution with oleyl amine at 1.5% substitution degree (mol substituent per 100 mol hydroxyvinylmonomer) and evaluated its functional properties with regard to ATRA complexation. The substituted polymer displayed ability to interact with ATRA both in aqueous solution and in the solid state following spray-drying of drug-polymer hydro-alcoholic solutions. The spray-dried complexes rapidly dissolved in water providing high levels of ATRA solubilization as a function of the drug-polymer weight ratio. The complexes characterized by 1:5 drug-polymer weight ratio provided higher levels of ATRA solubilization than 1:3 and 1:10 drug-polymer weight ratios respectively. Pre-formed polymeric micelles in water equilibrated in the presence of excess solid ATRA provided the lowest levels of solubilization. The drug release from the complexes was very slow in PBS, indicating their suitability in antitumor drug targeting where a fundamental requirement is stability towards drug release for at least 24 h, corresponding to the average circulation time period of macromolecular carriers. The cytotoxicity studies against neuroblastoma cell lines outlined increased cytotoxicity of complexed ATRA with respect to free ATRA, likely due to the increased bioavailability of the hydrophobic drug from the complex. We conclude that ATRA entrapped into self-assembling polymer micelles may be a useful parenteral ATRA formulation overcoming the unwanted pharmacological mechanism that lead to acquired retinoid resistance.

Poly(vinylalcohol-co-vinyloleate) for the preparation of micelles enhancing retinyl palmitate transcutaneous permeation.

The amphiphilic properties of poly(vinylalcohol) substituted with oleic acid was evaluated to assess the possibility to prepare polymeric micelles in an aqueous phase containing a hydrophobic core able to host lipophilic drugs such as retinyl palmitate and thereby enhance its transcutaneous absorption in the stratum corneum. The effect of the increased drug absorption suggests the possibility of interaction between the substituted polymer and the components present in the intercorneocyte spaces. Correlations between the drug concentration in the preparative mixture, micelle size, and drug permeation were evaluated to establish the best functional properties of the micellar systems enhancing retinyl palmitate absorption. Transcutaneous absorption increased with decreasing micelle size, and micelle size decreased on decreasing the drug concentration in the preparative mixture.

Hydrogels formed by crosslinked poly(vinyl alcohol) as sustained drug delivery systems.

Poly(vinyl alcohol) was crosslinked with ethylene glycol diglycidyl ether to obtain hydrogel-forming polymers. The polymers were also substituted with oleoyl chloride, providing hydrogels with weak solubility. These new polymeric materials were evaluated for the formulation of sustained drug delivery systems. Vancomycin hydrochloride was used as a peptidic model drug whose sustained release should minimize its inactivation in the upper part of the gastrointestinal tract. Spray-dried mixtures of the drug and the polymer [at 1:4 and 1:8 (w:w) ratios] were prepared and the release of the drugs from the mixtures was evaluated in vitro at pH 2.0, 5.5, 7.4, and 8.0. The results indicated that the crosslinked polymers slowed down the release of the drugs with respect to the pure drug at each pH. The degree of crosslinking of ethylene glycol diglycidyl ether and the extent of substitution with oleoyl chloride were found to influence drug release.

Influence of different chitosan salts on the release of sodium diclofenac in colon-specific delivery.

Chitosan (CH) was dissolved in aqueous solutions containing aspartic, glutamic, hydrochloric, lactic and citric acids to obtain different chitosan salts. Chitosan salts were collected from the solutions by spray-drying and the powders obtained were mixed with Sodium Diclofenac (SD), taken as a model anti-inflammatory drug. This study evaluated in vitro the influence of acid type on the release behaviour of SD from the physical mixture during gastrointestinal transit. The physical mixture of the chitosan salts with SD provided slower drug release than the pure drug both in acidic and alkaline pHs. In addition, the interaction with beta-glucosidase at pH 7.0 enhanced the release rate. Among the CH salts used, glutamic and aspartic salts provided the best control of release.

Hydrogels Formed by Crosslinked Poly(vinyl alcohol) as Sustained Drug Delivery Systems.

Poly(vinyl alcohol) was crosslinked with ethylene glycol diglycidyl ether to obtain hydrogel-forming polymers. The polymers were also substituted with oleoyl chloride, providing hydrogels with weak solubility.These new polymeric materials were evaluated for the formulation of sustained drug delivery systems. Vancomycin hydrochloride was used as a peptidic model drug whose sustained release should minimize its inactivation in the upper part of the gastrointestinal tract. Spray-dried mixtures of the drug and the polymer [at 1:4 and 1:8 (w:w) ratios] were prepared and the release of the drugs from the mixtures was evaluated in vitro at pH 2.0, 5.5, 7.4, and 8.0. The results indicated that the crosslinked polymers slowed down the release of the drugs with respect to the pure drug at each pH.The degree of crosslinking of ethylene glycol diglycidyl ether and the extent of substitution with oleoyl chloride were found to influence drug release.

Fatty acid substituted polyvinyl alcohol as a supporting material for microsphere preparation.

Polyvinyl alcohol, substituted with lauric, myristic, palmitic, and stearic acids at different substitution degrees was employed for the preparation of biodegradable microspheres containing progesterone or indomethacin. A solvent extraction/method was followed, starting from an oil-in-water dispersion containing the polymer and drug in the inner phase. Microspheres were obtained with high loading efficiency, whose release properties were dependent on the nature of the acyl substituent and the substitution degree. Kinetics approaching zero-order were obtained for the most hydrophile microspheres such as those based on the least substituted polymers and lowest molecular weight substituents. The hydrophilicity of these systems hindered protein absorption on their surface, suggesting their suitability for parenteral use.

Effect of a mucoactive compound (CO 1408) on airway hyperreactivity and inflammation induced by passive cigarette smoke exposure in guinea-pigs.

Environmental exposure to tobacco smoke contributes to the onset of several lung diseases, e.g. chronic bronchitis and asthma, including an increase in airway reactivity. We have investigated the effect of a new mucoactive compound, CO 1408, on airway hyperreactivity and lung inflammation induced in guinea-pigs by passive cigarette smoke exposure. Animals were exposed to cigarette smoke in a Plexi-glass box, three times a day for four days. Airway reactivity to histamine was assessed ex-vivo in lung parenchymal strips. As a measure of lung inflammation, the number of leucocytes was evaluated in bronchoalveolar lavage (BAL) fluids and histological sections. Passive smoke exposure potentiated histamine-induced contraction in lung parenchymal strips, a phenomenon associated with an increase in proinflammatory cells in the BAL fluids and enhanced eosinophil infiltration into parenchymal tissues. Pretreatment with oral CO 1408 at 400 mg.kg-1 but not 100 mg.kg-1, completely prevented the cigarette smoke-induced airway hyperreactivity. 400 mg.kg-1 CO 1408 also inhibited the increase in cell numbers in the BAL fluids, but not eosinophil recruitment in parenchymal tissues. The present data indicate the ability of CO 1408 to modulate smoke-induced airway hyperreactivity and, to some extent, lung inflammation, an effect which might be of value in the therapy of obstructive pulmonary diseases.

Protective activity of inhaled frusemide against immunological respiratory changes and mediator release in guinea-pigs.

The antianaphylactic activity of inhaled frusemide was studied in ovalbumin-sensitized guinea-pigs. The exposure of the animals to frusemide aerosol (1% solution for 20 min) attenuated the respiratory response to ovalbumin challenge (aerosol 1% solution) and was associated with a significant reduction of blood histamine (70%; P less than 0.01) and thromboxane-B2 (35%; P less than 0.01) compared to control animals. Similar results were obtained in isolated lungs perfused via the trachea excised from ovalbumin-sensitized guinea-pigs exposed to frusemide aerosol (1% solution for 20 min). In this series of experiments frusemide significantly prevented the increase in tracheal perfusion pressure (45%; P less than 0.01) and the concomitant release into the pulmonary effluent of both histamine (75%; P less than 0.01) and thromboxane-B2 (39%; P less than 0.01). In another series of experiments, frusemide (1 x 10(-4) M) significantly reduced the immune release of histamine from mast cells of ovalbumin-sensitized rats. The inhibitory activity of frusemide was in the same range of potency (66%; P less than 0.01) as that of disodium cromoglycate (1 x 10(-4) M). These data taken together indicate that frusemide when given by inhalation prevents histamine release secondary to antigen-antibody reaction.

Pharmacological studies on the new mucoactive agent (-)-6(S)-hydroxy-4(R)-(1-hydroxy-1-methylethyl)-1-cyclohexene-1-ethanol .

The pharmacological activity and acute toxicity of (-)-6(S)-hydroxy-4(R)-(1-hydroxy-1-methylethyl)-1-cyclohexene-1-ethanol (CO/1408, CAS 103079-06-7), a new mucoactive drug, were evaluated. After oral and intravenous administration CO/1408 increased the pulmonary secretion of fluorescein in rats, as an index of bronchosecretogogue activity. In addition, CO/1408 markedly increased the mucociliary transport rate. In in vitro study CO/1408 did not modify the viscosity of pig gastric mucin. Acute toxicity studies showed a very low toxicity after single dose indicating a high safety level for the doses used in this report. The results obtained point out the potential usefulness of CO/1408 to ameliorate the symptoms observed in some obstructive pulmonary diseases.

Prostaglandins and gastric mucosal protection by esaprazole in rats.

Esaprazole, N-cyclohexyl-1-piperazineacetamide monohydrochloride, was studied for its activity to prevent gastric mucosal damage induced by several necrotizing agents in the rat. Its effects on acid gastric secretion and the role of gastric mucosal prostaglandin generation were also investigated. Esaprazole, given orally, dose dependently prevented the formation of mucosal damage induced by absolute ethanol, 0.2 N NaOH or 0.6 N HCl. This activity occurred at doses lower than the antisecretory doses. Esaprazole was also found to increase the gastric mucosal prostaglandin content but at doses that exceeded the cytoprotective doses. The failure of indomethacin to impair the gastric mucosal protection provided by esaprazole suggests that mechanisms other than mobilization of endogenous prostaglandins may be involved.

Passive cigarette smoke exposure induces airway hyperreactivity to histamine but not to acetylcholine in guinea-pigs.

We have investigated the changes in airway reactivity induced in guinea-pigs by passive cigarette smoke exposure. In particular, we studied the development of airway hyperresponsiveness both in vivo and in vitro after passive exposure of the animals to cigarette smoke in a plexiglass box. Passive smoke exposure significantly (p less than 0.01) increased histamine induced bronchoconstriction. The dose-ratio calculated between histamine dose-response curves constructed in control and smoke exposed animals was 2.13 (95% confidence limits: 1.46-3.09). Acetylcholine induced bronchoconstriction was not potentiated after the same smoke exposure, indicating some specificity of the mediators involved in the airway hyperresponsiveness triggered by passive smoke exposure. The airway hyperreactivity induced by smoke exposure was associated with a specific increase in histamine contraction induced in vitro in lung parenchymal strips but not in tracheae or pulmonary arteries. Maximal histamine contraction in parenchymal strips taken from smoke exposed animals was significantly (p less than 0.01) enhanced by approximately 110% when compared to control. There was a significant (p less than 0.01) increase in the number of macrophages and eosinophils in the bronchoalveolar lavage fluid of animals passively exposed to cigarette smoke, but no mucus hypersecretion was evident. Our data demonstrate the occurrence of airway hyperreactivity induced by passive cigarette smoke exposure, which involves increased smooth muscle reactivity and cell recruitment.

Esaprazole, a new antiulcer agent, stimulates gastric mucus output in the rat.

The effect of esaprazole, a new antiulcer compound endowed with gastro-protective properties, on rat gastric mucus was investigated after acute oral administration. Both soluble (luminal) and insoluble (parietal) mucus were examined for their content of: acidic and neutral glycoproteins; N-acetylneuraminic acid by colorimetric techniques; and fucose by HPLC methods. One hour after dosing (50-200 mg/kg) a 2-15-fold increase in soluble mucus and a 2-4-fold increase in insoluble mucus output were observed. Under the same experimental conditions, carbenoxolone (200 mg/kg, p.o.) caused a similar increase in gastric mucus output. These results demonstrate that quantitative changes in both luminal and parietal mucus occurred after orally dosed esaprazole: it is tempting to speculate that this effect might be responsible, at least in part, for the gastro-protective action of the drug.

A rapid and highly predictive in vitro assay for non-steroidal anti-inflammatory agents.

The inhibition of the production of malonyldialdehyde (MDA) in guinea-pig lung homogenates, incubated in the presence of 50 microM arachidonic acid and 1.4 mM adrenaline, has been exploited as a simple and reliable assay to test in vitro non-steroidal anti-inflammatory agents (NSAIA). The inhibitory potencies of a series of reference NSAIA, which correlated fairly well with in vivo anti-inflammatory activity as determined by carrageenin oedema, are herewith reported. The specificity of the assay was also evaluated by testing up to forty miscellaneous drugs: none of these significantly reduced the MDA production.