Preclinical pharmacokinetics and tolerability of a novel meglumine-based parenteral solution of topiramate and topiramate combinations for treatment of status epilepticus.

OBJECTIVE: For an antiseizure medication (ASM) to be effective in status epilepticus (SE), the drug should be administered intravenously (i.v.) to provide quick access to the brain. However, poor aqueous solubility is a major problem in the development of parenteral drug solutions. Given its multiple mechanisms of action, topiramate (TPM) is a promising candidate for the treatment of established or refractory SE, as supported by clinical studies using nasogastric tube TPM administration. However, TPM is not clinically available as a solution for i.v. administration, which hampers its use in the treatment of SE. Here, we describe a novel easy-to-use and easy-to-prepare i.v. TPM formulation using the U.S. Food and Drug Administration (FDA)-approved excipient meglumine. METHODS: During formulation development, we compared the solubility of TPM in bi-distilled water with vs without a range of meglumine concentrations. Furthermore, the solubility of combinations of TPM and levetiracetam and TPM, levetiracetam, and atorvastatin in aqueous meglumine concentrations was determined. Subsequently, the pharmacokinetics and tolerability of meglumine-based solutions of TPM and TPM combinations were evaluated in rats, including animals following fluid percussion injury or pilocarpine-induced SE. RESULTS: The amino sugar meglumine markedly enhances the aqueous solubility of TPM. A comparison with data on dissolving TPM using sulfobutylether-ß-cyclodextrin (Captisol) demonstrates that meglumine is much more effective for dissolving TPM. Furthermore, meglumine can be used to prepare drug cocktails where TPM is co-administered with another ASM for SE treatment. The tolerability studies of the meglumine-based TPM solution and meglumine-based TPM combinations in normal rats and the rat fluid percussion injury and pilocarpine-induced SE models demonstrate excellent tolerability of the novel drug solutions. Preclinical studies on antiseizure efficacy in the SE model are underway. SIGNIFICANCE: In conclusion, the novel meglumine-based solution of TPM presented here may be well suited for clinical development.

Imepitoin Shows Benzodiazepine-Like Effects in Models of Anxiety.

Imepitoin is a low affinity partial agonist for the benzodiazepine binding site of γ-aminobutyric acid (GABAA) receptors, and is currently used as an antiepileptic in dogs. Here we tested imepitoin for anxiolytic properties. In an in vitro model, imepitoin was capable of preventing the effect of corticotrophin releasing factor (CRF) on locus coeruleus neurons without suppressing the basal activity of these cells, an activity which is suggestive for an anti-stress effect of imepitoin. In addition, we applied a battery of standard rodent preclinical tests for anxiety behavior including elevated plus mazes in mice and rats, light-dark-box in mice and rats, social interaction test in rats, or the Vogel conflict test in rats. In all models, the observed profile of imepitoin appeared similar to benzodiazepines and typical for anxiolytic drugs. We also observed anxiolytic activity in dogs in a provoked open field sound-induced fear model, where reactions to noises were elicited by a sound recording of thunderstorms. Imepitoin caused an increase in locomotion measured in distance traveled and an ameliorating effect on cortisol levels in response to thunderstorm noises. For comparison, dexmedetomidine caused a decrease in locomotion and had no effect on cortisol. In all animal models the doses needed for an anxiolytic effect were not associated with sedation. In rodents, there was at least a factor of 10 between anxiolytic doses and doses with mild signs of sedation. In summary, imepitoin showed similar anxiolytic activities as benzodiazepines but without producing the known adverse reactions of benzodiazepines such as sedation.

Clinical evaluation of a combination therapy of imepitoin with phenobarbital in dogs with refractory idiopathic epilepsy.

BACKGROUND: Imepitoin was tested as a combination treatment with phenobarbital in an open-label mono-centre cohort study in dogs with drug-resistant epilepsy. Diagnosis of idiopathic epilepsy was based on clinical findings, magnetic resonance imaging and cerebrospinal fluid analysis. Three cohorts were treated. In cohort A, dogs not responding to phenobarbital with or without established add-on treatment of potassium bromide or levetiracetam were treated add-on with imepitoin, starting at 10 mg/kg BID, with titration allowed to 30 mg/kg BID. In cohort B, the only difference to cohort A was that the starting dose of imepitoin was reduced to 5 mg/kg BID. In cohort C, animals not responding to imepitoin at >20 mg/kg BID were treated with phenobarbital add-on starting at 0.5 mg/kg BID. RESULTS: The add-on treatment resulted in a reduction in monthly seizure frequency (MSF) in all three cohorts. A reduction of ≥50% was obtained in 36-42% of all animals, without significant difference between cohorts. The lower starting dose of 5 mg/kg BID imepitoin was better tolerated, and an up-titration to on average of 15 mg/kg BID was sufficient in cohort A and B. In cohort C, a mean add-on dose of 1.5 mg/kg BID phenobarbital was sufficient to achieve a clinically meaningful effect. Six dogs developed a clinically meaningful increase in MSF of ≥ 50%, mostly in cohort A. Neither imepitoin nor phenobarbital add-on treatment was capable of suppressing cluster seizure activity, making cluster seizure activity an important predictor for drug-resistance. CONCLUSION: A combination treatment of imepitoin and phenobarbital is a useful treatment option for a subpopulation of dogs with drug-resistant epilepsy, a low starting dose with 5 mg/kg BID is recommended.

Efficacy, safety, and tolerability of imepitoin in dogs with newly diagnosed epilepsy in a randomized controlled clinical study with long-term follow up.

BACKGROUND: Imepitoin is a novel antiepileptic drug for the treatment of canine idiopathic epilepsy. The present study was conducted to demonstrate superior antiepileptic activity of a high dose of 30 mg/kg BID over a low dose of 1 mg/kg BID of imepitoin during 12 weeks of treatment under double blind conditions in a field population of dogs with previously untreated epilepsy. In a consecutive 12 weeks open label follow up (phase 2), all animals received 30 mg/kg BID, to evaluate the persistence of the antiepileptic activity, and to evaluate the effect of a dose step up to 30 mg/kg in the former low-dose animals. RESULTS: A treatment with 30 mg/kg BID resulted in a significantly greater reduction in monthly seizure frequency relative to baseline data as compared to the 1 mg/kg dose. Both generalized and partial seizures but not cluster seizures were significantly less frequent in the high dose group. The antiepileptic activity was maintained during study phase 2 in the high dose group. An increase to 30 mg/kg BID in the low- dose animals resulted in a significant reduction in generalized and partial seizures, but not cluster seizures. At the end of study phase 2, 32.1 and 46.8 % of dogs of the former high and former low-dose groups respectively, remained free of generalized tonic-clonic seizures. Imepitoin was well tolerated. The frequency of dogs with any adverse drug reactions was higher in the 30 mg/kg BID dose (59 % vs. 41 %, p = 0.041), and the main target organ was the central nervous system (CNS). The occurrence of CNS related adverse reactions was transient and findings were mostly restricted to the first weeks of treatment. No hepatic enzyme increase and no other organ toxicity were observed. CONCLUSION: The administration of imepitoin twice daily at a dose of 30 mg/kg results in significant and persistent antiepileptic effects in patients with newly diagnosed epilepsy and generalized tonic-clonic seizures, as observed over a study period of up to 6 months. Imepitoin was well tolerated. Most CNS related adverse drug reactions were transient. Both the antiepileptic activity and the safety profile make the drug suitable for long-term clinical use.

Ubiquitin is a versatile scaffold protein for the generation of molecules with de novo binding and advantageous drug-like properties.

In the search for effective therapeutic strategies, protein-based biologicals are under intense development. While monoclonal antibodies represent the majority of these drugs, other innovative approaches are exploring the use of scaffold proteins for the creation of binding molecules with tailor-made properties. Ubiquitin is especially suited for this strategy due to several key characteristics. Ubiquitin is a natural serum protein, 100% conserved across the mammalian class and possesses high thermal, structural and proteolytic stability. Because of its small size and lack of posttranslational modifications, it can be easily produced in Escherichia coli. In this work we provide evidence that ubiquitin is safe as tested experimentally in vivo. In contrast to previously published results, we show that, in our hands, ubiquitin does not act as a functional ligand of the chemokine receptor CXCR4. Cellular assays based on different signaling pathways of the receptor were conducted with the natural agonist SDF-1 as a benchmark. In none of the assays could a response to ubiquitin treatment be elicited. Furthermore, intravenous application to mice at high concentrations did not induce any detectable effect on cytokine levels or hematological parameters.

Evaluation of the efficacy of meloxicam for post-operative management of pain and inflammation in horses after orthopaedic surgery in a placebo controlled clinical field trial.

BACKGROUND: The benefit of pre and post-operative administration of non-steroidal anti-inflammatory drugs for the relief of post-operative pain and control of inflammation in horses following orthopaedic surgery has not been previously investigated in controlled clinical field trials, and the utility of such treatment is a matter of ongoing dispute. Recently the utility of post-operative pain management was emphasized. It was therefore our aim to determine the efficacy of meloxicam in horses following partial resection of fractured splint bones. This condition was selected since the limited extent of the insult and the defined surgical intervention allowed the conduct of a randomized, double blinded, placebo-controlled, parallel group, multi-centre clinical field study in a homogenous patient population. RESULTS: Sixty-six client owned horses requiring unilateral partial splint bone resection were recruited in 15 centres in Germany and were allocated in a 1:1 ratio to receive meloxicam, 0.6 mg/kg for 5 days. Lameness at trot grades prior to surgery were similar in the meloxicam and placebo treatment groups but were significantly lower in the meloxicam group on day 6 post surgery. Clinical scores for soft tissue swelling and assessment of analgesic and anti-inflammatory efficacy by the investigators at the end of the study were significantly better for the meloxicam compared to the placebo group. No treatment-related adverse reactions were observed. CONCLUSION: The administration of meloxicam i.v. once prior to surgery followed by once daily oral administration for four consecutive days is efficacious for the control of post-operative pain and inflammation in horses undergoing orthopaedic surgery.

Activity and Safety of Inhaled Itraconazole Nanosuspension in a Model Pulmonary Aspergillus fumigatus Infection in Inoculated Young Quails.

Pulmonary aspergillosis is frequently reported in parrots, falcons, and other birds held in captivity. Inhalation is the main route of infection for Aspergillus fumigatus, resulting in both acute and chronic disease conditions. Itraconazole (ITRA) is an antifungal commonly used in birds, but its administration requires repeated oral dosing, and the safety margin is narrow. To investigate the efficacy of inhaled ITRA, six groups of ten young quails (Coturnix japonica) were inoculated intratracheally with 5 × 10(6) spores (3 groups) or 5 × 10(7) spores (3 groups). Animals were exposed to nebulized ITRA nanosuspension as 10 % suspension or 4 % suspension, once daily for 30 min, starting 2 h after inoculation for 6 days. Control groups were exposed to nebulized saline for the same period of time. Survival and clinical scores were evaluated, and animals were subjected to gross pathology. In control animals, aspergillosis resulted in systemic disease without pulmonary or air sac granulomas. Animals died from multiple organ failure. Inhalation of 10 % ITRA nanosuspension blocked lethality and prevented disease-related symptoms in the quails exposed to the low dose of spores, while the disease course in quails inoculated with the high-spore dose was retarded. Inhalation of 4 % ITRA nanosuspension was less effective. Both inhalations were well tolerated, and gross pathology did not reveal signs of local toxicity. The data indicate that inhaled administration of 10 % ITRA nanosuspension is capable of alleviating an acute A. fumigatus infection in quails. A lower ITRA concentration may be only active in chronic pulmonary aspergillosis.

Anxiogenic- and antidepressant-like behavior in corneally kindled rats.

BACKGROUND: Anxiety and depression affect epileptic patients much more often than individuals from the general population. We were interested in whether corneal kindling in rats, which is a model of complex partial seizures with secondary generalization, would influence animal behavior in models of anxiety and depression. METHODS: Kindling was achieved by transcorneal electric stimulation and fully kindled rats were used in this study. Kindled and sham-stimulated rats were subjected to the elevated plus maze and forced swim test which are believed to be predictive models for anxiety and depression in humans, respectively. RESULTS: Kindling significantly decreased the percentage of time spent by the rats in open arms relative to time spent in open plus closed arms and it reduced immobility time in the swim test as compared with sham-stimulated rats. CONCLUSIONS: Our results suggest that corneal kindling produces antidepressant- and anxiety-like effects in rats and it may be a useful model to study epilepsy-associated anxiety.

Novel ubiquitin-derived high affinity binding proteins with tumor targeting properties.

Targeting effector molecules to tumor cells is a promising mode of action for cancer therapy and diagnostics. Binding proteins with high affinity and specificity for a tumor target that carry effector molecules such as toxins, cytokines, or radiolabels to their intended site of action are required for these applications. In order to yield high tumor accumulation while maintaining low levels in healthy tissues and blood, the half-life of such conjugates needs to be in an optimal range. Scaffold-based binding molecules are small proteins with high affinity and short systemic circulation. Due to their low molecular complexity, they are well suited for combination with effector molecules as well as half-life extension technologies yielding therapeutics with half-lives adapted to the specific therapy. We have identified ubiquitin as an ideal scaffold protein due to its outstanding biophysical and biochemical properties. Based on a dimeric ubiquitin library, high affinity and specific binding molecules, so-called Affilin® molecules, have been selected against the extradomain B of fibronectin, a target almost exclusively expressed in tumor tissues. Extradomain B-binding molecules feature high thermal and serum stability as well as strong in vitro target binding and in vivo tumor accumulation. Application of several half-life extension technologies results in molecules of largely unaffected affinity but significantly prolonged in vivo half-life and tumor retention. Our results demonstrate the utility of ubiquitin as a scaffold for the generation of high affinity binders in a modular fashion, which can be combined with effector molecules and half-life extension technologies.

The pharmacology of imepitoin: the first partial benzodiazepine receptor agonist developed for the treatment of epilepsy.

Although benzodiazepines (BZDs) offer a wide spectrum of antiepileptic activity against diverse types of epileptic seizures, their use in the treatment of epilepsy is limited because of adverse effects, loss of efficacy (tolerance), and development of physical and psychological dependence. BZDs act as positive allosteric modulators of the inhibitory neurotransmitter GABA by binding to the BZD recognition site ("BZD receptor") of the GABAA receptor. Traditional BZDs such as diazepam or clonazepam act as full agonists at this site, so that one strategy to resolve the disadvantages of these compounds would be the development of partial agonists with lower intrinsic efficacy at the BZD site of the GABAA receptor. Several BZD site partial or subtype selective compounds, including bretazenil, abecarnil, or alpidem, have been developed as anxioselective anxiolytic drugs, but epilepsy was not a target indication for such compounds. More recently, the imidazolone derivatives imepitoin (ELB138) and ELB139 were shown to act as low-affinity partial agonists at the BZD site of the GABAA receptor, and imepitoin was developed for the treatment of epilepsy. Imepitoin displayed a broad spectrum of anticonvulsant activity in diverse seizure and epilepsy models at tolerable doses, and, as expected from its mechanism of action, lacked tolerance and abuse liability in rodent and primate models. The more favorable pharmacokinetic profile of imepitoin in dogs versus humans led to the decision to develop imepitoin for the treatment of canine epilepsy. Based on randomized controlled trials that demonstrated antiepileptic efficacy and high tolerability and safety in epileptic dogs, the drug was recently approved for this indication in Europe. Hopefully, the favorable profile of imepitoin for the treatment of epilepsy in dogs will reactivate the interest in partial BZD site agonists as new treatments for human epilepsy.

A model for treating avian aspergillosis: serum and lung tissue kinetics for Japanese quail (Coturnix japonica) following single and multiple aerosol exposures of a nanoparticulate itraconazole suspension.

Aspergillosis is frequently reported in parrots, falcons and other birds held in captivity. Inhalation is the main route of infection for Aspergillus fumigatus, resulting in both acute and chronic disease conditions. Itraconazole (ITRA) is an antifungal commonly used in birds, but administration requires repeated oral dosing and the safety margin is narrow. We describe lung tissue and serum pharmacokinetics of a nanoparticulate ITRA suspension administered to Japanese quail by aerosol exposure. Aerosolized ITRA (1 and 10% suspension) administered over 30 min did not induce adverse clinical reactions in quail upon single or 5-day repeated doses. High lung concentrations, well above the inhibitory levels for A. fumigatus, of 4.14 ± 0.19 µg/g and 27.5 ± 4.58 µg/g (mean ± SEM, n = 3), were achieved following single-dose inhalation of 1% and 10% suspension, respectively. Upon multiple dose administration of 10% suspension, mean lung concentrations reached 104.9 ± 10.1 µg/g. Drug clearance from the lungs was slow with terminal half-lives of 19.7 h and 35.8 h following inhalation of 1% and 10% suspension, respectively. Data suggest that lung clearance is solubility driven. Lung concentrations of hydroxy-itraconazole reached 1-2% of the ITRA lung tissue concentration indicating metabolism in lung tissue. Steady, but low, serum concentrations of ITRA could be measured after multiple dose administration, reaching less than 0.1% of the lung tissue concentration. This formulation may represent a novel, easy to administer treatment modality for fungal lung infection, preventing high systemic exposure. It may also be useful as metaphylaxis to prevent the outbreak of aspergillosis in colonized animals.

Inhalable highly concentrated itraconazole nanosuspension for the treatment of bronchopulmonary aspergillosis.

Cystic fibrosis (CF) patients are suffering from multiple often chronic endobronchial infection. The stiff mucus in these patients represents a compartment, which cannot easily be reached by systemic treatment. While bacterial infections are now successfully treated with repeated inhalation of antibiotics such as tobramycine, 57% of CF patients are colonized by Aspergillus species. About 10-20% of colonized patients develop symptoms of allergic bronchopulmonary aspergillosis (ABPA). While current standard of treatment of ABPA in CF patients is to suppress the allergy related symptoms by administration of glucocorticoids, itraconazole (ITRA), administered orally at high doses, can alleviate the symptoms of ABPA. However, no inhalable formulation of ITRA is available to enable local treatment of aspergillosis. The aim of this study was to describe an aqueous nanosuspension of ITRA and to characterize the pharmacokinetics after single dose inhalation. Using wet-milling with organic milling beads, a stable nanosuspension with particle size in the range of 200nm and an ITRA concentration of 20% (v/w) could be obtained, using polysorbate 80 at a concentration of 14% relative to ITRA. The suspension was stable if stored at 8°C for 3 months without particle growth and could be nebulized using standard nebulizer technologies including mesh technology and pressured air nebulizers. A 10% suspension was well tolerated upon repeated dose inhalation once daily for 7 days at a predicted dose of 45mg/kg in rats. A single dose inhalation at a predicted dose of 22.5mg/kg resulted in maximum lung tissue concentration of 21.4µg/g tissue with a terminal half-life of 25.4h. Serum concentrations were lower, with a maximum concentration of 104ng/ml at 4h after dosing and a terminal half-life of 10.5h. The data indicate that ITRA nanosuspension represents an interesting formulation for inhaled administration in CF patients suffering from ABPA. High and long lasting lung tissue concentrations well above the minimal inhibitory concentration of Aspergillus species enable once daily administration with minimal systemic exposure.

The stable cyclic adenosine monophosphate analogue, dibutyryl cyclo-adenosine monophosphate (bucladesine), is active in a model of acute skin inflammation.

Anti-inflammatory therapeutic options for the topical treatment of skin diseases with inflammatory or allergic contribution are mostly limited to topical glucocorticoids and calcineurin inhibitors. Both compound classes induce adverse effects. Elevation of intracellular cyclic adenosine monophosphate (cAMP) by inhibition of phosphodiesterase 4 was shown to induce potent anti-inflammatory effects, but the safety profile of currently available compounds is not sufficient. A different approach to increase intracellular cAMP is the substitution of chemically stabilized cAMP analogues. Bucladesine is a stabilized cAMP analogue with an excellent safety profile which had been marketed as topical treatment of impaired wound healing. In the current study, a novel water free emulsion containing bucladesine was evaluated for anti-inflammatory effects. In the arachidonic acid induced ear oedema model in mice, single or multiple administration of an emulsion containing 1.5% was capable of significantly reducing the inflammatory oedema. The data indicate that bucladesine represents an interesting treatment option for skin diseases where an anti-inflammatory activity is indicated. Due to the established clinical safety, this agent may bridge the gap between potent agents such as glucocorticoids or calcineurin inhibitors and emollients without active compounds.

The atypical anxiolytic drug, tofisopam, selectively blocks phosphodiesterase isoenzymes and is active in the mouse model of negative symptoms of psychosis.

Tofisopam is a member of the 2,3-benzodiazepine compound family which is marketed for the treatment of anxiety in some European countries. In contrast to classical 1,4-benzodiazepines, the compound does not bind to the benzodiazepine binding site of the γ-aminobutyric acid receptor and its psychopharmacological profile differs from such compounds. In addition to anxiolytic properties, antipsychotic effects are reported. We now show that tofisopam, 50 mg/kg intraperitoneally (i.p.), administered in parallel to repeated doses of dizocilpine 0.2 mg/kg i.p. can ameliorate dizocilpine-induced prolongation of immobility, which is considered to be a model of negative symptoms of psychosis. We further show that tofisopam acts as an isoenzyme-selective inhibitor of phosphodiesterases (PDEs) with highest affinity to PDE-4A1 (0.42 µM) followed by PDE-10A1 (0.92 µM), PDE-3 (1.98 µM) and PDE-2A3 (2.11 µM). The data indicate that tofisopam is an interesting candidate for the adjuvant treatment of psychosis with focus on negative symptoms. Combined partial inhibition of PDE-4 and PDE-10 as well as PDE-2 may be the underlying mechanism to this activity. Due to the good safety profile of tofisopam as evident from long-term use of this agent in patients, it may be concluded that dual or triple inhibition of PDE isoenzymes with additive or synergistic effects may be an interesting approach to pharmacological activity, resulting in active compounds with beneficial safety profile. Dose-limiting side effects such as emesis induced by selective inhibition of PDE-4 may be prevented by such strategies.

Effects of sildenafil on pentylenetetrazol-induced convulsions in mice and amygdala-kindled seizures in rats.

Sildenafil is the first marketed phosphodiesterase 5 inhibitor for the treatment of erectile dysfunction and recently, for pulmonary hypertension. While the treatment was found to be highly effective, several adverse effects are associated with this compound. Among numerous central nervous system-related untoward effects, proconvulsant activity was reported. The purpose of this study was to assess the effect of sildenafil on seizure threshold in rodents. Two seizure models/tests were used: the timed intravenous (iv) pentylenetetrazol (PTZ) infusion test in mice and the amygdala-kindling model in rats. Sildenafil was administered intraperitoneally 30 min before induction of seizures. In the iv PTZ paradigm, the first myoclonic twitch, generalized clonus with loss of the righting reflex, and forelimb tonus were recorded. In the amygdala-kindling model in rats, the following parameters were analyzed: threshold for induction of epileptiform discharges in the stimulated amygdala (afterdischarge threshold, ADT), seizure severity, seizure duration, and afterdischarge duration. Sildenafil (dosage range of 5-40 mg/kg) did not significantly affect the threshold for myoclonic twitches in the timed iv PTZ infusion test in mice but significantly decreased the threshold for clonic seizures at a dose of 20 mg/kg. Sildenafil at all doses tested neither significantly influenced the focal seizure threshold in the amygdala-kindling model of epilepsy in rats nor influenced seizure severity. Sildenafil significantly shortened afterdischarge duration and seizure duration recorded at the ADT current, indicative of a weak anticonvulsant activity. Our results show that sildenafil may have both pro- and anticonvulsant activity, which depends on the experimental model of epilepsy, on animal species and the dose of sildenafil. Based on these data and in view of the clinical observations, sildenafil should be used in patients suffering from epilepsy with caution and only based on a careful individual risk/benefit evaluation.

Effects of sarcosine, a glycine transporter type 1 inhibitor, in two mouse seizure models.

Sarcosine, a natural amino acid found in muscles and other body tissues, is an endogenous glycine transporter type 1 inhibitor that increases the glycine concentration, resulting in an indirect potentiation of the N-methyl-D-aspartate (NMDA) subtype of glutamate receptors. Sarcosine, similar to other NMDA receptor-activating agents, is an effective adjuvant in the treatment of schizophrenia. It is widely accepted that increased glutamatergic neurotransmission is involved in the initiation and propagation of seizures. Because sarcosine facilitates NMDA receptor function, it may affect the seizure threshold. Therefore, we examined the effects of sarcosine on the seizure threshold in two different mouse seizure models: the timed intravenous (iv) pentylenetetrazole (PTZ) infusion test and the maximal electroshock seizure threshold test. In the iv PTZ test, sarcosine did not exert a significant effect on the seizure threshold at any of the doses tested (100, 200, 400 and 800 mg/kg, ip). However, at doses of 400 and 800 mg/kg, sarcosine significantly raised the threshold for electroconvulsions (p < 0.01). The present findings indicate that sarcosine did not lower the seizure threshold. Conversely, sarcosine showed weak anticonvulsant properties by increasing the threshold current for the induction of tonic seizures. Therefore, sarcosine may be considered as a safe adjuvant treatment for schizophrenia without proconvulsant risk. In addition, the compound may serve as an interesting addition to epilepsy treatment.

The putative lipid raft modulator miltefosine displays immunomodulatory action in T-cell dependent dermal inflammation models.

Miltefosine is currently marketed for treatment of skin metastasis of breast cancer and leishmaniasis. The mechanism of action is not fully understood, however, miltefosine is considered to be a prototype lipid raft modulator. The compound was shown to inhibit anti-IgE induced histamine release from human skin mast cells. After topical treatment it reduced skin reaction in allergic human volunteers undergoing a skin prick test. The aim of this study was to test whether miltefosine could also modify T-cell signalling and whether the drug may be useful for the treatment of atopic dermatitis. Miltefosine (20microM) inhibited T-cell proliferation by >50% in the mixed leukocyte test. In the toluene diisocyanate induced ear swelling test, miltefosine, administered topically as 2 and 6% solution or orally, attenuated ear swelling reaching 70% of the effect of dexamethasone at 100mg/kg p.o. (P<0.01). The ear tissue content of the cytokines IL1beta, IL4 and IL6 was also reduced reaching 56% or 52% reduction of IL1beta (P<0.01) after 2% topical or 100mg/kg p.o. Miltefosine significantly attenuated the allergic sensitization in the model of ovalbumin induced delayed-type hypersensitivity in mice. In a model of toluene diisocyanate induced scratching a significant (P=0.0047) reduction of scratching from 47 to 6 bouts was achieved with 100mg/kg p.o. The data indicate that miltefosine modulates T-cell function in models for Th1 and Th2 related activity. This profile opens up the possibility for the treatment of T-cell related allergic diseases with a novel class of lipid raft modulator drugs such as miltefosine.

Highly selective phosphodiesterase 4 inhibitors for the treatment of allergic skin diseases and psoriasis.

The phosphodiesterase (PDE) 4 is the predominant cyclic AMP degrading enzyme in a variety of inflammatory cells including eosinophils, neutrophils, macrophages, T cells and monocytes. In addition, this enzyme is expressed in non-immune cells such as keratinocytes and fibroblasts. Highly selective PDE4 inhibitors are currently under evaluation for the treatment of asthma and/or chronic obstructive pulmonary disease. Due to the broad anti-inflammatory/immuno-modulatory action of PDE4 inhibitors, it has been proposed that PDE4 inhibitors might also be efficacious for skin disorders such as atopic dermatitis. Consequently, PDE4 inhibitors including cilomilast and AWD 12-281 have been tested in several models of allergic and irritant skin inflammation. These PDE4 inhibitors displayed strong anti-inflammatory action in models of allergic contact dermatitis in mice, in the arachidonic acid induced skin inflammation in mice and in ovalbumin sensitised guinea pigs. The determination of cytokines in skin homogenates revealed that both Th1 as well as Th2 cytokines are suppressed by PDE4 inhibitors, indicating an anti-inflammatory activity in both the Th2 dominated acute phase as well as the Th1 dominated chronic phase of atopic dermatitis. Due to the suppression of Th1 cytokines, activity can also be expected in psoriasis. Results of early clinical trials with both topically (cipamfylline, CP80,633) and systemically (CC-10004) active PDE4 inhibitors demonstrated efficacy in atopic dermatitis and in the case of CC-10004, also in psoriasis. AWD 12-281 (GW 842470) is currently under clinical evaluation for the topical treatment of atopic dermatitis. Results concerning clinical efficacy of this potent and selective PDE4 inhibitor are anxiously awaited.

New GABA-modulating 1,2,4-oxadiazole derivatives and their anticonvulsant activity.

A series of 3- and 5-aryl-1,2,4-oxadiazole derivatives were prepared and tested for anticonvulsant activity in a variety of models. These 1,2,4-oxadiazoles exhibit considerable activity in both pentylenetetrazole (PTZ) and maximal electroshock seizure (MES) models. Compound 10 was protective in the PTZ model in rats with an oral ED(50) of 25.5mg/kg and in the MES model in rats with an oral ED(50) of 14.6mg/kg. Neurotoxicity (rotarod) was observed with an ED(50) of 335mg/kg. We found several oxadiazoles that acted as selective GABA potentiating compounds with no interaction to the benzodiazepine binding site.