Speed of onset of action of Tilarin

Intranasal Toxicity of BMS-181885, A Novel 5-HT1 Agonist

One-month intranasal toxicity studies were conducted with BMS-181885 at doses of 1.5, 9, or 15 mg/animal/day in rats and 4, 24, or 40 mg/animal/day in monkeys. A 1-month intermittent intranasal toxicity study was also conducted in monkeys at doses of 3, 6, and 12 mg/animal 3 days per week. BMS-181885 was generally well tolerated in rats but resulted in dose-dependent nasal mucosal injury, primarily characterized by subacute inflammation of the nasal mucosa, and degeneration, single-cell necrosis, and/or erosion of the olfactory epithelium and, to a lesser extent, the respiratory epithelium. In monkeys, daily BMS-181885 administration was well tolerated and produced similar dose-dependent nasal injury primarily characterized by subacute inflammation of the nasal mucosa with degeneration and erosion of the olfactory epithelium. In a separate experiment, intermittent administration also resulted in dose-dependent nasal injury. In cultured rat nasal mucosal cells, BMS-181885 was toxic to olfactory epithelial cells with a range of mean IC50s between 44 and 291 μM. In contrast, BMS-181885 had no effect on respiratory epithelial cells up to its maximum solubility. Cytochrome P450 inhibition had no effect on the toxicity of BMS-181885 in olfactory epithelial cells but produced dose-dependent toxicity in respiratory epithelial cells, which was not present previously. The in vitro data suggest that parent drug, rather than a toxic metabolite, caused the drug-associated nasal mucosal injury.

A clinical overview of Tilarin

Tilarin is a nasal spray containing 1% nedocromil sodium, a non-toxic pyranoquinoline dicarboxylate compound with potent antiallergic antiinflammatory properties. As a first-line topical treatment for seasonal allergic rhinitis (SAR) the pharmacokinetics of nedocromil sodium nasal formulation are such that it rivals sodium cromoglycate for safety. Less than 8% of the total dose of nedocromil sodium is systemically absorbed from the nasal mucosa, and this is reversibly bound to plasma proteins and is cleared rapidly from the circulation. Nedocromil sodium is eliminated unmetabolised in the urine and faeces, with an elimination half-life of 5.3 +/- 0.9 minutes. No significant adverse effects have been reported following intranasal administration of 1% nedocromil sodium four times daily, to a total of 964 patients with allergic rhinitis during clinical trials. Laboratory studies have shown that nedocromil sodium has a more wide-ranging pharmacological antiinflammatory profile than sodium cromoglycate and this is manifest in its clinical efficacy in allergic asthma and rhinoconjunctivitis. Analysis of pooled data from a series of double-blind, placebo-controlled group comparative studies in SAR patients demonstrated that, despite a significantly lower use of rescue antihistamines than with placebo treatment (31% reduction; p = 0.005), four times daily dosage with nedocromil sodium 1% nasal spray significantly reduced daily symptoms of rhinitis (p < 0.001) and was considered effective by the majority of patients (p < 0.001). Specific examples of the therapeutic efficacy of nedocromil sodium compared with placebo in patients with grass or ragweed pollen SAR can be found in the literature. One ragweed study (1) included four times daily sodium cromoglycate 4% nasal spray as an active comparator and showed a consistent, if non-significant, trend in favour of nedocromil sodium 1%, which was the more effective drug in comparison to placebo. An Italian paediatric study (2) compared nedocromil sodium 1% nasal spray with placebo in 149 children of whom 72% were under twelve years of age. After one week, the clinicians observed a significant reduction (p = 0.03) in sneezing with nedocromil sodium and after four weeks, patient (p < 0.01) and clinican (p < 0.001) opinions favoured the active treatment. Overall, the clinical profile of topical nedocromil sodium in SAR demonstrates fast relief of existing symptoms, sustained efficacy with four times daily use during peak pollen challenge, and a reduced need for concomitant symptomatic therapies. Nedocromil sodium 1% nasal spray is well tolerated, with minimal side-effects, and is acceptable to a wide age-range of patients.

Clinical implications of the pharmacological profile of Tilarin

The pharmacological activity of nedocromil sodium is extensive and the compound should affect a variety of inflammatory processes by preventing activation of the involved cells or blocking release of their mediators. Some in vitro actions of nedocromil sodium are particularly relevant to the mechanisms of allergic rhinitis, and the response of the nasal epithelium to pollutants such as ozone. The effects of nedocromil sodium on mucosal mast cells, eosinophils, sensory nerves and nasal epithelial cells can each be linked to its potential clinical effectiveness by our own biopsy studies from patients with active allergic rhinitis. Nedocromil sodium has been shown to modulate production of a number of powerful cytokines, such as GM-CSF and TNF alpha, which are produced by the human nasal epithelium, as well as by involved inflammatory cells and lymphocytes, and which orchestrate the inflammatory response to allergen or to pollutant provocation. So, in addition to inhibiting activated mast cells and eosinophils, nedocromil sodium acts on the nasal epithelium itself to prevent further accumulation of these cells and thus to break the inflammatory chain of events. On this evidence of its preclinical activity, nedocromil sodium promises to become a very useful topical treatment for allergic rhinitis.