Clinical implications of the pharmacological profile of Tilarin

Nedocromil sodium eye drops are more effective than sodium cromoglycate eye drops for the long-term management of vernal keratoconjunctivitis

BACKGROUND

Vernal keratoconjunctivitis (VKC) is a severe though transient form of ocular allergy, predominant in young males, which requires careful management. Corticosteroids are effective but also cause serious topical side-effects in the eye, such as glaucoma and cataracts. The safer, mast cell stabilizing anti-inflammatories (commonly sodium cromoglycate) therefore have an important role. This parallel group study compared efficacy, tolerability and safety of sodium cromoglycate 2% with nedocromil sodium 2%, administered as one drop per eye four times daily for a period of 5 months.

METHODS

Children aged 4-17 years, with a diagnosis of mostly limbal VKC in the last 12 months, entered a 2-week baseline during which they used only artificial tears, and were then randomized to treatment, in groups of 18, on an investigator single-masked basis. Daily symptom diary cards were kept by patients/guardians, and VKC was assessed by the clinician at approximately monthly intervals. Dexamethasone was provided for rescue control of severe symptoms, if needed.

RESULTS

A total of 34 patients completed the study. Both trial treatments produced rapid improvements and many ocular signs and symptoms, including Trantas' dots, chemosis, itching, soreness and sticky discharge, were fully controlled by the end of the study. However, nedocromil sodium took effect more quickly, with a significant reduction compared to sodium cromoglycate for itching, grittiness, hyperaemia and keratitis within 6 weeks. In addition, nedocromil sodium was the more efficacious overall (significant vs sodium cromoglycate for hyperaemia, keratitis, papillae and pannus at 22 weeks). Both treatments were well tolerated and without serious adverse effects. Final opinions favoured nedocromil sodium, with full control of VKC recorded for 94% (patient opinion) and 100% (clinician opinion) of this treatment group, compared with 29% and 0%, respectively, in the sodium cromoglycate group.

CONCLUSIONS

Nedocromil sodium 2% eye drops is significantly more effective than sodium cromoglycate for treatment of VKC.

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.