Prospective, Single-Arm, Investigator-Initiated Study to Evaluate Efficacy and Safety of Levocetirizine Hydrochloride 5 mg and Montelukast 10 mg (L-Montus) in Patients With Seasonal Allergic Rhinitis and Perennial Allergic Rhinitis.

Introduction To evaluate the efficacy and safety of a fixed-dose combination (FDC) of levocetirizine hydrochloride 5 mg and montelukast 10 mg (L-Montus) in the treatment of seasonal allergic rhinitis (SAR) and perennial allergic rhinitis ( PAR ) among adult patients in India. Methods This was a prospective, single-arm, multicenter clinical study conducted across three clinical sites in India. A total of 200 patients aged 18 to 64 years with moderate-to-severe SAR were enrolled. All patients received once-daily oral doses of the FDC for eight weeks, with follow-up extending to 13 weeks. Symptom severity was assessed using validated tools: total nasal symptom score (TNSS), total ocular symptom score (TOSS), and night-time symptom score (NTSS). Safety and treatment adherence were monitored throughout the study. Statistical significance was evaluated using the Friedman and Wilcoxon signed-rank tests. Results At baseline, nasal symptoms such as sneezing (100%), rhinorrhea in 194 patients (97%), and nasal congestion in 191 patients (95.5%) were highly prevalent. By week eight, TNSS decreased from 6.74±2.28 to 0.86±1.11 (p=0.005), TOSS from 5.60±2.44 to 0.61±0.87 (p=0.005), and NTSS from 4.99±2.28 to 0.37±0.59 (p=0.005), demonstrating significant symptom relief. The treatment was well-tolerated, with only 14% (28) of patients reporting mild adverse events; no serious adverse events or discontinuations were observed. Conclusions The FDC of levocetirizine and montelukast (L-Montus) demonstrated robust efficacy in reducing nasal, ocular, and nocturnal symptoms associated with SAR, with a favorable safety and adherence profile. The dual mechanism of action targeting histaminergic and leukotriene pathways likely contributed to the comprehensive symptom control. These findings support the FDC as an effective first-line therapeutic option in the Indian SAR population.