Comparative Evaluation of Moisture Content and Melting Point Characteristics of Commercial Aspirin Tablets Marketed In Tobruk, Libya

Abstract

Acetylsalicylic acid (aspirin) is a widely prescribed analgesic and antiplatelet agent that is susceptible to moisture-induced degradation. Monitoring moisture content and thermal behavior may provide useful preliminary information regarding physicochemical changes during storage. This study aimed to perform a laboratory-based comparative evaluation of moisture content and melting point characteristics among six commercial aspirin tablet products (75 mg) marketed in Tobruk, Libya, and to investigate the statistical relationship between these two physical parameters. Six commercially available 75 mg aspirin tablet products were purchased from community pharmacies in Tobruk, Libya, in May 2026. Moisture content (loss on drying) was determined using a halogen moisture analyzer (Mettler Toledo HB43-S) at 105°C until constant weight. Melting point measurements were performed on finely powdered tablet samples using a Stuart Scientific SMP3 digital melting point apparatus at a controlled heating rate of 1.0°C/min. All determinations were carried out in technical duplicates. Moisture content values ranged from 0.10% to 1.40% (mean = 0.70%), while melting point values ranged from 134.40°C to 136.50°C (mean = 135.45°C). Pearson correlation analysis demonstrated a statistically significant and very strong negative correlation between moisture content and melting point (r = −0.992, p < 0.001). Simple linear regression analysis showed that moisture content accounted for 98.3% of the observed variation in melting point values (R² = 0.983, p < 0.001). The findings indicate a strong inverse association between moisture content and melting point among the evaluated aspirin tablet products. Although melting point analysis provides useful preliminary screening information, comprehensive quality evaluation requires additional pharmacopoeial tests, including assay, dissolution  testing,  and  degradation-product  profiling.