Influence of melting point and hydrophilic/lipophilic balance on the release of salbutamol sulfate from lipid matrices

Salbutamol is a drug with a short elimination half life, and is thus a possible candidate for the development of sustained release formulations. We developed sustained release lipid matrices using Gelucires. Three different release profiles were observed : fast release, in the case of Gelucires 33/01, 35/10, 37/02, 42/12 and 44/14, with a mean dissolution time (Td₅₀) of 6, 16, 3, 40 and 12 min; a sustained release for Gelucires 48/09, 50/13 and 53/10 with a mean dissolution time of 186, 147 and 168 min; and a slow release for Gelucires 46/07 and 50/02, with a mean dissolution time of 310 and 621 min, respectively. The percentages of salbutamol released with Gelucires 46/07 and 50/02 were below 60% of the dose. Multiple regression analysis of the hydrophilic/lipophilic balance (HLB), melting point (MP), dissolution constant (K₁) and mean dissolution time (Td₅₀) yielded the following equations: K₁ = 3.13 - 0.262*HLB - 0.0648*MP + 0.00556HLB*MP, (R² =0.88), and Td₅₀ = - 1485 + 105*HLB + 43.2*MP - 3.03 HLB*MP, (R² = 0.91).