Self-nanoemulsifying ramipril tablets: a novel delivery system for the enhancement of drug dissolution and stability

Background: Ramipril (RMP) suffers from poor aqueous solubility along with sensitivity to mechanical stress, heat, and moisture. The aim of the current study is to improve RMP solubility and stability by designing solid self-nanoemulsifying drug delivery system (S-SNEDDS) as tablet. Methods: The drug was initially incorporated in different liquid formulations (L-SNEDDS) which were evaluated by equilibrium solubility, droplet size, and zeta potential studies. The optimized formulation was solidified into S-SNEDDS powder by the adsorbent Syloid^® and compressed into a self-nanoemulsifying tablet (T-SNEDDS). The optimized tablet was evaluated by drug content uniformity, hardness, friability, disintegration, and dissolution tests. Furthermore, pure RMP, optimized L-SNEDDS, and T-SNEDDS were enrolled in accelerated and long-term stability studies. Results: Among various liquid formulations, F5 L-SNEDDS [capmul MCM/transcutol/HCO-30 (25/25/50%w/w)] showed relatively high drug solubility, nano-scaled droplet size, and high negative zeta potential value. The optimized SNEDDS solidification with Syloid^® at ratio (1:1) resulted in a compressible powder with an excellent flowability. The optimized tablet (T-SNEDDS) showed accepted content uniformity, hardness, friability, and disintegration time (<15 minutes). The optimized L-SNEDDS, S-SNEDDS, and T-SNEDDS showed superior enhancement of RMP dissolution compared to the pure drug. Most importantly, T-SNEDDS showed significant (P<0.05) improvement of RMP stability compared to the pure drug and L-SNEDDS in both accelerated and long-term stability studies. Conclusion: RMP-loaded T-SNEDDS offers a potential oral dosage form that provides combined improvement of RMP dissolution and chemical stability.