Formulation and Evaluation of Nanosuspension Formulations of Ramipril using Hydrophilic Polymers
Nanosuspensions provide convenient formulations for improving the bioavailability and drug delivery. The objective of the investigation was to develop stable nanosuspension formulation of ramipril, with minimum surfactant concentration that could improve its solubility, stability and oral bioavailability. Ramipril is a potent antihypertensive drug, which act by inhibiting the angiotensin-converting enzyme. Nanosuspension was developed by antisolvent precipitation followed by high-pressure homogenization using hydrophilic polymers such as HPMC E5, HPMC E15, PVP K30, PVP K25, and PVA. The resulting nanosuspension was transformed into dry powder by freeze-drying process. Among all five formulations a formulation was choosen on the basis of results obtained from comparative study between different polymers based nanosuspension formulation of ramipril. The nanosuspension prepared was then evaluated for particle size, polydispesivity index, zeta potential, entrapment efficiency, saturated solubility study, scanning electron microscopy, differential scanning colorometry, and X ray diffraction. The combination of soya lecithin and pluronic F-68 as stabilizers yield nanosuspension with the smallest average particle size. The formulation of ramipril based on HPMC E 15 (Formulation B) shown enhanced dissolution rate. In which more than 60% of the drug was dissolved in the first 20 min compared to less than 25% of the pure drug within the same time period. The increase in the in vitro dissolution rate, nano size may favourably affect bioavailability.