Design and Characterization of Micro-Crystals of A Model Antihypertensive Drug for Enhanced Dissolution Rate

Elevated bioavailability is an advantage for most of the poorly soluble drugs. The present scenario of research investigation is concentrated on different techniques to alter the solubility characteristics of weakly soluble drugs and crystallization phenomenon is one amongst them. The low solubility problem can be solved by changing the crystal habit of drug. So, in the present research an attempt has been made to modify the solubility characteristics of Nifedipine, an anti-hypertensive drug, using solvent change method, Solvent evaporation technique and solvent change precipitation technique. Among them solvent change method gave a better formulation (NIF-MC-6) showing better dissolution (91.36% at the end of 240mins) as compared to pure drug and micro-crystals formulated using other methods. The formulated crystals of Nifedipine were subjected to various physico-chemical parameters like size distribution, solubility studies, in-vitro dissolution studies, drug content, FT- IR, DSC, crystallographic studies by PXRD and crystal morphology by SEM studies. The micro-crystals produced with PVPK30 and chloroform. FT-IR Results showed that there was no chemical interaction between the drug, solvent and the stabilizer. PXRD of micro-crystals showed higher peak height than pure drug indicating that crystal habit modification occurred in the micro-crystals without any polymeric changes and were found to be smaller in size than pure drug and free from any interactions. SEM studies indicated that the crystals are present in rectangular and square shape. The DSC curve showed that Nifedipine appeared an endothermic peak at about 1740C corresponding to its melting. However, the crystals prepared with PVP K30 shows shift of endothermic peak towards lower temperature at 170.820C respectively, dictating decreased melting point of the drug in the formed crystals, which accounted for increased solubility of the drugs.