ABSTRACT
The present work is aimed to develop and optimize pulsatile delivery during dissolution of an improved formulation of valsartan to coordinate the drug release with circadian rhythm. Preliminary studies suggested that ß cyclodextrin could improve the solubility of valsartan and showed AL type solubility curve. A 1:1 stoichiometric ratio of valsartan to ß cyclodextrin was revealed from phase solubility studies and Job's plot. The prepared complex showed significantly better dissolution efficiency (p < 0.05) compared to pure drug, which could be due to the formation of inclusion complex as revealed from FTIR and DSC studies. Continuous dissolution-absorption studies revealed that absorption of drug from valsartan ß cyclodextrin complex was significantly higher (p < 0.05) compared to pure drug, in second part press-coated tablets of valsartan ß cyclodextrin complex were subsequently prepared and application of the Plackett-Burman screening design revealed that HPMC K4M and EC showed significant effect on lag time. A 3(2) full factorial design was used to measure the response of HPMC K4M and EC on lag time and time taken for 90% drug release (T90). The optimized batch prepared according to the levels obtained from the desirability function had a lag time of 6 h and consisted of HPMC K4M:ethylcellulose in a 1:1.5 ratio with 180 mg of coating and revealed a close agreement between observed and predicted value (R(2 )= 0.9694).
