Reformulation and is a key strategy for formulation and Research development and it helps address the challenges of the current market. As compared with last two decades, during the last decade many controlled drug delivery systems for oral administration have been developed by using many techniques. Even though these techniques are having so many limitations and less applicable to weakly basic pH dependent soluble drugs which are exhibiting pH dependent solubility. Being weakly basic in nature, such drugs are more soluble at lower pH while Solubility decreases drastically with increase in pH. Such solubility behavior creates difficulty when conventional dosage form containing drug is administered to a patient. While in contact with stomach fluid low pH, drug is easily soluble, but as it is transferred to small intestine It precipitates out owing to low solubility at higher pH. These precipitates cannot dissolve easily at intestinal pH. A number of strategies have been developed to obtain controlled release of the drug. In this area of the research is very limited literature.
In the present Studies have been carried out highly prescribed two pH dependent soluble wekly basic drugs such as Ondansetron HCl is used for the treatment of chemotheraphy induced nausea vomiting and post-operative nausea vomiting and another drug Dipyridamole is used mainly to prevent blood clot at the time of valve replacement and vasodilator ,were selected to develop the pH independent extended release tablets using various rate controlled polymers such as Methocelk100, Methylacrylates, Kollidon SR 100 and polyethylene oxides as well as different techniques were investigated to achieve pH independent drug release, like pH modulating agents, anionic and cationic combination polymer precipitation inhibitors, by using enteric polymers,combination of enteric and pH modulating agents Non-polymeric precipitation inhibitors (HP β-Cyclodextrin). Formulations and processing parameters were developed and optimized in order to achieve the desirable rate of drug release from each drug delivery system. Various post compressing and pre-compression properties for the matrix tablets, were studied with an aim to commercialize final product. In vitro dissolution and in vivo bioavailability studies were conducted on selected ondansetron HCl formulations by using rabbits under hypercholhydria condition. Accelerated stability studies on some selected formulations were conducted as per ICH guidelines. Among all the technique ondansetron HCl sustained released tablets was optimized by using combination of pH modulating agents both fumeric acid and tartaric acid by using 32factorial design this method. Incase Dipyridamole a novel compression coating technique achieved pH independent drug release by using tartaric acid pellets. These formulated tablets were compared with Persantine 200mg dipyridamole market product.
This research study provided useful information on formulation development of novel pH independent matrix tablet dosage form of two pH dependent soluble drugs during development of pH independent controlled drug delivery systems with various techniques.the developed formulations of ondansetron and dipyridamole is very simple technique was developed this is applicable for commercial purpose.
