Formulation development and evaluation of osmotic drug delivery system for lornoxicam

Osmotic systems are the most reliable controlled drug delivery systems and can be employed as oral drug delivery systems. Osmotic pressure is used as the driving force for these systems to release the drug in a controlled manner. Osmotic pump tablet (OPT) generally consists of a core including the drug(s), an osmotic agent, other excipients and semipermeable membrane coat. The aim of current study was to develop osmotic drug delivery system for Lornoxicam. Two different approaches were used for formulation, one was controlled porosity osmotic tablet and other was elementary osmotic tablet. The formulations were evaluated for different parameters like appearance, uniformity of weight, drug content, hardness and drug release also the effect of different osmotic agents responsible for developing the osmotic pressure such as sodium chloride and mannitol along with different concentration of pore former sorbitol were studied and comparison was made between first controlled porosity osmotic tablet which include the osmotic tablet in which coating membrane contains water soluble pore forming polymers when the membrane comes in contact with water the leaching of polymers occur thereby permitting the water inside the wall and creating the osmotic pressure to release the drug and second the elementary osmotic tablet containing osmotic agent sodium chloride coated with the rate controlling semipermeable membrane of cellulose acetate, this membrane contains an orifice of a critical size through which the drug is delivered. From the results it was found that the developed formulation the controlled porosity osmotic tablet of Lornoxicam (CPOP) was able to release the drug over 12 hrs at zero order and also the concentration of osmotic agent, level of pore former and thickness of coating membrane are responsible for controlling the release of Lornoxicam. The coating membrane was subjected to SEM analysis which showed formation of pores in the membrane. The developed controlled porosity osmotic pump tablet of lornoxicam was found to control the release for 12 hrs.