No abstract

A biphasic gastroretentive floating drug delivery system with multiple-unit mini-tablets based on gas formation technique was developed to maintain constant plasma level of a drug concentration within the therapeutic window. The system consists of loading dose as uncoated core units, and prolonged-release core units are prepared by direct compression process; the latter were coated with three successive layers, one of which is seal coat, an effervescent (sodium bicarbonate) layer, and an outer polymeric layer of polymethacrylates. The formulations were evaluated for quality control tests, and all the parameters evaluated were within the acceptable limits. The system using Eudragit RL30D and combination of them as polymeric layer could float within acceptable time. The drug release was linear with the square root of time. The rapid floating and the controlled release properties were achieved in this present study. When compared with the theoretical release profile, the similarity factor of formulation with coating of RS:RL (1:3)-7.5%, was observed to be 74, which is well fitted into zero-order kinetics confirming that the release from formulation is close to desired release profile. The stability samples showed no significant change in dissolution profiles (p > 0.05). In vivo gastric residence time was examined by radiograms, and it was observed that the units remained in the stomach for about 5 h.

A gastro retentive floating drug delivery system with multiple-unit minitab's based on gas formation technique was developed in order to prolong the gastric residence time and to increase the overall bioavailability of the drug. The system consists of the drug-containing core units prepared by direct compression process, which are coated with three successive layers of an inner seal coat, effervescent layer (sodium bicarbonate) and an outer gas-entrapped polymeric membrane of an polymethacrylates (Eudragit RL30D, RS30D, and combinations of them). Only the system using Eudragit RL30D and combination of them as a gas-entrapped polymeric membrane could float. The time to float decreased as amount of the effervescent agent increased and coating level of gas-entrapped polymeric membrane decreased. The optimum system floated completely within 3 min and maintained the buoyancy over a period of 12 h. The drug release was controlled and linear with the square root of time. Increasing coating level of gas-entrapped polymeric membrane decreased the drug release. Both the rapid floating and the controlled release properties were achieved in the multiple-unit floating drug delivery system developed in this present study. The analysis of the parameter dissolution data after storage at 40 degrees C and 75% RH for 3 months showed, no significant change indicating the two dissolution profiles were considered to be similar (f2 value is more than 50).

No abstract

No abstract

Of all drug delivery systems, oral drug delivery remains the most preferred option for administration for various drugs. Availability of wide variety of polymers and frequent dosing intervals helps the formulation scientist to develop sustained/controlled release products. Oral Sustained release (S.R) / Controlled release (C.R) products provide an advantage over conventional dosage forms by optimizing bio-pharmaceutic, pharmacokinetic and pharmacodynamic properties of drugs in such a way that it reduces dosing frequency to an extent that once daily dose is  sufficient for therapeutic management through uniform plasma concentration providing maximum utility of drug  with reduction in local and systemic side effects and cure or control condition in shortest possible time by smallest quantity of drug to assure greater patient compliance. This review describes the various factors influencing the design and performance of sustained/controlled release products along with suitable illustrations.

The low aqueous solubility of celecoxib (CB) and thus its low bioavailability is a problem.    Thus, it is suggested to improve the solubility using cosolvency and solid dispersions techniques. Pure CB has solubility of 6.26±0.23µg/ml in water but increased solubility of CB was observed with increasing concentration of cosolvents like PEG 400, ethanol and propylene glycol. Highest solubility (791.06±15.57mg/ml) was observed with cosolvency technique containing the mixture of composition 10:80:10%v/v of water: PEG 400: ethanol. SDs with different polymers like PVP, PEG were prepared and subjected to physicochemical characterization using Fourier-transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), differential scanning calorimetry (DSC), solubility and dissolution studies. These studies reveals that CB exists mainly in amorphous form in prepared solid dispersions of PVP, PEG4000 and PEG6000 further it can also be confirmed by solubility and dissolution rate studies. Solid dispersions of PV5 and PV9 have shown highest saturation solubility and dissolution rate

The purpose of this investigation was to prepare a gastroretentive drug delivery system of ranitidine hydrochloride. Currently, floating tablets are one of the important categories of drug delivery systems with gastric retentive behavior. Ranitidine is a H2 blocker and absorbed from the upper part of GIT and hence there is need to develop a dosage form that releases the drug in stomach so that it can be absorbed from upper part of GIT leading to improved bioavailability. Six different gastroretentive tablets of ranitidine HCl were prepared by direct compression using different concentrations of Hydroxy propyl methyl cellulose (HPMC K4M), Carbopol, Sodium carboxy methyl cellulose, sodium bicarbonate and citric acid. The formulations were coded as HE1, HE2, HC1, HC2, HEC1 and HEC2. The formulations were evaluated for pharmacopoeial quality control tests and all the physical parameters evaluated for quality control were within the acceptable limits of Pharmacopoeia. All the formulations were subjected to in vitro drug release study and compared with that of marketed formulation. The floating lag time of the prepared formulations is good except for one formulation (HC1) and the floating time for all the formulations was >12 hours except HC1 which does not float at all. In conclusion, effervescent is essential for the formulation to have good floating property and carbopol retards the drug release in floating formulations. The statistical analysis of the parameters dissolution efficiency of dissolution data, floating behavior and drug content after storage at 40°C and 75% RH for three months showed no significant change by Student’s t-test indicating that formulation (HEC1) could provide a minimum shelf life of 2 years.