Improved design for in-vitro measurement of adhesion parameters of bioadhesive pharmaceutical systems

A simple apparatus was designed to measure the adhesion parameters, the detachment force and the work of adhesion, for solid and semisolid bioadhesive dosage forms. Validation of the new design using natural and synthetic bioadhesives showed that the system gave reproducible results. Two model membranes, the bovine cheek membrane and the bovine intestine, were tested as the biological platform using carbopol 934/HPMC systems in the ratios [100:0, 90:10, 50:50]. The bovine intestine gave more reproducible results than the bovine cheek membrane. Carbopol 974p/HPMC and carbopol 974p/HPC are the systems used to determine the effect of contact time on the adhesion parameters and to confirm the linear relationship between the detachment force and the work of adhesion

Formulation and evaluation of sustained release dextromethorphan resinate syrup

Aiming to decrease the dosing frequency of the antitussive dextromethorphan, different coated drug resinates were prepared and formulated in syrup form. Polystyrene divinylbenzene sulfonic acid ion exchanger [Amberlite IRP 69, H+ form] was used to prepare the resinates, which were further coated with different concentrations of carnauba wax, Eudragit RL 100, or ethyl cellulose. The in vitro release performance of the coated and uncoated resinates was determined in simulated gastric and intestinal fluids. Selected systems were formulated in syrup form and evaluated for their physicochemical and release performance when fresh and on storage. Dextromethorphan resinates showed relatively rapid release pattern, where 74.2% of the drug released through two hours in acid medium. The release pattern decreased from coated resinates on increasing polymer coat depending on the type of coating polymer. Coated dextromethorphan resinate syrups acquired mixed zero- and first-order release pattern with optimum release rates and suitable first flush values. The dextromethorphan flush in the first five minutes ranged between 9.1 and 12.3% with first-order release rate constants of 0.0048-0.0097 min-1

Formulation and evaluation of sucralfate suspension

Eight sucralfate suspension formulas were laid down and prepared using various suspending agents as hydroxypropyl methylcellulose K4M, methyl cellulose, carbopol 934, avicel RC 591, sorbitol, in addition to preservatives, flavoring and sweetening agents. The in vitro pharmaceutical studies in terms of sedimentation volume, scum formation were carried out. The physically stable formulations were subjected to rheological investigation as well as in vivo studies on rats to illustrate its protective effect on ethanol induced gastric ulceration. Results of in vitro studies showed that products of formula 6 containing avicel RC 591, sorbitol, glycerin and formula 8 composed of avicel RC 591, hydroxypropyl methylcellulose, as dispersant system exhibited the optimum characteristics of antacid suspensions. They showed reasonable rapidly redispersible sediments and homogeneous dense adherent scums. Also, rheological studies of these two products showed pseudoplastic thixotropic flow patterns which were kept stable on storage for 6 months. The in vivo studies on rats using suspensions of formulas 6 and 8 in comparison to plain sucralfate suspension [formula 1] showed that there is a significant protective effect which was more apparent through suspension of formula 6. This suspension could be successfully used in the prophylaxis of ulceration induced by ethanol as shown from its low ulcer index and high preventive index