In vitro and in vivo evaluation of sustained-release and enteric-coated microcapsules of diclofenac sodium

Evaluation of the USP dissolution test method A for enteric-coated articles by planar laser-induced fluorescence

The USP drug release standard for delayed-release articles method A was evaluated using planar laser-induced fluorescence (PLIF). Prior authors have suggested that high pH "hot spots" could develop during the buffer medium addition of the method A enteric test. Additionally, previous studies have shown heterogeneous flow patterns and low-shear regions in the USP Apparatus II dissolution vessel, which may result in poor mixing of the buffer and acid media during the pH neutralization step of the method A enteric test. In this study, PLIF was used to evaluate the mixing patterns and evolution of pH neutralization during the buffer medium addition with rhodamine-B dye and the pH-sensitive dye fluorescein, respectively. Additionally, a comparison of the methods A and B enteric tests was performed with enteric-coated tablets containing rhodamine-B in the film so as to image the dissolution rate of the coating polymer with PLIF in order to determine if rapid buffer addition for the method A procedure accelerates the rate of film coat dissolution. Rapid addition of the 250 mL of buffer medium over 5 s to the 750 mL of acidic medium shows efficient mixing and pH neutralization due to the generation of large-scale stirring and enhanced turbulence resulting from the descending buffer medium. Slow addition near the paddle shaft over 5 min showed segregation in the recirculating region around the paddle shaft. In contrast, slow addition near the vessel wall introduces the medium into fluid outside of the recirculation region and enables transport over the entire vessel. Enteric-coated tablets tested according to method A with rapid medium addition and method B enteric tests performed identically, indicating no difference in polymer dissolution rate between the two tests. From the results of the PLIF imaging studies with rhodamine-B, fluorescein, and enteric-coated tablets, it was seen that "hot spots" affecting the dissolution performance of enteric dosage forms are not generated during the neutralization step of the method A enteric test namely when the media is added rapidly or outside of the recirculating region that surrounds the paddle shaft.

A two-way cross-over bioequivalence study comparing two products of diclofenac sodium suppositories in healthy human volunteers

This report presents the results of two treatment cross-over investigations on 20 healthy male volunteers to assess the bioequivalence of two suppository products of diclofenac sodium. The study was carried out under US Food and Drug Administration Guidelines. The two products were voltaren (100 mg) suppository (Ciba-Giegy), as a reference product, and Inflaban (100 mg) suppository (The Arab Pharmaceutical Manufacturing Company, Ltd. "APM"), as a test product. Both products were administered rectally as a single dose (100 mg) separated by a one-week wash-out period. Following drug administration, blood samples were collected over 12 hr, and serum harvested from the blood was analyzed for diclofenac sodium using a sensitive and specific high performance liquid chromatographic assay. The results of this investigation indicated that there were no statistically significant differences between the two products in either the mean concentration-time profiles or in the obtained pharmacokinetic parameters, including area under the serum concentration-time curve for 12 hr (AUC(0-12h)), lag time between product administration and first appearance of the drug in serum (T(lag)), peak serum concentration (C(max)), and time to reach this peak serum concentration (T(max)). Concerning the relative extent of absorption, assessed by the AUC ratio (Inflaban/Voltaren) for 12 hr, the average value was found to be 1.00+/-0.09 with a 95% confidence limits (C.L.) of 0.82-1.18. Thus, these findings clearly indicate that the two products are bioequivalent in terms of rate and extent of drug absorption.

Spray-dried microspheres containing ketoprofen formulated into capsules and tablets

In this study, microspheres were prepared by a spray-drying technique using solutions of ketoprofen and two polymers, cellulose acetate butyrate (CAB) and hydroypropylmethylcellulose phthalate (HPMCP), in different weight ratios. Different total concentrations were used in the feed solutions: 3, 6 and 9% w/v. The spray-dried microparticles were characterized in terms of shape (SEM), size (light scattering method), production yield and encapsulation efficiency. They were formulated into capsules; tablets were prepared by direct compression of the microparticles mixed with maltose and, in some cases, hydroypropylmethylcellulose (HPMC). In vitro release studies were performed both at acidic and neutral pHs. The spray-drying process of solutions of ketoprofen with polymeric blends of cellulose derivatives leads to microparticles which, depending on their final formulation (capsules or tablets), can give a rapid or prolonged drug release. The formulations here described can be proposed for the oral administration of NSAIDs.

Solvent and plasticizer influences on ethylcellulose-microcapsules

Variations in microencapsulation processes give rise to different products and it seems there are no firm rules. It is thus difficult to know what kind of product will be obtained before the research is carried out. Changes in temperature, rate, time and type of stirring can cause great modifications in the system, most of which are responsible for variations in standard techniques. In our study, we investigate the solvent influence on ethylcellulose (EC) microcapsule formation. We have selected four different solvents: ethanol as an aqueous solvent and acetone, chloroform and toluene as organic solvents. Diclofenac sodium (DFNa), a non-steroidal anti-inflammatory agent, has been used as an encapsulated substance as it is inactivated in the gastric juices. This polymer and microencapsulation process was selected after an exhaustive study with different polymers and processes. Once the solvent influence was determined, ethylphthalate was incorporated in one type of microcapsule in order to study the influence of this plasticizer on drug release by the modification of film-permeability.