Determination of the in vitro disintegration profile of rapidly disintegrating tablets and correlation with oral disintegration.

The assessment of the in vitro disintegration profile of rapidly disintegrating tablets (RDT) is very important in the evaluation and the development of new formulations of this type. So far neither the US Pharmacopoeia nor the European Pharmacopoeia has defined a specific disintegration test for RDT; currently, it is only possible to refer to the tests on dispersible or effervescent tablets for the evaluation of RDT's disintegration capacity. In the present study, we have evaluated the disintegration profile of RDT manufactured by main commercialised technologies, using the texture analyser (TA). In order to simulate as much as possible the oral disintegration of these dosage forms, a new operating structure was developed. This structure mimics the situation in the patient's mouth and provides a gradual elimination of the detached particles during the disintegration process. The obtained time-distance profiles or disintegration profiles enabled the calculation of certain quantitative values as the disintegration onset (t1) and the total disintegration time (t2). These values were used in the characterisation of the effect of test variables as the disintegration medium and temperature on the disintegration time of RDT. Moreover, the oral disintegration time of the same products was evaluated by 14 healthy volunteers. Results obtained when artificial saliva at 37 degrees C was employed as disintegration medium were used to correlate the in vitro (t2) and oral disintegration times. Excellent correlation was found and in addition, we were able to achieve a qualitative measure of the mouthfeel by comparing the thickness of the tablets and the penetration distance obtained from the disintegration profile. This method also permitted the discrimination between different RDT, where differences in the disintegration mechanism were reflected on the disintegration profile achieved for each tablet.

The preparation of orally disintegrating tablets using a hydrophilic waxy binder.

The demand for rapidly disintegrating tablets (RDT) has been growing during the last decade especially for elderly and children who have swallowing difficulties. The problem of certain RDT is their low physical resistance and high friability. This work describes a new approach to prepare RDT with sufficient mechanical integrity, involving the use of a hydrophilic waxy binder (Superpolystate, PEG-6-stearate). Superpolystate is a waxy material with a melting point of 33-37 degrees C and an HLB value of 9. So it will not only act as a binder and increase the physical resistance of tablets but will also help the disintegration of the tablets as it melts in the mouth and solublises rapidly leaving no residues. The incorporation of Superpolystate in the formulation of RDT was realised by means of two different granulation methods: wet granulation by using an emulsion of this waxy binder as granulating liquid and melt granulation where the molten form of the binder was used. Granule size distributions of both wet and melt granules of crystallised Paracetamol and D-mannitol were compared using laser light diffractometer. Scanning electron microscopy (SEM) was used to examine their morphological characteristics. The potential of the intragranular addition of croscarmellose sodium as a disintegrating agent was also evaluated. The subsequent step encompassed the preparation and the evaluation of the tablets, including the effect of the extragranular introduction of croscarmellose sodium. An improvement in tablet hardness and friability was observed with both granulation methods where we were able to obtain RDT with a disintegration time of 40 +/- 2 s and a hardness of 47.9 +/- 2.5N.

In-vitro comparative study of buccal mucoadhesive performance of different polymeric films.

A comparison of the buccal mucoadhesive performance of different polymeric films was carried out using texture analyzer TA-XT2i. A large range of putative polymers differing in their chemical nature, molecular structure as well as hydration status was used. The used polymeric films were classified in rank order of buccal mucoadhesive performance, namely carbopol 971P>polycarbophil>Carrrageenan type lambda > Sodium carboxymethylcellulose. Swelling state as well as tensile strength of the used polymeric films was used as measuring parameters of mucoadhesive interaction. These two approaches gave two opposite orders of performance between CMC and Carrrageenan type lambda after a contact time of 15 min. However the measurement of the viscoelastic moduli of the hydrogels gave the same ranking order of mucoadhesive performance after the same contact time. In reference to the previous works, we noted the importance of the molecular weight, the density of charges, the composition of which the chains of molecules are capable to arrange themselves in a network like form, thus those which are characterized by a tan delta<1 (i.e network formation), are those which develop the best synergism with the mucus because of the reinforcement of an established link. The goal of this study is to assess the buccal mucoadhesive performance aiming to optimize the design of drug delivery via buccal mucoadhesive polymeric films