In vitro and in vivo evaluation of an oral sustained-release floating dosage form of amoxycillin trihydrate
ABSTRACT Various hydrophilic polymers were investigated for the preparation of amoxycillin trihydrate sustained-release (SR) tablets. The most suitable system contained a 1:2 ratio of hydroxypropylcellulose (HPC) to drug, which compressed easily and was not affected by alteration in normal compaction pressure. Intrinsic dissolution studies at pH 2 showed that reduction in drug loading decreased drug release, which being linear with time was characteristic of an eroding matrix with a hydrated layer. Examination of compacts over a wider range of pH showed the slowest rate of drug release at pH 6, corresponding to minimum solubility of the drug. Further formulation to enhance gastric retention time (GRT), by incorporation of a gas-generating system, yielded either bilayer tablets which prematurely failed or large single-layer tablets which remained buoyant for 6 h and had satisfactory in vitro SR. However, when the latter tablets were compared against conventional capsules in fasted humans at 500 mg equivalent dose of amoxycillin, their relative bioavailability was reduced to 80.5% and other pharmacokinetic parameters indicated lack of improved efficacy.
- SourceAvailable from: Jaganmohan Chandran[Show abstract] [Hide abstract]
ABSTRACT: Floating Drug delivery system is used to target the drug release in the stomach or to the upper parts of the intestine. The eradication of Helicobacter pylori requires the administration of various medicaments several times a day, which often results in poor patient compliance. More reliable therapy can be achieved by using FDDS which can be expected that the topical delivery of antibiotic through a FDDS may result in complete removal of the organisms in the fundal area due to bactericidal drug levels being reached in this area, and might lead to better treatment of peptic ulcer. Since gatifloxacin is a potential drug for eradication of H. Pylori infection responsible for gastric and duodenal ulcers, the oral delivery of antibiotic gatifloxacin was facilated by preparing a non-disintegrating floating dosage form which can increase its local availability in the stomach by increasing the drug's gastric residence time. The tablets were prepared in six batches F1 to F6 by the direct compression technique using polymers such as hydroxyl propylmethylcellulose (HPMC K4M, HPMCK 15M M, and HPMC K100M, along with sodium bicarbonate as the gas –generating agents. The prepared tablets were evaluated for their physicochemical properties and drug release. In-vitro release studies indicated that the gatifloxacin release form the floating dosage form was uniform F2 and F6 and followed Higuchi drug release. Sodium bicarbonate was used as the gas-generating agents which cause the tablets to float on the G.I fluids. Formulation showed a floating lag time less than 60 seconds and floating time above 12 hrs. INTRODUCTION Gastric emptying of dosage forms is an extremely variable process and ability to prolong and control the emptying time is a valuable asset for dosage forms, which reside in the stomach for a longer period of time than conventional dosage forms (S.S. Patel et al., 2006). Several difficulties are faced in designing controlled release systems for better absorption and enhanced Corresponding Author01/2012; 3:84-89.
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ABSTRACT: Success of oral drug delivery system depends on its degree of absorption through GIT. Thus, the idea of enhancing drug absorption in the GIT pioneered the idea of development of Gastroretentive drug delivery system. To design and evaluate the performance of GRDDS, it is important to understand the relevant anatomy and physiology of the GI tract. To achieve gastric retention, the dosage form should satisfy certain requirements; primarily, the dosage form must be able to withstand the forceful peristaltic waves in the stomach and the constant contractions, grinding and churning. To function as a gastric retention device, it must resist premature gastric emptying. Once the purpose has been served, the device should be removed from the stomach with ease. Floating DDS or hydrodynamically balanced systems (HBS) have a bulk density lower than the gastric fluids (<~1.004 g/cm³), and thus remain buoyant in the stomach without affecting the gastric emptying rate for a prolonged period of time. Using FDDS one can easily increase the absorption of gastric secretion-labile drugs.International Journal of Pharmaceutical Sciences Review and Research 05/2011; 8(2):154-159. · 2.19 Impact Factor
Article: Floating microspheres: a review[Show abstract] [Hide abstract]
ABSTRACT: Gastric emptying is a complex process, one that is highly variable and that makes in vivo performance of drug delivery systems uncertain. A controlled drug delivery system with prolonged residence time in the stomach can be of great practical importance for drugs with an absorption window in the upper small intestine. The main limitations are attributed to the inter- and intra-subject variability of gastro-intestinal (GI) transit time and to the non-uniformity of drug absorption throughout the alimentary canal. Floating or hydrodynamically controlled drug delivery systems are useful in such applications. Various gastroretentive dosage forms are available, including tablets, capsules, pills, laminated films, floating microspheres, granules and powders. Floating microspheres have been gaining attention due to the uniform distribution of these multiple-unit dosage forms in the stomach, which results in more reproducible drug absorption and reduced risk of local irritation. Such systems have more advantages over the single-unit dosage forms. The present review briefly addresses the physiology of the gastric emptying process with respect to floating drug delivery systems. The purpose of this review is to bring together the recent literature with respect to the method of preparation, and various parameters affecting the performance and characterization of floating microspheres.Brazilian Journal of Pharmaceutical Science 03/2012; 48(1):17-30. · 0.37 Impact Factor