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: Santosh Ambadas Payghan[show abstract] [hide abstract]
ABSTRACT: Among novel drug delivery systems, rate controlled oral drug delivery system forms an important area. Recent technological and scientific research has been devoted to the development of rate controlled drug delivery systems to overcome physiological adversities such as short gastric residence times and unpredictable gastric emptying times. Several approaches are currently utilized in the prolongation of the GRT, including floating drug delivery systems (FDDS), swelling and expanding systems, polymeric bioadhesive systems, high-density systems, modified-shape systems and other delayed gastric emptying devices. Floating Drug delivery system are designed to prolong the gastric residence time after oral administration, and controlling the release of drug especially useful for achieving controlled plasma level as well as improving bioavailability. Floating drug delivery systems are the systems which are retained in the stomach for a longer period of time. The main aim of the study was to design and evaluate nifedipine floating tablets. Hydroxypropyl methyl cellulose (HPMC K100M) was used as a polymer. This study proves that GFDDS of nifedipine can be designed using HPMC K100M as matrix polymer, which provides nearly zero order release kinetics and thus possible enhancement of oral bioavailability of the drug. INTRODUCTION: CDDS are those convenient means of drug delivery systems which are meant to obtain a reduction of daily administration of drugs with fast absorption and elimination. Many controlled release systems have been developed for maintaining a therapeutically effective concentration of drug in systemic circulation for longer period of time as well as to reduce side effects 1 .International Journal of Pharmaceutical Sciences and Research. 11/2011; 2(11):2929-2933.
- 11/2011; , ISBN: 978-953-307-976-9
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ABSTRACT: The current studies entail successful formulation of optimized gastroretentive tablets of lamivudine using the floating-bioadhesive potential of carbomers and cellulosic polymers, and their subsequent in-vitro and in-vivo evaluation in animals and humans. Effervescent floating-bioadhesive hydrophilic matrices were prepared and evaluated for in-vitro drug release, floatation and ex-vivo bioadhesive strength. The optimal composition of polymer blends was systematically chosen using central composite design and overlay plots. Pharmacokinetic studies were carried out in rabbits, and various levels of in-vitro/in-vivo correlation (IVIVC) were established. In-vivo gamma scintigraphic studies were performed in human volunteers using (99m) Tc to evaluate formulation retention in the gastric milieu. The optimized formulation exhibited excellent bioadhesive and floatational characteristics besides possessing adequate drug-release control and pharmacokinetic extension of plasma levels. The successful establishment of various levels of IVIVC substantiated the judicious choice of in-vitro dissolution media for simulating the in-vivo conditions. In-vivo gamma scintigraphic studies ratified the gastroretentive characteristics of the optimized formulation with a retention time of 5 h or more. Besides unravelling the polymer synergism, the study helped in developing an optimal once-a-day gastroretentive drug delivery system with improved bioavailability potential exhibiting excellent swelling, floating and bioadhesive characteristics.The Journal of pharmacy and pharmacology. 05/2012; 64(5):654-69.