Pharmacokinetic and pharmacodynamic aspects of gastroretentive dosage forms (original) (raw)
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European Journal of Pharmaceutics and Biopharmaceutics, 2008
The purpose of the study was to evaluate the pharmacokinetic effects obtained by gastroretentive dosage form (GRDF) for drugs absorbed by passive paracellular diffusion (atenolol, acyclovir) or active transport (valacyclovir). Model drugs were delivered as gastric infusion (GInf) through an implanted catheter (resembling GRDF), intravenous, oral (PO), and colonic administration to rats. For atenolol (highly soluble drug), GInf resulted in a prolonged T max and reduced C max in comparison to PO, whereas bioavailability was similar. Bioavailability after colonic bolus was significantly lower. Results were also simulated by a pharmacokinetic model. For acyclovir, GInf and PO demonstrated almost the same pharmacokinetic profile with low bioavailability, most probably due to the solubility-limited absorption. Valacyclovir demonstrated the significant change in the shape of pharmacokinetic profile as a function of the rate of gastric delivery, without variation in bioavailability. Valacyclovir was not absorbed from colon. Experimental and theoretical methodologies to assess the pharmacokinetic influences of GRDF mode of administration were developed, avoiding the need to compound the drug in a dosage form. GRDF provides a mean for controlled release of compounds that are absorbed by active transport in the upper intestine. It also enables controlled delivery for paracellularly absorbed drugs without a decrease in bioavailability.
Pharmaceutics
There have been many efforts to improve oral drug bioavailability and therapeutic efficacy and patient compliance. A variety of controlled-release oral delivery systems have been developed to meet these needs. Gastroretentive drug delivery technologies have the potential to achieve retention of the dosage form in the upper gastrointestinal tract (GIT) that can be sufficient to ensure complete solubilisation of the drugs in the stomach fluids, followed by subsequent absorption in the stomach or proximal small intestine. This can be beneficial for drugs that have an “absorption window” or are absorbed to a different extent in various segments of the GIT. Therefore, gastroretentive technologies in tandem with controlled-release strategies could enhance both the therapeutic efficacy of many drugs and improve patient compliance through a reduction in dosing frequency. The paper reviews different gastroretentive drug delivery technologies and controlled-release strategies that can be comb...
Archives of Pharmaceutical Sciences Ain Shams University
The oral route of administration is considered the easiest, most convenient, and most widely used drug delivery route. One of the hardest challenges facing oral drug delivery systems (DDS) is the erratic absorption of drugs through the gastrointestinal tract (GIT). The conventional oral dosage forms usually suffer from low bioavailability, especially in the case of drugs with narrow absorption windows (NAW). The oral controlled-release dosage forms could overcome the previous limitation by providing predicted and calculated drug release, resulting in an improvement of the efficacy of drugs. One of the most promising types of oral controlled-release dosage forms for this purpose is the gastro retentive drug delivery system (GRDDS), which was found to improve the gastric retention of the dosage form and maximize the absorption and bioavailability of the drugs with NAW. In this review, we summarize the different GRDDS techniques used for improving drug absorption, their methods of preparation, and their mechanisms of action.
The most popular route of administration for systemic action is oral route. It is probable that at least 90% of all the drugs given by oral route .There are different drug deliveries to give drug by oral route .Gastro retentive drug delivery system plays a vital role among novel drug delivery systems. The retention of oral dosage forms in the upper GIT causes prolonged contact time of drug with the GI mucosa, leading to higher bioavailability, and hence therapeutic efficacy, reduced time intervals for drug administration, potentially reduced dose size and thus improved patient compliance Therefore, extended release DDS possessing gastric retention properties may be potentially useful. In this review we summarised approaches and various perspectives of Gastro retentive drug delivery system.
GASTRORETENTIVE SYSTEM IMPROVES THE PROBLEMS OF ORAL DRUG DELIVERY SYSTEMS: A REVIEW
Gastroretention helps to provide better availability of new products with new therapeutic possibilities and substantial benefits for patients. Dosage forms with a prolonged gastric residence time, i.e. gastro retentive dosage forms (GRDFs), will provide us with new and important therapeutic options. GRDFs extend significantly the period of time over which the drug may be released. Thus, they not only prolong dosing intervals, but also increase patient compliance beyond the level of existing controlled release dosage forms. This application is especially effective in delivery of sparingly soluble and insoluble drugs. A number of approaches have been used to increase the GRT of a dosage form in a variety of concepts. These include Floating drug delivery systems, Bioadhesive systems, Swelling and expanding systems, Modified shape systems and High density drug delivery systems. This review also discusses the recent advances in the field of gastroretentive drug delivery systems. KEYWORDS: Delivery System, Gastroretentive, Gastric Residence Time, Bioavailability.
Gastroretentive Drug Delivery Systems: A Review of Formulation Approaches
The Pharma Innovation Journal, 2012
Gastroretentive dosage forms (GRDF) has received significant interest in the past few decades as they can improve the limitation of most conventional and oral controlled release drug delivery system related to fast gastric-emptying time. An optimum GRDF system can be defined as a system which retains in the stomach for a sufficient time interval against all the physiological barriers, releases active moiety in a controlled manner. This article gives an overview of the parameters affecting gastric emptying as well as on the main concepts used to design pharmaceutical dosage forms with prolonged gastric residence times. In particular, bioadhesive, size-increasing and floating drug delivery systems are presented and their major advantages and shortcomings are discussed. Both single and multiple unit dosage forms with dual working systems are reviewed. Dual working systems are more efficient than the traditional systems.
AN OVERVIEW ON LIMITATIONS OF GASTRORETENTIVE DRUG DELIVERY SYSTEM Review Article
2011
Gastric emptying is a complex process and makes in vivo performance of the drug delivery systems uncertain. Floating drug delivery systems (FDDS) can remain in the gastric region for several hours and hence significantly prolong the gastric residence time of drugs, thereby improving bioavailability, reduced drug waste and improved solubility for drugs that are less soluble at a higher pH environment. In order to understand the various physiological barriers to achieve gastric retention, a thorough understanding of the important factors controlling gastric retention is essential.
International Current Pharmaceutical Journal, 2018
In the field of oral drug delivery system, a gastroretentive system is gaining popularity day by day. Numerous of research work and extensive literature are published in past few years on gastroretentive drug delivery system. It is the one of the best and appropriate approaches for increasing the residence time of drug in the stomach and diffuses drug slowly in the sustained manner which helps in the site-specific delivery of the drug as well also increases the bioavailability at site-specific of delivery. This helps in many challenges associated with conventional oral drug delivery system. Different ways are used for approaching gastroretention viz. swelling and expandable system, high-density system, magnetic system, bioadhesive system and buoyant system with or without gas generating agents. During data mining well in vitro characterization and in vivo characterization including gamma scintigraphic and MRI techniques are well established and reported. But, still, today in vivo characterization technique is major challenging for the researcher due to its limitation. The documented literature explains the use of animal models like beagle dogs, rabbits and human subjects for in vivo evaluation parameter but it leads to increase in variation that's why this delivery system is limited in the market. This paper contains the latest literature compilation and various techniques used for gastroretention with its pros and cons. This review paper helps the researcher to take an overview of basics of gastroretentive drug delivery system and helps in understanding the basics of the system.