Decades of research in drug targeting to the upper gastrointestinal tract using gastroretention technologies: where do we stand?

Abstract

A major constraint in oral controlled release drug delivery is that not all the drug candidates are absorbed uniformly throughout the gastrointestinal tract (GIT). Drugs having "absorption window" are absorbed in a particular portion of GIT only or are absorbed to a different extent in various segments of the GIT. Thus, only the drug released in the region preceding and in close vicinity to the absorption window is available for absorption. The drug must be released from the dosage form in solution form; otherwise, it is generally not absorbed. Hence, much research has been dedicated to the development of gastroretentive drug delivery systems that may optimize the bioavailability and subsequent therapeutic efficacy of such drugs, as these systems have unique properties to bypass the gastric emptying process. These systems show excellent in vitro results but fail to give desirable in vivo performance. During the last 2-3 decades, researchers from the academia and industries are giving considerable importance in this field. Unfortunately, till date, few so-called gastroretentive dosage forms have been brought to the market in spite of numerous academic publications. The manuscript considers strategies that are commonly used in the development of gastroretentive drug delivery systems with a special attention on various parameters, which needs to be monitored during formulation development.

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“…This behavior has been attributed to the rapid dissolution of the drug from the surface near the surface of the matrix, while the polymer undergoes hydration to form a protective gel layer. HPMC and Pullulan gum have been used for modulating drug release and to prevent the burst release of highly soluble 4 . Venlafaxine hydrochloride, is a highly water soluble and structurally novel antidepressant for oral administration.…”

Updates on Approaches to Increase the Residence Time of Drug in the Stomach for Site Specific Delivery: Brief Review

“…1.064 g/cm 3 , therefore, remain buoyant in the stomach for the prolonged period of time (Awasthi et al, 2016). At last residual system is evacuated from the abdomen.…”

“…The time duration of each phase runs from 90 to 120 minute. The motion pattern of the stomach called as migrating motor complex (MMC) which maintain and regulates the gastrointestinal motility pattern (Awasthi et al, 2016). It consists of four phases: Phase I called as base or immediate phase, Phase II called as preburst phase, Phase III called as burst phase and Phase IV called as transition phase intervals (Figure 2).…”

“…During this, housekeeper waves are generated which sweep out undigested food and material (drug). Phase IV is the transition phase between phase III and I which lasts for 0 to 5 minutes (Awasthi et al, 2016;Vantrappen et al, 1979;Talukder et al, 2004).…”

Gastroretentive floating tablets: An investigation of excipients effect on tablet properties

“…Floating systems do not bind with gastric mucosal surfaces and reduce the safety problems associated with mucoadhesive systems. Drug delivery systems based on gastroretention mechanisms are not suitable for those drugs which cause gastric lesions such as, non-steroidal antiinflammatory agents (4).…”