INTRODUCTION:

With time, the modern drug delivery system has become increasingly complicated with improved clinical outcomes. And this was something brought in due to the better comprehension of the different physicochemical and biological parameters related to drugs. Pharmaceutical scientists around the world derived a new form of a drug delivery system which considerably differed from the conventional ones. It is essentially known as the controlled drug delivery system and plans to convey a coordinated, expected, at a foreordained rate to accomplish fundamentally higher clinical viability and insignificant toxicity.

It has effectively been shown to bypass the main drawbacks of conventional oral drug delivery systems such as low bioavailability and permeability due to poor solubility of drugs and enhance the therapeutic efficacy of orally administered drugs^1,2. Since it is being mainly applied for orally-administered drugs and relies on the increased gastro-retentivity of the dosage form, it has been aptly named the Gastro-Retentive drug delivery system (GRDDS)^3,4.

Benefits are:

· Enhance the bioavailability & therapeutic efficacy.

· Alteration in dose size.

· Better drug solubility of drugs such as Domperidone that is not highly soluble in the high pH environment.

· Reduced drug wastage.

· Targeted drug delivery to the small intestine and stomach⁵.

Stomach Physiology:

Since the stomach has an important role in the GRDDS, a clearer grasp of its anatomy and physiology is a must. Anatomically, the stomach is divided into two different parts, proximal and distal stomach. The former consists of fundus and body, while the latter have antrum and pylorus. These parts have their specific roles, with the fundus and body acting as the resting place for the undigested food while the antrum functions as a pump for carrying out emptying of gastric contents via the propelling action. Although it doesn't matter if the conditions are either fasted or fed as gastric emptying can occur nevertheless, the emptying pattern still showed significantly different patterns. During fasting state, multiple sequential electrical events precede the inner digestive process in both the stomach and small intestine at an interval of 90-120 min³.Whereas, during the fasted stage, the ingestion of food leads to the generation of motor activity which starts after 5-10 min of ingestion and can continue till the food remains in the stomach. This can potentially retard the gastric emptying and prolong the stay of chyme within the stomach⁶.

Strategies of GRDDS:

Strategies utilized for prolongation of GRT are mentioned below⁵:

1. Pharmacological approach

2. Physiological approach

3. Pharmaceutical approach

The various pharmaceutical approaches utilized in gastro-retentive drug delivery system⁷:

A. High-density system,

B. Ion-exchange resin system,

C. Magnetic systems,

D. Mucoadhesive system,

E. Expandable system

F. Low-density system,

G. Super porous hydrogel system,

H. Raft forming system,

I. Microballoons/Hollow microspheres,

J. Microporous Compartment System,

K. Inflatable gastrointestinal delivery system⁸

Factors Affecting Various Facets of GRDDS:

Different factors like pharmaceutical, physiological, and patient-related factors can considerably exert their effect and influence the activity of GRDDS dosage forms. In this review, they have been discussed in detail with special emphasis on how they impact the gastro-retentive dosage forms^9,10.

Pharmaceutical factors^11,12:

To optimize the bioavailability and therapeutic efficacy, various GRDDS have been used to improve the therapeutic efficacy of the drug with a narrow absorption window.

Physiological factors¹³:

Expansion in caloric thickness altogether expands the GRT. In recumbent positions, the non-drifting system has a more extended GRT contrasted with the drifting floating system. The gastric exhausting rate is quicker because of peristaltic compressions during supine posture.

Current Trends in pharmaceutical drug deliveries for GRDDS:

A huge approach towards current usage in the gastroretentive drug delivery system continues to be similar and that is, the increased GRT. Formulation has been designed in such a way that they indirectly or directly relate to the gastro-retentivity of the dosage forms. All of these approaches have been thoroughly discussed below:

[A] Floating or Low-density Approach^14-17:

Also known as Hydrodynamically Balanced System (HBS), the floating system relies on the density of the different developed dosage forms. For this approach to be successful, the density of formulated pellets must be lesser than 1 g/ml. This gives them the ability to float in the gastric fluid of the stomach, where they sustainably release the drug.

Classification of Floating Systems:

It is classified into two types,i.e. effervescent system and non-effervescent system.

1. Effervescent systems:

The effervescent floating system depends upon the phenomenon of effervescence to function as a GRDDS, composed of an effervescent agent and volatile liquids, which upon coming to contact with gastric fluid releases carbon dioxide gas. This gas gets trapped in the hydrocolloid matrix of the developed dosage form, and significantly influences its drug releasing property by altering the buoyancy property¹⁷.

The effervescent floating systems can be isolated into three unique classes

· Single-layer effervescent floating system.

· Double layer effervescent floating system.

· Multiple-unit buoyant-type floating systems¹⁸.

During a study, it was observed that the usage of sodium bicarbonate with the formulation of the HPMC matrix increased the surface area for drugdiffusion, which consequently leads to increased hydration volume, and an improved GRT time¹⁹.

2. Non-effervescent systems:

For the formulation of the non-effervescent systems, polysaccharides used are generally gel-forming or cellulose derivatives with a highly swellable. These floating systems are developed by intimately mixing the drug along with gel-forming or swelling-type hydrophilic polymers¹⁶. However, one of the major drawbacks of this system is that the release property of the drug directly depends on the floating property of dosage form²⁰.

[B] High Density Systems:

As the name suggests, the high-density system is a type of GRDDS in which the density of developed pharmaceutical formulation is greater than that of gastric fluid. It isn't unexpected information that very much like supplements, greatest ingestion of drug happens from the small digestive tract. Hence, delaying their transit time- which can be easily done by increasing their density- will give a much slower rate of absorption and provide the required delayed response²¹.

[C] Expandable Systems:

Additionally, named as the "plug-type system", expandable systems are one more kind of GRDDS in which the developed drug formulation shows delayed gastrointestinal travel time because of the augmentation in their volume and shape. Before their clinical significance was established in humans, they were extensively used for veterinary purposes^22,23. For a drug system to function as an expandable-type GRDDS system, it must fulfill the following pharmaceutical criteria⁴:

· Its size should be small for easy oral administration.

· It should have sufficient expansion to avoid passing into the small intestine via the pyloric sphincter.

· The dimension of the system should get reduced after the drug release for facilitating its evacuation^22,24.

The drug will be loaded on this patch, which upon adhering with the mucosa layer of GIT releases the drug in a controlled manner through the unfolding mechanism. However, expandable systems like any other pharmaceutical formulation have several restrictions. They lead to complications like intestinal adhesion, obstruction in bowel passage, and gastropathy conditions. Also, these formulations present storage difficulties, get conveniently hydrolyzed, and are less economical to manufacture^22,25.

[D] Superporous Hydrogel System:

Of all the GRDDS, super porous hydrogel systems are one of the most promising ones. A hydrogel is a crosslinked polymeric system with a network consisting of acidic, basic or neutral monomers. A super porous hydrogel is structurally similar to hydrogel with the presence of interconnected microscopic pores^26,27. Their usage as GRDDS comes from their capability to immensely swell upon absorption of water and stays back in the stomach for an extended period to release the drug. Their large volume prevents their movement through the pyloric sphincter and permits longer residence time. They can easily swell over 100 times and are effective in increasing the gastrointestinal residence time^28,29.

[E] Magnetic System:

This system employs the use of magnets to augment the gastrointestinal residence time. The developed pharmaceutical formulation has an internal magnet that is attracted with the help of an extracorporeal magnet^30,31. After a magnetic system, GRDDS has been orally administered; this extracorporeal magnet is placed over the stomach wall and is used to position the administered drug³². The properties of the extracorporeal magnet itself are very important, as its intensity and positioning can greatly affect the GRT^33-35.

[F] Ion-Exchange Resin System:

It was not until 1950 that the experimental work of Saunders and Srivastava shed light on the potential use of ion-exchange resins for the preparation of sustained-release formulations. They conducted several experiments on the uptake and release of alkaloids by an ion-exchange resin and proposed its use as a fitting chemical carrier in the drug delivery system³⁶. The property of IER makes them a favorable candidate for the GRDDS as they could be used to host a drug and release it in the GIT in the presence of other ions or the corresponding pH changes in its environment³⁷. The drug particles get ingested through the gastric mucosa of the stomach while the resin particles are eliminated by their biological breakdown or removed with the feces. The most widely used resins for the preparation of the ion-exchange resins are cross-linked polystyrene and polymethacrylate polymers³⁸. Furthermore, the rate of release is not satisfactory; it can be further controlled by an application of a permeable coating³⁹.

[G] Raft-forming System:

The raft-forming system too deploys the use of effervescent agents and a gel-forming polymer. This formed raft resists the peristaltic movement of the stomach and doesn't easily pass into the small intestine. Their modus operandi are quite similar to that of the floating system. It stays back in the stomach where it releases the drug in a sustained manner. However, it offers little mechanical strength and is easily disrupted by the migrating motor complex^40,41. Their light buoyancy aids them in floating near the esophageal opening for providing an effective localised effect³¹. Nabarawi et al. took mebeverine hydrochloride and devised a raft system to deliver the drug in a sustained manner. His formulation transformed into a viscous gel-like structure and entrapped carbon dioxide within its structure²⁸.

[H] Mucoadhesive System:

Developed GRDDS dosage form incorporates the utilization of synthetic/nature polymer which acts as a mucoadhesive agent and binds towards the mucosal surface. GRT (gastric retention time) of the drug is upgraded by holding them to the epithelial layer of the stomach^42,43. The parameters such as concentration, cross-linking extent, charge density and hydration energy also significantly influence the mucoadhesive strength of the polymer⁴⁴. Back in 1989 by Park and Robinson, the exact mechanism of the mucoadhesive system is still unknown⁴⁵. However, it has been established that mucoadhesion is a two-step process, namely contact stage and consolidation stage⁴⁶. Different theories such as wettability, diffusion, adsorption, electronic, and fracture have been postulated and discussed⁴⁷. Different theories of Mucoadhesive system are given in the Table 1.

Table 1: Different theories of Mucoadhesive system

Theories	Mechanism
Wettability	Greater the contact angle of the mucoadhesive with the surface, lesser is the adhesion. Hence for optimum the contact angle must be minimum as well.
Diffusion	The interpenetration of the mucin chain and polymer decide the degree of adhesion. Greater the interpretation of polymer, more is the mucoadhesive.
Fracture	This theory relies on the amount of mechanical force required to separate the adhered surface.
Adsorption	Different types of primary and secondary forces such as ionic, covalent, and hydrogen bonds are responsible for mucoadhesion.
Electronic	Built on the assumption that the mucoadhesive and biological layer possess opposite charges, which lead to attraction and the subsequent mucoadhesion.

Till date, the mucoadhesive GRDDS has been successfully formulated as capsules, films, tablets, with the usage of polymers like carbopol, chitosan, HPMC, etc^46,28,5.

[I] Microballoons/Hollow microspheres:

Microballoons with other polymer are developed by simple solvent evaporation to increase the GRT (gastric retention time) of the dosage form. Polymers are utilized to build up their systems which are cellulose acetate, calcium alginate, polycarbonate,low methoxylated pectin,and Eudragit S, etc. Drug release from dosage forms that depends upon the number of polymers, solvent, and plasticizer polymer ratios utilized in the formulation. Over the surface of acidic dissolution media, the micro balloons float continuously which consists of surfactant >12 hours. Recently, a system based on cross-linked beads builds up by Alginate beads, develop a multiple-unit floating system.They create by using Ca2+ and low methoxylated pectin. In this strategy, sodium alginate course of action is dropped into the watery plan of calcium chloride and cause the precipitation of calcium alginate. These globules are segregated and dried by means of air convection and freeze-drying, inciting the specifying of a penetrable system/permeable system, which can save a drifting power for in excess of 12 hrs. More than 5.5 hrs will be gastric maintenance time with the assistance of beads^48-50.

Evaluation parameters of GRDDS:

1. In vivo evaluation parameters

2. In vitro evaluation parameters

1. In Vivo Parameter of GRDDS:

To support the invivo adequacy of GRDDS, animal models and human studies are required. In in vivo studies, the developed pharmaceutical formulation is examined for its bioavailability and GRT⁵¹. Different diagnostic imaging procedures such as gastroscopy, radiology, scintigraphy, magnetic resonance imaging (MRI), and gamma scintigraphy are used for assessing the invivo parameters of GRDDS⁵². Usage of the gamma scintigraphy technique has greatly helped in the determination of the various parameters such as their location, extent, and their passage through the GIT²². The significant benefit of this procedure is that with the application of minute doses of radiation, results with a good safety profile can be obtained⁵³. For the finding and checking of GRDDS, one more strategy known as gastroscopy is additionally utilized, MRI are quite effective techniques for the invivo estimation of GRDDS⁴.

In the MRI, a strong magnetic field is utilized to see the whole anatomical structures and also the location of ingested dosage forms for visualization. It was successfully and accurately detected the location and RT(residence time) in human subjects²².

2. In vitro evaluation parameters:

In vitro evaluations of GRDDS can be utilized to anticipate the in vivo execution. For the evaluation of the floating behavior of low-density systems, we utilize floating behavior like, total floating duration and floating lag time. Moreover, to assess the floating capacity of the floating tablet, its floating force is also measured⁵⁴. Other assessment parameters, for example, the swelling rate, gel strength, and water take-up limit of the polymeric measurement structure can be surveyed using dissolution mode for somewhere around 8 h to ensure drug discharge, the floating component, and gel strength^55,56.

Future prospective:

The GRT of the conventional dosage form is one among fundamental difficulties. Drawbacks of conventional dosage forms are overcome by developing GRDDS. No single methodology may be awesome settling the issues. Combination approaches like effervescent floating systems and expandable floating systems might be valuable techniques.It is crucial to evaluate gastro retentive dosage forms in situations and different cases. The choice of a proper concentration of polymer is similarly significant for formulating and designing dosage forms. Quality by plan (QbD) approach can be significant for exploring the effect interaction and detailing factors on the fundamental quality credit.

CONCLUSION:

An intensive comprehension of the anatomy and physiological condition of the stomach, examinations concerning the process and formulation factors on dose quality is essential. Different GRDDS, for example, bio/mucoadhesive low density and high-density systems, magnetic, have been accounted for in the literature.

CONFLICT OF INTEREST:

All the authors declare no conflicts of interest associated with this publication.

REFRENCES:

1. Parikh DC and Amin AF. In vitro and in vivo techniques to assess the performance of gastro-retentive drug delivery systems: A review. Expert Opinion on Drug Delivery. 2008; 5(9): 951–965. doi: 10.1517/17425247.5.9.951.

2. Mehta M. Neeta. Pandey P. Mahajan S. Satija S. Gastro retentive drug delivery systems: An overview. Research Journal of Pharmacy and Technology. 2018; 11(5): 2157–2160. doi:10.5958/0974-360X.2018.00398.0.

3. Prajapati VD. Jani GK. Khutliwala TA. Zala BS. Raft forming system - An upcoming approach of gastroretentive drug delivery system. Journal of Controlled Release. 2013; 168(2): 151–165. doi: 10.1016/j.jconrel.2013.02.028.

4. Mandal UK. Chatterjee B. Senjoti FG. Gastro-retentive drug delivery systems and their in vivo success: A recent update. Asian Journal of Pharmaceutical Sciences. 2016; 11(5): 575–584. doi:org/10.1016/j.ajps.2016.04.007.

5. Patil H. Tiwari RV. Repka MA. Recent advancements in mucoadhesive floating drug delivery systems: A mini-review. Journal of Drug Delivery Science and Technology. 2016; 31: 65–71. doi:10.1016/j.jddst.2015.12.002.

6. Hwang SJ. Park H. Park K. Gastric retentive drug-delivery systems. Critical Reviews TM in Therapeutic Drug Carrier Systems. 1998; 15(3): 243–284. doi:10.1615/CritRevTherDrugCarrierSyst.v15.i3.20.

7. Tripathi J. Thapa P. Maharjan R. Jeong SH. Current state and future perspectives on gastroretentive drug delivery systems. Pharmaceutics. 2019; 11(4):193. doi: 10.3390/pharmaceutics11040193.

8. Davis SS. Formulation strategies for absorption windows. Drug Discovery Today. 2005; 10(4): 249–257. doi: 10.1016/S1359-6446(04)03351-3.

9. Thapa P and Jeong S. Effects of Formulation and Process Variables on Gastroretentive Floating Tablets with A High-Dose Soluble Drug and Experimental Design Approach. Pharmaceutics. 2018; 10(3): 161. doi: 10.3390/pharmaceutics10030161.

10. Talukder R and Fassihi R. Gastroretentive delivery systems: A mini review. Drug Development and Industrial Pharmacy. 2004; 30(10): 1019–1028. doi: 10.1081/ddc-200040239.

11. Salessiotis N. Measurement of the diameter of the pylorus in man. Part I. Experimental project for clinical application. The American Journal of Surgery. 1972 ; 124(3): 331–333. doi:org/10.1016/0002-9610(72)90036-0.

12. Clarke GM. Newton JM. Short MD. Gastrointestinal transit of pellets of differing size and density. International Journal of Pharmaceutics. 1993; 100 (1-3): 81–92. doi:10.1111/j.2042-7158.1990.tb06604.x.

13. Streubel A. Siepmann J. Bodmeier R. Drug delivery to the upper small intestine window using gastroretentive technologies. Current Opinion in Pharmacology. 2006; 6(5): 501–508. doi:10.1016/j.coph.2006.04.007.

14. Pattanayak D. Arun JK. Adepu R. Shrivastava B. Hossain CM. Das S. Formulation and Evaluation of Floating and Mucoadhesive Tablets containing Repaglinide. Research Journal of Pharmacy and Technology. 2020; 13(3): 1277–1284. doi:10.5958/0974-360X.2020.00235.8.

15. Sarmah J and Choudhury A. Formulation and Evaluation of Gastro Retentive Floating Tablets of Ritonavir. Research Journal of Pharmacy and Technology. 2020; 13(9): 4099–4104. doi:10.5958/0974-360X.2020.00724.6.

16. Devendiran B. Mothilal M. Damodharan N. Floating Drug Delivery an Emerging Technology with Promising Market value. Research Journal of Pharmacy and Technology. 2020 ;13(6): 3014–3020. doi:10.5958/0974-360X.2020.00533.8.

17. Gupta H. Bhandari D. Sharma A. Recent Trends in Oral Drug Delivery: A Review. Recent Patents on Drug Delivery and Formulation. 2009; 3(2): 162–173. doi:10.2174/187221109788452267.

18. Baumgartner S. Kristl J. Vrecer F. Vodopivec P. Zorko B. Optimisation of floating matrix tablets and evaluation of their gastric residence time. International Journal of Pharmaceutics. 2000; 195(1-2): 125–135. doi: 10.1016/s0378-5173(99)00378-6.

19. Jiménez-Martínez I. Quirino-Barreda T. Villafuerte-Robles L. Sustained delivery of captopril from floating matrix tablets. International Journal of Pharmaceutics.2008; 362(1-2): 37–43. doi:10.1016/j.ijpharm.2008.05.040.

20. Kim S. Hwang KM. Park YS. Nguyen TT. Park ES. Preparation and evaluation of non-effervescent gastroretentive tablets containing pregabalin for once-daily administration and dose proportional pharmacokinetics. International Journal of Pharmaceutics. 2018; 550(1-2): 160–169. doi: 10.1016/j.ijpharm.2018.08.038.

21. Tripathi J. Thapa P. Maharjan R. Jeong SH. Current State and Future Perspectives on Gastroretentive Drug Delivery Systems. Pharmaceutics. 2019; 11(4): 193. doi:10.3390/pharmaceutics11040193.

22. Klausner EA. Lavy E. Friedman M. Hoffman A. Expandable gastroretentive dosage forms. Journal of Controlled Release. 2003; 90(2): 143–162. doi:10.1016/s0168-3659(03)00203-7.

23. Garg R and Gupta G. Progress in Controlled Gastroretentive Delivery Systems. Tropical Journal of Pharmaceutical Research. 2008; 7(3): 1055–1066. doi:10.4314/tjpr.v7i3.14691.

24. Lopes CM. Bettencourt C. Rossi A. Buttini F. Barata P. Overview on gastroretentive drug delivery systems for improving drug bioavailability. International Journal of Pharmaceutics. 2016; 510(1): 144–158. doi:10.1016/j.ijpharm.2016.05.016.

25. Chen YC. Ho HO. Lee TY. Sheu MT. Physical characterizations and sustained release profiling of gastroretentive drug delivery systems with improved floating and swelling capabilities. International Journal of Pharmaceutics. 2013; 441(1-2): 162–169. doi:10.1016/j.ijpharm.2012.12.002.

26. Omidian H. Rocca JG. Park K. Advances in superporous hydrogels. Journal of Controlled Release. 2005; 102(1): 3–12. doi:10.1016/j.jconrel.2004.09.028.

27. Park H. Park K. Kim D. Preparation and swelling behavior of chitosan-based superporous hydrogels for gastric retention application. Journal of Biomedical Materials Research. 2006; 76(1): 144–150. doi:10.1002/jbm.a.30533.

28. Bardonnet PL. Faivre V. Pugh WJ. Piffaretti JC. Falson F. Gastroretentive dosage forms: Overview and special case of Helicobacter pylori. Journal of Controlled Release. 2006; 111(1-2): 1–18. doi:10.1016/j.jconrel.2005.10.031.

29. Bhalla S and Nagpal M. Comparison of Various Generations of Superporous Hydrogels Based on Chitosan-Acrylamide and In Vitro Drug Release. ISRN Pharmaceutics. 2013; 2013:1-8. doi:10.1155/2013/624841.

30. Fujimori J. Machida Y. Tanaka S. Nagai T. Effect of magnetically controlled gastric residence of sustained release tablets on bioavailability of acetaminophen. International Journal of Pharmaceutics. 1995; 119(1): 47–55. doi:10.1016/0378-5173(94)00368-F

31. Prajapati VD. Jani GK. Khutliwala TA. Zala BS. Raft forming system - An upcoming approach of gastroretentive drug delivery system. Journal of Controlled Release. 2013; 168(2): 151–165. doi: 10.1016/j.jconrel.2013.02.028.

32. Murphy C. Pillay V. Choonara YE. Toit LCD. Gastroretentive Drug Delivery Systems: Current Developments in Novel System Design and Evaluation. Current Drug Delivery. 2009; 6(5): 451–460. doi:10.2174/156720109789941687.

33. Gröning R. Berntgen M. Georgarakis M. Acyclovir serum concentrations following peroral administration of magnetic depot tablets and the influence of extracorporal magnets to control gastrointestinal transit. European Journal of Pharmaceutics and Biopharmaceutics. 1998; 46(3): 285–291. doi:10.1016/s0939-6411(98)00052-6.

34. Ito R. Machida Y. Sannan T. Nagai T. Magnetic granules: a novel system for specific drug delivery to esophageal mucosa in oral administration. International Journal of Pharmaceutics. 1990; 61(1-2): 109–117. doi:org/10.1016/0378-5173(90)90049-A.

35. Awasthi R and Kulkarni GT. Decades of research in drug targeting to the upper gastrointestinal tract using gastroretention technologies: where do we stand? Drug delivery. 2016; 23(2): 378–394. doi:10.3109/10717544.2014.936535.

36. Anand V. Kandarapu R. Garg S. Ion-exchange resins: Carrying drug delivery forward. Drug Discovery Today. 2001; 6(17): 905–914. doi:10.1016/s1359-6446(01)01922-5.

37. Jeong SH and Park K. Drug loading and release properties of ion-exchange resin complexes as a drug delivery matrix. International Journal of Pharmaceutics. 2008; 361(1-2): 26–32. doi:10.1016/j.ijpharm.2008.05.006.

38. Gaur PK. Mishra S. Bhardwaj S. Puri D. Kumar SS. Ion Exchange Resins in Gastroretentive Drug Delivery: Characteristics, Selection, Formulation and Applications. Journal of Pharmaceutical Sciences and Pharmacology. 2015; 1(4): 304–312. doi:10.1166/jpsp.2014.1037.

39. Seong HJ. Berhane NH. Haghighi K. Park K. Drug release properties of polymer coated ion-exchange resin complexes: Experimental and theoretical evaluation. Journal of Pharmaceutical Sciences. 2007; 96(3): 618–632. doi:10.1002/jps.20677.

40. Abouelatta SM. Aboelwafa AA. El-Gazayerly ON. Gastroretentive raft liquid delivery system as a new approach to release extension for carrier-mediated drug. Drug delivery. 2018; 25(1): 1161–1174. doi:10.1080/10717544.2018.1474969.

41. Youssef NAHA. Kassem AA. El-Massik MAE. Boraie NA. Development of gastroretentive metronidazole floating raft system for targeting Helicobacter pylori. International Journal of Pharmaceutics. 2015; 486(1-2): 297–305. doi:10.1016/j.ijpharm.2015.04.004.

42. Sarparanta MP. Bimbo LM. Mäkilä EM. Salonen JJ. Laaksonen PH. Helariutta AMK. Linder MB et al The mucoadhesive and gastroretentive properties of hydrophobin-coated porous silicon nanoparticle oral drug delivery systems. Biomaterials. 2012; 33(11): 3353–3362. doi:10.1016/j.biomaterials.2012.01.029.

43. Wang J. Tauchi Y. Deguchi Y. Morimoto K. Tabata Y. Ikada Y. Positively charged gelatin microspheres as gastric mucoadhesive drug delivery system for eradication of H. pylori. Drug delivery. 2000; 7(4): 237–243. doi:10.1080/107175400455173.

44. Shtenberg Y. Goldfeder M. Prinz H. Shainsky J. Ghantous Y. El-Naaj IA. Schroeder A et al Mucoadhesive alginate pastes with embedded liposomes for local oral drug delivery. International Journal of Biological Macromolecules. 2018; 111: 62–69. doi:10.1016/j.ijbiomac.2017.12.137.

45. Ch'ng HS. Park H. Kelly P. Robinson JR. Bioadhesive polymers as platforms for oral controlled drug delivery II: synthesis and evaluation of some swelling, water-insoluble bioadhesive polymers. Journal of Pharmaceutical Sciences.1985; 74(4): 399-405. doi:10.1002/jps.2600740407.

46. Smart JD. The basics and underlying mechanisms of mucoadhesion. Advanced Drug Delivery Reviews. 2005; 57(11): 1556–1568. doi:10.1016/j.addr.2005.07.001.

47. Andrews GP. Laverty TP. Jones DS. Mucoadhesive polymeric platforms for controlled drug delivery. European Journal of Pharmaceutics and Biopharmaceutics. 2009; 71(3): 505–518. doi:10.1016/j.ejpb.2008.09.028.

48. Inukai K. Takiyama K. Noguchi S. Iwao Y. Itai S. Effect of gel formation on the dissolution behavior of clarithromycin tablets. International Journal of Pharmaceutics. 2017; 521(1-2): 33–39. doi:10.1016/j.ijpharm.2017.01.065.

49. El-said IA. Aboelwafa AA. Khalil RM. ElGazayerly ON. Baclofen novel gastroretentive extended release gellan gum superporous hydrogel hybrid system: in vitro and in vivo evaluation. Drug Delivery. 2016; 23(1): 101–112. doi:10.3109/10717544.2014.905654.

50. Shah S and Pandya S. A Novel Approach In Gastro Retentive Drug Delivery System: Floating Drug Delivery System. International Journal Of Pharmaceutical Sciences And Research. 2021; 2(5): 7-18. doi:http://dx.doi.org/10.13040/IJPSR.0975-8232.

51. Biradar V. Basavarajaiah JM. Win MTT. Gudugunta L. Suresh KV. Kumar SM. Turagam N et al In vitro Evaluation of Gastro Retentive Drug Delivery System of Lansoprazole. Research Journal of Pharmacy and Technology.2019; 12(8): 3649–3653. doi:10.5958/0974-360X.2019.00622.X.

52. Abbott CR. Small CJ. Sajedi A. Smith KL. Parkinson JRC. Broadhead LL. Ghatei MA et al The importance of acclimatisation and habituation to experimental conditions when investigating the anorectic effects of gastrointestinal hormones in the rat. International Journal of Obesity. 2006; 30(2): 288-292. doi:10.1038/sj.ijo.0803137.

53. Badve SS. Sher P. Korde A. Pawar AP. Development of hollow/porous calcium pectinate beads for floating-pulsatile drug delivery. European Journal of Pharmaceutics and Biopharmaceutics. 2007; 65(1): 85–93. doi:10.1016/j.ejpb.2006.07.010.

54. Seth KCN and Gill NS. Gastro Retentive Drug Delivery System: A Significant tool to Increase the gastric residence time of drugs. International Journal of Current Pharmaceutical Research.2021; 13(1): 7–11. doi:org/10.22159/ijcpr.2021v13i1.40818.

55. Parikh DC and Amin AF. In vitro and in vivo techniques to assess the performance of gastro-retentive drug delivery systems: A review. Expert Opinion on Drug Delivery. 2008; 5(9): 951–965. doi:10.1517/17425247.5.9.951.

56. Tandon A and Jangra PK. Formulation and in vitro Evaluation of Lisinopril floating Gastroretentive Tablets. Research Journal of Pharmacy and Technology. 2021; 14(1): 207–213. doi:10.5958/0974-360X.2021.00036.6.

Received on 22.11.2021 Modified on 30.12.2021

Research J. Pharm. and Tech 2023; 16(1):453-458.

DOI: 10.52711/0974-360X.2023.00077