Gastroretentive Dosage Form Research Articles

Investigation of cannabidiol gastro retentive tablets based on regional absorption of cannabinoids in rats

The cannabis plant has been widely researched for many therapeutic indications and found to be effective in many chronic conditions such as epilepsy, neuropathic or chronic pain and more. However, biased opinion against compounds of the plant, regulatory as well as compounding challenges have led to very few approved cannabinoid medicinal products. Those formulations which are approved are dosed several times a day, creating an unmet need for controlled release (CR) formulations of cannabinoids. Conventional CR formulations rely on prolonged absorption of the drug, including absorption from the colon. The purpose of this work is to investigate regional absorption of major cannabinoids THC and CBD from the colon and develop a suitable CR formulation.As hypothesized by researchers, THC and CBD have poor absorption from the colon compared to small intestine, suggesting that these compounds have a narrow absorption window. The suggested CR formulation examined in-vitro was a floating gastro retentive tablet based on egg albumin matrix, gas generating agents and surfactants. In-vivo investigation of CBD containing formulation in the freely moving rat model proved a prolonged absorption phase with a substantial increase in bioavailability compared to CBD solution.The findings of this paper answer a crucial question regarding potential application of CR dosage forms for cannabinoids and shed light on the regional intestinal absorption of these compounds. Ultimately, these results cement the way for future development of cannabinoid gastro retentive dosage forms.

Formulation and evaluation of floating mucoadhesive microspheres loaded with antiulcer drug

The objective of the present study was to formulate and evaluate Floating-mucoadhesive microspheres which is loaded with famotidine for the treatment of Helicobacter pyloric (H. pylori) infection. Formulation of Gastro - Retentive Dosage Forms (GRDFs) containing suitable drug candidate which would remain in stomach and/or upper part of GIT for prolonged period of time thereby is maximizing the drug release at desired site within the time before GRDFs leave the stomach and or upper part of GIT. Tablets were prepared by Ionic gelation method by using the polymers such as HPMC K4m, ethyl cellulose, sodium alginate, calcium chloride and by keeping the concentration of HPMC, sodium alginate, calcium chloride were constant and five formulation were prepared was evaluated for drug - excipient compatibility, density, buoyancy test, mucoadhesion force, percentage yield, entrapment efficiency, particle size and in-vitro release profile and stability studies of optimized formulation. Analysis of drug release from tablet indicates drug release by zero order rate kinetics. No significant change was observed in physical appearance, drug content, floatability or in vitro dissolution pattern after storage at 40°C±2°/75% RH for six months. Formulation no: 5 was found to be the optimized one which is satisfying all the required specifications.

Pharmacokinetic and pharmacodynamic basis for developing modified-release formulations of furosemide

Furosemide has a narrow absorption window restricted to the upper part of the gastrointestinal tract due to its ionization in the gut. Therefore, dissolution of the dose entirely in the stomach was the main aim in the development of gastroretentive extended-release dosage forms in order to sustain its delivery without losing bioavailability. Just as pharmacokinetics (PK) is a prerequisite for observing a pharmacodynamic response (PD) in the individual, the intensity of such a response could also modulate the PK of the drug whenever some physiological mechanism triggered an increase or decrease in the renal fraction of cardiac output. The urine volume increase caused by furosemide triggers the arrival of a supplementary number of molecules at the site of action, and therefore its urinary excretion rate experiences an increase in line with this new cardiac output distribution. It was found that the diuretic effect of furosemide conditioned its urinary excretion clearance. Therefore, its urinary recovery would not reflect the systemic bioavailability of formulations, but both their actual bioavailability at the biophase and their diuretic responses instead. Extended drug input yielded a more efficient diuretic response than the whole dose given rapidly, provided that drug levels at the action site were above the minimum effective concentration. A deep knowledge in the pharmacodynamics-pharmacokinetics (PD-PK) relationships is fundamental to achieve successful furosemide dosage forms. The relation between: drug excretion rates and the intensity of urine output; diuretic efficiency and drug delivery rates; and the benefit of sustained drug delivery are here analyzed. All this together leads us to conclude that the best strategy for developing gastroretentive dosage forms of furosemide would be by including two moieties within the formulation: an accelerated-release loading dose and an extended-release maintenance dose.

Retentive drug delivery systems based on shape memory materials

ABSTRACTRetentive drug delivery systems are intended for prolonged residence and release inside hollow organs of the body, in pursuit of either local or systemic therapeutic goals. Because of the relatively long‐lasting period of time they could cover during operation, a primary advantage arising from their use would lie in reduced dosing frequency, thereby improving the overall adherence of patients to prescribed medication regimens. The treatment of numerous pathologies that affect the urinary bladder and the stomach could especially benefit from viability of such delivery technologies. Moreover, by making use of effective gastroretentive dosage forms, the bioavailability of drugs that are preferably absorbed from the upper gastrointestinal tract could be increased. Expansion of devices following administration is often exploited for retention purposes, and several formulation strategies have been proposed in this respect. Innovative applications of shape memory materials have also been explored, highlighting the great inherent potential for facing the challenges involved. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48798.

Effervescent Floating Drug Delivery System: A Review

Oral sustained release gastro-retentive dosage forms offer many advantages for drugs with the absorption from upper parts of the gastro intestinal tract. Gastric emptying is a complex process and it is highly variable. The floating drug delivery systems are useful methods to avoid this variability which increases the retention time of the drug delivery systems for more than 12 hours.these systems are useful for many of the problem occurred during development of pharmaceutical dosage form. The objective of the review is to understand the current approaches of this drug delivery system.

Formulation and In Vitro Evaluation of Sustained Release Floating Matrix Tablet of Levofloxacin by Direct Compression Method

The objective of the present work was to develop Gastro retentive dosage forms which would remain in the stomach and upper part or GIT for a prolonged period of time thereby maximizing the drug release at desired site within the time before GRDFs left the stomach and upper part of the GIT, has provoked a great deal of increased interest in the formulation of such drug as floating drug delivery systems. Levofloxacin, (BCS class I) is a fluoroquinolone anti-bacterial agent. The rationale for the formulation of floating matrix tablet are acidic solubility of levofloxacin, residence of Halicobactor pylori mainly in sub region of stomach and the overdosing associated adverse effect due to continuous intake of drug in acute infection. A simple visible spectrophotometric method was employed for the estimation of levofloxacin at 294 nm and Beer’s law is obeyed in the concentration range of 2-10 μg /ml. Floating matrix tablet of levofloxacin was prepared by direct compression method using different polymers like hydroxyl propyl methyl cellulose (HPMC K4) and carbopol 934 as matrix formation polymers, sodium bicarbonate and citric acid was used as gas generating agents. The FTIR spectra of the levofloxacin and other excipients alone and in combination show the compatibility of the drug and excipients. Six formulations of different polymer percentages were formulated (F1-F6). Pre-compression parameters were evaluated. The influence of matrix forming agents and binary mixtures of them on levofloxacin release was investigated. The formulated tablets were characterized by hardness, friability, thickness, weight variation and in vitro drug release. The formulated tablets had acceptable physicochemical characters. The data obtained from the in-vitro dissolution studies of optimized batch F4were fitted in different models. The optimized formulation F4 showed 99.25% drug content and swelling index of 79.85 %. Drug release mechanism was found to be first order kinetics. Levofloxacin floating tablets exhibited increased gastric residence time, there by improved bioavailability and therapeutic effect of the drug.

Formulation Optimization for Gastroretentive Drug Delivery System of Carvedilol Cocrystals Using Design of Experiment

The objective of this study was to develop a gastroretentive dosage form (GRDF) of carvedilol cocrystals that were prepared utilizing hot-melt extrusion (HME) in order to prolong its gastric residence time. GRDF was optimized using Box-Behnken Design. The carvedilol nicotinamide cocrystals prepared in the ratio of 1:2 (drug:coformer) utilizing hot-melt extrusion (Omega10). The tablets were prepared by direct compression using cocrystals along with remaining excipients that include HPMC K4M, HPMC E50, Carbopol 934P, sodium bicarbonate, microcrystalline cellulose, talc, and magnesium stearate. Concentrations of HPMC E50, HPMC K4M, and Carbopol 934P were selected as independent factors while the gastroretentive parameters such as floating lag time (FLT), percentage of drug release in 2 h, and percentage of cumulative drug release in 12 h were selected as dependent variables in optimizing GRDF of carvedilol cocrystals. Test such as total floating time (TFT), floating lag time (FLT), swelling studies, dissolution studies, and precompression parameters such as bulk density (BD), tapped density (TD), compressibility index (CI), Hausner’s ratio (HR), and angle of repose were carried out on the optimized formulation. The optimized tablets (F2) prepared by direct compression showed FLT of 11 s after placing the tablets in 0.1 N HCl (pH 1.2) with controlled drug release for 12 h where the mechanism of drug release was found to be Non-Fickian type of diffusion (swelling, erosion, and diffusion). The in vitro drug release profile of the optimized formulation (F2) was found to be 81.4% at 12 h in comparison with a formulation containing only carvedilol (65.55% drug release at 12 h). The study concluded that the cocrystals of carvedilol that were successfully prepared by HME could be used to prepare and optimize the floating tablets to achieve desired gastroretentive performance with good drug release profile for carvedilol. The results of the comparison of drug release profile between optimized formulation and formulation containing pure drug stressed the importance of preparing cocrystals. The formulation scientist in the future may adopt these strategies in developing GRDF for cocrystals of any drug.

Overview on Trends in Development of Gastroretentive Drug Delivery System

The present review on gastroretentive Drug Delivery Systems was aim with overview on various trends in development of gastroretentive approaches in the area of site-specific orally administered controlled release drug delivery. Gastroretentive dosage form can improve the delivery and performance of drug into the stomach because the drug remains in stomach for sufficient time of interval. The review summarized various physiological requirements and factors affecting gastric retention with merit and demerits of gastroretentive system. Various gastroretentive approaches designed and developed by researchers such as high density (sinking), floating system, bioadhesive, expandable, unfoldable, super porous hydrogel and magnetic systems were highlighted in the article.

Development and Evaluation of Gastro Retentive Controlled Release Dosage Form of Chlordiazepoxide

The aim of present study was to develop and evaluate gastro retentive controlled release dosage form - Hydrodynamically balanced system of Chlordiazepoxide by using Hydroxy Propyl Methyl Cellulose K 4 M and Xanthum gum to avoid accumulation of metabolites of Chlordiazepoxide and to reduce dosing frequency. Tablets were prepared successfully by wet granulation method by using PVP K30 as binding agent and HPMC K4M, Xanthum gum as retarding polymer. Optimization of formulation was done by using 32 full factorial design where independent variables are X1 (concentration of HPMC K4M ) and X2 (concentration of Xanthum gum).The prepared blend of tablet were evaluated for precompression parameters like bulk density, tapped density, carr’s index, hausner’ ratio, in vitro drug release, % swelling index and stability study. The prepared blend has good flow property and compressibility.Due to combination of HPMC K4M and Xanthum gum polymers tablets maintain its matrix integrity and show good prolonged release in controlled manner. Swelling index was in range from 33 to 75 %. In vitro drug release of tablet was carried in 0.1N HCL up to 18 hrs. and its show 95-98 % drug release. Use of Xanthum gum control the initial burst drug release effect of matrix tablet and HPMC is rapidly swelling hydrophilic polymer which form highly viscous gel barrier which control the drug release from system.

Gastro retentive Drug Delivery of Cyclobenzaprine Hydrochloride

Drugs that are easily absorbed from the GI tract and have a short half-life are eliminated quickly from the blood circulation, require frequent dosing. To avoid this problem, the oral controlled release formulations are being developed. Gastro-retentive dosage forms have the potential from use as controlled release systems. The purpose of this research is to develop the gastro retentive drug delivery system of centrally acting alpha adrenergic agonist cyclobenzaprine Hydrochloride (cyclobenzaprine HCl). It is well absorbed from the upper part of the GIT, due to short gastric residence time the bioavailability is low and hence it is need to develop a dosage form that releases the drug in stomach using gastro retentive system. Different formulations of cyclobenzaprine HCl gastro-retentive floating tablets were prepared by wet granulation method using various concentrations of HPMC K4M / HPMC K100M and combination of Psyllium husk and HPMC K100M as matrix forming agent. Sodium bicarbonate and citric acid were used as a gas generating agent that helps in maintaining the buoyancy. The prepared cyclobenzaprine HCl gastro-retentive floating granules were subjected to pre-compression properties to comply with pharmacopoeial limits and the prepared gastro-retentive floating tablets were characterized for weight variation, hardness, thickness and friability drug content, swelling studies. The floating lag time of all formulation is good and the Total floating time of all the formulations was >12 hours. The tablets were evaluated for in vitro release characteristics for 12hrs in 0.1N HCl at 37 oC and from this in vitro release studies the formulations F-5, F-9 and F-15 exhibited good controlled release profile of about 96.0%, 94.5% and 95.0% when compared with other formulations while floating on the dissolution medium.

DESIGN AND CHARACTERIZATION OF ALFUZOSIN HCL GASTRORETENTIVE FLOATING MATRIX TABLETS EMPLOYING HPMC K 100M

The present investigation involves developing gastro retentive drug delivery systems (GFDDS) of alfuzosin HCl using HPMCK100M a is the matrixing agent and floating enhancer. Sodium bicarbonate in the acidic environment reacts with the acid and produces carbon dioxide. The gastro retentive tablets can be formulated to increase the gastric residence time and thereby increase the oral bioavailability. From the drug release study, it was concluded that the AFTB4 formula of HPMC K 100 M matrix tablets gives the controlled release up to 12 hours by showing increased release with floating lag time 24 seconds. Non – Fickian diffusion was the drug release mechanism from the matrix tablets formulated employing HPMC K 100 M. The matrix tablets (AFTB4) formulated employing 40 % HPMC K 100 M are best suited to be used for gastro retentive dosage form of alfuzosin HCl. Finally, it can be concluded that good candidates for the preparation of gastro retentive dosage forms due its gastric stability, gastric absorption and better bioavailability.

GASTRORETENTIVE DRUG DELIVERY SYSTEM

Oral route of drug administration is the most preferable route because of its flexibility in formulation, ease of administration, and patient compliance. But this route has certain limitations like limited gastric residence time (GRT) for sustained drug delivery system and for the drugs which are absorb from specific region of gastrointestinal tract (GIT). To overcome these limitations, various approaches have been proposed to increase the gastric retention time of the delivery system in the upper part of gastrointestinal tract. Gastroretentive dosage form (GRDF) prolongs the GRT by targeting site-specific drug release in upper part of GIT. GRDFs enable continuous and the extended duration of drug release and improve bioavailability of drugs that have narrow therapeutic window, by this way they prolong dosing interval and increase compliance of the patient. The purpose of this article is to compile the various gastroretentive approaches. In order to understand various physiological difficulties to achieve gastric retention, we have summarized important factors controlling gastric retention. Finally the evaluation parameters of gastroretentive drug delivery systems are covered. The present review addresses briefly about the current status of various leading gastroretentive drug delivery technologies, developed until now, i.e. high density (sinking), floating, bio- or mucoadhesive, expandable, unfoldable, super porous hydrogel, magnetic systems etc. In addition, important factors controlling gastroretention, advantages and finally, future potential are discussed.Keywords: Floating Delivery, Gastro retentive system.Â

FORMULATION AND EVALUATION OF FLOATING MATRIX TABLETS OF LEVOFLOXACIN HEMIHYDRATE USING HYDROXYPROPYL METHYLCELLULOSE K4M TO TREAT HELICOBACTER PYLORI INFECTION

Objective: The aim of the study was to develop a floating drug delivery system of levofloxacin (LVF) hemihydrate for sustained drug delivery to improve the extended retention in the stomach, oral bioavailability, and local site-specific action in the stomach. Methods: Preparation of LVF tablets using melt granulation method using hydroxypropyl methylcellulose (HPMC) K4M with sodium bicarbonate as gas generating agent. From LFTA1 to LFTA5, formulations were developed and evaluated for floating properties for swelling characteristics and in vitro drug release studies. In vitro dissolution was carried out using USP II paddle method using 0.1N HCI pH buffer at 50 rpm and samples were measured at 294 nm using ultraviolet-visible spectroscopy. Results: Obtained Fourier-transform infrared charts indicated that there is no positive evidence for the interaction between LVF and ingredients of the optimized formula. In vitro drug release was performed and drug release kinetics were evaluated using the linear regression method and were found to be followed the zero-order release by diffusion controlled release. Optimized formula was found to be LFTA4 with 20% of a polymer with 99.03% of drug release with 12 h of floating time and 32 s floating lag time. Conclusion: Matrix tablets (LFTA4) formulated employing 20% HPMC K4M are best suited to be used for gastroretentive dosage form of LVF.

FORMULATION AND EVALUATION OF COMPRESSION COATING FLOATING TABLETS OF CARVEDILOL PHOSPHATE ONCE DAILY DOSE

Objective: The rationale for the study was to develop a once-daily dose of immediate as well as a gastro-retentive form of carvedilol phosphate by compression coating floating technique.Methods: In the presented study the core tablet was containing half the quantity of the drug formulated as floating drug delivery using different controlled release polymers blend in various proportions like ethyl cellulose, carbopol, hydroxypropyl methylcellulose (HPMC) K4, K15, and K100 by direct compression method. Outer coat layer was formulated with rest of the drug with the blend of different super disintegrants in various proportions like crospovidone, croscarmellose sodium (CCS), sodium starch glycolate (SSG) for the immediate release of the drug. Both the immediate and controlled formulation was separately formulated from sf1 to sf9 and f1 to f9 respectively. Based on the evaluation parameters finally, formulation F1 to F9 were formulated by applying compression coating floating method. These formulations were characterized for their tablet density, disintegration time, floating lag time, in vitro drug release, drug-excipients interaction and accelerated stability studies etc.Results: The result revealed formulation sf9 containing SSG of 15% was able to 97.2% of drug release within 15 min towards the achievement of immediate release. Similarly, the formulation f9 containing 0.5:0.5:4.5 ratios of ethyl cellulose, carbopol and HPMC K15 was able to 95.3% of drug release within 16h. From compressed coat tablets batches of F1 to F9, based on the dissolution data F9 was considered as an optimized formulation which was able to release 48.6% of drug release within 15 min and cumulatively controlled the release up to 96.4% for 16 h, followed zero-order kinetics and Higuchi pattern.Conclusion: The results obtained in this research work clearly indicated that the compression coating floating tablet of carvedilol phosphate was the best dosage form for the treatment of hypertension. Results of the evaluation of prepared batches indicate that the batch F9 is a promising formulation for both a quick onset of action as well as gastro-retentive dosage form to maintain the constant drug action which would improve the maximum therapeutic efficacy and patient compliance.

Influence of Postprandial Intragastric Pressures on Drug Release from Gastroretentive Dosage Forms.

Despite extensive research in the field of gastroretentive dosage forms, this "holy grail" of oral drug delivery yet remained an unmet goal. Especially under fasting conditions, the reproducible retention of dosage forms in the stomach seems to be an impossible task. This is why such systems are often advised to be taken together with food. But also the postprandial motility can contribute significantly to the failure of gastroretentive dosage forms. To investigate the influence of postprandial pressure conditions on drug release from such systems, we used a novel in vitro dissolution tool, the dissolution stress test device. With the aid of this device, we simulated three different intragastric pressure profiles that may occur after postprandial intake. These transit scenarios were based on recently obtained, postprandial SmartPill® data. The tested systems, Glumetza® 1000 and Madopar® HBS 125, are marketed dosage forms that are based on different approaches to achieve proper gastric retention. All three transit scenarios revealed a highly pressure-sensitive drug release behavior, for both drugs. For Madopar® HBS 125, nearly complete drug release was observed even after early occurring pressures. Glumetza® 1000 seemed to be more resistant to these, most likely due to incomplete wetting of the system. On the contrary to these findings, data from standard dissolution tests using the paddle apparatus displayed controlled drug release for both systems for about 6h. Based on these results, it can be doubted that established gastroretentive systems stay intact over a longer period of time, even under postprandial conditions.

Evaluation of Ciprofloxacin Floating-Bioadhesive Tablet Formulated with Okra Gum as Multifunctional Polymer

Floating drug delivery systems and bioadhesive drug delivery systems are gastroretentive systems for increasing gastric residence time to obtain improved drug bioavailability. This study was to evaluate the floating and bioadhesive characteristics of Ciprofloxacin tablets formulated with Abelmoschus esculentus gum (okra gum).Okra gum was extracted and granules were prepared using the extracted Okra gum as well as sodium alginate and HPMC at concentrations of 2.5, 5 and 10 % w/w. Ciprofloxacin floating bioadhesive (CFB) tablets were evaluated for hardness, friability, in vitro buoyancy test, ex vivo bioadhesion test and drug release profiles. The floating lag time (FLT) and total floating time (TFT) for CFB tablets formulated with 10% w/w okra gum were 5.7 minutes and 8 hours respectively while the bioadhesive force was 1.324 N. Formulations of ciprofloxacin tablets containing admixtures of okra gum and sodium alginate or HPMC resulted in significant decrease (p < 0.05) in the floating lag times (≤ 3.1 minutes) and significant increase (p < 0.05) in total floating times (> 12 h). The bioadhesive force for CFB tablets containing admixtures of okra gum and sodium alginate or HPMC gave higher values in the range of 1.766 – 2.207 N. The in vitro release profiles for CFB tablets formulated with okra gum alone did not show sustained release below 10 % w/w. Batches FB10 and FB11 containing admixtures showed sustained release with maximum release of 86% at maximum time of 9 h. The dissolution profiles of tablets from batches F10 and F11 compared favourably with the profile for the commercial brand of floating ciprofloxacin tablet, MF. From the study Okra gum has shown to possess good floating and bioadhesive properties and may be utilized in the formulation gastro-retentive dosage form of ciprofloxacin which can possibly be harnessed as a targeted site-specific delivery system in the eradication of Helicobacter pylori in gastric ulcer disease as well as in the treatment of Salmonella typhi induced enteric fever.

Gastro retentive drug delivery systems: An overview

Orally administered gastro retentive dosage forms draws great attention in the pharmaceutical research industry. These systems improved patient compliance with increased therapeutic index of drugs increase importance of gastro-retentive drug delivery systems (GRDDS). Numerous physiological constraints associated with gastroretentive dosage forms such as short gastric retentive time, variations in gastric emptying time can be reduced by various technological advanced utilized in the design and fabrication of gastroretentive dosage. Currently different development approaches are utilized to increase gastric retention time, including High density systems, Expanding systems, Unfoldable and Swellable systems and Superporous hydrogels. The present review briefly addresses various gastroretentive dosage forms for prolongation gastric residence time.

A Comprehensive Note on Gastro-Retentive Dosage Forms

Controlled release drug delivery system has achieved greater importance in the field of pharmaceutical sciences to provide therapeutic advantages over the conventional drug delivery system. Nowadays, the gastrointestinal controlled drug delivery systemis more prominent than the controlled release system because these can govern the release rate of therapeutically active drug for a sustained period. A Gastro retentive dosage form improves the therapy by prolonging the gastric residence time of the drugs. Prolonged gastric retention improvesbioavailability, reduces drug waste and improves solubility for drugs that are less soluble in a high pH environment. In this review, we have discussed various systems associated with gastro retentive drug delivery with their effective mode of action. Also, the approaches and factors to increase the gastric retention time have also been discussed. This drug delivery system has potential to overcome the limitations of the conventional system. The present study is performed for the motivation of the graduates towards publication and research. Hence, we have encouraged the graduates to prepare an informative article on the present subject.

FORMULATION DEVELOPMENT AND EVALUATION OF GASTRO-RETENTIVE DOSAGE FORM OF ATAZANAVIR SULPHATE

Objective: To improve dissolution properties of atazanavir sulphate by preparing gastro-retentive granules by solid dispersion method and development of RP-HPLC method for estimation of this drug.Methods: Estimation of atazanavir sulphate was done using high performance liquid chromatography (HPLC) on inertsil column (5 µm, 250x4, 6 mm) with a mobile phase consists of methanol: water (91:9 v/v), at 0.5 ml/min flow rate and 249 nm UV detection. The method was validated as per ICH guidelines. Selection of the carrier for gastro-retentive formulation was based on phase solubility study of the drug. Solid dispersions of gastro-retentive granules of different composition of drug and carrier, were prepared by the kneading, heating and solvent evaporation. A 32factorial design was applied to optimize the gastro-retentive formulation. The amounts of polyethylene glycol 6000 (PEG 6000) (X1) and hydroxypropyl methyl cellulose (HPMC) (X2) were selected as independent variables and in vitro-release at 5, 9 h and total floating time was selected as dependent variables. Results: HPLC method was found to be linear in a concentration range of 10-60 μg/ml of the drug (r2= 0.999). The low value of % RSD in precision study indicates reproducibility of the method. The low value of LOD and LOQ suggests the sensitivity of the method. The solubility enhancement study of drug with various carriers followed descending order of solubility [Gelucire 44/14>PEG 6000>polyvinyl pyrrilidone (PVP)]. Highest % cumulative release was observed for the heating method at drug polymer (PEG 6000) ratio 1:5. Hence, this ratio has been selected for preparation of solid dispersion. From comparison of dissolution profile of formulated batches, formulation F4 [containing PEG6000 (1.6 g) and HPMC (200 mg)] showed promising dissolution parameters with desired floating properties.Conclusion: Results obtained by validation studies suggested that the developed HPLC method is simple, accurate, precise and can be used for routine analysis of atazanavir sulphate formulation. Results of evaluation of prepared batches indicate that batch F4 is a promising formulation for gastro-retentive dosage form of drug.

Pharmaceutical Formulations to Increase Gastric Residence Time: Concepts and Strategies

Background and Objective: Gastroretentive dosage forms have emerged as efficient means for oral controlled delivery of several drugs. The objective of this review is to bring under one umbrella, all the necessary knowledge regarding gastroretentive dosage forms, especially floating dosage forms. Methods: The review covers basic anatomy and physiology of gastrointestinal tract, gastric emptying and related problems in drug absorption, candidate drugs and drugs unsuited for gastroretentive formulations, pharmacokinetics of gastroretentive formulations and factors affecting gastric residence time of dosage forms. Various approaches coined by different researchers to achieve prolonged gastric residence time like low density floating systems, high density sinking systems, modified shape systems, size controlled systems, muco-adhesive systems and magnetic systems are also detailed. Special emphasize is given to floating dosage forms, their advantages, disadvantages, excipients used in the formulation, critical parameters and methods of evaluation. Conclusion: The article is expected to motivate the researchers to investigate on gastroretentive dosage forms systematically. Keywords: Gastroretentive, floating, mucoadhesive, drug delivery, bioavailability, stomach specific.