bioavailability

Gastroretentive drug delivery systems (GRDDS) have emerged as an advanced approach to overcome the limitations of conventional oral dosage forms by prolonging gastric residence time and improving drug bioavailability. The objective of these systems is to remain buoyant in gastric fluid for extended periods, allowing controlled release of drugs and enhanced absorption of medications with limited absorption windows. Floating tablets achieve buoyancy using low-density excipients, such as gas-generating substances like sodium bicarbonate, or swellable polymers like hydroxypropyl methylcellulose (HPMC). Formulation strategies generally employ polymeric matrices, effervescent components, or coating technologies to regulate release kinetics and enhance stability. Evaluation parameters, such as floating lag time, total floating duration, and in vitro and in vivo correlation, are essential for assessing system performance. GRDDS can improve the therapeutic efficacy of medicines used in gastrointestinal disorders and those requiring localized gastric delivery. Despite significant advancements, variability in gastric motility and physiological factors limit the reproducibility and scalability of formulations. This review consolidates current progress and identifies future directions for optimized gastroretentive floating tablet technology.

The present research work describes the  improvement of  bioavailability of Isradipine through buccal delivery. Isradipine buccal tablets were prepared with β cyclodextrin which improved the photostability of the drug. Buccal formulations were evaluated for in vitro release, moisture absorption, mechanical properties, and bioadhesion, and optimized formulation was subjected for bioavailability studies in healthy human volunteers and compared with marketed tablet. The pharmacokinetic parameters Cmax, tmax and AUCo-t of test formulation were calculated and compared with the reference i.e., marketed product. It was observed from the study that the drug release from the test formulation could be sustained and it was concluded that the test formulation was able to sustain the drug release as compared to reference marketed product with 1.672 fold increase in extent of absorption i.e., AUC0-t.

In pharmaceutical industry the major problem of dosage form development is low aqueous solubility. In present review the particle engineering concept and solubility, permeability approaches design and method used in improvement of particle size. The different methods are used in particle engineering like supercritical fluid technology, controlled precipitation, and mechanical technique, evaporation precipitation to aqueous solution, freezing technique, and sonication technology etc. discussed. The improvements of aqueous solubility need to be formulation development for dosage form very essential. The BCS class II drugs modified to soluble form for need of bioavailability of drugs. The solid dispersion method with a different carrier improves the solubility.

The present investigation aims on the preparation and in-vitro/in-vivo examination of inclusion complex of Diacerein (DAR) an anthraquinone derivative indicated for treatment of osteoarthritis by inhibiting interlukin-1 and hydroxypropyl-β-cyclodextrin (HP-β-CD). In this study, the inclusion complexes of DAR with β-cyclodextrin (β-CD), HP-β-CD, methyl-β-cyclodextrin (M-β-CD) and γ-cyclodextrin (γ-CD) were prepared and characterized for phase solubility study and inclusion efficiency. On the basis of results obtained, HP-β-CD was selected to prepare inclusion complexes with DAR by physical mixing, kneading method and freeze drying method and subjected to solid state characterizations. Differential Scanning Calorimetry (DSC), X-ray Diffraction (XRD) and Infra-red spectroscopy (IR) analysis confirmed the formation of perfect inclusion complex of DAR with HP-β-CD in solids. In-vitro dissolution and % drug content of DAR in freeze dried inclusion complex showed its superiority over plain drug and commercial formulation. . In-vitro cell cytotoxicity studies (MTT Assay) using Caco-2 cell line model confirmed the bio-tolerability of DAR-inclusion complex. . The relative oral bioavailability of DAR in Albino rabbits resulted from Freeze dried inclusion complex was found 3.32 fold and 2.03 fold greater than plain DAR and marketed formulation, respectively which ultimately demonstrated the enhancement of oral bioavailability of DAR in freeze dried inclusion complex with HP-β-CD.

Even today the most preferred delivery of drugs is still through oral route but because of some inherited limitations with this route, various other routes have been explored including transdermal. Delivery and complete absorption of the drugs is the major concern these days due to various reasons including poor solubility and incomplete bioavailability, this could be due to incomplete presystemic absorption or presystemic degradation. Transdermal drug delivery system is the method by which the drug absorption occurs through the skin primarily for its systemic effect. It provides better therapeutic efficacy and safety for the administration of insulin. Most of the oral anti-diabetic drug exhibit low bioavailability and hence a poor patient compliance. Hence, it can be used as better site for delivery of numerous drugs including proteins and peptides such as insulin.

Quetiapine Fumarate is a antipsychotic agent indicated for treatment of Schizophrenia and Bipolar disorder. Quetiapine Fumarate is BCS Class II drug which is  poorly water soluble and may show dissolution limited absorption. Hence to improve dissolution rate and bioavailability, Solid dispersion of Quetiapine Fumarate by Solvent Evaporation method were prepared using 1:1, 1:2, 1:3, 1:4 and 1:5 ratios of Quetiapine Fumarate and Polyvinyl Pyrrolidone K30(PVP K30). The solid dispersion (SD) was characterized for physical appearance, solubility, FTIR, DSC, XRD studies and in vitro dissolution studies. FTIR study revealed that there was no drug-carrier chemical interaction in Solid dispersion. DSC studies revealed that, the peak observed for the melting of Quetiapine Fumarate is found to be absent in SD with PVP K30 carrier. XRD studies suggested that there has been a large change in the nature of Quetiapine Fumarate in the solid dispersion. Solubility of Quetiapine Fumarate from SD increased in distilled water. The drug content was found to be high and uniformly distributed in the formulation. The in vitro dissolution studies were carried using USP type II (paddle) type dissolution apparatus. The prepared Solid dispersion showed marked increase in the dissolution rate of Quetiapine Fumarate than that of pure drug. The Solid dispersion with PVP K30 (1:5) by Solvent evaporation method showed faster dissolution rate as compared to other Solid dispersions. It is concluded that dissolution of the Quetiapine Fumarate could be improved by the Solid dispersion.

Tamoxifen Citrate (TC), an antiestrogenic drug, is used in both pre and post menopausal breast cancer treatment in women. One of the major causes of its poor bioavailability is attributed to its poor aqueous solubility. In this study an effort has been made to improve the aqueous solubility of the hydrophobic drug using methods like cosolvency and micellisation. Cosolvents (ethanol, polyethylene glycol-400), and surfactants [polyoxyethylene sorbitan monooleate (Tween-80), Poloxamer-407 and Poloxamer-188] were tested for their solubilizing potential. Solubility enhancement approaches showed variable degrees of increase in solubility of TC. Solubility studies with different concentrations of Ethanol and PEG-400 at 37°C showed that higher efficiency of increasing solubility by cosolvency was achieved with ethanol (6.10 fold) than that with PEG 400 (5.62 fold) while in case of varying concentrations of surfactants (tween 80, Poloxamer 188 and Poloxamer 407). Poloxamer 407 exhibited maximum potential in solubilizing TC in water (7.1 fold). However, among the solubilizing techniques and solubilizing agents used, micellization with polysorbate 80 as surfactant was found to be the most effective. Data suggests that using simple techniques, improvement of solubility of TC can be attained which may help in improving its poor bioavailability.

Most demanding route of administration is oral. Several times dosing of conventional drug delivery system to achieve effective therapeutic range is always abhorred by the patient. Demanding new approach to reduce the number of intake; leading to introduction of gastric retention concept. As most of drugs are absorbed in upper intestinal tract GI retention was base to it. The floating drug delivery system is an admirable approach to gastric retention. Aim of delineating this review on Floating Drug Delivery System was to stash up the recent literature with special cogitation toward principal mechanism to attain gastric retention, also including details of Floating Drug Delivery System such as Classification, Mechanism of work, Method of preparation, Aspect of characterisation, Different factors to be taken care during process of formulation. This review is loaded with data of previous work performed on Floating Drug Delivery System, which includes desirable point to solve, the queries regarding FDDS.

Mucoadhesive dosage forms may be designed to enable prolonged retention at the site of application, providing a controlled rate of drug release for better therapeutic results. Mucoadhesive drug delivery systems are used to prolong the residence time of the dosage form at the site of application or absorption and to facilitate intimate contact of the dosage form with the underlying absorption surface to improve and enhance the bioavailability of drug. Some of the promising plymers that have been commonly used in these systems include polycarbophil, carbopol, lectins, chitosan, carboxymethylcellulose, pectin, carragenan, alginic acid, polylysine, polybrene, polyethylene glycol, polyvinyl pyrrolidone , dextran etc. Now  scientists are developing mucoadhesive micro and nanoparticulate systems by using  novel mucoadhesive polymers for better therapeutic results and site specific targeting with lesser side effects. Improvements in mucoadhesive based oral delivery and, in particular, the development of novel, highly-effective and mucosa-compatible polymers, are creating new commercial and clinical opportunities for delivery of narrow absorption window drugs at the target site to maximize their efficacy. This review is an effort to provide information on such mucoadhesive drug delivery systems that are developed for oral, buccal, nasal, rectal and vaginal routes for both systemic and local effect.

Solubility plays a vital role in achieving the therapeutic efficacy of a drug from a dosage form. Advances in molecular screening techniques for identification of potential drug molecules investigated an increased number of new pharmacologically active lipophilic compounds that are poorly water soluble. About 40% of new chemical entities have been discovered as poorly water soluble. Numbers of technical strategies have been investigated for improving bioavailability like solid dispersions, cyclodextrins, micronization, surfactants, nanoparticles, lipids, permeation enhancers etc. It is a great task for pharmaceutical scientist to formulate oral dosage forms of these drug candidates with sufficient bioavailability. Among the various approaches to improve oral bioavailability of these drug candidates, Self- dispersing lipid formulations (SDLF’s) is one of the approaches used to improve the bioavailability of lipophilic drugs. SDLF’s is very broad area which covers Self-emulsifying drug delivery systems (SEDDS), Self-microemulsifying drug delivery systems (SMEDDS) and Self-nanoemulsifying drug delivery systems (SNEDDS) as carrier systems that have been developed. This review article covers basics of SDLF’s particularly SMEDDS and recent research updates in SDLF’s i.e. the research carried out and most recent solid SDLF’s.