Background/Aim: The aim of the present investigation is to prepare and evaluate in situ gel-forming ophthalmic drug delivery system of moxifloxacin hydrochloride. Materials and Methods: Sodium alginate, a novel ophthalmic gel-forming mucoadhesive polymer, which gets converted to gel in the presence of divalent-cations (calcium ion) present in the lachrymal fluid, was used as the gelling agent. Hydroxy propyl methyl cellulose (HPMC) is a mucoadhesive polymer used as viscosity enhancer. Suitable concentrations of buffering agents were used to adjust the pH to 6.5. All the formulations were sterilized in an autoclave at 121°C for 15 minutes. The formulations were evaluated for clarity, pH measurement, gelling capacity, drug content estimation, rheological study, in vitro diffusion study, antibacterial activity, isotonicity, and eye irritation study. Results: The developed formulations exhibited sustained release of drug from formulation over a period of 10 hours thus increasing residence time of the drug. The optimized formulations were tested for eye irritation on albino rabbit (male). The formulations were found to be non-irritating with no ocular damage or abnormal clinical signs to the cornea, iris or conjunctiva observed. Conclusion: These in situ gelling systems containing gums may be a valuable alternative to the conventional systems.

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Amongst the various routes of drug delivery, the field of ocular drug delivery is one of the most interesting and challenging endeavors facing the pharmaceutical scientist for past 10-20 years. As an isolated organ, eye is very difficult to study from a drug delivery point of view. Despite this limitation, improvements have been made with the objective of maintaining the drug in the biophase for an extended period. A major problem in ocular therapeutics is the attainment of an optimal drug concentration at the site of action. To achieve effective ophthalmic therapy, an adequate amount of active ingredient must be delivered and maintained within the eye. The most frequently used dosage forms, i.e., eye solution, eye ointments, eye gels, and eye suspensions are compromised in their effectiveness by several limitations leading to poor ocular bioavailability. Ophthalmic use of viscosity-enhancing agents, penetration enhancers, cyclodextrins, prodrug approaches, and ocular inserts, and the ready existing drug carrier systems along with their application to ophthalmic drug delivery are common to improve ocular bioavailability. Amongst these hydrogel (stimuli sensitive) systems are important, which undergo reversible volume and/or sol-gel phase transitions in response to physiological (temperature, pH and present of ions in organism fluids, enzyme substrate) or other external (electric current, light) stimuli. They help to increase in precorneal residence time of drug to a sufficient extent that an ocularly delivered drug can exhibit its maximum biological action. The concept of this innovative ophthalmic delivery approach is to decrease the systemic side effects and to create a more pronounced effect with lower doses of the drug. The present article describes the advantages and use stimuli sensitive of hydrogel systems in ophthalmic drug delivery.

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Background: The purpose of the present research work was to extract jackfruit mucilage, use it as a mucoadhesive agent, and to develop extended release buccoadhesive tablets with an intention to avoid hepatic first-pass metabolism, by enhancing residence time in the buccal cavity. Materials and Methods: The mucilage was isolated from the jackfruit pulp by the aqueous extraction method and characterized for various physiochemical parameters as well as for its adhesive properties. Three batches of tablets were prepared (wet granulation method) and evaluated containing three mucoadhesive components: Methocel K4M, Carbopol 974P, and isolated jackfruit mucilage using chlorpheniramine maleate (CPM) as a model drug and changing the proportion of the mucoadhesive component (1:2:3), resulting in nine different formulations. Results: The results of the study indicate that the isolated mucilage had good physicochemical and morphological characteristics, granules and tablets conformed to the Pharmacopoeial specifications, and in vitro release studies showed the sustained action of drug with increasing concentration of the isolated natural mucoadhesive agent in the formulations. Permeability studies indicated that changing the mucoadhesive component, permeability behavior was not statistically different (P > 0.05). FTIR and UV spectroscopy studies between mucilage and CPM suggested the absence of a chemical interaction between CPM and jackfruit mucilage. Conclusion: The developed mucoadhesive tablets for buccal administration containing natural mucilage (MF3) have a potential for the sustained action of drug release. Thus, mucoadhesive tablets for controlled release were successfully developed using natural jackfruit mucilage.

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Background/Aim: The purpose of the study was to prolong the gastric residence time of stavudine by designing its floating tablets and to study the influence of different polymers on its release rate. Materials and m0 ethods: The floating mix matrix tablets of stavudine were prepared by melt granulation method. Beeswax was used as hydrophobic meltable material. Hydroxypropyl methylcellulose (HPMC), sodium bicarbonate, and ethyl cellulose were used as matrixing agent, gas generating agent, and floating enhancer, respectively. The prepared tablets were evaluated for physicochemical parameters such as hardness, weight variation, friability, floating properties (floating lag time, total floating time), drug content, stability study, and in vitro drug release. The drug- polymer interaction was studied by Differential Scanning Calorimetry (DSC) thermal analysis and Fourier transform infared (FT-IR). Results: The floating lag time of all the formulations was within the prescribed limit (<3 min). All the formulations showed good matrix integrity and retarded the release of drug for 12 h except the formulation F5.The concentration of beeswax (X ₁ ), HPMC K ₄ M (X ₂ ), and ethyl cellulose (X ₃ ) were selected as independent variables and drug release values at 1 (Q ₁ ), at 6 (Q ₆ ) and at 12 h (Q ₁₂ ) as dependent variables. Formulation F7 was selected as an optimum formulation as it showed more similarity in dissolution profile with theoretical profile (similarity factor, f ₂ = 70.91). The dissolution of batch F7 can be described by zero-order kinetics (R ² =0.9936) with anomalous (non-Fickian) diffusion as the release mechanism (n=0.545). There was no difference observed in release profile after temperature sensitivity study at 40 ^o C/75% relative humidity (RH) for 1 month. Conclusion: It can be concluded from this study that the combined mix matrix system containing hydrophobic and hydrophilic polymer minimized the burst release of drug from the tablet and achieved a drug release by zero-order kinetics, which is practically difficult with only hydrophilic matrix.

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Background: Many polymeric systems have been used to fabricate ocular inserts for improve ocular bioavailability and retention to drug of which matrix systems have shown advantages of reduce dosing frequency and increased corneal residence time. The objective of the present investigation was to prepare and evaluate ocular inserts of gatifloxacin. Materials and Methods: Ocular insert was made from an aqueous dispersion of gatifloxacin, sodium alginate, polyvinyl alcohol, and glycerin by solvent casting method. Ocular insert (5.5 mm) was cross-linked by CaCl ₂ and was coated with Eudragit RL-100 or Eudragit RS-100. The ocular inserts were characterized for thickness; uniformity of weight, drug content uniformity, % moisture absorption or moisture loss, and surface pH. The in vitro diffusion studies were carried out by putting insert on Millipore membrane filter (0.8 μm) fixed between donor and receptor compartment of an all glass modified Franz diffusion cell. Results: The thickness and drug content of ocular insert were found in the range of 0.11 ± 0.003 to 0.24 ± 0.010 mm and 0.718 ± 0.002 to 0.867 ± 0.007 mg, respectively. The surface pH, % moisture absorption or moisture loss and weight variation values were obtained in satisfactory range. The cross-linked ocular insert coated with Eudragit RL-100 shows maximum drug permeation i.e. 89.53 % ± 0.43 at 11 h. The stability studies suggest that all ocular insert remained stable, showed lesser degradation rate and maximum shelf life. Conclusion: Ocular inserts of gatifloxacin were prepared successfully by using solvent casting method for sustained drug delivery. The cross-linked and Eudragit RL-100 coated ocular insert of gatifloxacin provides better in vitro drug release and sustained upto 11 h.

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Background: Lacidipine (LCDP) is a 1,4-dihydropyridine derivative categorized as an anti-hypertensive Ca2+ channel blocker having very low solubility, and thus very low oral bioavailability, which presents a challenge to the formulation scientists. Homogeneous distribution of poorly water-soluble drugs like LCDP in polyvinylpyrrolidone (PVP), a hydrophilic carrier, is definitely a suitable way to improve the bioavailability of such drugs. Materials and Methods: The aim of the study was to develop a combined thermal, imaging, and spectroscopic approach, and characterize physical state, dissolution behavior, and elucidation of drug-PVP interaction in LCDP/PVP solid dispersion (SD) using differential scanning calorimetry (DSC), X-ray diffractometry (XRD), fourier transform infrared (FTIR) spectroscopy, and hot stage microscopy (HSM), which is the prerequisite for the development of a useful drug product. Results: Dissolution studies of LCDP and its physical mixture with PVP showed less than 50% release even after 60 min, whereas SD of LCDP/PVP ratio of 1:10% w/w showed complete dissolution within 45 min. DSC and powder XRD proved the absence of crystallinity in LCDP/PVP SD at a ratio of 1:10% w/w. The FTIR spectroscopy indicated formation of hydrogen bond between LCDP and PVP. In the SD FTIR spectra, the -NH stretching vibrations and the -C=O stretch in esteric groups of LCDP shift to free -NH and C=O regions, indicating the rupture of intermolecular hydrogen bond in the crystalline structure of LCDP. Conclusion: Solid-state characterization by HSM, DSC, XRD, and FTIR studies, in comparison with corresponding physical mixtures, revealed the changes in solid state during the formation of dispersion and justified the formation of high-energy amorphous phase.

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