Polymer Carbopol Research Articles

Formulation, optimization and characterization of gastro retentive olanzepine microsphere using 32 factorial design.

Olanzepine microsphere prepared by external Inotropic gelation technique by using sodium alginate and carbopol 974 P as a polymer and calcium chloride as a cross linking agent. In this formulation combination of sodium alginate and carbopol 974 P used as a polymer that helps to retard the releasing the drug and increases bioavaibility of drug. The Olanzepine microsphere has other characterization is in the term ofdrug content, drug entrapment efficiency, P XRD, Differential Scanning Colorimetry, FTIR , SEM, in vitro drug release and in vivo drug release. The in vitro release pattern of Olanzepine microsphere studied in 900 ml of 0.1 N Hydrochloric acids, using USP dissolution apparatus I. The optimized batch F7 shows greater than 80 % of drug release that is due to using carbopol polymer that helps to retarded the drug release at targeted site over the other formulation. Optimized formulation shows better antidepressant action as compare to pure Olanzepine drug.

Formulation and Evaluation of Herbal Anti-bacterial gel containing Ethanolic extracts of Rosa indica and Tagetes minuta

The present research has been undertaken with the aim to formulate and evaluate herbal gel containing ethanolic extracts of Rosa indica and Tagetes minuta. The antibacterial activity and phytochemical screening was performed for ethanolic extract. The gel preparation was designed by utilizing ethanol extract of Rosa indica and Tagetes minuta petals in varied concentrations (1.0%, 2.0%, 4.0%) and evaluated using physiological measurements. The gel was formulated by using polymer carbopol 934. Rosa indica and Tagetes minuta petals, methyl paraben, propyl paraben and required amounts of distilled water. The antibacterial activity of the gel was evaluated by agar well diffusion method by using microbial strains are E.coli and Staphylococcus aureus. The physicochemical parameters (pH, viscosity, spreadability and homogeneity) was determined. The results showed that formulation containing 4% concentration of gel containing ethanolic extracts of Rosa indica and Tagetes minuta have better antibacterial activity than other formulations.

Formulation and Evaluation Sustained Release of Lomefloxacin Hydrochloride from In-Situ Gel for Treatment of Periodontal Diseases

Periodontal diseases is a world wide prevalent chronic infection, which is caused by accumulation of specific microorganism or group of microorganisms in dental plaque, which results in the progressive loss of bone around teeth leading to loss of teeth. The present study was developed and evaluated in situ gelling system of Lomefloxacin hydrochloride by using different concentrations of Carbopol 934 for treatment of periodontitis. The drug-polymer compatibility were study using DSC. The seven formulation (L1 to L7) were prepared and their appearance, pH, viscosity, gelling capacity, %drug content, syringeability and in vitro drug release were investigated. The findings of compatibility study indicates that the drug was compatible with polymer. The developed formulations showed satisfactory results for pH, viscosity, gelling capacity, %drug content, syringeability and in vitro drug release. Based on maximum desirability and cost effectiveness formulation L7 with 1.0 % of polymer Carbopol 940, showed a sustained release of drug for 16 hrs.

Formulation and Evaluation of Topical Polyherbal Antiacne Gels Containing Luffa Acutangula, Amaranthus Spinosus and Morus Alba

Anti-acne herbal formulations are used for the treatment of acne vulgaris with the added advantage of not producing adverse effects unlike synthetic drugs. Acne is an inflammatory skin disease that occurs due to blockages in polysebase and inflammation that are caused by bacteria. Topical and systemic antibiotics are always used for treatment of acne, but the gradual resistance to antibiotics can affect the success rate of acne cure. Medicinal plants play an important role in the development of potent therapeutic agents. Plant based drugs provide outstanding contribution to modern therapeutics as a source of many valuable secondary metabolites which serves as plant defence mechanisms against predator such as microorganism, insects and herbivores which have been proved to be potentially active compounds. There is a tremendous increase in search of antimicrobial plant extracts due to the fact that the resistance offered against antibiotic by the microorganism, in short the effective life span of any antibiotic is limited. Propionibacterium acnes are common pus-forming microbes responsible for the development of various forms of acne. In the present study anti-acne gels were prepared using polymer carbopol 940 along with the hydroalcoholic extracts of plants fruits of Luffa acutangula, leaves of Amaranthus spinosus and Morus alba and evaluated for their physicochemical properties, like pH, washability, extrudability, spreadability and viscosity. The formulations (PHG1-PHG6) were tested for the anti-acne activity by well diffusion method against Propionibacterium acnes. Results showed that the gels were non-irritant, stable and possess anti-acne activity. The efficacy when tested with a standard was almost same to that of Clintop (Marketed gel). This suggests that fruits of Luffa acutangula, leaves of Amaranthus spinosus and Morus alba have potential against acne causing bacteria and hence they can be used in topical anti-acne preparations and may address the antibiotic resistance of the bacteria.
 Keywords: Luffa acutangula, Amaranthus spinosus, Morus alba, Propionibacterium acnes, Acne vulgaris, Carbopol, Physicochemical properties.

FORMULATION AND EVALUATION OF TOPICAL HERBAL GEL FOR TREATMENT OF ACNE

The objective of the study was to develop a topical herbal gel for the treatment of mild acne vulgaris. Aqueous extracts Withania somnifera formulated using different gelling agent like carbopol-934, Xanthan gum, & HPMC K100 M. Nine formulations of the gel were prepared by varying the proportions of polymer and evaluated for their physicochemical properties like appearance, pH, spreadability, viscosity, assay, and microbial assay. FTIR studies reveals that there was no interaction between the Withania somnifera and selected polymers Carbopol 934, Xanthan gum and HPMC K 100 M. In vitro drug diffusion studies showed percentage CDR of 100.16 % at the end of 3 hours. The microbial assay of all the formulations demonstrated better inhibitory activity against Staphylococcus epidermidis compared to the marketed clindamycin phosphate gel. The stability study carried out of the selected gel F2 at room temperature and 40 ± 2 °C / 75 ± 5 % RH was found to be stable for a period of 45 days in terms of drug content, physical appearance and pH etc. Based on these results, Formulation F2 containing 1.5 % carbopol-934 was selected as best formulation.
 Key words: Herbal gel, Withania somnifera, In vitro diffusion, Zone of inhibition.

Surface functionalization of carbon nanotubes by biological adhesive polymers carbopol for developing high‐permittivity polymer composites

Surface functionalization of carbon nanotubes (CNTs) by biological adhesive polymers carbopol (CP) was developed by simply mixing CNT suspension and an aqueous solution of CP without any toxic solvents. CP can be easily coated onto CNTs through hydrogen bonds OCOH⋯NH2CO and electrostatic interaction between COO on CP and NH3+ on CNTs. After modification, the surface of the CNT is endowed with a large number of carboxyl groups, which can effectively prevent the reaggregation of CNT by electrostatic repulsion between the ionized carboxyl groups. Hence, highly dispersed functionally modifying CNT by CP (CP‐CNT) filler in polydimethylsiloxane (PDMS) matrix can be obtained. More important, with the help of adhesive properties of CP, the interfacial compatibility between fillers and matrix can also be improved. Thus, the CP‐CNT/PDMS composites exhibited higher dielectric permittivity comparing with CNT/PDMS composites at the same filler content. We present a potential and green approach of surface functionalization of CNT for preparing high‐permittivity polymer composites. J. VINYL ADDIT. TECHNOL., 26:165–172, 2020. © 2019 Society of Plastics Engineers

First results of humidity sensors based on CeO2 thick film deposited by a new deposition technique from a suspension of nanoparticles

In this paper, we show the possibility to deposit a CeO2 thick film on (111) silicon substrate from a suspension of CeO2 nanoparticles by a new process of thick layer deposition in order to realize a humidity sensor. This new technique is derived from the spin-coating technology. The suspension is based on ultra-fine grinding of CeO2 firstly in a stirred media mill coupled then in a sonication cell. Suspension viscosity has been adjusted with carbopol polymer and its rheological properties have been analyzed in order to cover completely the silicon substrate by the CeO2 layer. Then, the impact of a conventional annealing on the crystallinity of the CeO2 film has also been investigated by Raman spectroscopy and by scanning electron microscopy. Finally, gold interdigitated electrodes have been screen printed on the thick film surface in order to realize a sensor and first promising results on the humidity sensitivity have been highlighted.

Development and Evaluation of Ion Induced in Situ Gelling System of Opoid Analgesic for Nose to Brain Delivery

Aim of the study: The purpose of the study was to formulate and develop mucoadhesive in situ gel of Tapentadol hydrochloride for nasal administration and to evaluate it for physicochemical properties like gel strength, mucoadhesion, drug release rate. Materials and Methods: The insitu gel of Tapentadol was subjected to FT-IR and DSC analysis and compared with that of the pure drug to assess drug excipient interaction. The optimized in situ gel was further subjected for stability studies. Result: The optimized mucoadhesive in situ gel prepared using combination of Tapentadol HCL with mucoadhesive polymer carbopol 934-P and Gellan-gum showed effective gelation viscosity, gel strength, drug release properties along with good mucoadhesive strength. The drug release mechanism of the gel matrices was found to be anomalous and following the Higuchi equation. Conclusion: The observations indicated that there was no remarkable damage to the nasal mucosa so it seems to be safe for preclinical use. The optimized formulation also retained good stability at accelerated conditions over the period of 30 days. So it is good alternative for effective delivery of the drug for the nasal route which would definitely useful for neuronal pain.

Detecting Glucose Levels in Blood Plasma and Artificial Tear by Au(I) Complex on the Carbopol Polymer: A Microfluidic Paper-Based Method.

We report on a selective paper-based method and a microfluidic paper-based analytical device (μPAD) for the detection of human plasma glucose and tear glucose using carbopol polymer-encapsulated Au(I) complex (AuC2C6H4OMe)2(Ph2P(C6H4)3PPh2), (B5). To the best of our knowledge, this demonstrates for the first time the glucose sensing based on dual emission, i.e., fluorescence and phosphorescence, of a single type molecule on the carbopol polymer. Upon addition of human blood treated with anticoagulants to μPADs, plasma is separated from the blood and flows into the response region of the μPADs to react with carbopol polymer-encapsulated B5, in which the ratiometric luminescence is analyzed. The plasma glucose concentration can be quantitively detected at 1.0–50.0 mM on paper, and tear glucose can be detected at 0.1–4.0 mM on μPADs. Owing to the structural design, this device has superior ratiometric changes of dual emission over other Au(I) complexes for signal transduction. The encapsulation of carbopol polymer also offers long-term storage stability. In tear measurement, carbopol polymer is not only used to encapsulate enzyme to remain the enzyme’s activity, but also played as a glue (or media) to connect microfluidic channel and response region. This further improves the sensitivity and limit of detection for glucose. Moreover, this sensor provides a faster response time, a wider range for glucose sensing than reported previously, and no statistical difference of the data from a commercial glucometer, allowing for practical diagnosis of diabetes and healthy individuals.

Subconjunctival Exposure to Carbopol Causes Chronic Histiocytic Inflammatory Response in Rabbits.

PurposeWe recently reported a clinical association between surgical exposure to the ophthalmic lubricant GenTeal gel and postoperative subconjunctival necrotizing granulomatous inflammation. We used a rabbit model to test our hypothesis that subconjunctival exposure to the carbopol 980 component is responsible for inciting chronic inflammation.MethodsOf eight adult wild-type Dutch belted rabbits, 16 eyes received subconjunctival injections of the following: hydroxypropyl methylcellulose (HPMC) 0.3% with carbopol 980 (GenTeal gel, n = 4), HPMC 0.3% (GenTeal tears, n = 3), 0.1% carbopol 980 in sterile water (n = 3), HPMC 1.7% (ImproVue, n = 3), and balanced salt solution (BSS, negative control, n = 3). Rabbits were examined weekly for clinical evidence of inflammation, and biopsies were taken for final pathology 10 weeks postinjection.ResultsAll seven eyes exposed to subconjunctival carbopol 980 (HPMC 0.3% with carbopol 980 or 0.1% carbopol 980) demonstrated conjunctival injection and edema at 4 weeks followed by yellow subconjunctival lesions with scattered pigmentation at 10 weeks. Each of these eyes demonstrated chronic histiocytic inflammation on pathology. No eyes treated with HPMC 0.3%, HPMC 1.7%, or BSS (noncarbopol-containing agents) developed clinical abnormalities or histiocytic inflammation (Fisher's exact test P < 0.0001).ConclusionsSubconjunctival exposure to ophthalmic lubricants containing carbopol 980 stimulates a chronic histiocytic inflammatory response. HPMC-based lubricants lacking carbopol 980 are well tolerated in the subconjunctival space.Translational RelevanceOphthalmic lubricants containing carbopol polymers should be avoided during surgical procedures that may result in subconjunctival exposure. Caution should be exercised when considering surgical use of biomedical products containing highly cross linked, high molecular weight acrylic acid polymers.

DEVELOPMENT AND IN VITRO EVALUATION OF AN ORAL FLOATING TABLET OF METRONIDAZOLE

The present study was undertaken with an aim to develop and evaluate gastroretentive floating tablets of Metronidazole that are designed to retain in the stomach for a long time and have developed as a drug delivery system for better eradication of Helicobacter Pylori in peptic ulcer diseases. The floating tablets of Metronidazole were made by direct compression method using polymer Carbopol 934 and sodium bicarbonate and citric acid as gas generating agent. The tablets were evaluated by pre and post compression parameters such as weight variation, thickness, friability, hardness, drug content, in- vitro buoyancy studies and in-vitro dissolution studies and results were within the limits. Hardness was found to be in the range of 7.6 ± 0.27 kg/ cm² to 7.9 ± 0.35 kg/cm², the percent friability was in the range of 0.48% to 0.52% w/w and the tablets showed 94% to 97% uniformity in drug content. The in-vitro dissolution studies were carried out in a USP type- II apparatus in 0.1N HCl. The formulations were able to within 2-7 minutes and showed buoyancy &gt;12 hrs. The drug-polymer ratio, viscosity grades of Carbopol 934 and gas generating agents were found to influence the release of drug and floating characteristics from the prepared floating drug delivery system of Metronidazole. Kinetically, among the 4 assessed models the release pattern of Metronidazole from the tablets fitted best to Higuchi’s and zero order indicated that diffusion is the predominant mechanism controlling the drug release. Keywords: Metronidazole, Floating tablets, Carbopol 934, Gastroretentive, Dissolution

Chemical and microstructural controls on viscoplasticity in Carbopol hydrogel

Many engineering and natural materials, as well as earth systems, exhibit a combination of elastic-plastic and viscous behaviors, but precisely evaluating their rheology, and the micromechanics and chemical-mechanical feedbacks governing such rheology, can be a challenge. The cross-linked polymer Carbopol has long been used to explore fundamental rheological behaviors, most recently including fracturing during viscous creep in nature. Here, through rheometer experiments we establish that Carbopol 940 is, to a first order, a Herschel-Bulkley material. However, we further establish that the yield stress and viscosity are affected by chemically-sensitive micromechanical controls, namely pH and concentration of the polymer mixture. We explore these effects via the novel use of cryogenic scanning electron microscopy (SEM). Through the SEM imaging we show that there is a semi-quantitative relationship between pH, porosity at the >10-μm scale, and yield stress, a result of the ionic repulsion between polymer links at the molecular scale. We appeal to a model wherein the yield stress is a direct function of jamming expressed at the SEM scale, similar to those described in granular systems. As the pH of polymer dispersion increases, and the porosity decreases, the yield strength increases as a result of the increasingly jammed system. The initial viscosity is thus controlled by the yield stress, but after failure evolves with increasing shear rate due to characteristic unjammed flow of the material. The different controls on the yield stress versus viscous flow rates has implications for borehole engineering efforts (carbon capture and storage) employing Carbopol, and could prove instructive for modeling of natural viscoplastic deformation.

Formulation and evaluation of Itraconazole mucoadhesive tablets for sustained release

The aim of this research was to prepare and evaluate sustain release mucoadhesive tablet ofitraconazole, in order to overcome its poor biopharmaceutical property and therapeutical efficacy. Itraconazole have low aqueous solubility and high permeability, hence in order to improve its solubility in both HCl and water it is formulated as solid dispersion by using solvent evaporation method. Solid dispersion was formulated using with itraconazole PEG 6000 in the ratio of 1: 2. Solid dispersion was then formulated in matrix of hydrophilic mucoadhesive polymers Carbopol 934P (CP) and HPMC E5LV into mucoadhesive sustained release tablet. Further, formulation were optimized for various amounts of CP and HPMC. Various amount of HPMC and Carbapol were taken as formulation variables for optimizing response variables i.e. dissolution parameters. Solid dispersion leads to enhancement in solubility of itraconazole in water up to 5.95% and in HCl it was 6.43%. In addition to enhancement of solubility in HCl and water they also lead to the slow release of drug up to 1.44% in 1 hour. Optimum combination of mucoadhesive polymers Carbopol 934P (CP) and HPMC E5LV provided adequate fairly regulated release profile. The experimental and predicted results for optimum formulations were found to be in close agreement. The formulation showed percentage drug release upto 86% for 9hour.

Development and Characterization Pulsatile Microspheres of Nifedipine for Hypertension.

To develop pulsatile microspheres of Nifedipine blend of polymers Carbopol 971P and Eudragit RS100 for antihypertensive to release the drug at a particular lag time. Pulsatile nifedipine microspheres were prepared using the blend of Carbopol 971P and Eudragit RS100 at different ratios in a mixture of solvents. Formulations were prepared and optimized on the basis of particle size, percentage yield and drug entrapment efficiency. Optimized formulations were further analyzed at different resolutions per minute (rpm) by optical microscopy, scanning electron microscopy (SEM), in-vitro dissolution studies and kinetics model. The most promising formulation was compared with the marketed products. The recent patents on microsphere used for hypertension for drug used Liensinine (CN104757561). Dopamine antagonist (US20030069232A1), Human Serum Albumin (EP19990304616) and Omeprazole (IN2107/DEL/2014) helped in selecting the drug and polymers. The formulated microspheres had mean particle size ranging from 177.31 to 277.48 &amp;micro;m. Formulation F83 showed slow release of drug initially for 4 h and drastically release of drug enhanced at a particular lag time (Showed pulsatile release) after 6 h. However, conventional marketed products showed maximum release initially at 1 h and decreased gradually while controlled released marketed product showed sustained pattern. On the basis of data formulation F83 showed slow release and at a particular lag time followed by pulsatile release pattern and followed first order kinetics model. It was concluded that the formulated nifedipine pulsatile dosage form could be useful in the treatment of hypertension.

FORMULATION AND EVALUATION OF GASTRORETENTIVE FLOATING BIOADHESIVE TABLETS OF HYDROCHLORTHIAZIDE

Objective: Floating bioadhesive tablets of hydrochlorothiazide were developed to prolong gastric residence time leading to an increase in drugbioavailability where here a combination of floating and bioadhesion mechanism is combined.Methods: Tablets are prepared by direct compression technique using polymers xanthan gum, carbopol 974 P, HPMC K15M, HPMC K100M, magnesiumStearate USP-NF (Avicel PH 102), microcrystalline cellulose Ph 102, Talc, and sodium bicarbonate.Results: Tablets were evaluated for their physical characteristics, namely, hardness, thickness, friability and weight variation, drug content, andfloating properties. The best formulation subjected for kinetic treatment, i.e., zero order, first order, peppas, Higuchi, and Hixon-crowel. The R valuesare 0.9366, 0.9364, 0.9680, 0.9974, and 0.9283, respectively.Conclusion: Optimized formulae F4 containing polymers HPMC K4M and CARBOPOL 974 P showed more bioadhesion with a controlled release over12 hrs. Therefore, formulation F4 identified as a successful formulation for the development of floating bioadhesive tablets.Keywords: Hydrochlorothiazide, Floating tablets, Gastroretentive drug delivery system.

DESIGN AND EVALUATION OF INTRAGASTRIC BUOYANT TABLETS OF VENLAFAXINE HYDROCHLORIDE

Objective: The present study was undertaken to prolong the release of orally administered drug. The aim is to formulate, develop, and evaluate theintragastric buoyant tablets of venlafaxine hydrochloride, which releases the drug in a sustained manner over a period of 12 hrs. Different formulationswere formulated using the polymers Carbopol 934 P, xanthan gum, hydroxypropyl methylcellulose (HPMC K100M) with varying concentration ofdrug: Polymer ratio of 1:1, 1:1.5, 1:2, in which sodium bicarbonate acts as gas generating agent, and microcrystalline cellulose as a diluent.Methods: The tablets were prepared by direct compression and evaluated for tablet thickness, weight variation, tablet hardness, friability, in vitrobuoyancy test, in vitro drug release and Fourier transform infrared spectroscopy. Formulations were evaluated by floating time, floating lag time and in vitro drug release. Dissolution profiles were subjected for various kinetic treatments to analyze the release pattern of drug.Results: It was found that drug release depends on swelling, erosion, and diffusion, thus following the non-Fickian/anomalous type of diffusion.Formulation F8 was considered as an optimized formulation for gastro retentive floating tablet of venlafaxine hydrochloride. The optimizedformulation showed sustained drug release and remained buoyant on the surface of the medium for more than 12 hrs. As the concentration of HPMCK100M increases in the formulation the drug release rate was found to be decreased. The optimized formulation was subjected for the stability studiesand was found to be stable as no significant change was observed in various evaluated parameters of the formulation.Conclusion: It can be concluded that floating drug delivery system of venlafaxine hydrochloride can be successfully formulated as an approach toincrease gastric residence time, thereby improving its bioavailability.Keywords: Venlafaxine hydrochloride, Intragastric buoyant, Floating drug delivery systems, Hydroxypropyl methyl cellulose K100M, Carbopol 934 P,Xanthan gum.

Formulation and Evaluation of Thermoreversible In Situ Nasal Gels Containing Mometasone Furoate for Allergic Rhinitis.

The purpose of the present work was to develop a mucoadhesive thermoreversible nasal gel with a tailored gelling temperature to provide the prolonged contact between mometasone furoate and the nasal mucosa and in order to prevent drainage of the formulation. For this purpose, in situ gel containing a thermogelling polymer poloxamer 407 (Pluronic® F-127) and a mucoadhesive polymer Carbopol® 974P NF was prepared. In this content, formulations were designed to have gelation temperature below 34°C to obtain gelation at intranasal cavity. Evaluation of the prepared in situ gels was carried out by the determination of sol-gel transition temperature, rheological and mechanical characteristics, mucoadhesion strength, drug content, physicochemical stability, in vitro release profiles, and ex vivo permeation across sheep nasal mucosa of formulations. Consequently, the in situ gel (CP5) which had favorable gelation temperature (30.1±0.24°C), rheological and mechanical characteristics, in vitro release profile (T%100 180min), and mucoadhesion strength (0.289±0.0069mJ) was developed. Consequently, the in situ gel system has been concluded as a promising approach in order to improve the therapeutic effects of intranasal mometasone furoate administration.

Development of hydrogel ointments based on carbopol with α-lipoic acid

This article presents the results of hydrogel ointments development based on carbopol polymer with α-lipoic acid for their application as transdermal therapeutic delivery systems for antibacterial treatment of diabetic foot syndrome. Complex formation of bioavailable α-lipoic acid with hydroxypropyl-β-cyclodextrin was studied using differential scanning calorimetry and scanning electron microscopy. Optimal rheological characteristics of obtained ointments have been estimated. Antimicrobial activity in relation to Staphylococcus aureus and Escherichia coli have been observed for ointments containing α-lipoic acid. Transdermal drug delivery properties of obtained hydrogel ointments were investigated using cellulose membrane as a model system and a pig skin.

Influence of bioadhesive polymers on the protective effect of fluoride against erosion

ObjectiveThis study investigated if the incorporation of the bioadhesive polymers Carbopol 980, Carboxymethyl cellulose (CMC), and Aristoflex AVC in a fluoridated solution (NaF–900ppm) would increase the solution’s protective effect against enamel erosion. MethodsEnamel specimens were submitted to a 5-day de-remineralization cycling model, consisting of 2min immersions in 0.3% citric acid (6x/day), 1min treatments with the polymers (associated or not with fluoride), and 60min storage in artificial saliva. Ultrapure water was used as the negative control and a 900ppm fluoride solution as positive control. The initial Knoop microhardness (KHN1) was used to randomize the samples into groups. Another two microhardness assessments were performed after the first (KHN2) and second (KHN3) acid immersions, to determine initial erosion in the first day. The formula: %KHNalt=[(KHN3-KHN2)/KHN2]*100 was used to define the protective effect of the treatments. After the 5-day cycling, surface loss (SL, in μm) was evaluated with profilometry. Data were analyzed with 2-way ANOVA and Tukey’s tests (p<0.05). ResultsFor %KHNalt, the polymers alone did not reduce enamel demineralization when compared to the negative control, but Carbopol associated with NaF significantly improved its protective effect. The profilometric analysis showed that Carbopol, associated or not with NaF, exhibited the lowest SL, while CMC and Aristoflex did not exhibit a protective effect, nor were they able to improve the protection of NaF. ConclusionsIt is concluded that Carbopol enhanced NaF’s protection against initial erosion. Carbopol alone or associated with NaF was able to reduce SL after several erosive challenges. Clinical significanceCarbopol by itself was able to reduce the erosive wear magnitude to the same extent as the sodium fluoride, therefore, is a promising agent to prevent or control enamel erosion.

Biointerfacial phenomena of amlodipine buccomucosal tablets of HPMC matrix system containing polyacrylate polymer/β-cyclodextrin: Correlation of swelling and drug delivery performance

ABSTRACTObjectives: This study focuses on the development of amlodipine bilayer buccal tablets of hydroxypropyl methylcellulose (HPMC) matrix system containing polyacrylate polymer (Carbopol®)/β-cyclodextrin as the drug layer and ethylcellulose as the non-swellable backing layer, and their biointerfacial phenomena.Methods: Tablets were evaluated for swelling, erosion and mucoadhesion using buccal mucosal tissue ex vivo. In vitro drug release and ex vivo drug transport across mucosal tissue were also performed in phosphate buffer (pH 6.8). The relationship of swelling with buccoadhesion and buccal permeation of various bilayer tablet formulations containing HPMC alone and in combination with Carbopol or drug-β-cyclodextrin complex has been prepared.Results: Overall buccoadhesion of the tablet with combination of HPMC and Carbopol was increased significantly compared with that of HPMC alone. Presence of cyclodextrin did not change bioadhesion force and swelling behavior significantly. Ex vivo permeation was increased with the increase of HPMC proportion in other formulations as observed in in vitro dissolution.Conclusion: Drug–cyclodextrin complexes in the tablet improved permeation due to its improved dissolution at the site of biointerface of tablet and buccomucosa. Correlations of ex vivo and in vitro data have been established to predict the buccomucosal permeation from the swelling index or drug release alone.