Comparative analysis of tetracycline-containing dental gels: Poloxamer- and monoglyceride-based formulations

Insights into Intra Periodontal Pocket Pathogenesis, Treatment, In Vitro-In Vivo Models, Products and Patents, Challenges and Opportunity

Periodontal disease is a multifactorial pathogenic condition involving microbial infection, inflammation, and various systemic complications. Here, a systematic and comprehensive review discussing key-points such as the pros and cons of conventional methods, new advancements, challenges, patents and products, and future prospects is presented. A systematic review process was adopted here by using the following keywords: periodontal diseases, pathogenesis, models, patents, challenges, recent developments, and 3-D printing scaffolds. Search engines used were "google scholar", "web of science", "scopus", and "pubmed", along with textbooks published over the last few decades. A thorough study of the published data rendered an accurate and deep understanding of periodontal diseases, the gap of research so far, and future opportunities. Formulation scientists and doctors need to be interconnected for a better understanding of the disease to prescribe a quality product. Moreover, prime challenges (such as a lack of a vital testing model, scarcity of clinical and preclinical data, products allowing for high drug access to deeper tissue regions for prolonged residence, lack of an international monitoring body, lack of 4D or time controlled scaffolds, and lack of successful AI based tools) exist that must be addressed for designing new quality products. Generally, several products have been commercialized to treat periodontal diseases with certain limitations. Various strategic approaches have been attempted to target certain delivery regions, maximize residence time, improve efficacy, and reduce toxicity. Conclusively, the current review summarizes valuable information for researchers and healthcare professional to treat a wide range of periodontal diseases.

Antibacterial effectiveness of multi-strain probiotics supernatants intracanal medication on Enterococcus faecalis biofilm in a tooth model

BACKGROUND

To assess the antibacterial activity of multi-strain probiotics supernatants (MSP); Lactobacillus plantarum, Lactobacillus rhamnosus, and Lactobacillus acidophilus as an intracanal medication on Enterococcus faecalis (E. faecalis) biofilm in a tooth model.

METHODS

Sixty extracted human single-rooted teeth with single canals were instrumented, sterilized, and inoculated with E. faecalis. After 21 days of incubation, four specimens were randomly selected to validate the biofilm formation by scanning electron microscope (SEM). The remaining specimens were randomly divided (n = 14), according to the intracanal medication (ICM) received into: Ca(OH)₂: calcium hydroxide paste (35% Ultra Cal XS Ca(OH)₂), Probiotics supernatants: MSP in poloxamer gel vehicle Poloxamer: poloxamer gel vehicle and, Control: E. faecalis biofilm only. The tested groups were further subdivided into two equal subgroups (n = 7) according to the incubation period (24 h and 7 days). Shaved dentin chips were obtained and collected by H-files and paper points, respectively for bacterial culture. The antibacterial activity was assessed after each incubation period quantitatively and qualitatively using bacterial colony-forming units per milliliter (CFUs/ml) and SEM, respectively.

RESULTS

The lowest CFUs/ml was found in Ca (OH)₂ with a significant difference compared to other groups after 24 h. After 7 days, a similar outcome was found with a further significant reduction of CFUs/ml in all groups with no statistical difference between Ca(OH)₂ and probiotics supernatants groups. Ca (OH)₂ and Probiotics supernatants groups showed a significant (p < 0.05) percentage of overall bacterial reduction (100.00 ± 0.00% and 70.30 ± 12.95%, respectively) compared to poloxamer and control groups (27.80 ± 14.45 and 28.29 ± 19.79). SEM images showed a bacteria-free state in the Ca(OH)₂ group after 7 days while few bacteria were found in the probiotics supernatants group. An extensive invasion of bacteria was found in poloxamer and controls groups.

CONCLUSION

MSP has a potential antibacterial effect on E. faecalis growth closely similar to the routinely used Ca (OH)₂.

Evaluation of the antibacterial activity of Lactobacilli probiotics supernatants against Enterococcus faecalis (in-vitro study)

Background

There is an increasing demand to find a potent antibacterial agent against endodontic pathogens with the least toxic effect. The study aimed to evaluate the antibacterial activity of Lactobacilli probiotics on Enterococcus faecalis (E. faecalis) in comparison to calcium hydroxide paste.

Methods

The study involved two stages; (stage one): determination of the antibacterial properties of three strains of Lactobacilli probiotics supernatants (PS); Lactobacillus plantarum, Lactobacillus rhamnosus, Lactobacillus acidophilus, and a cocktail mix of the three supernatants against E. faecalis using agar well diffusion method in both solution and gel phase. The formed zones of inhibition (ZOI) were measured in millimeters (mm) and compared to each other. PS solution and gel of the largest ZOI were further compared with calcium hydroxide paste (35% Ultra Cal XS Ca(OH)₂) This was followed by (stage two): assessment of the minimum inhibitory concentration (MIC) of the PS that showed the largest ZOI against E. faecalis by agar well diffusion assay for both PS solution and gel.

Results

All supernatants showed growth inhibition against E. faecalis, and the cocktail mix showed the largest ZOI. However, no significant difference was found between the supernatants in both the solution and gel phases (p > 0.05). Ca(OH)₂ showed a significantly lower effect than both the cocktail mix solution and gel (p < 0.05). The MIC of the cocktail mix solution and gel against E. faecalis was 50 mg/ml. (p > 0.05).

Conclusion

PS has an antibacterial effect on E. faecalis and was more effective than Ca(OH)_2.Lactobacilli probiotics could be a promising antibacterial agent used as an irrigant or an intracanal medication.

Enhanced Skin Permeation of Punicalagin after Topical Application of Pluronic Micelles or Vesicles Loaded with Lafoensia pacari Extract

Punicalagin, the principal ellagitannin of Lafoensia pacari leaves, has proven antioxidant activity, and standardized extracts of L. pacari can be topically used for skin aging management. We hypothesized that Pluronic nanomicelles or vesicles could solubilize sufficiently large amounts of the standardized extracts of L. pacari and provide chemical stability to punicalagin. The standardized extracts of L. pacari were obtained with an optimized extraction procedure, and the antioxidant activity was characterized. Formulations containing Pluronic at 25% and 35% were obtained with or without Span 80. They were characterized by average diameter, polydispersity index, punicalagin content, physicochemical stability, and rheology. A release and skin permeation study was carried out in vertical diffusion cells. The extraction procedure allowed quantifying high punicalagin content (i.e., 141.61 ± 3.87 mg/g). The standardized extracts of L. pacari showed antioxidant activity for all evaluated methods. Pluronic at 25 and Pluronic at 35 with standardized extracts of L. pacari showed an average diameter of about 25 nm. The addition of Span 80 significantly increased the mean diameter by 15-fold (p < 0.05), indicating the spontaneous formation of vesicles. Pluronic formulations significantly protected punicalagin from chemical degradation (p < 0.05). Pluronic at 25 formulations presented as free-flowing liquid-like systems, while Pluronic at 35 resulted in an increase of about 44-fold in |ƞ*|. The addition of Span 80 significantly reduced the Pluronic sol-gel transition temperature (p < 0.05), indicating the formation of vesicles. Formulations with Span 80 significantly enhanced punicalagin skin permeation compared to formulations without Span 80 (p < 0.05). Formulations with Span 80 were demonstrated to be the most promising formulations, as they allowed significant permeation of punicalagin (about 80 to 315 µg/cm²), which has been shown to have antioxidant activity.

Method for screening antimicrobial gels against multi-species oral biofilms

We described a microtiter plate-based method that was effectively tailored for testing gel formulations against oral multispecies biofilms established on peg-lids. This method lifts the limitations imposed mainly by the anaerobic nature of the targeted bacterial species and the viscous properties of the targeted treatments.

Poloxamer Hydrogels for Biomedical Applications

This review article focuses on thermoresponsive hydrogels consisting of poloxamers which are of high interest for biomedical application especially in drug delivery for ophthalmic, injectable, transdermal, and vaginal administration. These hydrogels remain fluid at room temperature but become more viscous gel once they are exposed to body temperature. In this way, the gelling system remains at the topical level for a long time and the drug release is controlled and prolonged. Poloxamers are synthetic triblock copolymers of poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO), also commercially known as Pluronics®, Synperonics® or Lutrol®. The different poloxamers cover a range of liquids, pastes, and solids, with molecular weights and ethylene oxide-propylene oxide weight ratios varying from 1100 to 14,000 and 1:9 to 8:2, respectively. Concentrated aqueous solutions of poloxamers form thermoreversible gels. In recent years this type of gel has arouse interest for tissue engineering. Finally, the use of poloxamers as biosurfactants is evaluated since they are able to form micelles in an aqueous environment above a concentration threshold known as critical micelle concentration (CMC). This property is exploited for drug delivery and different therapeutic applications.

Gallic acid loaded poloxamer gel as new adjuvant strategy for melanoma: A preliminary study

The present study describes the production and characterization of poloxamer gels containing the antioxidant molecule gallic acid. The gels were particularly designed in order to obtain a formulation suitable for administration on the skin to treat melanoma. The polymer concentration was selected after rheological characterization and determination of gel transition temperature. In order to study the gallic acid diffusion, in vitro experiments were performed using Franz cells associated to different membranes. As first approach the gallic acid diffusion was evaluated through synthetic membranes, such as cellulose, nylon, polycarbonate, polytetrafluoroethylene, polyvinylidene fluoride and the commercial Strat-M® membrane. The membranes were employed separately or in association and compared to stratum corneum epidermis membranes, in order to find a system able to reproduce the gallic acid diffusion through the skin. Selected membranes were used for studying gallic acid diffusion from poloxamer gel. It was found that the diffusion of gallic acid was dramatically influenced by the type of membrane, both in the case of the aqueous solution or poloxamer gel. Scratch wound healing and migration assays conducted on human keratinocytes and melanoma cells demonstrated the ability of gallic acid loaded gel to inhibit cellular migration, suggesting its potential as adjuvant strategy for melanoma.

Local Drug Delivery Based Treatment Approaches for Effective Management of Periodontitis

Background:

Periodontal disease is an immuno-inflammatory condition of tissues that surround and hold the teeth. It is the disease which succeeds in all races, groups and both genders. Almost 10 to15% of the global population gets suffered from severe periodontitis as per WHO reports. Periodontal disease may likely cause other systemic diseases such as cardiovascular disease and pre-term low birth weight infants. Mechanical removal of plaques and calculus deposits from supra and subgingival environment is the backbone of periodontal treatment till date whereas complete elimination of these deleterious agents is quite unrealistic as the pocket depth increases.

Recent Approaches:

Recently controlled local drug delivery application is more encouraging in comparison to systemic approach as it mainly targets to enhance the therapeutic efficacy by maintaining site-specificity, avoiding first pass metabolism, reduction in gastrointestinal (GI) side effects and decreasing the dose. Several drugs such as antiseptics and antibiotics alongwith various carriers are being formulated as local drug delivery systems for effective management of the disease. Various local delivery systems reported are fibers, films, strips, compacts, injectables, microparticles, vesicular carriers, gels and nanoparticles. These local carriers provide effective prolonged treatment at the site of infection at reduced doses. This review enlightens detailed pathophysiology and various phases of periodontitis, challenges in treatment of disease and various antimicrobial agents (along with their marketed formulations) used. The main emphasis of the review is to cover all carrier systems developed so far for local delivery application in the effective management of periodontitis, as a patient compliant drug therapy.

Liquid crystal delivery of ciprofloxacin to treat infections of the female reproductive tract

Infections of the female reproductive tract are a major cause of morbidity and mortality in humans, requiring significant investment to sustain treatment and representing a major challenge to health. The increasing prevalence of bacterial resistance, and an almost complete absence of new antibiotic therapies for the past five decades, mean there is a desperate need for novel approaches to the treatment of bacterial infections. Within the present study, we demonstrate the effective ex vivo treatment of bacterial infection of the female reproductive tract using a controlled-release, liquid crystal-based platform. Liquid crystal encapsulation of ciprofloxacin significantly enhanced its bactericidal efficacy and reduced cell toxicity. Liquid crystal structures are low-cost, simple to manufacture and provide a sustained-release profile of encapsulated ciprofloxacin. Treatment of Escherichia coli infected reproductive tract epithelial cells and whole organ cultures with liquid crystal encapsulated ciprofloxacin proved to be an effective strategy for reducing bacterial load and reproductive tract inflammatory responses to infection. These data suggest that such an approach could provide an efficacious treatment modality for enhancing the effectiveness of current antibiotic therapies.

Cubosomes with surface cross-linked chitosan exhibit sustained release and bioavailability enhancement for vinpocetine

Cubosomes with surface cross-linked chitosan exhibit anti-digestion effect, sustained drug release behavior, and significantly enhanced oral bioavailability of vinpocetine.

Periodontal thermoresponsive, mucoadhesive dual antimicrobial loaded in-situ gel for the treatment of periodontal disease: Preparation, in-vitro characterization and antimicrobial study

Background

This study aimed to formulate and characterize in-situ gel containing levofloxacin and metronidazole to release drugs in controlled manner for treatment of periodontitis.

Material and Methods

Medicated in-situ gel with levofloxacin (10% w/v), metronidazole (25% w/v) and vehicle in-situ gel without drugs having poloxamer 407 (20% w/v) and chitosan (0.5%, 1%, 1.5%, 2.0% 2.5% w/v) were prepared and characterized for physicochemical, mechanical properties, stability and in-vitro drug release. Fourier transform infrared spectroscopy and differential scanning calorimetery studies were done. Optimized formulation was evaluated by scanning electron microscope (SEM) and in-vitro antimicrobial activity against 5 bacterial strains.

Results

The results revealed that drugs and polymers were compatible to formulate. All formulations were light yellow, clear and syringeable except formulation having 2.5% w/v chitosan. pH was in the range of 6.20 to 6.74. 1.0% w/v and 1.5% w/v chitosan formulations showed gelation temperature 37 ± 0.32 °C and 34 ± 0.21 °C. Further, mucoadhesive strength indicated mucoadhesivity of gel. In-vitro release study of 1.5% w/v chitosan formulation showed initial burst where about 55-60% MZ and 60-70% LVF got released within 6-7 hrs followed by sustained release upto 48 hrs. SEM images of 1.5% w/v chitosan optimized medicated in-situ and vehicle in-situ gel appeared similar indicating homogeneous mixing of polymers with drugs. In-vitro antimicrobial study showed that medicated in-situ gel was more effective than vehicle.

Conclusions

In conclusion, optimized 1.5% w/v chitosan in-situ gel was thermoresponsive, mucoadhesive, syringeable, and released drugs in slow and controlled manner with effectiveness against broad range of microbes.

Role of clove oil in solvent exchange-induced doxycycline hyclate-loaded Eudragit RS in situ forming gel

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Role of clove oil (CO) in doxycycline hyclate (DH)-loaded Eudragit RS (ERS) in situ forming gel (ISG) was investigated.

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CO could solubilize ERS and increase the viscosity of ISG and also minimize DH burst release with sustainable DH release.

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ISGs comprising CO could expel through the 27-gauge needle and transform into matrix depot in simulated crevicular fluid.

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Antimicrobial activities against all test bacterias were increased when increasing CO and N-methyl pyrrolidone (NMP) ratio.

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DH-loaded ERS ISG comprising CO could be used as a local drug delivery system for periodontitis treatment.

Solvent exchange induced in situ forming gel (ISG) is the promising drug delivery system for periodontitis treatment owing to the prospect of maintaining an effective high drug level in the gingival crevicular fluid. In the present study, the influence of clove oil (CO) on the characteristics of doxycycline hyclate (DH)-loaded ISG comprising Eudragit RS (ERS) was investigated including viscosity/rheology, syringeability, in vitro gel formation/drug release, matrix formation/solvent diffusion and antimicrobial activities. CO could dissolve ERS and increase the viscosity of ISG and its hydrophobicity could also retard the diffusion of solvent and hinder the drug diffusion; thus, the minimization of burst effect and sustained drug release were achieved effectively. All the prepared ISGs comprising CO could expel through the 27-gauge needle for administration by injection and transform into matrix depot after exposure to the simulated gingival crevicular fluid. The antimicrobial activities against Staphylococcus aureus, Escherichia coli, Streptococcus mutans and Porphyromonas gingivalis were increased when the ratio of CO and N-methyl pyrrolidone (NMP) was decreased from 1:1 to 1:10 owing to higher diffusion of DH except that for C. albicans was increased as CO amount was higher. Therefore, CO could minimize the burst while prolonging the drug release of DH-loaded ERS ISG for use as a local drug delivery system for periodontitis treatment.

Effect of Liquid Crystalline Systems Containing Antimicrobial Compounds on Infectious Skin Bacteria

This study aimed (i) to prepare liquid crystalline systems (LCS) of glyceryl monooleate (GMO) and water containing antibacterial compounds and (ii) to evaluate their potential as drug delivery systems for topical treatment of bacterial infections. Therefore, LCS containing CPC (cetylpyridinium chloride) (LCS/CPC) and PHMB (poly(hexamethylene biguanide) hydrochloride) (LCS/PHMB) were prepared and the liquid crystalline phases were identified by polarizing light microscopy 24 h and 7 days after preparation. The in vitro drug release profile and in vitro antibacterial activity of the systems were assessed using the double layer agar diffusion method against Staphylococcus aureus, methicillin-resistant S. aureus, Staphylococcus epidermidis, Escherichia coli, and Enterococcus faecalis. The interaction between GMO and the drugs was evaluated by a drug absorption study. Stable liquid crystalline systems containing CPC and PHMB were obtained. LCS/PHMB decreased the PHMB release rate and exerted strong antibacterial activity against all the investigated bacteria. In contrast, CPC interacted with GMO so strongly that it became attached to the system; the amount released was not sufficient to exert antibacterial activity. Therefore, the studied liquid crystalline systems were suitable to deliver PHMB, but not CPC. Accordingly, it was demonstrated that GMO interacts with each drug differently, which may interfere in the final efficiency of GMO/water LCS.

Polymeric Hydrogels as Technology Platform for Drug Delivery Applications

Hydrogels have become key players in the field of drug delivery owing to their great versatility in terms of composition and adjustability to various administration routes, from parenteral (e.g., intravenous) to non-parenteral (e.g., oral, topical) ones. In addition, based on the envisioned application, the design of bioadhesive or mucoadhesive hydrogels with prolonged residence time in the administration site may be beneficial. For example, hydrogels are used as wound dressings and patches for local and systemic therapy. In a similar way, they can be applied in the vaginal tract for local treatment or in the nasal cavity for a similar goal or, conversely, to target the central nervous system by the nose-to-brain pathway. Overall, hydrogels have demonstrated outstanding capabilities to ensure patient compliance, while achieving long-term therapeutic effects. The present work overviews the most relevant and recent applications of hydrogels in drug delivery with special emphasis on mucosal routes.

Designing Solvent Exchange-Induced In Situ Forming Gel from Aqueous Insoluble Polymers as Matrix Base for Periodontitis Treatment

An in situ forming gel is a dosage form which is promised for site-specific therapy such as periodontal pocket of periodontitis treatment. Ethylcellulose, bleached shellac, and Eudragit RS were applied in this study as a polymeric matrix for in situ forming gel employing N-methyl pyrrolidone (NMP) as solvent. Solutions comprising ethylcellulose, bleached shellac, and Eudragit RS in NMP were evaluated for viscosity, rheology, and rate of water penetration. Ease of administration by injection was determined as the force required to expel polymeric solutions through a needle using texture analyzer. In vitro gel formation and in vitro gel degradation were conducted after injection into phosphate buffer solution pH 6.8. Ethylcellulose, bleached shellac, and Eudragit RS could form the in situ gel, in vitro. Gel viscosity and pH value depended on percentage amount of the polymer, whereas the water diffusion at early period likely relied on types of polymer. Furthermore, the solutions containing higher polymer concentration exhibited the lower degree of degradation. All the preparations were acceptable as injectable dosage forms because the applied force was lower than 50 N. All of them inhibited Staphylococcus aureus, Escherichia coli, Candida albicans, Streptococcus mutans, and Porphyrommonas gingivalis growth owing to antimicrobial activity of NMP which exhibited a potential use for periodontitis treatment. Moreover, the developed systems presented as the solvent exchange induced in situ forming gel and showed capability to be incorporated with the suitable antimicrobial active compounds for periodontitis treatment which should be further studied.

Liquid Crystal Systems in Drug Delivery

Liquid crystals have been recently studied as novel drug delivery system. The reason behind this is their similarity to colloidal systems in living organisms. They have proven to be advantageous over Traditional, Dermal, Parentral and Oral Dosage forms. Liquid crystals are thermodynamically stable and possess long shelf life. Liquid crystals show bio adhesive properties and sustained release effects. Objective of this book chapter is to provide in-depth information of Pharmaceutical crystal technology. It shall deal with cubic and hexagonal liquid crystal and their applications in Drug delivery system.

Doxycycline hyclate-loaded bleached shellac in situ forming microparticle for intraperiodontal pocket local delivery

Bleached shellac (BS) is a water-insoluble polyester resin made up of sesquiterpenoid acids esterified with hydroxy aliphatic acids. In this study, BS dissolved in N-methyl pyrrolidone (NMP), dimethyl sulfoxide (DMSO) and 2-pyrrolidone was used as the internal phase of oil in oil emulsion using olive oil emulsified with glyceryl monostearate (GMS) as the external phase of in situ forming microparticles (ISM). Doxycycline hyclate (DH)-loaded BS ISMs were tested for emulsion stability, viscosity, rheology, transformation into microparticles, syringeability, drug release, surface topography, in vitro degradation and antimicrobial activities against Staphylococcus aureus, Streptococcus mutans and Porphyromonas gingivalis. All emulsions exhibited pseudoplastic flow and notably low syringeability force. Slower transformation from emulsion into microparticles of ISM prepared with 2-pyrrolidone was owing to slower solvent exchange of this solvent which promoted less porous structure of obtained BS matrix microparticles. The system containing 2-pyrrolidone exhibited a higher degradability than that prepared with DMSO. Developed DH-loaded BS ISMs exhibited a sustainable drug release for 47days with Fickian diffusion and effectively inhibited P. gingivalis, S. mutans and S. aureus. Therefore a DH-loaded BS ISM using olive oil containing GMS as the external phase and 2-pyrrolidone as a solvent was a suitable formulation for periodontitis treatment.

Cubosomes and hexosomes as versatile platforms for drug delivery

Nonlamellar liquid crystalline phases are attractive platforms for drug solubilization and targeted delivery. The attractiveness of this formulation principle is linked to the nanostructural versatility, compatiblity, digestiblity and bioadhesive properties of their lipid constituents, and the capability of solubilizing and sustaining the release of amphiphilic, hydrophobic and hydrophilic drugs. Nonlamellar liquid crystalline phases offer two distinct promising strategies in the development of drug delivery systems. These comprise formation of ISAsomes (internally self-assembled ‘somes’ or particles) such as cubosomes and hexosomes, and in situ formation of parenteral dosage forms with tunable nanostructures at the site of administration. This review outlines the unique features of cubosomes and hexosomes and their potential utilization as promising platforms for drug delivery.

Solvent exchange-induced in situ forming gel comprising ethyl cellulose-antimicrobial drugs

Solvent-exchanged in situ forming gel is a drug delivery system which is in sol form before administration. When it contacts with the body fluid, then the water miscible organic solvent dissipates and water penetrates into the system, leading the polymer precipitation as in situ gel at the site of injection. The aim of this research was to study the parameters affecting the gel properties, drug release and antimicrobial activities of the in situ forming gels prepared from ethyl cellulose (EC) dissolved in N-methyl pyrrolidone (NMP) to deliver the antimicrobial agents (doxycycline hyclate, metronidazole and benzyl peroxide) for periodontitis treatment. The gel appearance, pH, viscosity, rheology, syringeability, gel formation, rate of water diffusion into the gels, in vitro degradation, drug release behavior and antimicrobial activities against Staphylococcus aureus, Escherichia coli, Candida albicans, Streptococcus mutans and Porphyrommonas gingivalis were determined. Increasing the amount of EC increased the viscosity of system while still exhibiting Newtonian flow and increased the work of syringeability whereas decreased the releasing of drug. The system transformed into the rigid gel formation after being injected into the simulated gingival crevicular fluid. The developed systems containing 5% w/w antimicrobial agent showed the antimicrobial activities against all test bacteria. Thus the developed solvent exchange-induced in situ forming gels comprising EC-antimicrobial drugs exhibited potential use for periodontitis treatment.

Nanostructured reverse hexagonal liquid crystals sustain plasma concentrations for a poorly water-soluble drug after oral administration

Reverse hexagonal (H2) liquid crystals formed from selachyl alcohol were demonstrated to sustain the absorption of the poorly water-soluble drug cinnarizine (CZ) after oral administration to rats. When CZ was administered as a bolus lipid solution in selachyl alcohol, the T max was observed to be 23.5 ± 5.9 h, significantly longer than the control suspension (1 h). Administration of selachyl alcohol as dispersed nanoparticles (hexosomes) also resulted in a sustained plasma profile, with drug concentrations maintained from 20 to 40 ng/mL over the first 24 h after administration. Sustained absorption of CZ from the selachyl alcohol hexosomes led to a significant enhancement (p < 0.05) in oral bioavailability (F% = 17%) compared to the control CZ suspension (9%). Analysis of selachyl alcohol hexosomes using small-angle x-ray scattering indicated that neither the presence of CZ (7 mg/g) nor simulated intestinal fluid altered the H2 nanostructure. Selachyl alcohol is not susceptible to digestion. Prolonged absorption from the selachyl alcohol-based H2 systems was attributed to the non-digestible nature of the lipid, similar to non-digestible phytantriol cubic (V2) systems previously reported. Furthermore, the likely presence of non-sink conditions in the gastric compartment provides a drug reservoir requiring gastric emptying to stimulate drug release from the formulation. This study highlights the potential use of non-digestible liquid crystalline systems generally and nanostructured liquid crystalline particles in particular as novel sustained oral drug delivery systems.

Mucoadhesive system formed by liquid crystals for buccal administration of poly(hexamethylene biguanide) hydrochloride

Antimicrobial approaches are valuable in controlling the development of buccal diseases, but some antibacterial agents have a short duration of activity. Therefore, the development of prolonged delivery systems would be advantageous. Liquid crystalline systems comprising monoolein (GMO)/water have been considered to be a potential vehicle to deliver drugs to the buccal mucosa because of the phase properties that allow for controlled drug release as well as its mucoadhesive properties. Therefore, the aim of this study was to develop a GMO/water system for the slow release of poly(hexamethylene biguanide) hydrochloride (PHMB) on the buccal mucosa and test the properties of this system with regard to swelling, release profile, antimicrobial activity, and strength of mucoadhesion, with the overall goal of treating buccal infections. The tested systems were capable of modulating drug release, which is controlled by diffusion of the drug throughout the system. Furthermore, PHMB appeared to improve the mucoadhesive properties of the system and may synergistically act with the drug to promote antimicrobial activity against S. mutas and C. albicans, indicating that liquid crystals may be suitable for the administration of PHMB on the buccal mucosa. Therefore, this system could be proposed as a novel system for mucoadhesive drug delivery.

Comparative study to investigate the effect of meloxicam or minocycline HCl in situ gel system on local treatment of periodontal pockets

In situ gelling formulations allow easy application to the target area. Gelation is induced by physiological stimuli at the site of application where the formula attains semisolid properties and exerts sustained drug release. In situ gelling formulations containing either 3% meloxicam (Mx) or 2% minocycline HCl (MH) were prepared for local application into the periodontal pockets. Gel formulations were based on the thermosensitive Pluronic(®) (Pl) and the pH-sensitive Carbopol(®) (C) polymers. C gels were prepared in combination with HPMC (H) to decrease its acidity. The total percent drug released from Pl formulae was 21.72% after 1 week for Mx and 85% after 3 days for MH. Their release kinetics data indicated anomalous non-Fickian behavior that could be controlled by both diffusion and chain relaxation. Addition of MH to C/H gels (1:2.5) resulted in liquefaction, followed by drug precipitation. Regarding C/H gel containing Mx, it showed a prolonged release rate up to 7 days with an initial burst effect; the kinetics data revealed Fickian-diffusion mechanism. The in vitro antibacterial activity studies for MH gel in Pl revealed that the drug released exceeded the minimum inhibitory concentration (MIC) of MH against Staphylococcus aureus ATCC 6538; placebo gel showed no effect on the microorganism. Clinical evaluation of Pl gels containing either Mx or MH showed significant improvement in chronic periodontitis patients, manifested by decrease in pocket depth and gingival index and increase in bone density.

Bioactive factor delivery strategies from engineered polymer hydrogels for therapeutic medicine

Polymer hydrogels have been widely explored as therapeutic delivery matrices because of their ability to present sustained, localized and controlled release of bioactive factors. Bioactive factor delivery from injectable biopolymer hydrogels provides a versatile approach to treat a wide variety of diseases, to direct cell function and to enhance tissue regeneration. The innovative development and modification of both natural-(e.g., alginate (ALG), chitosan, hyaluronic acid (HA), gelatin, heparin (HEP), etc.) and synthetic-(e.g., polyesters, polyethyleneimine (PEI), etc.) based polymers has resulted in a variety of approaches to design drug delivery hydrogel systems from which loaded therapeutics are released. This review presents the state-of-the-art in a wide range of hydrogels that are formed though self-assembly of polymers and peptides, chemical crosslinking, ionic crosslinking and biomolecule recognition. Hydrogel design for bioactive factor delivery is the focus of the first section. The second section then thoroughly discusses release strategies of payloads from hydrogels for therapeutic medicine, such as physical incorporation, covalent tethering, affinity interactions, on demand release and/or use of hybrid polymer scaffolds, with an emphasis on the last 5 years.

Cubic and hexagonal liquid crystals as drug delivery systems

Lipids have been widely used as main constituents in various drug delivery systems, such as liposomes, solid lipid nanoparticles, nanostructured lipid carriers, and lipid-based lyotropic liquid crystals. Among them, lipid-based lyotropic liquid crystals have highly ordered, thermodynamically stable internal nanostructure, thereby offering the potential as a sustained drug release matrix. The intricate nanostructures of the cubic phase and hexagonal phase have been shown to provide diffusion controlled release of active pharmaceutical ingredients with a wide range of molecular weights and polarities. In addition, the biodegradable and biocompatible nature of lipids demonstrates the minimum toxicity and thus they are used for various routes of administration. Therefore, the research on lipid-based lyotropic liquid crystalline phases has attracted a lot of attention in recent years. This review will provide an overview of the lipids used to prepare cubic phase and hexagonal phase at physiological temperature, as well as the influencing factors on the phase transition of liquid crystals. In particular, the most current research progresses on cubic and hexagonal phases as drug delivery systems will be discussed.

In situ forming implants for periodontitis treatment with improved adhesive properties

Novel in situ forming implants are presented showing a promising potential to overcome one of the major practical hurdles associated with local periodontitis treatment: limited adhesion to the surrounding tissue, resulting in accidental expulsion of at least parts of the implants from the patients' pockets. This leads to high uncertainties in the systems' residence times at the site of action and in the resulting drug exposure. In the present study, the addition of different types and amounts of plasticizers (acetyltributyl citrate and dibutyl sebacate) as well as of adhesive polymers (e.g., cellulose derivatives such as hydroxypropyl methylcellulose) is shown to allow for a significant increase in the stickiness of poly(lactic-co-glycolic acid)-based implants. The systems are formed in situ from N-methyl pyrrolidone-based liquid formulations. Importantly, at the same time, good plastic deformability of the implants can be provided and desired drug release patterns can be fine-tuned using several formulation tools. The antimicrobial activity of this new type of in situ forming implants, loaded with doxycycline hyclate, was demonstrated using the agar well diffusion method and multiple Streptococcus strains isolated from the oral microflora of patients suffering from periodontitis.

Effect of ethylcellulose and propylene glycol on the controlled-release performance of glyceryl monooleate-mertronidazole periodontal gel

Controlled-release metronidazole, mucoadhesive gel proposed as a drug-delivery system for periodontal application was developed and characterized. The system was based on a mixture of glycerylmonooleate (GMO) and ethylcellulose (EC). The mechanism of release depends: firstly, on the ability of GMO to form a viscous liquid crystalline mesophases and secondly on the solubilized EC to form a hydrophobic network when the mixture comes into contact with water resulting in sustaining the release of the drug. Ethylcellulose dissolved in GMO had a profound influence on the rate of drug release, reduced the initial drug release and prolonged the sustained release of metronidazole. Propylene glycol (PG) was added to increase the solubility of the drug and water was added with PG to control the viscosity. A controlled release formulation containing w/w, 20% metronidazole, 10% PG, 5% water and 65% GMO that contains 7% EC was found to be mucoadhesive, easily injectable at room temperature, and to follow Fickian diffusion release mechanism. When the drug loading was increased the drug release was accelerated, and the mechanism followed anomalous controlled-release mechanism. Stability studies indicated that the formulation should be stored at 4 °C in a dark place.

Preparation and evaluation of bioadhesive dibucaine gels for enhanced local anesthetic action

In relieving local pains, dibucaine, one of ester type local anesthetics, has been used. In case of their application such as ointments and creams, it is difficult to expect their effects for a required period of time, because they are easily removed by wetting, movement and contacting. To develop suitable bioadhesive gels, the bioadhesive force of hydroxypropyl cellulose (HPC) was tested using auto-peeling tester. The effect of drug concentration on drug release was studied from the prepared 2% HPC-HF gels using synthetic cellulose membrane at 37 +/- 0.5 degrees C. We investigated the enhancing effects on drug permeation into skins, using some kind of enhancers such as the glycols, the non-ionic surfactants, the fatty acids, and the propylene glycol derivatives. Anesthetic effects of dibucaine gels containing polyoxyethylene 2-oleyl ether were measured by tail flick analgesic meter. The bioadhesive force of various types of HPC such as GF, MF, and HF, was 0.0131, 0.0501, and 0.1346 N, at 2% HPC concentration, respectively. The HPC-HF gels showed the highest bioadhesive force. As the concentration of HPC-HF increased, the drug release increased. As the temperature increased, the drug release increased. Among the enhancers used, polyoxyethylene 2-oleyl ether showed the highest enhancing effects. According to the rat tail flick test, 1% drug gels containing polyoxyethylene 2-oleyl ether showed the prolonged local anesthetic effects. In conclusion, the dibucaine gel containing penetration enhancer and vasoconstrictor showing enhanced local anesthetic action could be developed by using the bioadhesive polymer, HPC.

Design and formulation of mebeverine HCl semisolid formulations for intraorally administration

Gel formulations of mebeverine hydrochloride (MbHCl) containing hydroxypropylmethylcellulose (HPMC), metolose (MTL), and poloxamer 407 (PLX) were prepared to be used in the treatment of different oral painful conditions. HPMC was used as a mucoadhesive gel base while MTL and PLX were used to prepare sol-gel thermosensitive gels. MTL and PLX formulations showed proper sol-gel transition temperature for intraoral application. Formulations were evaluated in terms of their viscosity, mechanical properties, mucoadhesivity, stability, and in vitro drug release. The formulation prepared with 2% of HPMC K100M provided the highest viscosity at room temperature. However, the viscosity of HPMC-PLX mixture showed a significant increase at body temperature. The greatest mucoadhesion was also noted in HPMC-PLX combinations. Texture profile analysis exhibited the differences of the adhesion, hardness, elasticity, cohesiveness, and compressibility of the formulations. The release profiles of MbHCl were obtained, and non-Fickian release was observed from all the formulations. The formulations were stored at different temperature and relative humidity. No significant changes were observed at the end of the 3 months. HPMC-PLX formulation of MbHCl was chosen for in vivo studies, and it remained longer than dye solution on the rabbit's intraoral mucosal tissue. It was found worthy of further clinical evaluation.

Biodegradable thermogelling poly[(R)-3-hydroxybutyrate]-based block copolymers: micellization, gelation, and cytotoxicity and cell culture studies

A series of biodegradable multiblock poly(ester urethane)s having poly[(R)-3-hydroxybutyrate] (PHB), poly(ethylene glycol) (PEG), and poly(propylene glycol) (PPG) segments was prepared. The critical micellization concentration (CMCs) of these water-soluble poly(ester urethane)s were determined at different temperatures in order to calculate the thermodynamic parameters for the process of micelle formation. The process for micelle formation was found to be entropy-driven. The thermogelling behavior of the aqueous polymer solution was studied by (1)H and (13)C NMR spectroscopy at different temperatures. We obtained valuable molecular level information regarding the state of the copolymer in solution based on the variation of the peak widths. Cytotoxicity studies performed on the extracts of the copolymer gel indicate good cell compatibility. Cells attach on the surface of the gel much better than on the commercially available PEG-PPG-PEG triblock copolymer. These studies indicate a potential for the copolymer gel to be used for tissue engineering applications.

Metronidazole-containing gel for the treatment of periodontitis: an in vivo evaluation

The aim of this investigation was to monitor metronidazole concentrations in the gingival crevicular fluid (GCF) collected from periodontal pockets of dogs after treatment with an experimental 15% metronidazole gel. Five dogs had periodontitis induced by cotton ligatures placed subgingivally and maintained for a 30-day period. After the induction period, only pockets with 4 mm or deeper received the gel. Each pocket was filled up to the gingival margin by means of a syringe with a blunt-end needle. GCF was collected in paper strips and quantified in an electronic device before and after 15 minutes, 1 h, 6 h, 24 h and 48 h of gel administration. The GCF samples were assayed for metronidazole content by means of a high performance liquid chromatography method. Concentrations of metronidazole in the GCF of the 5 dogs (mean +/- SD, in microg/mL) were 0 +/- 0 before gel application and 47,185.75 +/- 24,874.35 after 15 minutes, 26,457.34 +/- 25,516.91 after 1 h, 24.18 +/- 23.11 after 6 h, 3.78 +/- 3.45 after 24 h and 3.34 +/- 5.54 after 48 h. A single administration of the 15% metronidazole gel released the drug in the GCF of dogs in levels several-fold higher than the minimum inhibitory concentration for some periodontopathogens grown in subgingival biofilms for up to one hour, but metronidazole could be detected in the GCF at least 48 hours after the gel application.

Development of satranidazole mucoadhesive gel for the treatment of periodontitis

The aim of the paper was to develop satranidazole-containing mucoadhesive gel for the treatment of periodontitis. Different mucoadhesive gels were prepared, using various gelling agents like sodium carboxymethylcellulose (SCMC), poloxamer 407, hydroxyethylcellulose, hydroxypropylcellulose, hydroxypropylmethylcellulose, and the mucoadhesive polymer carbopol 934P. The selected formulations (based on the mucoadhesive force) were studied for different mechanical properties, such as mucoadhesive strength, hardness, compressibility, adhesiveness, and cohesiveness through Texture Profile Analyzer. In vitro satranidazole release from the prepared formulations was also determined and compared with marketed preparation of metronidazole (Metrogyl gel). The formulation SC30 (containing SCMC 3% w/v) showed maximum mucoadhesive strength (167.72 +/- 3.76 g) and adhesiveness (-46.23 +/- 0.34 N mm), with low hardness (9.81 +/- 0.04 N) and compressibility (40.05 +/- 0.48 N mm) and moderate cohesiveness (0.87 +/- 0.01). SC30 formulation exhibited long-term release. Thus, SC30 gel was evaluated for its clinical effectiveness along with marketed metronidazole gel. At the end of the study (42 days of clinical studies), both formulations were found to significantly reduce the probing depth, plaque index, gingival index, calculus criteria, and bleeding index. However, the SC30 gel was more effective in reducing the above parameters than marketed metronidazole gel. This study confirmed the acceptability and effectiveness of satranidazole gel for treatment of periodontitis.

Formulation and Evaluation of Alendronate Sodium Gel for the Treatment of Bone Resorptive Lesions in Periodontitis

Alendronate sodium is formulated into gels and evaluated for the treatment of bone resorptive lesions in periodontitis. Carbopol 934P was used for the preparation of gels in three different concentrations. The prepared gel was evaluated for various properties such as preformulation, content uniformity, viscosity, compatibility, sterility, in vitro diffusion, and in vivo studies. The drug and the polymer were found to be compatible and confirmed by Fourier transform infrared spectroscopy. Viscosity of the gels increased with the increase in the polymer concentration. The formulations were found to be sterile. In vitro release study revealed that drug released from the gel follows non-Fickian diffusion followed by first-order release. In vivo studies were carried out for 6 months in patients. The results revealed a significant improvement in the clinical parameters such as gingival index, probing pocket depth, clinical attachment level, and potent inhibitory effect on bone resorption by inhibition of osteoclasts. In addition, there was increase in the new bone formation.

Formulation and evaluation of PLA and PLGA in situ implants containing secnidazole and/or doxycycline for treatment of periodontitis

The purpose of this study is to formulate in situ implants containing doxycycline hydrochloride and/or secnidazole that could be used in the treatment of periodontitis by direct periodontal intrapocket administration. Biodegradable polymers [poly (lactide) (PLA) and poly (lactide-co-glycolide) (PLGA)], each polymer in two concentrations 25%w/w, 35%w/w were used to formulate the in situ implants. The rheological behavior, in vitro drug release and the antimicrobial activity of the prepared implants were evaluated. Increasing the concentration of each polymer increases the viscosity and decreases the percent of the drugs released after 24 h. PLA implants showed a slower drugs release rate than PLGA implants in which the implants composed of 25% PLGA showed the fastest drugs release. The in vitro drug release and antimicrobial activity results were compared with results of Atridox. Results revealed that the pharmaceutical formulation based on 25% PLGA containing secnidazole and doxycycline hydrochloride has promising activity in treating periodontitis in comparison with Atridox.