Photodynamic antimicrobial chemotherapy (PACT) and antimicrobial peptides (AMPs) are two promising strategies to combat the increasing prevalence of antibiotic-resistant bacteria. To take advantage ...of these two strategies, we integrated a novel antimicrobial peptide (WLBU2) and a potent generation II photosensitizer (temoporfin) into liposomes by preparing WLBU2-modified liposomes, aiming at bacteria targeted delivery of temoporfin for PACT. WLBU2 was successfully coupled to temoporfin-loaded liposomes using a functional phospholipid. The delivery of temoporfin to bacteria was confirmed by fluorescence microscopy and flow cytometry, thus demonstrating that more temoporfin was delivered to bacteria by WLBU2-modified liposomes than by unmodified liposomes. Consequently, the WLBU2-modified liposomes eradicated all methicillin-resistant Staphylococcus aureus (MRSA) and induced a 3.3 log(10) reduction of Pseudomonas aeruginosa in the in vitro photodynamic inactivation test. These findings demonstrate that the use of AMP-modified liposomes is promising for bacteria-targeted delivery of photosensitizers and for improving the PACT efficiency against both gram-positive and gram-negative bacteria in the local infections.
Current research aims to find alternatives to conventional methods for suppressing periodontopathogenic bacteria. Photodynamic therapy (PDT) could be a suitable treatment procedure of periodontal ...infections.
In the present study, the PDT method was tested with two photosensitizers, chlorine e6 and BLC1010, in an experiment on beagle dogs. The animals were infected with Porphyromonas gingivalis (Pg) and Fusobacterium nucleatum (Fn) in all subgingival areas. After infection, we observed clinical signs of gingival inflammation, including an increase of redness and bleeding on probing. Microbiological monitoring before and after treatment was performed using polymerase chain reaction (PCR). PDT was conducted with a diode laser with a wavelength of 662 nm using a power of 0.5 W and the photosensitizers.
The PDT procedure carried out with either of the photosensitizers caused a significant reduction in the clinical inflammation signs of redness and BOP, compared to the controls (laser only and no treatment). Furthermore, PDT with chlorine e6 caused a significant reduction in P. gingivalis-infected sites, whereas there was a lack in suppression after PDT with BLC1010. F. nucleatum could hardly be reduced with chlorine e6, and only to a certain extent with BLC 1010 and laser only. In the control groups, the Pg-infected test sites did not change.
This study demonstrated that the photodynamic therapy using photosensitizer and a 662 nm laser light source is distinctly advantageous in reducing the periodontal signs of redness and bleeding on probing. The procedure also appears to significantly suppress P. gingivalis.
The aim of this study was to evaluate a new approach for killing periodontopathogenic bacteria using photodynamic therapy (PDT).
In this study, we investigated the photosensitizers chlorin e6, BLC ...1010, and BLC 1014 by three different methods for their effect in PDT on the viability of periodontopathogenic bacterial species. The methods included examination of inhibition zones on agar plates, determination of colony-forming units (CFU), and the use of a bacterial viability kit.
Using the CFU method, we were able to demonstrate that the anaerobic bacteria Porphyromonas gingivalis, Fusobacterium nucleatum, and Capnocytophaga gingivalis can be photoinactivated completely by illumination with an intensity of 5.3 J/cm2 in the presence of 10 microM chlorin e6 and 10 microM BLC 1010. With the photosensitizers chlorin e6 and BLC 1010, we were able to induce zones of inhibition on agar plates. BLC 1014 failed to produce a zone of inhibition. The results of the bacterial viability test also showed that the photosensitizer BLC 1014 provides the lowest photodynamic effect in comparison to the others.
The data collected to date suggest that photodynamic therapy with chlorin e6 and BLC 1010 is advantageous for suppressing periodontopathogenic bacteria.
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Temoporfin (mTHPC) has a great potential for the topical photodynamic therapy. However, it presents a highly hydrophobic second generation photosensitizer with low percutaneous ...penetration. In order to use mTHPC for dermal/transdermal delivery it is necessary to employ some of the penetration enhancement methods. In this study invasomes were used as a highly effective drug nanocarrier system to enhance its skin penetration, being composed of non-hydrogenated soybean lecithin (10% w/v), ethanol (3.3%w/v), a mixture of terpenes (1% w/v of the mixture cineole:citral:d-limonene = 45:45:10 v/v) and phosphate buffer saline up to 100% w/v. A pharmacokinetic/biodistribution study was performed in mice bearing s.c. implanted human colorectal tumor HT29 upon the application of mTHPC-loaded invasomes onto the skin above the underlying tumor. The aim was to obtain the biodistribution profile of mTHPC i.e. to gain data on mTHPC-distribution in the body (tumor, treated skin, muscle, blood, liver and untreated skin) of mice after the topical application of mTHPC-loaded invasomes. The results revealed that a significant mTHPC-amount was found in treated skin already after 2 h of incubation time. As to the tumor, significant amounts were found after 12 h, while the highest mTHPC-amount was found after 24 h. This study showed that invasomes applied onto the skin may deliver mTHPC to the tumor being necessary for PDT. Since mTHPC was also found in blood and liver, transdermal mTHPC delivery was confirmed. In conclusion, mTHPC-invasomes could be used for topical PDT of cutaneous and subcutaneous lesions, however with general photoxicity induced by systemic apsorption of mTHPC lasting only for 2 weeks. Additionally, due to systemic absorption of mTHPC after invasomes application onto the skin, they could be used transdermally for the PDT treatment of diseases, which need systemic drug absorption. However, it should be emphasized that mice were used in the study, differing in the skin properties compared to human skin. Thus, additional studies should be conducted.
Temoporfin (mTHPC) is a highly hydrophobic second generation photosensitizer with low percutaneous penetration. In order to enhance its percutaneous penetration it was necessary to develop a ...mTHPC-loaded drug carrier system for enhanced skin delivery. mTHPC-loaded invasomes were developed, characterized and investigated for the in vitro percutaneous penetration of mTHPC into abdominal human skin using Franz diffusion cells. mTHPC-loaded invasomes were prepared using non-hydrogenated soybean lecithin (10% w/v), ethanol (3.3% w/v) and a mixture of terpenes (0.5 and 1% w/v). The invasomes obtained were of a sufficiently small particle size (<
150 nm) and polydispersity index (<
0.3). The particle size of invasomes increased following an increase in the amount of terpenes in the invasomes. All invasomes possessed a negative surface charge. The vesicles appeared to be unilamellar and oligolamellar, spherical and oval in shape. An interesting phenomenon was the finding that with increasing the amount of terpenes, the number of deformed vesicles in the dispersion increased. In vitro skin penetration data revealed that the invasome dispersion with 1% of the mixture of terpenes showed a significantly enhanced deposition (
p
<
0.05) of the drug in the SC compared to liposomes without terpenes and the ethanolic solution.
Foscan®, a formulation comprising temoporfin dissolved in a mixture of ethanol and propylene glycol, has been approved in Europe for palliative photodynamic therapy of squamous cell carcinoma of the ...head and neck. During clinical and preclinical studies it was observed that considering the administration route, the drug presents a rather atypical plasma profile as plasma concentration peaks delayed. Possible explanations, as for example the formation of a drug depot or aggregation after intravenous administration, are discussed in current literature.
In the present study an advanced in silico model was developed and evaluated for the detailed description of Foscan® pharmacokinetics. Therefore, in vitro release data obtained from experiments with the dispersion releaser technology investigating dissolution pressures of various release media on the drug as well as in vivo data obtained from a clinical study were included into the in silico models. Furthermore, precipitation experiments were performed in presence of biorelevant media and precipitates were analyzed by nanoparticle tracking analysis. Size analysis and particle fraction were also incorporated in this model and a sensitivity analysis was performed. An optimal description of the in vivo situation based on in vitro release and particle characterization data was achieved, as demonstrated by an absolute average fold error of 1.21. This in vitro-in vivo correlation provides an explanation for the pharmacokinetics of Foscan® in humans.
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Over the years, a wide variety of nanomedicines has entered global markets, providing a blueprint for the emerging generics industry. They are characterized by a unique ...pharmacokinetic behavior difficult to explain with conventional methods. In the present approach a physiologically-based nanocarrier biopharmaceutics model has been developed. Providing a compartmental framework of the distribution and elimination of nanocarrier delivery systems, this model was applied to human clinical data of the drug products Doxil®, Myocet®, and AmBisome® as well as to the formulation prototypes Foslip® and NanoBB-1-Dox. A parameter optimization by differential evolution led to an accurate representation of the human data (AAFE < 2). For each formulation, separate half-lives for the carrier and the free drug as well as the drug release were calculated from the total drug concentration-time profile. In this context, a static in vitro set-up and the dynamic in vivo situation with a continuous infusion and accumulation of the carrier were simulated. For Doxil®, a total drug release ranging from 0.01 to 22.1% was determined. With the time of release exceeding the elimination time of the carrier, the major fraction was available for drug targeting. NanoBB-1-Dox released 76.2–77.8% of the drug into the plasma, leading to an accumulated fraction of approximately 20%. The mean residence time of encapsulated doxorubicin was 128 h for Doxil® and 0.784 h for NanoBB-1-Dox, giving the stealth liposomes more time to accumulate at the intended target site. For all other formulations, Myocet®, AmBisome®, and Foslip®, the major fraction of the dose was released into the blood plasma without being available for targeted delivery.
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Today, a growing number of nanotherapeutics is utilized to deliver poorly soluble compounds using the intravenous route of administration. The drug release and the direct transfer of ...the active pharmaceutical ingredient to serum proteins plays an important role in bioavailability and accumulation of the drug at the target site. It is closely related to the formation of a protein corona as well as the plasma protein binding of the compound. In the present study, two in vitro drug release methods, the flow-through cell and the dispersion releaser technology, were evaluated with regards to their capability to measure a time-resolved profile of the serum protein binding. In this context, the photosensitizer temoporfin and temoporfin-loaded liposomes were tested. While in the fine capillaries of the flow-through cell a rapid agglomeration of proteins occurred, the dispersion releaser technology in combination with the four-step model enabled the measurement of the transfer of drugs from liposomes to proteins. In presence of 10% of fetal calf serum approximately 20% of the model compound temoporfin were bound to serum proteins within the first 3 h. At higher serum concentration this binding remained stable for approximately 10 h.
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Over the years, the performance of the liposomal formulations of temoporfin, Foslip® and Fospeg®, was investigated in a broad array of cell-based assays and preclinical animal models. ...So far, little attention has been paid to the influence of drug release and liposomal stability on the plasma concentration–time profile. The drug release is a key attribute which impacts product quality and the in vivo efficacy of nanocarrier formulations. In the present approach, the in vitro drug release and the drug-protein transfer of Foslip® and Fospeg® was determined using the dispersion releaser technology. To analyze the stability of both formulations in physiological fluids, nanoparticle tracking analysis was applied. A comparable drug release behavior and a high physical stability with a vesicle size of approximately 92 ± 2 nm for Foslip® and at 111 ± 5 nm for Fospeg® were measured. The development of a novel hybrid in silico model resulted in an optimal representation of the in vivo data. Based on the information available for previous formulations, the model enabled a prediction of the performance of Foslip® in humans. To verify the simulations, plasma concentration–time profiles of a phase I clinical trial were used. An absolute average fold error of 1.4 was achieved. Moreover, a deconvolution of the pharmacokinetic profile into different fractions relevant for the in vivo efficacy and safety was achieved. While the total plasma concentration reached a cmax of 2298 ng/mL after 0.72 h, the monomolecular drug accounted for a small fraction of the photosensitizer with a cmax of 321 ng/mL only.
