Towards harmonization of solutions used for cystic fibrosis diagnosis by nasal potential difference measurements: A formulation approach with CHESS® software.

BACKGROUND: One diagnosis of cystic fibrosis involves measuring the nasal transepithelial potential difference (NPD) as a complementary technique in the forms of the disease, where the sweat test is non-discriminating. The NPD is measured using solutions with and without chlorides, containing a variety of substances whose activities on nasal mucus membranes are studied or assessed. Among the solutions described in the literature and used in specialized centers, none seems to be best adapted for industrial production for reasons of stability (formulas of the international consensus of Rowe et al. and formulas of Knowles et al.) and/or potential toxicity (formulas of Middleton et al.). OBJECTIVE(S): Defining new formulas, according to those of the international consensus, with greater physicochemical and microbiological stability. METHODS: The reformulation tests were conducted on the formulas of Rowe et al., using CHESS® (CHemical Equilibrium of Species and Surfaces) software for modeling aqueous systems that substantially reduced the number of experiments. CHESS® software was first validated using models of ideal and non-ideal solutions. Thereafter, experimentation was carried out for the sake of comparison with theoretical data. RESULTS: CHESS® software using models of ideal and non-ideal solutions were validated. The experimentation confirmed the theoretical data, and new formulas were assessed based on their physicochemical (pH, content, Osmolality) and microbiological stability. CONCLUSION: The new formulas defined here guarantee excellent physicochemical and microbiological stability of diagnostic solutions, indispensable criteria for harmonizing and comparing results from different specialized centers using NPD measurements. These new formulas apply to the harmonization approach of techniques for measuring the nasal transepithelial potential difference.

[Health technology assessment of innovative medical devices: Timing and decision at national and local level]. / Accès au marché des dispositifs médicaux innovants : articulation entre évaluations nationales et hospitalières.

INTRODUCTION: The Medical Device Committee (CODIMS) evaluates all innovative medical devices (MD) before their introduction in the hospitals of the Assistance publique-hôpitaux de Paris (AP-HP). At the national level, the Medical Device and Health Technology Evaluation Committee (CNEDiMTS) provides recommendation for MD with respects to reimbursement by the National Health Insurance Fund. The aim of this study is to compare the recommendations of both committees and to analyze their timing on a six-year period. MATERIAL AND METHOD: We selected all innovative MD assessed by the CODIMS between 2013 and 2018. We retrieved all the recommendations for these MD from the CNEDiMTS. We performed quantitative and qualitative analysis of data collected. RESULTS: On 30 innovative MD assessed by both the CODIMS and the CNEDiMTS, 11 (37%) evaluations were performed by the CODIMS before the CNEDiMTS evaluation. They occurred approximately a year before the CNEDiMTS recommendation (an average of 378 days). Among the 25 MD with a recommendation of both committees, the two opinions were consistent in 88 per cent of all cases. DISCUSSION/CONCLUSION: This study highlights that there is a good consistency between the recommendations of both committees. This suggests that the MD evaluations conducted at the hospital level are relevant and timely. Finally, a better coordination between the national and local levels should be promoted for the MD assessment.

[3D printed medical devices and anatomical models: What kind of distribution and which uses in French hospitals?] / Dispositifs médicaux et modèles anatomiques produits par impression 3D : quelle diffusion et quelles utilisations dans les établissements de santé français ?

3D printing plays an increasingly important role in the medical sector and particularly in surgery. Nowadays, numerous manufacturers benefit from this technology to produce their medical devices and some hospitals have also purchased 3D printers. In this context, the aim of the present study was to study the distribution and the use of 3D printing in French hospitals in order to its main features in surgery. By conducting a national survey, we targeted hospitals equipped with 3D printers and those using external providers to benefit from this technology. Forty-seven hospitals were identified as using 3D printing including eight equipped with in-house 3D printers. This work gives us a first picture of 3D printing for hospital use in France and it raises questions about hospital pharmacists' involvement in 3D printed medical device production.

Medicinal leech therapy and Aeromonas spp. infection.

While the use of medicinal leech therapy (MLT) in reconstructive and orthopaedic surgery is widely described, post-operative complications related to leeches remain a major concern. Aeromonas spp. strains are involved in the majority of reported cases. As surgical success rate is directly impacted, an adapted antibiotic prophylaxis should be instituted in order to minimize these complications. We assessed pharmaceutical process, microbiological control and related infections in order to provide data and choose the appropriate antibiotherapy for patients requiring MLT. We report a clinical and microbiological study over a 24-month period. Clinical data were collected from patients' database, and microbiological analysis both on leeches' tank water and crushed leeches were performed to characterize isolated strains and their susceptibility to antibiotics. A total of 595 leeches were used to treat 28 patients (12 in plastic surgery and 16 in orthopaedic surgery), and three documented cases of post-operative infections were reported. Aeromonas spp. isolates yielded from 62 % of analyzed batches (75 % of Aeromonas veronii). Eighteen Aeromonas spp. isolates yielded from 23 water samples and three crushed leeches. Isolates were similar in tank and crushed leeches. Strains were susceptible to fluoroquinolones, sulfamethoxazole/trimethoprim, aminosides, and third-generation cephalosporins but resistant to amoxicillin/clavulanic acid and second-generation cephalosporins. According to collected data, routine tank water microbiological analyses are mandatory in order to identify leeches' batches containing resistant strains and to discard them. In this context, the surgeon is able to select an appropriated antibiotic prophylaxis in order to avoid MLT associated serious post-operative complications.

[Hospital-based health technology assessment in France: how to proceed to evaluate innovative medical devices?]. / Évaluation des technologies de santé en milieu hospitalier : quelle organisation pour évaluer et acquérir des dispositifs médicaux innovants ?

Innovative medical devices offer solutions to medical problems and greatly improve patients' outcomes. Like National Health Technology Assessment (HTA) agencies, hospitals face numerous requests for innovative and costly medical devices. To help local decision-makers, different approaches of hospital-based HTA (HB-HTA) have been adopted worldwide. The objective of the present paper is to explore HB-HTA models for adopting innovative medical devices in France and elsewhere. Four different models have been conceptualized: "ambassador" model, "mini-HTA" model, "HTA unit" model and "internal committee". Apparently, "HTA unit" and "internal committee" (or a mixture of both models) are the prevailing HB-HTA models in France. Nevertheless, some weaknesses of these models have been pointed out in previous works. Only few examples involving hospital pharmacists have been found abroad, except in France and in Italy. Finally, the harmonization of the assessment of innovative medical devices in France needs a better understanding of HB-HTA practices.

[Computerized prescription for medical devices: examples, interest and limits]. / Vers la prescription informatisée des dispositifs médicaux : exemples d'application, intérêts et limites.

INTRODUCTION: Related to the good practice contract implemented in hospitals, the prescription dedicated to medical devices, such as pharmaceuticals, could promote safety and good practice. MATERIAL AND METHOD: We attempted to implement a computerized prescription for medical devices. In order to illustrate the method, two examples were selected: the Negative Pressure Wound Therapy (NPWT) and the Drug Eluting Stents (DES). RESULTS: In partnership with the medical teams was elaborated a computerized protocol which included all the needed items for the good use of NPWT. For DES, a pre-existing questionnaire was used. We updated it in order to integrate new items such as the prescriber's name, the patient's name, the characteristics of the wound, the DES references and the indications. DISCUSSION AND CONCLUSION: Computerized prescriptions for high-risk and expensive medical devices seem to be an interesting approach to guarantee the patient care safety and to reduce the budget impacts. In order to monitor the indications funded as fee-for-service medical devices, a prescription will emerge as a gold standard in the future in France. Eventually, this study highlights a new activity of clinical pharmacy for hospital pharmacists dealing with medical devices.

Interest of flow injection spectrophotometry as an orthogonal method for analyzing biomolecule aggregates: Application to stressed monoclonal antibody study.

This study aimed to explore the suitability of flow injection spectrophotometry (FIS) to analyze three degraded therapeutic monoclonal antibodies (bevacizumab, nivolumab, and rituximab). For this purpose, aggregates were generated with stirring, freeze-thaw, and heat stresses. The intact and stressed mab samples were filtered with 0.22 µm hydrophilic filters and analyzed by size exclusion chromatography (SEC), cation-exchange chromatography (CEX), and FIS. In terms of quantitative and qualitative analysis, protein loss and structural changes were assessed. Various aggregates profiles were obtained according to the mabs and the stresses. FIS allowed performing very satisfactory quantifications for each mab with intermediate precision RSD < 3.0 % and recovery between 97.9 and 102.0 %. From the protein loss measurements, it appears that SEC underestimates the mab aggregate proportions up to two times less as compared with FIS since the latter avoids any non-specific interactions (electrostatic or hydrophobic interactions). Using second derivative spectroscopy and multivariate data analysis, we noticed apparent structural differences, located in the regions 245-265 nm for rituximab and nivolumab and 280-300 nm for bevacizumab, depending on the stress. The FIS complementarity with the other techniques used in this study allowed us to demonstrate that the three mabs behave differently for a given stress condition. While extreme mechanical stress formed large aggregates irrespective of the mabs, rituximab showed to be less stable and more sensitive than the two other mabs under freeze-thaw and heat stresses, generating large aggregates (>200 nm) and partial unfolding. Nivolumab tends to form small aggregates less than 50 nm when heated and freeze-thawed. Moreover, freeze-thaw seems to generate native IgG-1 aggregates with rituximab. Similarly, bevacizumab showed to form these IgG-1 aggregates and was resistant to freeze-thaw, likely thanks to trehalose cryoprotectant from its formulation. Finally, FIS associated with multivariate analysis can provide rich information in one single run and appears to be a fast, simple, and reliable method to set complementary and orthogonal approaches for protein aggregates monitoring.

Clinical outcomes of lung-transplant recipients treated by voriconazole and caspofungin combination in aspergillosis.

BACKGROUND AND OBJECTIVE: Invasive pulmonary aspergillosis (IPA) is a serious cause of death among immune-compromised patients such as organ-transplant recipients. Recently, voriconazole has been approved for first-line therapy in IPA. Theoretically, optimal voriconazole blood level (superior to 1 mg/L according to recent studies) should be reached within 24 h. In practice, a significantly longer time seems to be needed in lung-transplant recipients. Therefore, caspofungin is now used in combination with voriconazole to provide cover against Aspergillus spp. infection during this gap. The first aim of this study was to investigate Aspergillus spp. infection treated with this combination and the atter's tolerability. The median time for attainment of apparently active blood levels in lung transplant recipients were compared between those with cystic fibrosis and those without. METHODS: Lung-transplant recipients who received a combination of voriconazole and caspofungin between 2002 and 2008 as primary therapy were identified retrospectively. The median number of days to reach active voriconazole blood levels was compared between cystic fibrosis and other patients by Student's t-test. Statistical significance was defined by P-value <0.05. RESULTS: Four patients were treated for Aspergillus colonization before transplantation and their culture were negative at 90 days. Eleven patients were treated for proven or probable invasive aspergillosis and 14 of them had a complete response. Hallucinations (n = 2) and significant hepatic toxicity (n = 2) were reported. Among the 15 studied transplant recipients, a median of 12.3 days was observed for active voriconazole blood levels to be reached. With cystic fibrosis patients, time tended to be longer than with other recipients (14.9 days vs. 8.3 days). Tacrolimus blood levels (between 5 and 15 ng/mL) may have been increased by voriconazole. CONCLUSION: This retrospective study describes practical experience in the management of this rare and severe disease in a referral centre for cystic fibrosis lung transplantation. Voriconazole and caspofungin combination was acceptably safe and was associated with good clinical outcomes in almost all patients. We showed that in 15 lung-transplant recipients a median of 12.3 days was required for voriconazole to reach high enough blood levels. Caspofungin in combination with voriconazole provides cover against Aspergillus infection during the period when voriconazole may be at subtherapeutic levels with good tolerability.

[Photosensitizing anticancer tetrapyrroles: or how photophysics becomes a mechanism of action]. / Tétrapyrroles anticancéreux photosensibilisants : ou comment la photophysique devient mécanisme d'action.

The macrocyclic tetrapyrrole derivatives used for the treatment of certain solid tumors include porphyrins and their chlorine and bacteriochlorin derivatives. These are highly conjugated, rigid molecules characterized by a strong absorbance in the spectral domain from near ultra-violet to far red (350-750 nm). The combination of tetrapyrroles plus light is called dynamic phototherapy (DPT). This combination transforms the molecule to its triplet form which by deactivation generates free radicals and a singlet oxygen from molecular oxygen, causing tumor destruction. Tetrapyrroles are thus, with psoralens, used for the treatment of psoriasis. They are the only drugs whose mechanism of action results exclusively from their electronic and photophysical spectroscopic characteristics. This class of anticancer agents is usually free of any specific cytotoxic effect. We describe here the current elements linking structure and spectroscopy and observations leading to the design of compounds with strong tumor selectivity and optimal cytotoxic properties.

UV spectroscopy and least square matching for high throughput discrimination of taxanes in commercial formulations and compounded bags.

The need for high-throughput quality control of pharmaceuticals after compounding is often required before the treatment of the patients. Ultra-fast analysis using flow injection analysis coupled to UV spectroscopy and least square matching was assessed for the simultaneous quantification and identification of three therapeutic taxanes after dilution in physiological saline (cabazitaxel, docetaxel, and paclitaxel). In-depth preliminary analysis of the zero and first order UV spectra of the taxanes using principal component analysis (PCA) allowed us focusing on relevant spectral range with very low formulation influence. Least square-matching algorithm available on basic HPLC software was applied to these spectra yielding very high match scores (>999) with significant difference (P < 0.0001). The approach was qualitatively assessed through specificity and sensitivity which were excellent for the three taxanes (100%, n = 378), irrespective of their formulation. In terms of quantification, satisfactory linearity and accuracy were achieved for each of the taxanes according to their therapeutic range (0.05 to 1.02 mg·mL-1). The RSD (%) of the precision was satisfactory (<3%). Finally, the suitability of the approach for the taxanes QC has been demonstrated under routine application.

Simple and ultra-fast recognition and quantitation of compounded monoclonal antibodies: Application to flow injection analysis combined to UV spectroscopy and matching method.

Compounding of monoclonal antibody (mAbs) constantly increases in hospital. Quality control (QC) of the compounded mAbs based on quantification and identification is required to prevent potential errors and fast method is needed to manage outpatient chemotherapy administration. A simple and ultra-fast (less than 30 s) method using flow injection analysis associated to least square matching method issued from the analyzer software was performed and evaluated for the routine hospital QC of three compounded mAbs: bevacizumab, infliximab and rituximab. The method was evaluated through qualitative and quantitative parameters. Preliminary analysis of the UV absorption and second derivative spectra of the mAbs allowed us to adapt analytical conditions according to the therapeutic range of the mAbs. In terms of quantitative QC, linearity, accuracy and precision were assessed as specified in ICH guidelines. Very satisfactory recovery was achieved and the RSD (%) of the intermediate precision were less than 1.1%. Qualitative analytical parameters were also evaluated in terms of specificity, sensitivity and global precision through a matrix of confusion. Results showed to be concentration and mAbs dependant and excellent (100%) specificity and sensitivity were reached within specific concentration range. Finally, routine application on "real life" samples (n = 209) from different batch of the three mAbs complied with the specifications of the quality control i.e. excellent identification (100%) and ±â€¯15% of targeting concentration belonging to the calibration range. The successful use of the combination of second derivative spectroscopy and partial least square matching method demonstrated the interest of FIA for the ultra-fast QC of mAbs after compounding using matching method.

Some insights about 1,6-diphenyl-1,3,5-hexatriene-lipid supramolecular assemblies by steady-state fluorescence measurements.

1,6-Diphenyl-1,3,5-hexatriene (DPH) is the most widely proposed molecular probe for the post-column fluorescence derivatization of lipids after liquid chromatography separation. This kind of detection consists of a supramolecular combination of DPH and eluted lipids. The detection is optimally performed in a mainly aqueous environment (over 80% v/v) because the weak fluorescence of DPH in water is drastically enhanced upon formation of supramolecular assemblies with lipids. In the present study, and in order to obtain better spectroscopic insights into the nature of these supramolecular assemblies, two different lipids were tested, 1,2,3-tridodecanoylglycerol (LLL) as a model triglyceride (nonpolar lipid) and dimyristoylphosphatidylcholine (DMPC) as a model phosphatidylcholine (charged amphiphilic lipid). Stoichiometry and association constants were determined on the basis of the variation of fluorescence intensity in the presence of various concentrations of lipids. LLL(60)-DPH(2) and DMPC(200)-DPH(2) complexes were identified with association constants as high as K(2) = (5.8 +/- 0.5) x 10(13) M(-2) and (17.3 +/- 2.0) x 10(13) M(-2) for LLL and DMPC, respectively. The fluorescence intensity of DPH in the presence of LLL is greater than in the presence of DMPC. An attempt to characterize the insertion mode of DPH in the lipidic supramolecular assemblies is also made.

Release of ibuprofen from beads for embolization: in vitro and in vivo studies.

Ibuprofen (IBU) loaded polyvinyl alcohol-based hydrogel beads (IBU-BB) were designed to alleviate side effects such as inflammation and pain following uterine artery embolization for the treatment of leiomyomata. The present in vitro and in vivo study examines whether IBU-BB provide a sustained-release of the drug. In vitro release studies of IBU from IBU-BB (10, 50, 100 mg/mL), IBU solution (PEDEA) and IBU powder were compared using the T apparatus and the beaker method. The pharmacokinetic profile of IBU release was examined in vivo, following sheep uterine artery embolization with 100 mg/mL IBU-BB or after intra-arterial injection of IBU solution. IBU-BB can deliver high concentrations of the drug over time. The in vitro release from IBU-BB was markedly slower compared to IBU solution. Increasing the concentration of loaded IBU from 10 to 100 mg/mL decreased the rate of release. IBU release from the T apparatus was slower than the release in the beaker. In vivo, the release of the drug was progressive, without the early peak observed with IBU solution. A high level of correlation was obtained between in vivo and in vitro (T apparatus) results. Theoretically, IBU-BB could sustainably release high concentrations of IBU at the site of the uterine fibroids, which makes it a promising approach for the control of post-embolization pain.

Liquid chromatography on porous graphitic carbon with atmospheric pressure photoionization mass spectrometry and tandem mass spectrometry for the analysis of glycosphingolipids.

The study of several structural variations (the length, the degree of unsaturation and hydroxylation of the alkyl chains, the number and nature of osidic residues) helped understand the behaviour of neutral glycosphingolipids (GSLs) on porous graphitic carbon stationary phase (PGC). Atmospheric pressure photoionization mass spectrometry (APPI) and tandem mass spectrometry were used to perform the detection and the identification of molecular species in positive mode where [M+H](+) and [M-H(2)O+H](+) ions provided structural information on the fatty acid and the sphingoid base. The retention of GSLs increased with the hydrocarboneous volume of their alkyl chains and with the number of osidic residues in agreement with hydrophobic properties and polar retention effect of graphite, respectively. The presence of polar groups, such as OH-group or double bond within alkyl chains, decreased their retention. The coupling of chromatography on PGC with APPI tandem mass spectrometry detection appeared a powerful technique to discriminate isobaric molecules. Isobaric solutes differing by the position of two double bonds or by the repartition of hydrocarboneous skeleton were discriminated according to their chromatographic comportment or their mass spectrum, respectively. Among isobaric molecules, only few structures differing by the nature of osidic residue were not discriminated (i.e. glucosylceramide and galactosylceramide with similar ceramide skeleton were co-eluted and no difference in mass spectra was observed).

[Imaging mass spectrometry: a new tool for the analysis of skin biopsy. Application in Fabry's disease]. / Imagerie par spectrométrie de masse: un nouvel outil pour l'analyse de biopsies cutanées. Application à la maladie de Fabry.

The advent of innovative techniques in mass spectrometry, especially in the area of imaging, prompted us to evaluate two promising techniques: secondary ion mass spectrometry (SIMS) and matrix-assisted laser desorption/ionization (MALDI) mass spectrometry. For this purpose, sections of cutaneous biopsies from patients affected by Fabry's disease and control patients were analyzed. In the course of this disease, two physiological glycosphingolipids [globotriasylceramide (Gb3) and the galabiosylceramide (Ga2)] accumulate in certain tissues owing to a catabolism failure. The ability of these techniques to localize sites of accumulation in body tissues and their capacity to identify the accumulated lipid structures by mass spectra were evaluated. Results demonstrated that these two techniques provide complementary information:-secondary ion mass spectrometry enabled precise localization of areas of accumulation with lateral resolution in the micrometer range;-the signal obtained with matrix-assisted laser desorption/ionization mass spectrometry was high enough to identify these structures according to their molecular weight.

Discrimination and quantification of two isomeric antineoplastic drugs by rapid and non-invasive analytical control using a handheld Raman spectrometer.

Raman spectroscopy is a rapid, non-destructive and non-invasive method that is a promising tool for real-time analytical control of drug concentrations. This study evaluated a handheld Raman device to discriminate and quantify two isomeric drugs used to treat cancer. Doxorubicin (DOXO) and epirubicin (EPIR) samples were analyzed at therapeutic concentrations from 0.1 to 2mg/mL (n=90) and 0.08-2mg/mL (n=90) by non-invasive measurements using a portable Raman spectrometer. The discrimination of these two molecules was demonstrated for all concentrations (n=180) by qualitative analysis using partial least square discriminant analysis (PLS-DA) with 100% classification accuracy, sensitivity and specificity and 0% error rate. For each molecule, quantitative analyses were performed using PLS regression. The validity of the model was evaluated using root mean square error of cross validation (RMSECV) and prediction (RMSEP) that furnished 0.05 and 0.02mg/mL for DOXO and 0.17 and 0.16mg/mL for EPIR after pretreatment optimization. Based on the accuracy profile, the linearity range was from 1.256 to 2.000mg/mL for DOXO (R2=0.9988) and from 0.553 to 2.000mg/Ml for EPIR (R2=0.9240) and repeatability (CV% max of 1.8% for DOXO and 3.2% for EPIR) and intermediate precision (CV% max of 2.8% for DOXO and 4.5% for EPIR) were both acceptable. Despite the narrow validated concentration range for quantitative analysis, this study shows the potential of a handheld Raman spectrometer coupled to chemometric approaches for real-time quantification of cytotoxic drugs, as well for discriminating between two drugs with similar UV absorption profiles. Finally, the use of a handheld spectrometer with the possibility of a direct measurement of substances in containers is a potentially valuable tool for combining patient safety with security of healthcare workers.

Fluorescence probe assisted post-column detection for lipid analysis in microbore-LC.

A general approach, still few exploited so far and never associated with microbore-LC, consisting of detection of various lipid classes (i.e. phospholipids, triglycerides, ceramides and glycosphingolipids) by non-covalent association with 1,6-diphenyl-1,3,5-hexatriene (DPH) fluorescence probe is developed. This mode of detection was coupled with non-aqueous reversed-phase microbore-LC (C18) by using classical post-column fluorescence detection. The classical LC system was first adapted to microbore-chromatography (internal diameter 1 mm) without apparatus miniaturization of the solvent delivery system and the detection cell. For this purpose, the detection parameters (probe concentration, post-column flow rate, post-column reactor length and post-column system temperature) were optimized by a central composite design (CCD) using a mixture of phosphatidylcholine (PC) species as a lipid model and DPH (lambda(ex) = 350 nm, lambda(em) = 430 nm) as a fluorescence probe. The optimal conditions of detection for the various molecular species of PC were determined for a DPH concentration of 3.35 micromol/L, a post-column flow rate of 0.5 mL/min, a reactor length of 1.4 m and a temperature of 35 degrees C. The fluorescence response was linear over a wide range of PC species from 5 microg/mL to 100 microg/mL and the lower limit of detection (signal/noise = 3) was about 1 microg/mL, that is equivalent to evaporative light scattering detection (ELSD). Others molecular species of various classes of lipids, i.e. triglycerides, ceramides and glycosphingolipids were also easily detected. Thus, this study demonstrated the versatility of the proposed system of detection which was shown to be sensitive, easy to perform, non-destructive and allowed, in contrast to ELSD, for a linear response with various polarity lipid classes.

Physicochemical properties and stability of anthralin in model systems and human skin.

The physico-chemical properties and the stability of anthralin, a potent antipsoriatic agent, has been investigated in model systems by optical absorption and fluorescence spectroscopy and by gas chromatography coupled to mass spectrometry. Systematic studies were carried out on anthralin and its oxidation products (1,8-dihydroxyanthraquinone and 1,8-1',8'-tetrahydroxydianthron). Anthralin and 1,8-dihydroxyanthraquinone are shown to readily bind to human serum albumin and not to DNA. Anthralin bound to albumin readily oxidizes, yielding the 1,8-dihydroxyanthraquinone which is fairly stable. These results are correlated with those obtained with intact whole human epidermis and suction blister fluid showing that, in the former case, anthralin binds to protein as suggested by absorption and fluorescence spectroscopies. Gas chromatography-mass spectrometry analysis makes it easy to detect anthralin and 1,8-dihydroxyanthraquinone in suction blister fluid doped with anthralin but not in suction blister obtained after topical application on normal human skin.

pH compartmented w/o/w multiple emulsion: a diffusion study.

In order to develop w/o/w emulsions characterized by two separate aqueous phases of different pH, a preliminary study was carried out to obtain a better insight into the possible diffusion processes taking place between an inner acidic aqueous phase and an external phase of higher pH (pH approximately 6). In fact, such systems could be of great interest for pharmaceutical use. For this purpose, a model emulsion was formulated. The study of pH and conductivity showed that acidic species transport take place between the two aqueous compartments. The three main release mechanisms that might be responsible for this passage across the oil phase were investigated: breakdown of oil globules, facilitated transport by surfactant micelles across the oil phase or by Fickian diffusion. It appears that this last mechanism was involved. In order to control this diffusion process, an alkaline species, octadecylamine was introduced in the oil phase. This compound could form an ion pair with the lactate ion at the interface of the external aqueous phase and the oil phase, thus, limiting the acidification of the external aqueous phase.

Fluorescence and mass spectrometry studies of meta-tetra(hydroxyphenyl)chlorin photoproducts.

The meta-tetra(hydroxyphenyl)chlorin (m-THPC), a second-generation sensitizer used in photodynamic therapy (PDT), is currently under clinical trial. In vivo fluorometry provides direct evidence that photobleaching processes are induced at the tumor site during PDT. Photoproduct formation has thus to be taken into account to fully understand PDT treatment. A preliminary step is to determine the fluorescence characteristics of photoproducts formed in solution. Solutions of m-THPC irradiated at 514 nm have been separated by HPLC using absorption and fluorescence detection. Six main photoproducts have been isolated. According to matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOFMS) results, five fluorescent photoproducts emitting at 652 nm have been attributed to three mono-, one di- and one tri-hydroxy derivatives (m/z 697, 713 and 729, respectively). Fluorescence characteristics of mono-hydroxy forms were found to be similar to those of m-THPC, whereas fluorescence yields in di- and tri-hydroxy derivatives were very low. Another product, corresponding to a MALDI-TOF MS main signal at m/z 542, showed an absorption spectrum maximum at 522 nm while a weak fluorescence was detected at 480 nm. The loss of the Soret band suggests that this photoproduct results from the opening of the reduced pyrrole ring. The part played by each of these products in the photobleaching phenomenon of m-THPC is discussed.