MALA: Acidosis láctica asociado al uso de metformina, una revisión a propósito de casos clínicos

La metformina es el fármaco preferido en el manejo inicial de la diabetes mellitus tipo 2 (DMT2). Aunque se recomienda su uso ampliamente, se debe tener precaución al prescribirla a poblaciones susceptibles a condiciones de riesgo de hipoperfusión sistémica, ya que puede provocar acumulación en el organismo y alteraciones metabólicas que desemboquen en acidosis láctica asociada a metformina, una complicación grave que a menudo es subdiagnosticada. Con el propósito de promover un mejor conocimiento sobre este tema, la presente revisión se centra en el análisis de la clínica, fisiopatología, diagnóstico y manejo de la acidosis láctica asociada a metformina, prestando especial atención al manejo mediante terapias de reemplazo renal. El análisis se basará en la experiencia de una serie de casos de acidosis láctica asociada a metformina atendidos en un centro clínico hospitalario en Chile.

Metformin is the preferred medication for the initial management of type 2 diabetes mellitus (T2DM). Although its use is widely recommended, caution should be exercised when prescribing it to populations susceptible to systemic hypoperfusion conditions, as it can lead to accumulation in the body and metabolic disturbances that may result in metformin-associated lactic acidosis. This severe complication is often underdiagnosed. To promote a better understanding of this topic, the present review focuses on the analysis of the clinical, pathophysiological, diagnostic, and management aspects of metformin-associated lactic acidosis, with particular attention to management through renal replacement therapies. The analysis will be based on the experience of a series of cases of metformin-associated lactic acidosis treated at a hospital clinical center in Chile.

[MALA: Lactic acidosis associated with the use of metformin, review of clinical cases]. / MALA: Acidosis láctica asociado al uso de metformina, una revisión a propósito de casos clínicos.

Metformin is the preferred medication for the initial management of type 2 diabetes mellitus (T2DM). Although its use is widely recommended, caution should be exercised when prescribing it to populations susceptible to systemic hypoperfusion conditions, as it can lead to accumulation in the body and metabolic disturbances that may result in metformin-associated lactic acidosis. This severe complication is often underdiagnosed. To promote a better understanding of this topic, the present review focuses on the analysis of the clinical, pathophysiological, diagnostic, and management aspects of metformin-associated lactic acidosis, with particular attention to management through renal replacement therapies. The analysis will be based on the experience of a series of cases of metformin-associated lactic acidosis treated at a hospital clinical center in Chile.

A new method to evaluate temperature vs. pH activity profiles for biotechnological relevant enzymes.

BACKGROUND: Glycoside hydrolases are important for various industrial and scientific applications. Determination of their temperature as well as pH optima and range is crucial to evaluate whether an enzyme is suitable for application in a biotechnological process. These basic characteristics of enzymes are generally determined by two separate measurements. However, these lead to a two-dimensional assessment of the pH range at one temperature (and vice versa) and do not allow prediction of the relative enzymatic performance at any pH/temperature combination of interest. In this work, we demonstrate a new method that is based on experimental data and visualizes the relationship among pH, temperature, and activity at a glance in a three-dimensional contour plot. RESULTS: In this study, we present a method to determine the relative activity of an enzyme at 96 different combinations of pH and temperature in parallel. For this purpose, we used a gradient PCR cycler and a citrate-phosphate-based buffer system in microtiter plates. The approach was successfully tested with various substrates and diverse assays for glycoside hydrolases. Furthermore, its applicability was demonstrated for single enzymes using the endoglucanase Cel8A from Clostridium thermocellum as well as the commercially available complex enzyme mixture Celluclast®. Thereby, we developed a fast and adaptable method to determine simultaneously both pH and temperature ranges of enzymes over a wide range of conditions, an easy transformation of the experimental data into a contour plot for visualization, and the necessary controls. With our method, the suitability of an enzyme or enzyme mixture for any chosen combination of temperature and pH can easily be assessed at a glance. CONCLUSIONS: We propose a method that offers significant advantages over commonly used methods to determine the pH and temperature ranges of enzymes. The overall relationship among pH, temperature, and activity is visualized. Our method could be applied to evaluate exactly what conditions have to be met for optimal utilization of an enzyme or enzyme mixture for both lab-scale and industrial processes. Adaptation to other enzymes, including proteases, should be possible and the method may also lead to a platform for additional applications, such as inactivation kinetics analysis.

[Declaration of the Chilean Academy of Medicine of Law 20.850 “On clinical trials of pharmaceutical products and medical devices” and of the bylaw that will regulate its application]. / Declaración de la Academia Chilena de Medicina sobre el Título V de la Ley 20.850 (Ley Ricarte Soto) y su proyecto de reglamento “De los ensayos clínicos de productos farmacéuticos y elementos de uso médico”.

In Chile, high cost treatments required by selected medical conditions are financed by the State, according to Law 20.850. A bylaw under discussion by the Senate regulates clinical trials, posing complex issues that will endanger local interest in front-line research: 1. The exclusive and mandatory control bestowed to the Institute of Public Health during all stages of the trials and also the surveillance of institutions performing clinical trials, overriding their Clinical Research Review Boards; 2.The 10 year period during which any adverse event is assumed to have been caused by the medication or devise evaluated by the trial, unless the contrary is proven in a judicial process; 3. Individuals submitted to the trials are entitled to free post trial access to the treatment received during the study, financed by the trial supporting entities and as long as the drug or devise is considered to be useful. While agreeing with the need to have a National Registry of Clinical Trials, we predict that the mentioned critical issues in the bylaw will lead to difficulties and unnecessary judicial processes, thus limiting clinicians’ interest in performing research. We propose to modify the bylaw, excluding responsibilities on events associated with the natural evolution of the medical condition, with patients’ ageing or with comorbidities and clinical events considered unpredictable when the protocol was accepted. We recommend that the free post trial access should be a joint decision involving the patient and the attending physician, taking in consideration that the volunteer has been exposed to risks and burdens, or when discontinuation of treatment entails a vital risk until the treatment under study has been approved and becomes available in the national market.

Characterization of the arabinoxylan-degrading machinery of the thermophilic bacterium Herbinix hemicellulosilytica-Six new xylanases, three arabinofuranosidases and one xylosidase.

Herbinix hemicellulosilytica is a newly isolated, gram-positive, anaerobic bacterium with extensive hemicellulose-degrading capabilities obtained from a thermophilic biogas reactor. In order to exploit its potential as a source for new industrial arabinoxylan-degrading enzymes, six new thermophilic xylanases, four from glycoside hydrolase family 10 (GH10) and two from GH11, three arabinofuranosidases (1x GH43, 2x GH51) and one ß-xylosidase (GH43) were selected. The recombinantly produced enzymes were purified and characterized. All enzymes were active on different xylan-based polysaccharides and most of them showed temperature-vs-activity profiles with maxima around 55-65°C. HPAEC-PAD analysis of the hydrolysates of wheat arabinoxylan and of various purified xylooligosaccharides (XOS) and arabinoxylooligosaccharides (AXOS) was used to investigate their substrate and product specificities: among the GH10 xylanases, XynB showed a different product pattern when hydrolysing AXOS compared to XynA, XynC, and XynD. None of the GH11 xylanases was able to degrade any of the tested AXOS. All three arabinofuranosidases, ArfA, ArfB and ArfC, were classified as type AXH-m,d enzymes. None of the arabinofuranosidases was able to degrade the double-arabinosylated xylooligosaccharides XA2+3XX. ß-Xylosidase XylA (GH43) was able to degrade unsubstituted XOS, but showed limited activity to degrade AXOS.

Declaración de la Academia Chilena de Medicina sobre el Título V de la Ley 20. 850 (Ley Ricarte Soto) y su proyecto de reglamento “De los ensayos clínicos de productos farmacéuticos y elementos de uso médico” / Declaration of the Chilean Academy of Medicine of Law 20. 850 On clinical trials of pharmaceutical products and medical devices” and of the bylaw that will regulate its application

In Chile, high cost treatments required by selected medical conditions are financed by the State, according to Law 20.850. A bylaw under discussion by the Senate regulates clinical trials, posing complex issues that will endanger local interest in front-line research: 1. The exclusive and mandatory control bestowed to the Institute of Public Health during all stages of the trials and also the surveillance of institutions performing clinical trials, overriding their Clinical Research Review Boards; 2.The 10 year period during which any adverse event is assumed to have been caused by the medication or devise evaluated by the trial, unless the contrary is proven in a judicial process; 3. Individuals submitted to the trials are entitled to free post trial access to the treatment received during the study, financed by the trial supporting entities and as long as the drug or devise is considered to be useful. While agreeing with the need to have a National Registry of Clinical Trials, we predict that the mentioned critical issues in the bylaw will lead to difficulties and unnecessary judicial processes, thus limiting clinicians’ interest in performing research. We propose to modify the bylaw, excluding responsibilities on events associated with the natural evolution of the medical condition, with patients’ ageing or with comorbidities and clinical events considered unpredictable when the protocol was accepted. We recommend that the free post trial access should be a joint decision involving the patient and the attending physician, taking in consideration that the volunteer has been exposed to risks and burdens, or when discontinuation of treatment entails a vital risk until the treatment under study has been approved and becomes available in the national market.

Leptin receptor JAK2/STAT3 signaling modulates expression of Frizzled receptors in articular chondrocytes.

OBJECTIVE: Differentiated articular chondrocytes express a functional bisoform of the leptin receptor (LRb); however, leptin-LRb signaling in these cells is poorly understood. We hypothesized that leptin-LRb signaling in articular chondrocytes functions to modulate canonical Wnt signaling events by altering the expression of Frizzled (FZD) receptors. METHODS: Human chondrocyte cell lines and primary articular chondrocytes were grown in serum containing growth media for 24h, followed by a media change to Dulbecco's modified Eagle's medium (DMEM) containing 1% Nutridoma-SP to obtain a serum-deficient environment for 24h before treatment. Treatments included recombinant human leptin (10-100nM), recombinant human IL-6 (0.3-3nM), or recombinant human erythropoietin (Epo) (10mU/ml). Cells were harvested 30min-48h after treatment and whole cell lysates were analyzed using immunoblots or luciferase assays. RESULTS: Treatment of cells with leptin resulted in activation of Janus kinase 2 (JAK2) and subsequent phosphorylation of specific tyrosine residues on LRb, followed by dose- and time-dependent increases in the expression of Frizzled-1 (FZD1) and Frizzled-7 (FZD7). Leptin-mediated increases in the expression of FZD1 were blocked by pre-treatment with the protein synthesis inhibitor cycloheximide or the JAK2 inhibitor AG490. Experiments using a series of hybrid Epo extracellular domain-leptin intracellular domain receptors (ELR) harboring mutations of specific tyrosine residues in the cytoplasmic tail showed that increases in the expression of FZD1 were dependent on LRb-mediated phosphorylation of STAT3, but not ERK1/2 or STAT5. Leptin pre-treatment of chondrocytes prior to Wnt3a stimulation resulted in an increased magnitude of canonical Wnt signaling. CONCLUSION: These experiments show that leptin-LRb signaling in articular chondrocytes modulates expression of canonical Wnt signaling receptors and suggests that direct cross-talk between these pathways is important in determining chondrocyte homeostasis.

On the ropivacaine-reducing effect of low-dose sufentanil in intrathecal labor analgesia.

BACKGROUND: Combining ropivacaine with sufentanil for intrathecal (i.t.) analgesia in labor is well recognized, but information on dosing is limited. This study aimed to determine the ED 50 of i.t. ropivacaine and to assess the effect of adding defined low doses of sufentanil. METHODS: This was a two-phase, double-blind, randomized and prospective study. One hundred and fifteen parturients receiving combined spinal epidural analgesia were allocated to one of four groups to receive ropivacaine or sufentanil alone or in combination. In phase one, sufentanil dose-response was calculated using logistic regression. In phase two, ED 50 of ropivacaine and of the combination with a fixed dosage of sufentanil at ED 20 and ED 40 was evaluated using the technique of up-down sequential allocation. Analgesic effectiveness was assessed 15 min after injection using a 100 mm visual analog scale, with <10 mm lasting for 45 min defined as effective. Furthermore, side effects and duration were recorded. RESULTS: The ED 50 of i.t. ropivacaine was 4.6 mg [95% confidence intervals (95% CI) 4.28, 5.31]. Adding sufentanil at ED 20 significantly decreased the ED 50 of i.t. ropivacaine to 2.1 mg (95%CI 1.75, 2.5) (P<0.005); at ED 40, the reduction was similar (P<0.005). Combining sufentanil with ropivacaine resulted in a dose-independent prolongation of analgesia. Besides pruritus, which was well tolerated, there were no differences in side effects. CONCLUSION: Adding sufentanil at ED 20 results in a more than 50% dose-sparing effect of ropivacaine and considerably prolongs analgesia. Increasing dosage implicates no clinical benefit.

Reduced hands-off-time and time to first shock in CPR according to the ERC Guidelines 2005.

BACKGROUND AND AIM: Chest compressions and early defibrillation are crucial in cardiopulmonary resuscitation (CPR). The Guidelines 2005 brought major changes to the basic life support and automated external defibrillator (BLS-AED) algorithm. We compared the European Resuscitation Council's Guidelines 2000 (group '00) and 2005 (group '05) on hands-off-time (HOT) and time to first shock (TTFS) in an experimental model. METHODS: In a randomised, cross-over design, volunteers were assessed in performing BLS-AED over a period of 5min on a manikin in a simulated ventricular fibrillation cardiac arrest situation. Ten minutes of standardised teaching and 10min of training including corrective feedback were allocated for each of the guidelines before evaluation. HOT was chosen as the primary and TTFS as the secondary outcome parameter. RESULTS: Forty participants were enrolled; one participant dropped out after group allocation. During the 5-min evaluation period of adult BLS-AED, HOT was significantly (p<0.001) longer in group '00 [273+/-3s (mean+/-standard error)] than in group '05 (188+/-3s). The TTFS was significantly (p<0.001) longer in group '00 (91+/-3s) than in group '05 (71+/-3s). CONCLUSION: In this manikin setting, HOT and TTFS improved with BLS-AED performed according to Guidelines 2005.

Practical impact of the European Resuscitation Council's BLS algorithm 2005.

BACKGROUND: The European Resuscitation Council (ERC) guidelines 2005 have brought major changes in the BLS algorithm. The aim of our investigation was to look for the practical impact of these modifications. METHODS: In a randomized cross-over design we evaluated how adults would adhere to the BLS algorithm of the ERC guidelines 2000 (group A) compared to the guidelines 2005 (group B). The secondary endpoint was to determine the amount of time that elapsed before the start of the chest compressions in the two different groups. Participants were recruited from the streets and an office building of the Austrian Red Cross and were randomized to commence either with A or B. The volunteers were taught the allocated BLS sequence according to their group placement, and before evaluation each of the two groups was given the opportunity to train until they felt confident in using the algorithm. Performance during evaluation was documented automatically with a recording resuscitation manikin (Resusci-Anne, Skill Reporter). RESULTS: Sixty people were included in the study, one individual dropped out after randomisation. In group A 9/59 (15.25%) participants followed the algorithm correctly versus 24/59 (40.68%) in group B (p=0.006). The time to start of chest compressions was significantly shorter in group B (21.31+/-7.11s), compared to group A (36.68+/-11.75s, p<0.01). CONCLUSION: Compared to the 2000 BLS algorithm, the 2005 BLS sequence seems to be easier to learn and to retain, though nearly 60% of participants did not follow the new algorithm correctly. As expected, there was a significantly shorter time elapsing before the start of chest compressions when applying the 2005 algorithm. These findings should translate to better survival after cardiac arrest.

Death in correctional facilities: opportunities for automated external defibrillation.

BACKGROUND: Death due to cardiovascular disease occurs more frequently in prisons than the national average. Due to close surveillance 24 h/day, the ability to reach the patient within 3 min and time consuming access for the EMS crews, it was hypothesised that the deployment of automated external defibrillators (AEDs) might make improvements regarding Call-to-the-First-AED-Prompt (CTP) interval and formed the aim of this study. METHODS: Our investigation was analysed on an intention to treat basis and conducted in a prospective, open and observational design. As the primary outcome, the CTP-intervals were compared to the arrival intervals of the EMS. As a secondary outcome, an analysis of all deceased inmates was described. RESULTS: The average daily population of inmates in Austrian correctional facilities is 7714. During a period of 13 months, 10 instances in which an AED was activated and electrodes attached to a collapsed inmate, were reported. The CTP-interval (median+/-S.D.) was 2.3+/-1.6 S.D. min. It took the EMS 10.0+/-4.3 S.D. min. to arrive at the patient's side. Four out of 10 cases of cardiac arrest occurred due to myocardial infarction. Of 39 deceased inmates, a post mortem examination was completed in 34 cases. In 13 cases, cardiovascular disease was the cause of death. DISCUSSION: The main finding was a four-fold reduction of the CTP-interval. This fact indicates the potential improvements which could be achieved with the deployment of AEDs. Our secondary objective revealed that death due to cardiovascular disease was found in a high proportion and could be considered to be a strong incentive to initiate programmes to counter cardiovascular death in prison.

[Long-term outcome of type V lupus membranous glomerulonephritis]. / Curso clínico de la nefropatía membranosa lúpica pura.

BACKGROUND: The long-term outcome of the pure form of WHO type V lupus membranous glomerulonephritis is apparently more benign than that of other forms of lupus glomerulonephritis. However 12% of such patients progress to terminal renal failure. The presence of proteinuria may be an indication of cytotoxic agents. AIM: To study the clinical long-term outcome of WHO type V lupus membranous glomerulonephritis. MATERIAL AND METHODS: A retrospective analysis of all kidney biopsies of a University Pathology Department, with the diagnosis of WHO type V lupus membranous glomerulonephritis. Review of medical records of patients with the disease and one clinical assessment of all living patients. RESULTS: Between 1973 and 2000, 703 kidney biopsies were done to patients with systemic lupus erythematosus. Of these, 40 were membranous glomerulonephritis and in 33 patients (28 women, age range 6-71 years), data on the evolution and survival was obtained. Nineteen had type Va and the rest type Vb nephritis. Two presented with renal failure and 11 with proteinuria over 3.5 g/24 h. The median follow-up since the renal biopsy was 63 months (range 1-316). At the end of follow-up, four had a creatinine clearance of less then 15 ml/h and four a clearance between 15 and 29 ml/h (one of these received a renal allograft). Eleven (33%) patients had died, mostly due to infections. Life expectancy at five years with a creatinine clearance over 15 ml/h was 75%. Bad prognostic factors were an elevated creatinine clearance over 15 ml/h was 75%. Bad prognostic factors were an elevated creatinine and high blood pressure at the moment of the biopsy. CONCLUSIONS: The clinical outcome of these patients was bad. Twelve percent reached a stage of terminal renal failure. This is in contrast with the 3% progression to a similar stage of proliferative glomerulonephritis treated with i.v. cyclophosphamide. New therapies for this condition must be sought.

Curso clínico de la nefropatía membranosa lúpica pura / Long-Term outcome of type V lupus membranous glomerulonephritis

Background: The long-term outcome of the pure form of WHO type V lupus membranous glomerulonephritis is apparently more benign than that of other forms of lupus glomerulonephritis. However 12percent of such patients progress to terminal renal failure. The presence of proteinuria may be an indication of cytotoxic agents. Aim: To study the clinical long-term outcome of WHO type V lupus membranous glomerulonephritis. Material and methods: A retrospective analysis of all kidney biopsies of a University Pathology Department, with the diagnosis of WHO type V lupus membranous glomerulonephritis. Review of medical records of patients with the disease and one clinical assessment of all living patients. Results: Between 1973 and 2000, 703 kidney biopsies were done to patients with systemic lupus erythematosus. Of these, 40 were membranous glomerulonephritis and in 33 patients (28 women, age range 6-71 years), data on the evolution and survival was obtained. Nineteen had type Va and the rest type Vb nephritis. Two presented with renal failure and 11 with proteinuria over 3.5 g/24h. The median follow-up since the renal biopsy was 63 months (range 1-316). At the end of follow-up, four had a creatinine clearance of less then 15 ml/h and four a clearance between 15 and 29 ml/h (one of these received a renal allograft). Eleven (33percent) patients had died, mostly due to infections. Life expectancy at five years with a creatinine clearance over 15 ml/h was 75percent. Bad prognostic factors were an elevated creatinine clearance over 15 ml/h was 75percent. Bad prognostic factors were an elevated creatinine and high blood pressure at the moment of the biopsy. Conclusions: The clinical outcome of these patients was bad. Twelve percent reached a stage of terminal renal failure. This is in contrast with the 3percent progression to a similar stage of proliferative glomerulonephritis treated with i.v. cyclophosphamide. New therapies for this condition must be sought.

Proteína C recombinante activada en pancreatitis aguda grave sin infección documentada: revisión en relación a un caso clínico / Recombinant human activated protein C in serious acute pancreatitis without documented infection: review in relation to a clinical case

Presentamos el caso de un paciente con pancreatitis aguda grave (PAG) que evolucionó rápidamente con un Síndrome de Respuesta Inflamatoria Sistémica (SIRS) severo manejado con Proteína C humana recombinante (PCHR). Entre 10 a 15 por ciento de las pancreatitis agudas desarrollarán un SIRS, que lleva a un curso fulminante con extensa necrosis y falla multiorgánica. En series internacionales esta condición se asocia a una mortalidad mayor al 25 por ciento, pero existen escasas publicaciones sobre el uso de PCHR en pacientes con PAG. Algunos estudios ya han descrito que en presencia de una respuesta inflamatoria severa documentada con score de APACHE mayor a 25 existe una recuperación sustancial con el uso del PCRH. Comunicamos su cuadro clínico, evolución y resultado.

Clinical protocol. Purging of autologous stem cell sources with bcl-x(s) adenovirus for women undergoing high-dose chemotherapy for stage IV breast carcinoma.

High-dose chemotherapy (HDCT) and autologous bone marrow transplantation (BMT) is frequently used to treat patients with metastatic cancer including breast cancer and neuroblastoma. However, the bone marrow of such patients is often contaminated with tumor cells. Recently, we have found that a recombinant adenovirus vector that contains a bcl-x, minigene (a dominant negative inhibitor of the bcl-2 family), called the bcl-x(s) adenovirus, is lethal to cancer cells derived from epithelial tissues, but not to normal human hematopoietic cells. To determine the mechanism, by which this virus spares normal hematopoietic cells, we isolated normal mouse hematopoietic stem cells and infected them with an adenovirus that contains a beta-galactosidase minigene. Such cells do not express beta-galactosidase, indicating that hematopoietic stem cells do not express transgene encoded by adenovirus vectors based upon the RSV-AD5 vector system. When breast cancer cells mixed with hematopoietic cells were infected with the bcl-x(s) adenovirus, cancer cells were selectively killed by the suicide adenoviruses. Hematopoietic cells exposed to the suicide vectors were able to reconstitute the bone marrow of mice exposed to lethal doses of y-irradiation. These studies suggest that adenovirus suicide vectors may provide a simple and effective method to selectively eliminate cancer cells derived from epithelial tissue that contaminate bone marrow to be used for autologous BMT. We therefore propose to initiate a phase I clinical trial to test the safety of this virus in women with breast cancer undergoing high does chemotherapy and autologous BMT.

Trigonal-prismatic versus octahedral molecular structures in [CH3)nMX6-n]] compounds.

The molecular structures of [(CH3)5MoOCH3], [(CH3)4Mo(OCH3)2], [(CH3)5WCl], and [(CH3)3WCl(OCH3)2] are reported. The first three structures are based on trigonal-prismatic geometry, the last one on octahedral geometry.

Topical transfection using plasmid DNA in a water-in-oil nanoemulsion.

Expression plasmids encoding chloramphenicol acetyltransferase (CAT) or human interferon-alpha2 cDNA were formulated in water-in-oil nanoemulsions and applied to murine skin. The histological location of transfected cells was assessed by in situ DNA PCR and showed that the deposition of plasmid DNA was primarily in follicular keratinocytes. Transgene expression in the skin was monitored for 24-72 h, following topical application of either single or multiple daily doses by quantitative RT-PCR and ELISA. It was found that transgene expression was optimal at 24 h following topical application of a single dose of water-in-oil nanoemulsion containing plasmid DNA. Dose-response studies using a total dose of 3, 10 or 30 microg of plasmid DNA suggested that topical transfection using nanoemulsions is subject to both threshold and saturation effects. None of the cationic liposome formulations tested as controls mediated transgenic protein expression at levels higher than background values of the ELISAs used to assay transgenic protein. Single and multiple dose experiments using human interferon-alpha2 as a transgene indicated that the efficiency of nanoemulsion mediated transfection was most effective in the context of normal versus atrophic hair follicles. In addition, the total amount of human interferon-alpha2 present in skin appeared to accumulate as a consequence of multiple dosing. Histologic evaluation of treated skin showed no overt signs of toxicity or irritation associated with the short-term application of the nanoemulsions. The results suggest that water-in-oil nanoemulsions can be used to facilitate transfection of follicular keratinocytes in vivo.

Topical transport of hydrophilic compounds using water-in-oil nanoemulsions.

A variety of water-in-oil nanoemulsions were prepared using sorbitan monooleate (Span80), polyoxyethylene 20 sorbitan monooleate (Tween80), olive oil and water. The nanoemulsions were tested for their ability to facilitate transport of a model hydrophilic solute, inulin, across hairless and hairy mouse skin and hairy rat skin following topical in vitro application. The transport of inulin incorporated in water-in-oil nanoemulsions was found to be significantly higher (5- to 15-fold) than that obtained with micellar dispersions or aqueous controls. The rate and extent of inulin transport across hairy mouse skin was found to be highly dependent on the hydrophile-lipophile balance (HLB) of the surfactant mixture in the nanoemulsion. Nanoemuslions prepared using mixtures with lower HLB exhibited significantly higher rate and extent of transport. It was also found that nanoemulsion-mediated transport was independent of molecular size of the hydrophilic solute and the nature of the aqueous phase. More importantly, transport of inulin from nanoemulsions was independent of animal skin characteristics such as stratum corneum thickness and follicle-type. The combined results suggest that water-in-oil nanoemulsions that are compatible with the lipophilic sebum environment of the hair follicle facilitate efficient transport of incorporated hydrophilic solutes and imply that such transport is predominantly transfollicular in nature.