Separation of Steroids and the Determination of Estradiol Content in Transdermic Patches by Microemulsion Electrokinetic Chromatography

A novel microemulsion electrokinetic capillary chromatography (MEEKC) method has been developed which separates a range of nine steroids. A microemulsion containing ethyl acetate, butan-1-ol, sodium dodecyl sulfate, 15% (v/v) acetonitrile and 12 mmol L(-1) sodium tetraborate aqueous buffer at pH 9.2 was used with direct UV detection at 200 nm. The method was validated for the determination of 17 beta-estradiol content, a hormone steroid, in transdermal patches. Adequate sensitivity (DL = 0.88 mu g mL(-1); QL = 2.65 mu g mL(-1)) without interference from sample excipients was obtained. 17 beta-Estradiol migrates in approximately 5.4 min. Estrone was used as internal standard and acceptable precision (< 1.2% RSD), linearity (r = 0.9996; range from 40.0 to 60.0 mu g mL(-1)), and recovery (100.4 +/- A 0.9% at three concentration levels) were obtained. The principal advantage of the method is that it is rapid and avoids the need of time consuming and expensive sample pre-treatment steps.

Síndrome de insuficiência androgênica: critérios diagnósticos e terapêuticos

A síndrome da insuficiência androgênica na mulher (SIA) desperta, mesmo nos dias atuais, muitas discussões e encerra muitas controvérsias. Sabe-se, no entanto, que os níveis plasmáticos de testosterona declinam progressivamente ao longo do período reprodutivo. Conceitua-se a SIA como o conjunto de sintomas clínicos, a presença de biodisponibilidade diminuída de testosterona e os níveis normais de estrogênios. Entre os principais sintomas, citam-se o comprometimento do bem-estar, o humor disfórico, a fadiga sem causa aparente, o comprometimento do desejo sexual, o emagrecimento e a instabilidade vasomotora em mulheres pós-menopáusicas sob terapêutica estrogênica. Esses sintomas, no entanto, são potencialmente atribuíveis a diferentes etiologias e dificultam o correto diagnóstico na maioria dos casos, ainda que ele seja lembrado com freqüência em pacientes que se submetem à ooforectomia bilateral. O diagnóstico da SIA parece ser essencialmente clínico, não havendo a necessidade das dosagens laboratoriais para a sua comprovação. Não se deve indicar a terapêutica androgênica (TA) em pacientes que não estejam adequadamente estrogenizadas. Considera-se a testosterona o hormônio ideal para a TA. As pacientes com sintomas sugestivos de SIA, excluídas outras causas identificáveis, especialmente se pós-menopáusicas, são candidatas à TA. Não existem dados de segurança sobre a TA em usuárias em longo prazo. A via transdérmica - através de adesivos, cremes e gel - parece ser preferível à oral.

Association of bilateral acute anterior uveitis with a capsaicin patch

PURPOSE To report a case of bilateral acute anterior uveitis in association with the application of an analgesic transdermal capsaicin patch. METHODS Case report and review of literature. RESULTS A 38-year-old woman suffered from bilateral acute anterior uveitis, manifesting 12-24 h after application of an analgesic capsaicin patch (Isola Capsicum N Plus) that served to alleviate muscular neck pain. Systemic immune-mediated and infectious diseases were excluded by medical history and laboratory testing. Control of inflammation was achieved with topical corticosteroid treatment within 1 week. Over the course of a 1-year follow-up, no further recurrence of uveitis was observed. CONCLUSIONS The case suggests a possible association of capsaicin-containing transdermal patches and acute anterior uveitis.

Is postmenopausal hormone replacement therapy suitable after a cardio- or cerebrovascular event?

PURPOSE Vascular disease is the leading cause of death in women. One-third of acute events affect women below age 60, when the prevalence of menopausal symptoms is high. This raises the question if hormone replacement therapy (HRT) may be an appropriate treatment for individual women although vascular disease is generally considered a contraindication. METHODS Selective literature search was used for this study. RESULTS In healthy women, HRT increases risks for venous thromboembolism and ischemic stroke, but for cardiovascular disease apparently only beyond 10 years after menopause or 60 years of age. Limited data in women with cardio or cerebrovascular disease have not demonstrated an increased risk for a vascular recurrent event, but for the first year after initiation. In HRT users affected by a cardiovascular event continuation of HRT has not been found to be associated with adverse outcome. Low dose estradiol--preferentially as transdermal patches, if necessary combined with metabolically neutral progestins--appears to convey lower risk. CONCLUSIONS Safety data on HRT in survivors of cardiovascular events or ischemic stroke are limited, but exceptionally increased risk appears to be excluded. If off-label use of HRT is considered to be initiated or continued in women with cardio- or cerebrovascular disease, extensive counseling on the pros and cons of HRT is mandatory.

Toward A Reliable Quality Control Test For Microneedle Insertion

Microneedles (MNs) are emerging devices that can be used for the delivery of drugs at specific locations1. Their performance is primarily judged by different features and the penetration through tissue is one of the most important aspects to evaluate. For detailed studies of MN performance different kind of in-vitro, exvivo and in-vivo tests should be performed. The main limitation of some of these tests is that biological tissue is too heterogeneous, unstable and difficult to obtain. In addition the use of biological materials sometimes present legal issues. There are many studies dealing with artificial membranes for drug diffusion2, but studies of artificial membranes for Microneedle mechanical characterization are scarce3. In order to overcome these limitations we have developed tests using synthetic polymeric membranes instead of biological tissue. The selected artificial membrane is homogeneous, stable, and readily available. This material is mainly composed of a roughly equal blend of a hydrocarbon wax and a polyolefin and it is commercially available under the brand name Parafilm®. The insertion of different kind of MN arrays prepared from crosslinked polymers were performed using this membrane and correlated with the insertion of the MN arrays in ex-vivo neonatal porcine skin. The insertion depth of the MNs was evaluated using Optical coherence tomography (OCT). The implementation of MN transdermal patches in the market can be improved by make this product user-friendly and easy to use. Therefore, manual insertion is preferred to other kind of procedures. Consequently, the insertion studies were performed in neonatal porcine skin and the artificial membrane using a manual insertion force applied by human volunteers. The insertion studies using manual forces correlated very well with the same studies performed with a Texture Analyzer equipment. These synthetic membranes seem to mimic closely the mechanical properties of the skin for the insertion of MNs using different methods of insertion. In conclusion, this artificial membrane substrate offers a valid alternative to biological tissue for the testing of MN insertion and can be a good candidate for developing a reliable quality control MN insertion test.

Investigation of in vitro transdermal absorption of fentanyl from patches placed on skin samples obtained from various anatomic regions of dogs

Objective-To investigate in vitro transdermal absorption of fentanyl from patches through skin samples obtained from various anatomic regions of dogs. Sample Population-Skin samples from 5 Greyhounds. Procedure-Skin samples from the dogs' thoracic, neck, and groin regions were collected postmortem and frozen. After samples were thawed, circular sections were cut and placed in Franz-type diffusion cells in a water bath (32degreesC). A commercial fentanyl patch, attached to an acetate strip with a circular hole, was applied to each skin sample. Cellulose strips were used as control membranes. Samples of receptor fluid in the diffusion cells were collected at intervals for 48 hours, and fentanyl concentrations were analyzed by use of high-performance liquid chromatography. Results-Mean +/- SD release rate of fentanyl from the patch, defined by its absorption rate through the non-rate-limiting cellulose membrane, was linear during the first 8 hours (2.01 +/- 0.05 pg/cm(2) of cellulose membrane/h) and then decreased. Fentanyl passed through skin from the groin region at a faster rate and with a significantly shorter lag time, compared with findings in neck or thoracic skin samples. Conclusions and Clinical Relevance-In vitro, fentanyl from a patch was absorbed more quickly and to a greater extent through skin collected from the groin region of dogs, compared with skin samples from the thoracic and neck regions. Placement of fentanyl patches in the groin region of dogs may decrease the lag time to achieve analgesia perioperatively; however, in vivo studies are necessary to confirm these findings.

Microemulsions Containing Medium-Chain Glycerides as Transdermal Delivery Systems for Hydrophilic and Hydrophobic Drugs

We evaluated the ability of microemulsions containing medium-chain glycerides as penetration enhancers to increase the transdermal delivery of lipophilic (progesterone) and hydrophilic (adenosine) model drugs as well as the effects of an increase in surfactant blend concentration on drug transdermal delivery. Microemulsions composed of polysorbate 80, medium-chain glycerides, and propylene glycol (1:1:1, w/w/w) as surfactant blend, myvacet oil as the oily phase, and water were developed. Two microemulsions containing different concentrations of surfactant blend but similar water/oil ratios were chosen; ME-lo contained a smaller concentration of surfactant than ME-hi (47:20:33 and 63:14:23 surfactant/oil/water, w/w/w). Although in vitro progesterone and adenosine release from ME-lo and ME-hi was similar, their transdermal delivery was differently affected. ME-lo significantly increased the flux of progesterone and adenosine delivered across porcine ear skin (4-fold or higher, p < 0.05) compared to progesterone solution in oil (0.05 +/- 0.01 mu g/cm(2)/h) or adenosine in water (no drug was detected in the receptor phase). The transdermal flux of adenosine, but not of progesterone, was further increased (2-fold) by ME-hi, suggesting that increases in surfactant concentration represent an interesting strategy to enhance transdermal delivery of hydrophilic, but not of lipophilic, compounds. The relative safety of the microemulsions was assessed in cultured fibroblasts. The cytotoxicity of ME-lo and ME-hi was significantly smaller than sodium lauryl sulfate (considered moderate-to-severe irritant) at same concentrations (up to 50 mu g/mL), but similar to propylene glycol (regarded as safe), suggesting the safety of these formulations.

Characterization of calcium-activated chloride channels in patches excised from the dendritic knob of mammalian olfactory receptor neurons

We investigated the properties of calcium-activated chloride channels in inside-out membrane patches from the dendritic knobs of acutely dissociated rat olfactory receptor neurons. Patches typically contained large calcium-activated currents, with total conductances in the range 30-75 nS. The dose response curve for calcium exhibited an EC50 of about 26 mu M. In symmetrical NaCl solutions, the current-voltage relationship reversed at 0 mV and was linear between -80 and +70 mV. When the intracellular NaCl concentration was progressively reduced from 150 to 25 mM, the reversal potential changed in a manner consistent with a chloride-selective conductance. Indeed, modeling these data with the Goldman-Hodgkin-Katz equation revealed a P-Na/P-Cl of 0.034. The halide permeability sequence was P-Cl > P-F > P-I > P-Br indicating that permeation through the channel was dominated by ion binding sites with a high field strength. The channels were also permeable to the large organic anions, SCN-, acetate(-), and gluconate(-), with the permeability sequence P-Cl > P-SCN > gluconaie. Significant permeation to gluconate ions suggested that the channel pore had a minimum diameter of at least 5.8 Angstrom.

Targeting local tissues by transdermal application: Understanding drug physicochemical properties that best exploit protein binding and blood flow effects

The targeting of topically applied drug molecules into tissues below a site of application requires an understanding of the complex interrelationships between the drug, its formulation, the barrier properties of the skin, and the physiological processes occurring below the skin that are responsible for drug clearance from the site, tissue, and/or systemic distribution and eventual elimination. There is still a certain amount of controversy over the ability of topically applied drugs to penetrate into deeper tissues by diffusion or whether this occurs by redistribution in the systemic circulation. The major focus of our work in this area has been in determining how changes in drug structure and physicochemical properties, such as protein binding and lipophilicity, affect drug clearance into the local dermal microcirculation and lymphatics, as well as subsequent distribution into deeper tissues below an application site. The present study outlines our recent thinking on the drug molecule optimal physical attributes, in terms of plasma and tissue partitioning behaviour, that offer the greatest potential for deep tissue targeting. Drug Dev. Res. 46:309-315, 1999. (C) 1999 Wiley-Liss, Inc.

Odorant-induced currents in intact patches from rat olfactory receptor neurons: Theory and experiment

Odorant-induced currents in mammalian olfactory receptor neurons have proved difficult to obtain reliably using conventional whole-cell recording. By using a mathematical model of the electrical circuit of the patch and rest-of-cell, we demonstrate how cell-attached patch measurements can be used to quantitatively analyze responses to odorants or a high (100 mM) K+ solution. High K+ induced an immediate current flux from cell to pipette, which was modeled as a depolarization of similar to 52 mV, close to that expected from the Nernst equation (56 mV), and no change in the patch conductance. By contrast, a cocktail of cAMP-stimulating odorants induced a current flux from pipette into cell following a significant (4-10 s) delay. This was modeled as an average patch conductance increase of 36 pS and a depolarization of 13 mV, Odorant-induced single channels had a conductance of 16 pS. In cells bathed with no Mg2+ and 0.25 mM Ca2+, odorants induced a current flow from cell to pipette, which was modeled as a patch conductance increase of similar to 115 pS and depolarization of similar to 32 mV, All these results are consistent with cAMP-gated cation channels dominating the odorant response, This approach, which provides useful estimates of odorant-induced voltage and conductance changes, is applicable to similar measurements in any small cells.

Transdermal estrogen therapy effects on fibrinogen levels in women with a past history of venous thromboembolism: a pilot study

Objective: To evaluate thromboelastographic parameters and fibrinogen levels in women treated with transdermal 17 beta estradiol. Methods: 29 menopausal women with a history of venous thromboembolic disease were included. Nine patients composed the treatment (HT) group and 20 the control group. Coagulation was assessed by thromboelastography in samples of whole blood and platelet-poor plasma (PPP). The following thromboelastographic variables were measured: time for initial coagulation (R), blood clotting speed (K and the a angle), clot tensile strength (MA and G), global index of coagulation (Cl) and fibrinolysis (LY30) and fibrinogen levels. Results: There were no differences in the other parameters comparing both groups. Fibrinogen levels showed a 13.77 +/- 19.94% reduction in the HT group and a 5.51 +/- 8.09% increase in the control group after 6 months. Conclusions: Our data suggested that transdermal estrogen may not increase blood coagulability, but that it reduces fibrinogen levels in FIT women.

Low-dose transdermal hormone therapy does not interfere with the blood pressure of hypertensive menopausal women: a pilot study

Objectives To determine the effects of low-dose transdermal hormone therapy (HT) on systolic (SBP) and diastolic (DBP) blood pressure (BP) evaluated by 24-h ambulatory blood pressure monitoring (ABPM) in hypertensive postmenopausal women. Methods The study was conducted on 24 hypertensive postmenopausal women aged, on average, 54 years and under treatment with enalapril maleate (10-20 mg/day) combined or not with hydrochlorothiazide (25 mg/day). Thirteen women used a transdermal adhesive containing estradiol and norethisterone (25 and 125 mu g active substance/day, respectively) and 11 did not receive HT. ABPM, lipid profile, and climacteric symptoms were evaluated before and 3 and 6 months after treatment. Results After 3 and 6 months of follow-up, there was a statistically significant reduction of the Blatt-Kupperman menopausal index in the treated group (19.6 +/- 8.3 vs. 9.6 +/- 5.9 vs. 9.7 +/- 7.0; P=0.01). No significant difference in any of the ABPM variables (areas under the systolic and diastolic curves, mean SBP and DBP, SBP and DBP loads and wakefulness-sleep variation) or in the lipid profile was observed between or within groups at the three time points studied. Conclusion Low-dose transdermal HT administered for 6 months was effective in improving climacteric symptoms and did not change BP values or circadian pattern in postmenopausal women with mild-to-moderate arterial hypertension taking antihypertensive medications.

Transdermal Pharmacology of Small Molecule Cyclic C5a Antagonists

Overproduction or underregulation of the proinflammatory complement component C5a has been implicated in numerous immune and inflammatory conditions. Therefore, targeting the C5a receptor (C5aR) has become an innovative strategy for antiinflammatory drug development. The novel cyclic peptide C5aR antagonist, AcF-[OP(D-Cha)WR] (PMX53), attenuates injury in numerous animal models of inflammation following intravenous, subcutaneous, intraperitoneal, and oral administration. In the present study the transdermal pharmacology of PMX53 and three analogs designed with increased lipophilicity, hydrocinnamate-[OP(D-Cha)WCit] (PMX200), AcF-[OP(D-Cha)WCit] (PMX201) and hydrocinnamate-[OP(D-Cha)WR] (PMX205), have been examined in order to assess their transdermal permeability and inhibitory effect on C5a-mediated lipopolysaccharide (LPS)-induced systemic responses. In the rat, PMX53, PMX201, and PMX205, were bioavailable following topical dermal administration (10 mg/50 cm(2) site/rat). All analogs functionally antagonized neutropenia and hypotension induced by systemic challenge with LPS (I mg/kg i.v.). Interestingly, PMX200 attenuated LPS-induced neutropenia more effectively than other analogs, despite undetectable (< 5 ng/ml) circulating levels following topical administration. In conclusion, we have demonstrated that cyclic peptide C5aR antagonists can penetrate transdermally sufficiently to have systemic effects. However, increasing lipophilicity in these compounds did not result in increased blood levels. Nonetheless, topical application of C5aR antagonists produced circulating levels of the drugs that antagonized the LPS-induced systemic responses of neutropenia and hypotension. This suggests that these small-molecule C5aR antagonists may be developed for topical administration for the treatment of local and systemic inflammatory conditions in the human and veterinary pharmaceutical markets.

Patchy populations in stochastic environments: Critical number of patches for persistence

We introduce a model for the dynamics of a patchy population in a stochastic environment and derive a criterion for its persistence. This criterion is based on the geometric mean (GM) through time of the spatial-arithmetic mean of growth rates. For the population to persist, the GM has to be greater than or equal to1. The GM increases with the number of patches (because the sampling error is reduced) and decreases with both the variance and the spatial covariance of growth rates. We derive analytical expressions for the minimum number of patches (and the maximum harvesting rate) required for the persistence of the population. As the magnitude of environmental fluctuations increases, the number of patches required for persistence increases, and the fraction of individuals that can be harvested decreases. The novelty of our approach is that we focus on Malthusian local population dynamics with high dispersal and strong environmental variability from year to year. Unlike previous models of patchy populations that assume an infinite number of patches, we focus specifically on the effect that the number of patches has on population persistence. Our work is therefore directly relevant to patchily distributed organisms that are restricted to a small number of habitat patches.

An equivalent waveguide approach to designing of reflect arrays with the use of variable-size microstrip patches

An equivalent unit cell waveguide approach (WGA) is described to study the behavior of a multilayer reflect array of variable-size patches/dipoles, The approach considers normal incidence of a plane wave on an infinite periodic array of identical radiating elements and introduces an equivalent unit cell waveguide to obtain the reflection coefficient. A field matching technique and method of moments (MoM) is used to determine fields in different layers of the equivalent waveguide. Good agreements for the phase of the reflection coefficient between the proposed model and those published in selected literatures are obtained. (C) 2002 Wiley Periodicals, Inc.