Malathion percutaneous absorption after repeated administration to man

Prediction of exposure and toxic potential of pesticides such as malathion are routinely based upon acute exposure and single-dose percutaneous absorption determination. What has become obvious with pesticide exposure such as the malathion spraying for the medfly is that chronic daily exposure is the more relevant situation. Our objective was to determine the percutaneous absorption of chronically applied malathion in man and to compare chronic absorption to single-dose absorption. The experimental design was to first topically apply [14C]malathion to human male volunteers. This procedure was followed by repeated administration of nonradioactive malathion to the same site of application (ventral forearm). [14C]Malathion was reapplied (Day 8) when urinary excretion of radioactivity from the first application reached minimum detectable levels. The first [14C]malathion absorption was compared to the second [14C]malathion application. The percutaneous absorption from the first [14C]malathion application was 4.48 +/- 1.3% (SD) of the applied dose. The absorption from the second [14C]malathion administration was 3.53 +/- 1.0%, a value not significantly (p greater than 0.05) different from the first application. Therefore, for malathion the single-dose application data are relevant for predicting the toxic potential for longer-term exposure.     

Evaluation of cutaneous absorption and safety of idoxuridine after topical administration

The absorption of a preparation of the antiviral drug 5-iodo-2'-deoxyuridine (idoxuridine or IDU] has been assessed in rats. A 40% w/v solution of 3H-IDU in dimethyl sulfoxide (DMSO) was topically applied to rats; cutaneous absorption was determined by morphometric evaluation of autoradiographic preparations of the skin. Passage of the drug to the bloodstream was followed using radioisotopic techniques. In addition, the potential irritative action of the same preparation of IDU was investigated in a more suitable animal model. A predictive guinea pig sensitization study was performed according to the Magnusson and Kligman method. 3H-IDU was detected in the epidermis of the rat 60 min after local application. However, it was not possible to determine noticeable levels of the radiolabelled drug in the circulating blood. Experiments on guinea pigs showed slight transient erythematous responses in three animals of the test group following first challenge, and in one animal of the test group and one of the control group, following the second challenge. The overall results of the sensitization test were negative. These results give experimental support for the safety of the IDU preparation studied.     

硝酸舍他康唑泡腾胶囊的制备工艺和含量测定

目的研究硝酸舍他康唑泡腾胶囊的制备工艺及含量测定。方法确定处方的组成,制备泡腾胶囊,并用紫外分光光度法测定硝酸舍他康唑的含量。结果紫外分光光度法测定硝酸舍他康唑含量的标准曲线为A=0．0075p＋0．0096（r=0．9997）,在质量浓度10～90mg·L^-1内吸光度与质量浓度之间的线性关系良好。结论该泡腾胶囊的制备方法简单,用紫外分光光度法测定含量,方法可靠。     

Dermal absorption of permethrin following topical administration

Objective Permethrin is an insecticide used in the treatment of lice and scabies infections. Although its efficacy and safety have been well documented, pharmacokinetic data are sparse. The objective of this study was to determine the systemic exposure of permethrin and the duration of residence in the human body following topical administration.Methods The study consisted of three parts. In six young healthy men (part 1), 50 ml of an ethanolic solution containing 215 mg permethrin (cis/trans: 25/75) was administered to the hair of the head. In another six young healthy men (part 2) and in six male or female scabies patients (part 3), 60 g of cream containing 3 g permethrin was administered to the skin of the whole body. Urine was collected up to 168 h post-dose. Urinary excretion of the main metabolite of permethrin, 3-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane carboxylic acid, and its conjugates was measured using a gas chromatography/electron capture detection method.Results Pharmacokinetics were similar in all study parts. The time of maximal urinary excretion rate was 12.3, 20.0 and 14.6 h, terminal elimination half-life was 32.7, 28.8 and 37.8 h and urinary recovery of the metabolite reached 0.35, 0.47 and 0.52 M percent of the permethrin dose, respectively, in parts 1, 2 and 3 (means). The treatment was well tolerated.Conclusions The extent of systemic exposure following external therapeutic administration of permethrin is very low compared with doses used for preclinical toxicity studies, and elimination is virtually complete after 1 week. These data provide the pharmacokinetic basis for the clinical safety of topical permethrin.     

新型抗真菌药硝酸舍他康唑的药理作用及临床评价

硝酸舍他康唑(sertaconazole nitrate)是一种新的局部用抗真菌药,具有抗菌谱广、疗效好、安全性高等特性,并在临床实践中显示出较好的应用前景.现对其作用机制、药动学、临床应用和药物不良反应等进行综述.     

Rate and extent of absorption of clonidine from a transdermal therapeutic system

The in-vivo performance of a clonidine transdermal therapeutic system (TTS 3.5 cm2, 2.5 mg) was assessed in 12 healthy normal volunteers. Particular attention was paid to the rate and extent of absorption of clonidine from the TTS dosage form by reference to a 2 h i.v. infusion of clonidine. The absolute bioavailability of clonidine from the TTS dosage form was found to be approximately 60% with clonidine being released from the TTS at a relatively reproducible and consistent rate of 4.32 micrograms h-1 over a 7-day period.     

Evaluation of percutaneous absorption of 4-nerolidylcathecol from four topical formulations

Antioxidants such as vitamins E and C are known to play a significant role in ameliorating or preventing oxidative damage to the skin. However, to provide a satisfactory protection they must first permeate the skin, which serves as a permeation barrier. In this study we evaluated the influence of three different formulations (gel, gel-emulsion and emulsion) on the percutaneous absorption of 4-nerolidylcathecol, an antioxidant compound isolated from Pothomorphe umbellata root extracts. Also, the absorption of the isolated 4-nerolidylcathecol was compared with its absorption when dried P. umbellata root ethanolic extract was incorporated into a gel formulation. The 'lag time method' was employed for the analysis of the in vitro permeation data. All formulations showed satisfactory percutaneous penetration with the 4-nerolidylcathecol-gel presenting a higher rate of penetration leading to higher dry drug levels in the tissue.     

Treatment of interdigital tinea pedis: once-daily therapy with sertaconazole nitrate

The treatment of cutaneous fungal infections has been shown to be directly affected by the extent of patients' adherence to therapy regimens that are often cumbersome and last for several weeks. One useful alternative approach is once-daily dosing of topical antifungal agents rather than the traditional twice-daily regimen, an example of what has been called a "forgiving" regimen, designed to promote patient adherence. Sertaconazole, an imidazole antifungal agent, is known to be safe and effective when used twice daily in the treatment of tinea pedis. This report discusses a small (n=32) clinical trial designed to determine whether sertaconazole nitrate 2% cream, used once daily, is as effective as the traditional regimen. Results demonstrated that sertaconazole is as effective when used once daily for four weeks. Patients showed rapid improvement in pruritus as early as week 2, and at six weeks' follow up, all patients were free of erythema while 93.8 percent were free of pruritus; no relapses had occurred. These encouraging findings suggest that sertaconazole nitrate may be useful in a once-daily regimen and also may result in better patient adherence to therapy.     

Effect of skin pretreatment with fatty acids on percutaneous absorption and skin retention of piroxicam after its topical application.

The enhancing effect of several fatty acids from different subclasses: saturated (lauric acid), mono-unsaturated (oleic acid) and poly-unsaturated (linoleic and linolenic acids) in the percutaneous absorption of piroxicam was investigated. These fatty acids were applied on the skin membrane in three different ways: included in the vehicle, as a pretreatment or both. An increase in piroxicam flux value was found for lauric and oleic acids in the following order: skin pretreatment with 5% fatty acids followed by application of gels containing 5% fatty acids>skin pretreatment with 5% fatty acids followed application of control gel>gel containing 5% fatty acids without skin pretreatment. For linoleic and linolenic acids, the piroxicam flux in the two pretreatment experiments was almost the same, although higher than when fatty acids were included in the formulation. Skin pretreatment with 5% linolenic acid in propylene glycol followed by application of control gel or a gel containing 5% linolenic acid, showed the highest enhancing capacity. After skin pretreatment with fatty acids, the lag time values decreased nearly three times compared to those obtained when the same fatty acids were included in the formulation. The amount of piroxicam retained in the skin after pretreatment with fatty acids was found to be very similar for all fatty acids and 3-fold higher than in the experiments without skin pretreatment.     

In vitro and in vivo percutaneous absorption of topical dosage forms: case studies

This article evaluated the influence of vehicle compositions on topical drug availability. In vitro drug release and in vivo experiments were performed in case of the hydrophilic ketamine hydrochloride and the lipophilic piroxicam. Ketamine hydrochloride is a NMDA receptor antagonist that has been useful for anesthesia and analgesia. The study of transdermal ketamine delivery is a novelty, because nobody has investigated the hypnotic effects of ketamine after this administration route. In vitro measurements gave a good basis for screening among the developed products. The physiological changes after ketamine administration showed, that there were significant differences among the parameters tested (breathing rate, duration of sleep) from the developed products (hydrogel, lyotropic liquid crystal and o/w cream) compared to the reference product (Carbopol gel). The in vivo feedback for piroxicam was the measurement of the anti-inflammatory activity by edema inhibition percentage. Significant differences were measured in case of the developed systems compared to the reference.     

Skin penetration and tissue permeation after topical administration of diclofenac

Objective: Topical delivery of drugs is an alternative to oral administration, often with similar efficacy but potentially a more favorable tolerability profile. However, topical formulations need to be able to penetrate the skin and permeate to the target areas in quantities sufficient to exert a therapeutic effect. Many factors can affect this process, including the physicochemical properties of the drug, the formulation used, and the site and mode of application. It is believed that measurement of drug concentrations at the sites of action may be an indicator of their likely efficacy. This review addresses these issues, with reference to topically administered diclofenac in osteoarthritis.

Methods: Articles relevant to this review were identified after a systematic search of Medline and Embase, using the key words “diclofenac”, "topical administration" and “osteoarthritis” in the search strategy.

Results: The sparse data available indicate that topical diclofenac can penetrate and permeate to deeper tissues, with a lower plasma to tissue ratio than oral diclofenac. The tissue diclofenac levels after topical delivery are sustained over time (at least several hours). However, there is not enough data to establish how diclofenac levels in the joint compare with IC₅₀ levels (50% of the maximum inhibition of prostaglandin synthesis) established following oral administration.

Conclusions: After topical application, diclofenac can penetrate the skin and permeate to deeper tissues, where it reaches a concentration that appears to be sufficient to exert a therapeutic effect. More robust methods are required for in vivo characterization to better estimate the clinical efficacy of topically applied drugs.     

Effect of microemulsion in topical sertaconazole hydrogel: in vitro and in vivo study

Purpose: A topical microemulsion (ME)-based hydrogel was developed to enhance permeation of an antifungal drug, sertaconazole (STZL) for effective eradication of cutaneous fungal infection.

Methods: Pseudo-ternary phase diagrams were used to determine the existence of MEs region. ME formulations were prepared with oleic acid, Tween 80, propylene glycol (PG) and water. Carbopol 940 (0.75% w/w) was used for preparation of hydrogel of STZL microemulsion (HSM) and characterized. The in vitro and in vivo evaluation of prepared HSM and commercial cream of STZL were compared.

Results: The viscosity, average droplet size and pH of HSM were 154.23?±?0.54 to 162.52?±?0.21?Pas, 42.3–91.7?nm and 6.9–7.2?, respectively. Permeation rate of STZL from optimized formulation (HSM-4), composed with oleic acid (8.75 % w/w), Tween 80 (33.35% w/w), PG (33.35% w/w) and water (24.55% w/w) was observed higher in compare with other HSMs and commercial cream. HSM-4 was stable, three times higher drug retention capacity in skin than commercial cream and did not caused any erythema or edema based on skin sensitivity study on rabbit. The average zone of inhibition of HSM-4 (23.54?±?0.72?mm) was higher in compare with commercial cream (16.53?±?0.63?mm) against Candida albicans.

Conclusion: The results of study showed that ME played a major role in permeation enhancing and skin retention effect of HSM and the concentration of STZL used for cutaneous fungal infection could be decreased by using ME based hydrogel preparation.     

Assessment of drug absorption after oral administration

Simulated data using a linear two-compartment body model (2CBM) with drugs having different absorption characteristics and dosage forms with different dissolution rates were used to evaluate the inherent problems of pharmacokinetic data analysis (flip-flop phenomenon and vanishing exponential terms). When absorption from solution is slow or release from the solid dosage form is rate limiting, the characteristic nose of the 2CBM was lost and a one-compartment model prevailed. After the 2CBM disposition kinetic parameters were obtained from solution data, absorption kinetics were evaluated by the Loo-Riegelman method. The data were also evaluated by the statistical moments method. The statistical moments method consistently demonstrated superiority in regard to providing reliable results and ease in calculation. The information provided can be particularly useful for in vivo-in vitro correlation.     

Comparison of tissue concentrations after intramuscular and topical administration of ketoprofen

Purpose. To assess whether topical ketoprofen, which has been reported to provide analgesic effects in clinical studies, reaches predictable tissue concentrations high enough to account for the reported analgesia. Intramuscular ketoprofen was used as positive control. Methods. Muscle and subcutaneous tissue concentrations were assessed by microdialysis. Plasma and tissue concentrations after intramuscular injection were described using a three-compartment population pharmacokinetic model. The prediction performance of the model was assessed by superimposing tissue concentrations of 12 subjects that did not participate in the present study. Results. Most dialysate concentrations after topical dosing of ketoprofen (100 mg) were below the quantification limit of 0.47 ng/ml. Plasma concentrations increased slowly and reached an apparent plateau of 7-40 ng/ml at 10-12h. No decline was observed up to 16 h. Tissue concentrations after intramuscular injection (100 mg) were about 10 times higher than those after topical dosing. Tissue concentrations measured in the majority of the 12 subjects that did not participate in the present study were found within the range of two-thirds of the predicted concentrations. Conclusion. Predictable and cyclooxygenase-inhibiting concentrations of ketoprofen were achieved in subcutaneous and muscle tissue after intramuscular but not after topical dosing. Thus, the tissue concentrations of ketoprofen after topical administration can hardly explain the reported clinical efficacy of topical ketoprofen.     

Novel dithranol phospholipid microemulsion for topical application: development, characterization and percutaneous absorption studies

The objective of this study was to develop and characterize a novel dithranol-containing phospholipid microemulsion systems for enhanced skin permeation and retention. Based on the solubility of dithranol, the selected oils were isopropyl myristate (IPM) and tocopherol acetate (TA), and the surfactants were Tween 80 (T80) and Tween 20 (T20). The ratios of cosurfactants comprising of phospholipids and ethanol (1?:?10) and surfactant to co-surfactant (1?:?1 and 2.75?:?1) were fixed for the phase diagram construction. Selected microemulsions were evaluated for globule size, zeta potential, viscosity, refractive index, per cent transmittance, stability (freeze thaw and centrifugation), ex vivo skin permeation and retention. The microemulsion systems composed of IPM and T80 with mean particle diameter of 72.8?nm showed maximum skin permeation (82.23%), skin permeation flux (0.281?mg/cm2/h) along with skin retention (8.31%) vis-à-vis systems containing TA and T20. The results suggest that the developed novel lecithinized microemulsion systems have a promising potential for the improved topical delivery of dithranol.     

Novel dithranol phospholipid microemulsion for topical application: development,characterization and percutaneous absorption studies

The objective of this study was to develop and characterize a novel dithranol-containing phospholipid microemulsion systems for enhanced skin permeation and retention. Based on the solubility of dithranol, the selected oils were isopropyl myristate (IPM) and tocopherol acetate (TA), and the surfactants were Tween 80 (T80) and Tween 20 (T20). The ratios of cosurfactants comprising of phospholipids and ethanol (1?:?10) and surfactant to co-surfactant (1?:?1 and 2.75?:?1) were fixed for the phase diagram construction. Selected microemulsions were evaluated for globule size, zeta potential, viscosity, refractive index, per cent transmittance, stability (freeze thaw and centrifugation), ex vivo skin permeation and retention. The microemulsion systems composed of IPM and T80 with mean particle diameter of 72.8?nm showed maximum skin permeation (82.23%), skin permeation flux (0.281?mg/cm²/h) along with skin retention (8.31%) vis-à-vis systems containing TA and T20. The results suggest that the developed novel lecithinized microemulsion systems have a promising potential for the improved topical delivery of dithranol.     

Relationship between contact time of applied dose and percutaneous absorption of minoxidil from a topical solution

Twenty-two healthy male volunteers completed a four-way, multiple-dose, randomized crossover study to determine the relationship between contact time of applied drug on the scalp and minoxidil absorption from a 2% topical solution. One milliliter of solution was applied twice daily over 150 cm2 of bald scalp to each subject for 6 days. Unabsorbed drug was washed off the scalp after 1, 2, 4, and 11.5 h of contact time in each of four treatments. Cumulative urinary excretion profiles within steady-state, 12-h dosing intervals were well described by straight lines for all treatments, indicating that systemic minoxidil elimination was rate controlled by constant, zero-order percutaneous drug absorption. The extent of minoxidil absorption, expressed as steady-state urinary excretion of unchanged minoxidil, minoxidil glucuronide, or the sum of these, increased in a disproportionate manner with increase in contact time of drug on the scalp. Relative to the amount absorbed after a contact time of 11.5 h, absorption was approximately 50% complete by 1 h and greater than 75% complete by 4 h. This suggests that minoxidil absorption from the vehicle into skin occurs rapidly relative to diffusion through skin. The rate of minoxidil absorption from vehicle into skin was characterized as nonlinear, whereas minoxidil excretion into urine was rate controlled by diffusion from one or more components of the skin which apparently serve as a reservoir, or depot, for minoxidil.     

Zinc absorption after oral administration of zinc sulfate

The administration of 200 mg of ZnSO₄.7H₂O to six normal healthy males gave rise to increased serum zinc levels when this drug was taken in a fasting state, whereas administration during a light meal caused no increased levels.     

Difference in percutaneous absorption and intracutaneous distribution in guinea pigs among topical antifungal drugs (tioconazole solution, tioconazole cream, miconazole nitrate solution and bifonazole solution)

Tioconazole (TCZ) is an imidazole antifungal agent with broad spectrum activity. Percutaneous absorption and intracutaneous distribution of TCZ solution have been compared with TCZ cream, miconazole nitrate (MCZ) solution and bifonazole (BFZ) solution following a single topical application to abdominal skin of guinea pigs. Following application of TCZ solution, TCZ concentrations in the stratum corneum, epidermis-cutis and subcutaneous tissue were higher than those after TCZ cream application suggesting superior percutaneous penetration after TCZ solution application. The percutaneous penetration after applications of MCZ solution and BFZ solution was comparable to that of TCZ cream, but inferior to that of TCZ solution. TCZ concentrations in the stratum corneum were much higher than those in epidermis-cutis and subcutaneous tissue after applications of both TCZ formulations. The majority of applied TCZ remained in the stratum corneum at high levels for a long duration. TCZ concentrations in the stratum corneum within 24 h after applications of both TCZ formulations were more than several hundred times higher than the minimum inhibitory concentrations against most of the dermatophytes and yeasts. The effectiveness of both TCZ formulations against dermatophytoses may be due to this favorable pharmacokinetic property in the skin tissues, together with its potent antifungal activity. Percutaneous absorption of TCZ after applications of both formulations was negligible suggesting that these treatments are unlikely to produce systemic side effects.