PubMed · 14036997
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A KAMINSKY, L JAIMOVICH. 1962. [Tertiary syphilis].. https://pubmed.ncbi.nlm.nih.gov/14036997/
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Valid and reliable semi-quantitative dermal exposure assessment methods for epidemiological research and for occupational hygiene practice, applicable for different chemical agents, are practically nonexistent. The aim of this study was to assess the reliability of a recently developed semi-quantitative dermal exposure assessment method (DREAM) by (i) studying inter-observer agreement, (ii) assessing the effect of individual observers on dermal exposure estimates for different tasks, and (iii) comparing inter-observer agreement for ranking of body parts according to their exposure level. Four studies were performed in which a total of 29 observers (mainly occupational hygienists) were asked to fill in DREAM while performing side-by-side observations for different tasks, comprising dermal exposures to liquids, solids, and vapors. Intra-class correlation coefficients ranged from 0.68 to 0.87 for total dermal exposure estimates, indicating good to excellent inter-observer agreement. The effects of individual observers on task estimates were estimated using a linear mixed effect model with logged DREAM estimates as explanatory variable; "task", "company/department", and the interaction of "task" and "company/department" as fixed effects; and "observer" as a random effect. Geometric mean (GM) dermal exposure estimates for different tasks were estimated by taking the exponent of the predicted betas for the tasks. By taking the exponent of the predicted observer's intercept (exp(omega i)), a multiplier (M(O)) was estimated for each observer. The effects of individual observers on task estimates were relatively small, as the maximum predicted mean observers' multiplier was only a factor 2, while predicted GMs of dermal exposure estimates for tasks ranged from 0 to 1226, and none of the predicted individual observers' multipliers differed significantly from 1 (t-test alpha = 0.05). Inter-observer agreement for ranking of dermal exposure of nine body parts was moderate to good, as median values of Spearman correlation coefficients for pairs of observers ranged from 0.29 to 0.93. DREAM provides reproducible results for a broad range of tasks with dermal exposures to liquids, solids, as well as vapors. DREAM appears to offer a useful advance for estimations of dermal exposure both for epidemiological research and for occupational hygiene practice.
Iontophoretic transport of rotigotine across human stratum corneum (HSC) was studied in vitro in side by side diffusion cells according to the following protocol: 6 h of passive diffusion, 9 h of iontophoresis followed by 5 h of passive diffusion. A current density of 0.5 mA cm(-2) was applied. The parameters studied were the influence of the rotigotine concentration in donor phase and the influence of the molecular weight of the co-ions. To this end, Na(+) was replaced by tetra ethyl ammonium (TEA(+)) or tetra butyl ammonium (TBA(+)) (both at pH 5 and 6). In addition, the influence of the acceptor phase temperature (32 degrees C versus room temperature), the replacement of HSC by dermatomed human skin (DHS), and the relation between drug transport and current density were examined. The estimated steady-state flux (Flux(ss)) gradually increased with the drug concentration in the donor phase in a linear manner. The flux was also linearly correlated with the applied current density providing a convenient approach to individual dose titration. The use of TEA(+) as co-ion increased the rotigotine iontophoretic flux significantly, while TBA(+) did not. Replacing HSC by DHS reduced the iontophoretic rotigotine transport, while an increase in temperature to 32 degrees C increased the rotigotine flux. The maximum Flux(ss) achieved was around 80 nmol cm(-2) h(-1) indicating that by means of iontophoresis, a therapeutic level of rotigotine might be achieved with a reasonable patch size.
We hypothesised that the depletion of propylene glycol from topical formulations applied at clinically relevant doses (approximately mg/cm2) would limit its penetration enhancement effect. The in vitro percutaneous permeation of a model drug-loperamide hydrochloride-in formulations containing propylene glycol was therefore investigated under finite dose conditions. The flux of loperamide and propylene glycol across dermatomed human skin was measured. The first study examined the effect of topical loading of a gel containing 12% propylene glycol. The second study investigated the effect of propylene glycol content in creams containing 15 and 40%. Both studies showed a correlation between the amount of propylene glycol dosed on the skin and the amount of drug that had permeated. The substantial permeation of propylene glycol and relatively small permeation of loperamide, strongly suggests, that the time dependent permeation of the drug was due to the depletion of propylene glycol at the skin surface and not to the depletion of the drug itself. As often doses applied in in vitro skin permeation experiments do not match the intended clinical dosage-they are usually much greater-this study suggests that the penetration enhancement effect of propylene glycol can be overestimated in in vitro studies.