Alternative method for predicting phenytoin levels.
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Humans↗
Biomedical subjects
T Jochsberger
Publications and source records attributed to T Jochsberger.
Differential pulse polarography of some degradation products of tetracycline.
In an attempt to develop a more rapid, convenient, and precise method for the direct detection and analysis of the degradation products of tetracycline, a study of those products utilizing differential pulse polarography was initiated. The investigation was concentrated on the subject of the kinetics of the epimerization of anhydrotetracycline to 4-epianhydrotetracycline in acetate buffer. The reaction was followed at 25 and 50 degrees. Duplicate experiments were run at each temperature. The apparent rate constants obtained were 4.17 +/- 0.13 X 10(-1)/hr (25 degrees) and 6.97 +/- 1.00 X 10(-2)/hr (50 degrees).
Biotransformation↗
In vitro adsorption studies of cimetidine.
The adsorption of cimetidine on selected pharmaceuticals including kaolin, activated charcoal, talc, and nonsystemic antacids was determined at pH 5.0 and 25 degrees. The Langmuir and Freundlich adsorption isotherms showed that cimetidine adsorption was significant with activated charcoal, kaolin, talc, and magnesium trisilicate and was virtually nonexistent with magnesium hydroxide and aluminum hydroxide. Equations expressing the Freundlich and Langmuir adsorption isotherms were evaluated for each adsorbent. The approximate amounts of cimetidine adsorbed per gram of adsorbent were 25.6, 0.402, 0.291, and 0.343 mg for charcoal, kaolin, talc, and magnesium trisilicate, respectively. These in vitro studies indicate that some cimetidine may be lost when it is administered concomitantly with pharmaceutical adsorbents.
Adsorption↗
Differential pulse polarography of tetracycline: determination of complexing tendencies of tetracycline analogs in the presence of cations.
The complexation tendencies, stoichiometries, and stability constants for tetracycline, minocycline, and demeclocycline with the metallic ions calcium(II), magnesium (II), zinc(II), aluminum(III), iron(II), and iron (III) were evaluated using a polarographic technique. Changes in pulse peak heights for each tetracycline deravative were measured as a function of cation concentration. The method provides an in vitro method of evaluating the selectivity of particular metal ions for different tetracycline analogs.
Aluminum↗
Effect of brand on the serum level of aspirin.
The authors present a case of a four-year-old female, treated with aspirin for juvenile rheumatoid arthritis. A generic preparation was given first, but plasma salicylate levels remained significantly below the required therapeutic range. Upon changing to a brand-name product, however, therapeutic levels were achieved after one day. The authors conclude that the source of aspirin used had a marked effect on the serum salicylate level.
Arthritis, Juvenile↗
Precautions in the use of Michaelis-Menten kinetics in the prediction of phenytoin levels.
The Michaelis-Menten equation is one of the various techniques available for predicting steady-state plasma levels of phenytoin. In actual practice, however, data are not always available or reliable. This case report emphasizes the importance of establishing the quality of the data and determining that steady state has been achieved. The addition of a third point to the graph used to estimate parameters greatly increases prediction accuracy.
Child↗
Controlled release from an electrorheological fluid dosage form: experimental results for a prototype system.
A new controlled-release technology that is based on electrorheological fluids (ERF) is described, and a model system is investigated. Humidified starch (duration of humidification is 30-35 minutes) was used as a filler material (approximately 20% w/w) in olive oil to make the ER system, and benzocaine (BZN) was used as the model drug. The average particle size of starch in the olive oil was approximately 200 nm. 1N HCl was used as the receiver medium and BZN was assayed by UV spectroscopy at 226 nm. A series of studies was done at five temperatures (25 degrees, 30 degrees, 35 degrees, 40 degrees, and 45 degrees C) and two external electric fields (E-fields) that were generated by applying potential drops across the diffusion apparatus of 0 V and 290 V. Control studies of BZN release from olive oil without filler showed little or no increase in release rates resulting from application of E-fields. In addition, while reversing the polarity for BZN in olive oil caused differences in release rates, these differences were too small to explain the results obtained for the ER systems. It was found that release of BZN increased significantly with the application of the electric field (approximately 53% increase at 25 degrees C). A plot of the log of the release rate vs 1/T was linear for the 0 V data but deviated from linearity for the 290 V data. The increase in release rates due to the E-field became smaller as the temperature was increased. The results are consistent with (but are not sufficient to prove) the hypothesis that the increased release rate is due to a small amount of ordering of the cornstarch filler particles in response to the applied E-field, which results in a reduction in the tortuosity of the system.
Anesthetics, Local↗