Single-dose fasting bioequivalence assessment of erythromycin stearate tablets in man

Yakatan, Gerald J.; Poynor, Wesley J.; Harris, Roderick; Martin, A.; Leonard, Robert G.; Briggs, Arthur H.; Doluisio, James T.

doi:10.1007/bf01062534

Cited by 8 publications

(2 citation statements)

References 13 publications

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“…Thus, the doses used in the current study are equivalent to the clinical doses in humans. In addition, the T max values of ketoconazole, erythromycin and diltiazem are 2, 3 and 2 h after single administration, respectively (Yakatan et al 1979, Baxter et al 1986, Backman et al 1994, suggesting that these inhibitors should reach at the enzyme site after the absorption phase. Thus, we judged drug-drug interaction based on the inhibition by CYP3A inhibitors could be evaluated by this method, if inhibitors have an effect on midazolam pharmacokinetics after intravenous administration of midazolam.…”

Section: Discussionmentioning

confidence: 97%

Model for the drug–drug interaction responsible for CYP3A enzyme inhibition. I: evaluation of cynomolgus monkeys as surrogates for humans

et al. 2004

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1. Anti-human cytochrome P450 (CYP) 3A4 antiserum completely inhibited midazolam metabolism in monkey liver microsomes, suggesting that midazolam was mainly metabolized by CYP3A enzyme(s) in monkey liver microsomes. 2. Midazolam metabolism was also inhibited in vitro by typical chemical inhibitors of CYP3A, such as ketoconazole, erythromycin and diltiazem, and the apparent K(i) values for ketoconazole, erythromycin and diltiazem were 0.127, 94.2 and 29.6 microM, respectively. 3. CYP3A inhibitors increased plasma midazolam concentrations when midazolam and CYP3A inhibitors were co-administered orally. However, the pharmacokinetic parameters of midazolam were not changed by treatment with CYP3A inhibitors when midazolam was given intravenously. This suggests that CYP3A inhibitors modified the first-pass metabolism in the liver and/or intestine, but not systemic metabolism. 4. The drug-drug interaction responsible for CYP3A enzyme(s) inhibition was observed when midazolam and inhibitors were co-administrated orally. Therefore, it was concluded that monkeys given midazolam orally could be useful models for predicting drug-drug interactions in man based on CYP3A enzyme inhibition.

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Section: Discussionmentioning

confidence: 97%

Model for the drug–drug interaction responsible for CYP3A enzyme inhibition. I: evaluation of cynomolgus monkeys as surrogates for humans

et al. 2004

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“…This is because the local heating of electrodes enhances mass transport and electron transfer kinetics which, in turn, increases the rate of faradaic reactions and the magnitude of, for example, voltammetric currents. Thus, motivated in part by the desire to achieve ever decreasing limits of detection for electrochemistry-based sensing, the scientific community has explored the development of controllable microelectrode heating approaches since the 1980s. − To date, various strategies have been developed that can be classified into two groups: (1) direct methods, including shining a laser beam onto electrode surfaces , or passing low-frequency ac currents through the electrode body, , and (2) indirect methods, including heating electrodes via microwave radiation or high-frequency ac fields applied between working and counter electrodes. , In both cases, however, the locally applied heating perturbations increase the temperature of the electrolyte near the electrode surface without affecting the temperature of the bulk electrolyte solution.…”

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confidence: 99%

Hot-SWV: Square Wave Voltammetry with Hot Microelectrodes

et al. 2020

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A promising strategy to lowering detection limits in electrochemical analysis is the active modulation of the electrode temperature. Specifically, by tuning the electrode's surface temperature one can enhance detection limits due to improved electrode process kinetics and increased mass transfer rates, all without affecting the bulk solution. Motivated by this argument, here we report the development of a new electroanalytical technique based on electrode-temperature modulation, which we call hot square wave voltammetry (Hot-SWV). The technique utilizes the superposition of conventional SWV, already considered as one of the most sensitive voltammetric techniques, and a high frequency alternating current (ac) waveform to electrically polarize microelectrodes. By applying about 100 MHz ac frequencies (with varying V rms amplitudes), our method generates an electrothermal fluid flow (ETF) in the electrolyte surrounding the electrode, thereby increasing the sensitivity of the SWV-based detection. We demonstrate this by investigating the oxidation of ferrocyanide and iron(II) ions, as well as the reduction of the coordination compound ruthenium(III) hexamine under various experimental conditions. We validate our experimental results against a theoretical model built using finite element analysis and observe agreement within ≤15% error at temperatures ≤39 °C. Using Hot-SWV, we observe at least one-order-of-magnitude improvement in the limit of detection of ferrocyanide ions relative to conventional, mm-size electrodes at 25 °C. In addition, we anticipate that Hot-SWV will be particularly useful for electroanalytical measurements of ultralow (≤pM) concentrations of analytes in environmental and biomedical applications.

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Estimation problem due to multiple solutions in pharmacokinetic curve fitting to two‐compartment model and its avoidance

Murata

Kohno

1989

Biopharm & Drug Disp

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A size of error in observed data for fitting curves and an estimation problem due to multiple solutions in a two-compartment model were studied by using two different non-linear least-squares regression programs, SALS and NONLIN. It was found that bolus intravenous data have generally 5-10 per cent errors and oral data contain 10-25 per cent errors against the fitted data with respect to total 151 data sets of 11 different drugs. Parameters of five drugs reported in references were used to obtain simulated concentrations at the sampling times, and five different data sets containing 25 per cent normally distributed random errors as a coefficient of variation were generated using each data set of these simulated concentration. In the two-compartment model with tri-exponential equations, unreasonable estimates were occasionally observed, resulting in reversed relative values to the theoretical ones of L/M, L/N, M/N or Ka/alpha, which are analogous to the well-known flip-flop phenomenon in the one-compartment model, when number of parameters to be estimated is not less than five or errors of data exceed about 10 per cent. In an attempt to avoid such unreasonable values, initial estimates for curve fitting was successfully obtained by using a microcomputer program SIMPLEX based on a simplex method. On the basis of these results, some problems in curve fitting of plasma drug concentration data are discussed.

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Single-dose fasting bioequivalence assessment of erythromycin stearate tablets in man

Cited by 8 publications

References 13 publications

Model for the drug–drug interaction responsible for CYP3A enzyme inhibition. I: evaluation of cynomolgus monkeys as surrogates for humans

Model for the drug–drug interaction responsible for CYP3A enzyme inhibition. I: evaluation of cynomolgus monkeys as surrogates for humans

Hot-SWV: Square Wave Voltammetry with Hot Microelectrodes

Estimation problem due to multiple solutions in pharmacokinetic curve fitting to two‐compartment model and its avoidance

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