European journal of clinical pharmacology
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Eur. J. Clin. Pharmacol. · Jan 1996
A pharmacokinetic-pharmacodynamic model for a muscle relaxant: atracurium.
Our goal was to develop a pharmacokinetic-pharmacodynamic model that describes the fate of atracurium and its metabolite laudanosine as well as the time course of the neuromuscular block. The model was based on the consideration of mass balance of atracurium and was constructed by postulating an effect compartment linked to the central compartment in the previously described open mammillary model for atracurium. The entry and exit rate constants, kCE and kEC, were adjusted to satisfy the requirement that the peak amount in the effect compartment coincides with the peak submaximal block. ⋯ Laplace transforms were used to define the model, and the solution was obtained by iterative numeric adjustments of the rate constants. The model provides an excellent fit of the observed plasma concentrations of atracurium and laudanosine and simulates well the development and waning of the neuromuscular block. The model projects that the peak amount of atracurium in the effect compartment amounts to 14% of the injected dose and is reached at 7.6 min after the injection.
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Eur. J. Clin. Pharmacol. · Jan 1996
Therapeutic monitoring of nalbuphine: transplacental transfer and estimated pharmacokinetics in the neonate.
Nalbuphine, a mixed agonist-antagonist opiate, is commonly used as a systemic analgesic during labour. Recent reports of perinatal adverse effects prompted us to carry out therapeutic nalbuphine monitoring in obstetric analgesia. Because data on fetomaternal transfer are scarce and the pharmacokinetics of this drug in the neonate are largely unknown, we report data obtained from 28 parturients treated with nalbuphine either intramuscularly and/or intravenously during labour. ⋯ An estimated plasma half-life of 4.1 h was calculated from two determinations in the neonate based on the assumption of a monoexponential decay of nalbuphine concentrations. Apart from a flattening of the fetal heart rate tracing in 54% of the cases, only one neonate had a low Apgar score at birth. The apparent prolonged half-life of nalbuphine in the neonate indicates the usefulness of an intramuscular injection of naloxone to prevent recurrence of cardiorespiratory depression due to nalbuphine administration to the mother.
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Eur. J. Clin. Pharmacol. · Jan 1996
Population pharmacokinetics and pharmacodynamics of oral levodopa in parkinsonian patients.
The population pharmacokinetics and pharmacodynamics of a standardised oral test dose of levodopa have been determined in patients with mild to severe Parkinson's disease using parametric, non-linear mixed effect modelling with the program NON-MEM. Levodopa plasma concentration data and motor effect behaviour (tapping times) were obtained from 46 patients, for whom a total of 970 observations were available (approximately 21 pharmacokinetic and pharmacodynamic observations per patient). The pharmacokinetic-pharmacodynamic model used was a one-compartment first-order absorption model linked to the sigmoid EMax representation of the Hill equation via an equilibration rate-constant, ke0. The model was also tested via a reduction in the number of pharmacokinetic and pharmacodynamic data points to a total of four to eight per patient. ⋯ In a clinical setting knowledge of the population pharmacokinetic and pharmacodynamic parameters for oral levodopa may prove useful in estimating the duration of the drug's beneficial motor activity in patients with mild to severe Parkinson's disease (Hoehn and Yahr status I-IV).
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Eur. J. Clin. Pharmacol. · Jan 1995
Randomized Controlled Trial Clinical TrialRecovery characteristics following anaesthesia with sevoflurane or propofol in adults undergoing out-patient surgery.
The aim of the study was to compare recovery characteristics in adult patients following general anaesthesia either with the new investigational volatile agent sevoflurane or with propofol. Accordingly, two groups of 25 adults undergoing outpatient surgery were entered into a prospective, randomised study. ⋯ Modified Aldrete scores were also higher in this group within the first hour after anaesthesia than in the propofol group. Sevoflurane appears to be a useful alternative to propofol in outpatient anaesthesia.
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According to the World Health Organisation, a country's morphine consumption is an important indicator of progress in cancer pain relief. Due to its very high opioid consumption, Denmark is often pointed out as a country worthy of imitation. The aim of the present study was to analyse Danish opioid consumption in order to elucidate the usage pattern and to identify the consumers. ⋯ The consumption of long acting opioids (sustained release morphine, methadone, buprenorphine) and short acting opioids (others) increased by 1427% and 105%, respectively. Analysis of a sample of 1854 prescriptions for opioids revealed that less than 10% of the prescriptions were issued for cancer pain conditions. It is concluded: that if other countries consider Denmark as worthy of imitation in opioid treatment for cancer pain, attention should be paid to the pattern of the Danish opioid consumption, which is outstanding with respect to quantity but the quality may be questionable.