Use of muscle relaxants in intensive care units.
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Drug Monitoring↗
Biomedical subjects
J J Savarese
Publications and source records attributed to J J Savarese.
Pharmacokinetics and pharmacodynamics of doxacurium in young and elderly patients during isoflurane anesthesia.
Preliminary disposition studies of the investigational, long-acting muscle relaxant doxacurium chloride (Nuromax) have demonstrated dual elimination by renal and hepatobiliary pathways, as well as slow hydrolysis by plasma cholinesterase. The present study compares the kinetics and dynamics of doxacurium in eight ASA physical status I or II elderly patients (67-72 yr of age) and eight ASA I or II young patients (22-49 yr of age). After institutionally approved written informed consent, kinetic and dynamic measurements were made after a 25-micrograms/kg bolus injection of doxacurium during 1.25 MAC nitrous oxide/oxygen/isoflurane anesthesia. Maximum twitch depression was similar in older patients (96.4% +/- 1.3%) to that in the young patients (96.6% +/- 1.8%). The time to achieve this level of block was significantly longer in the elderly than in the young (11.2 +/- 1.1 min versus 7.7 +/- 1.0 min, respectively). Recovery times to twitch heights of 5% and 25% of control tended to be prolonged and were more variable in the elderly (82.6 +/- 17.2 and 97.1 +/- 20.1 min, respectively) than in the young (54.8 +/- 9 and 67.5 +/- 8.2 min, respectively). Elimination half-life (96 +/- 20 min) and clearance (2.47 +/- 0.69 mL.kg-1.min-1) in the elderly patients were not statistically different from values found in the younger group. Volume of distribution at steady state in the elderly (220 +/- 80.2 mL/kg) was significantly larger than in the young (150 +/- 40.0 mL/kg).(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Evaluation of a cancer pain model for the testing of long-acting analgesics. The effect of MS Contin in a double-blind, randomized crossover design.
A double-blind, double-dummy, crossover study compared oral controlled-release morphine sulfate (MS Contin tablets [MSC], Purdue Frederick, Norwalk, CT) every 12 hours, and immediate-release morphine sulfate (IRMS) tablets, every 4 hours, in 14 evaluable patients with chronic cancer pain. The test model described showed assay sensitivity for steady-state analgesia, requiring relatively few subjects to yield statistical significance in pharmacologic potency estimates. Initial doses were the calculated equivalents of about one third the previous opioid requirements or at least 30 mg MSC every 12 hours or 15 mg IRMS every 4 hours. This was generally subtherapeutic; hence, additional IRMS was available for break-through pain. Doses of MSC and IRMS were titrated upwards until the requirement for rescue IRMS was less than 20% of the total daily amount of morphine. In both study phases, the total dose of morphine increased significantly from the first day to the last, on which it was significantly (34%) higher for IRMS than MSC. Pain was significantly less intense and frequent in the last 24 hours of each treatment arm than in the first, and equally well controlled by both regimens. The two treatments were equipotent in a pharmacologic assay using dosages and pain scores. The requirement for rescue analgesia was similarly comparable for both treatments, decreasing significantly with upward dose titration. The few side effects experienced (one with MSC and three with IRMS) did not include serious reactions such as respiratory depression. It is concluded that MSC, 12-hourly, controls cancer pain as effectively and safely as IRMS on a 4-hour schedule. MS Contin exhibits a 12-hour duration of action as previously shown in other well-controlled trials. A problem of pain exacerbation at the start of each study phase was found to be associated with the design of this study. It may be resolved with a higher initial study dose and/or use of a patient-controlled analgesia device for parenteral rescue doses.
Administration, Oral↗
Neuromuscular and cardiovascular effects of doxacurium in children anaesthetized with halothane.
The neuromuscular and cardiovascular effects of doxacurium chloride (BW A938U) were evaluated in 27 children (2-12 yr) anaesthetized with 1% halothane and nitrous oxide in oxygen. In nine children the incremental technique was used to establish a cumulative dose-response curve by train-of-four stimulation. The remaining children received either 30 or 50 micrograms kg-1 of the drug as a single bolus. The median ED50 and ED95 of doxacurium in children were 19 and 32 micrograms kg-1, respectively. No clinically significant change in heart rate or arterial pressure occurred. Following doxacurium 30 micrograms kg-1 and 50 micrograms kg-1, recovery to 25% of control occurred in 25 (SEM 6) and 44 (3) min, respectively. The recovery index (25-75% of control) was 27 (2) min. The duration of action of doxacurium is similar to that of tubocurarine and dimethyl-tubocurarine in children. Compared with adults, children seem to require more doxacurium (microgram kg-1) to achieve a comparable degree of neuromuscular depression, and they recover more rapidly.
Anesthesia Recovery Period↗
Neuromuscular and cardiovascular effects of mivacurium in children.
The neuromuscular and cardiovascular effects of mivacurium chloride (BW B1090U) were evaluated in 90 children (2-12 yr) during N2O:O2 halothane or N2O:O2 narcotic anesthesia. Neuromuscular response was evaluated by recording the force of contraction of the adductor of the thumb during train-of-four stimulation at 0.1 Hz. The children were divided into two groups. Patients in group A (n = 45) were anesthetized with N2O:O2 and halothane (1% inspired) and patients in group B (n = 45) were anesthetized with N2O:O2 and fentanyl or morphine. Each group was further divided into five subgroups of nine children. Children in the first three sets of subgroups (A1-A3, B1-B3) received an initial dose of 0.02, 0.04, 0.05, 0.06 or 0.07 mg/kg mivacurium to determine dose response relationships under the different anesthetic regimens. The ED50 and ED95 neuromuscular blocking doses calculated from this single dose technique were 0.051 mg/kg and 0.095 mg/kg, respectively, in children anesthetized with halothane N2O:O2, and 0.059 mg/kg and 0.11 mg/kg in children anesthetized with N2O:O2 narcotic. The fourth subset of each group (A4 and B4) received 0.09 mg/kg and 0.11 mg/kg mivacurium, the estimated ED95 for each respectively. The last subsets (A5 and B5) received 0.2 mg/kg. This dose induced 100% depression of the twitch response in all 18 patients in 1.8 +/- 0.1 min, with recovery to 5%, 25%, and 95% of control occurring in 8.4 +/- 0.5, 11.2 +/- 0.6 and 18.4 +/- 1.6 min, respectively. The recovery indices for all patients were 4.6 +/- 0.6 min for 25-75% recovery and 9.7 +/- 1.3 min for 5-95% recovery.(ABSTRACT TRUNCATED AT 250 WORDS)
Anesthesia↗
The cardiovascular effects of mivacurium chloride (BW B1090U) in patients receiving nitrous oxide-opiate-barbiturate anesthesia.
The dose-effect relationship of mivacurium chloride on arterial blood pressure, heart rate, and plasma histamine was determined in 97 consenting ASA physical status I-II patients receiving nitrous oxide-oxygen-opiate-barbiturate anesthesia. In the absence of surgical stimulation during steady state anesthetic conditions with controlled ventilation, average maximum change in tachograph-counted heart rate was 7% or less after 10-15-s injection of mivacurium at all doses from 0.03 to 0.30 mg/kg. Average peak change in mean arterial pressure measured via radial arterial catheter was 7% or less after all doses from 0.03 to 0.15 mg/kg. Transient (0.2-4.5 min) decreases in arterial blood pressure were noted after 10-15-s injection in some patients at 0.20, 0.25, and 0.30 mg/kg. When they occurred, these changes were usually accompanied by facial erythema lasting 2-5 min and were correlated with increases in plasma histamine level (P less than 0.001). Facial erythema, decrease in blood pressure, and elevation of histamine level were all accentuated by increasing the dose of mivacurium and by more rapid injection of the drug. For example, mean blood pressure decreased an average of 13% after injection of mivacurium 0.25 mg/kg over 10-15 s. In contrast, during administration over 30 and 60 s of this dose, arterial pressure decreased 7.6 and 1.5%, respectively (P less than 0.001, 10-15 s vs. 60-s injection). Average peak histamine level, which increased to 132% of control after administration of 0.25 mg/kg over 10-15 s, did not change after injection over 60 s.(ABSTRACT TRUNCATED AT 250 WORDS)
Adolescent↗
Principles of cancer pain management. Use of long-acting oral morphine.
Oral morphine is increasingly recognized as the pharmacologic standard for cancer pain management. Yet for the primary care physician and oncologist alike, misconceptions of the safety and efficacy of oral morphine along with lack of recognized guidelines for use have often resulted in inadequate cancer pain therapy. Use of controlled-release oral morphine sulfate (MSC) requires additional guidelines for optimum analgesia. Proposed are ten principles of dosing oral morphine, especially MSC, which were followed in a clinical trial involving cancer patients. MSC dosed at 8-, 10-, and 12-hour intervals was compared with immediate-release morphine (IRMS) dosed every four hours, and with prestudy analgesics. Patients achieved satisfactory analgesia at daily doses (mean +/- SE) of 118.0 +/- 8.6 mg and 111.4 +/- 12.6 mg (P greater than .05) for IRMS and MSC, respectively. Dosing endpoints were determined by titration with IRMS and MSC to a minimal and equivalent amount of supplemental short-acting analgesic. Side effects were typical for opioids and tolerated except for one dropout on IRMS (nausea and constipation). The ten principles have been incorporated into a dosing scheme as a practical guide for MSC therapy.
Administration, Oral↗
Rescue factor: a design for evaluating long-acting analgesics.
A design is described that uses need for supplemental (rescue) analgesic as a factor predicting effectiveness of a test analgesic. This methodology is especially suited for evaluating long-acting analgesics given repeatedly. Rescue use is measured over dosing intervals as test drug is titrated from a subanalgesic dose to that requiring no or minimal rescue. This design was used to evaluate oral long-acting morphine sulfate (MS Contin) given every 12 hours in a crossover study of cancer pain using oral immediate-release morphine sulfate given every 4 hours as reference. Less morphine was required for MS Contin given every 12 hours relative to immediate-release morphine sulfate given every 4 hours (186 +/- 22 mg vs. 239 +/- 35 mg; p = 0.04). Total daily morphine for both regimens correlated linearly (r = 0.96) with a slope of 1.27 +/- 0.11, significantly (p = 0.03) different from equivalence (slope of unity) in favor of MS Contin. This design features assay sensitivity (dose-response) and provides relative potency estimates for analgesics given at specific regimens.
Administration, Oral↗
Clinical pharmacology of mivacurium chloride (BW B1090U) infusion: comparison with vecuronium and atracurium.
Mivacurium chloride (BW B1090U) is a new, short-acting non-depolarizing neuromuscular blocking agent. It is a synthetic bis-benzylisoquinolinium diester, which is hydrolysed rapidly by plasma cholinesterase. This study compares mivacurium, atracurium and vecuronium by continuous i.v. infusion. The duration of mivacurium infusion ranged from 29.5 to 286 min. The steady state infusion rates necessary to maintain 95 (SEM 4)% twitch suppression were: mivacurium 8.3 (0.7) micrograms kg-1 min-1; atracurium 7.9 (0.4) micrograms kg-1 min-1; vecuronium 1.2 (0.3) micrograms kg-1 min-1. Following infusions of mivacurium, various recovery times (for example: 25-75%, 6.9 (0.3) min; 25-95%, 11.0 (0.4) min; 5-95% 14.5 (0.4) min) did not differ significantly from those following single bolus doses. Recovery times following cessation of mivacarium infusions were approximately 50% of those for equivalent durations of infusion of atracurium (10.9 (0.3) min for 25-75% recovery and 26.6 (0.4) min for 5-95% recovery). For vecuronium, corresponding recovery times were 13.8 (0.9) and 32.0 (1.2) min, respectively. Comparative recovery times for mivacurium were 40-50% of those for vecuronium. There was a significant correlation between the infusion rate of mivacurium required to maintain 95% twitch depression and the plasma cholinesterase activity of individual subjects.
Adolescent↗
The clinical neuromuscular pharmacology of mivacurium chloride (BW B1090U). A short-acting nondepolarizing ester neuromuscular blocking drug.
Mivacurium chloride (BW B1090U), a bis-benzylisoquinolinium diester compound, was found to undergo hydrolysis in vitro by purified human plasma cholinesterase in a pH-stat titrator at 88% of the rate of succinylcholine at pH 7.4, 37 degrees C and 5 microM substrate concentration. In 72 consenting ASA Physical Status I-II patients receiving nitrous oxide/oxygen-narcotic-thiopental anesthesia, the neuromuscular blocking effect of mivacurium was assessed following bolus doses from 0.03 to 0.30 mg/kg, as well as during and following continuous infusions from 35 to 324 min in length. The calculated ED95 for inhibition of adductor pollicis twitch evoked at 0.15 Hz was 0.08 mg/kg. At 0.1 mg/kg, 96% block developed, onset to maximum block required 3.8 +/- 0.5 min, and recovery to 95% twitch height occurred 24.5 +/- 1.6 (SE) min after injection. At 0.25 mg/kg, onset was 2.3 +/- 0.3 min; 95% recovery developed within 30.4 +/- 2.2 min, an increase in duration of action of only 24% versus 150% higher dosage. Comparative recovery indices from 5 to 95% or from 25 to 75% twitch heights did not differ significantly among all dosage groups from 0.1 to 0.3 mg/kg (range 12.9 to 14.7 and 6.6 to 7.2 min, respectively). In 38 patients who received mivacurium by continuous infusion (duration 88.1 +/- 7.1/47.1 min, SE/SD) for maintenance of 95 +/- 4% twitch inhibition, the mean 5-95% and 25-75% recovery indices after discontinuation of infusion were 14.4 +/- 0.6 and 6.5 +/- 0.3 min (P greater than 0.5 vs. all single bolus doses). The train-of-four (T4) ratio, within 2.6 +/- 0.5 min after 95% twitch recovery following bolus doses, averaged 79.5 +/- 1.8% (n = 32). Similarly, after discontinuation of infusions, the T4 ratio reached 73.4 +/- 1.9% within 3.4 +/- 1.9 min after 95% twitch recovery (n = 33). Antagonism of residual block was seldom indicated, but, to test ease of reversal, eight patients electively received neostigmine (0.06 mg/kg) with atropine (0.03 mg/kg) at 67 to 93 (76.6 +/- 3.5) % block. Twitch returned to 95% of control within 4.5 to 9.5 (6.3 +/- 0.5) min after neostigmine. Mivacurium may offer increased versatility in providing clinical muscle relaxation in a variety of situations. Further studies seem appropriate.
Adult↗
Clinical pharmacology of doxacurium chloride. A new long-acting nondepolarizing muscle relaxant.
Doxacurium chloride (BW A938U) is a bis-quaternary benzylisoquinolinium diester nondepolarizing neuromuscular blocking compound that is minimally hydrolyzed by human plasma cholinesterase. The effect of bolus doses of doxacurium ranging from 10 to 80 micrograms/kg were studied in 81 consenting ASA physical status I and II patients anesthetized with nitrous oxide-oxygen-fentanyl-thiopental. The neuromuscular and cardiovascular effects of doxacurium were compared with those of eight patients receiving 100 micrograms/kg of pancuronium receiving identical anesthesia. The calculated ED95 for evoked twitch inhibition of the adductor pollicis at 0.15 Hz was 30 micrograms/kg. At 1.3 times the ED95 dose of doxacurium, recovery times to 5% and 25% of control twitch height were 59.2 +/- 4.1 (n = 23 of 26) and 75.7 +/- 5.6 (n = 23 of 26) min respectively. For pancuronium comparable recovery times were 81.7 +/- 10.3 (n = 8 of 8) and 83.0 +/- 8.4 (n = 5 of 8) min. Residual doxacurium blockade was readily antagonized by neostigmine. No dose-related effect on heart rate or mean arterial pressure was seen with doxacurium at doses up to and including 2.7 times the ED95 (80 micrograms/kg). Doxacurium administration did not result in any elevation of plasma histamine at doses up to and including 2.7 times the ED95. In this study doxacurium appears to be a long-acting nondepolarizing relaxant with readily reversible neuromuscular blocking effects and devoid of cardiovascular effects. This profile offers clinical advantages over current long-acting agents and further clinical trials seem appropriate.
Adolescent↗
Reversal of pancuronium. Neuromuscular and cardiovascular effects of a mixture of neostigmine and glycopyrronium.
Moderate to deep (67-99% single twitch depression) pancuronium-induced neuromuscular blockade was antagonised with neostigmine (30 micrograms/kg, 60 micrograms/kg, or 80 micrograms/kg) in combination with glycopyrronium. Twenty-seven patients were reversed from 91%-99% twitch depression. Recovery of the first twitch of a train-of-four to 95% of control twitch took at least 20 minutes with neostigmine 30 micrograms/kg. The higher doses were significantly faster (60 micrograms/kg p less than 0.05, 80 micrograms/kg p less than 0.01) and took 15.8 and 14.8 minutes respectively. Reversal to a train of four ratio of 0.75 was not consistently achieved in under 30 minutes with any dose of neostigmine. Nineteen patients were antagonised from a 67%-80% depression of first twitch and in all but two recovery to 95% of control took under 10 minutes. To achieve a train of four ratio of 0.75 took less than 12.5 minutes except in three patients, two of whom, both given neostigmine 30 micrograms/kg, took longer than 20 minutes. Neostigmine 60 micrograms/kg produced as rapid a degree of antagonism as 80 micrograms/kg. Heart rates after reversal decreased gradually in all groups, although the decrease was initially greater in the low dose neostigmine (30 micrograms/kg) group. A fixed 5:1 ratio of neostigmine and glycopyrronium will usually antagonise a moderate (70%-80%) pancuronium block to a train of four of greater than 75% within 12.5 minutes if at least 60 micrograms/kg of neostigmine is administered. More than 30 minutes may be required for reversal whatever the dose of neostigmine, for antagonism from greater than 90% twitch depression.
Adolescent↗
Management of cancer pain with oral controlled-release morphine sulfate.
Morphine sulfate Contin (MSC) is an investigational matrix delivery system for oral morphine sulfate that allows for prolonged blood levels of morphine. Twenty-six patients with inadequately controlled cancer-related pain were examined in an open but controlled study using MSC. Initially, all patients were converted from the prestudy analgesic regimen to an equianalgesic amount of immediate-release morphine sulfate (IRMS) on a q4h dose schedule that was in turn titrated to the level of adequate pain relief. Patients then were switched to MSC q8h and eventually to q12h, starting at doses representing the same total daily amount of morphine that was in the final IRMS dose. Of the 18 patients who completed the study, all achieved satisfactory levels of analgesia on MSC, seven at q8h and 11 at q12h dosing intervals. All patients reported better analgesia while taking MSC compared with their previous regimen. Side effects associated with MSC included sedation and constipation but not nausea or respiratory difficulty. Significant drug tolerance did not develop during a mean follow-up period of four weeks (range, 1-18 weeks). MSC is an effective oral opioid analgesic that allows an increased dose interval without increased side effects or decreased potency. It can improve the quality of life of cancer patients by allowing them to be maintained without frequent dosing or parenteral medication.
Administration, Oral↗
Controlled-release oral morphine sulfate in the treatment of cancer pain with pharmacokinetic correlation.
The bioavailability and clinical effects of an oral controlled-release morphine sulfate tablet, MS-contin (MSC; Purdue-Frederick, Norwalk, CT) in comparison to an immediate-release (IRMS) preparation were evaluated in normal subjects and cancer patients, respectively. The inherent slow-release character of MSC was confirmed by 2 1/2 X T1/2 absorption rate, one-half Cmax, and twice Tmax relative to IRMS. The T1/2 elimination of the two morphine preparations was similar, demonstrating insignificant risk of MSC accumulation. The difference in the mean number of side effects experienced by the control group per subject was significant (.70 for MSC and 1.26 for IRMS, P = .05) and was consistent with peak plasma morphine attenuation. The cancer patients were initially switched from their previous analgesic to four hourly IRMS and then to MSC at double the dose every eight hours. The majority had their MSC dosing interval lengthened to every 12 hours with a decrease in the total daily morphine requirement. While the mean duration on MSC was 20.5 days, many patients were followed poststudy for an extended period with no appreciable development of tolerance. Overall, MSC analgesia and side effects were perceived by the patients as superior compared with prestudy opioids. The advantage of less frequent dosing may lead to improvement of the quality of life of cancer patients.
Adult↗
Clinical relaxation: current controversy.
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Androstane-3,17-diol↗
Clinical pharmacology of atracurium given in high dose.
The safety and efficacy of atracurium 0.8 mg kg-1 was determined in healthy patients with particular attention to the speed of onset of blockade, and to changes in haemodynamic variables. Atracurium 0.8 mg kg-1 had a shorter onset time than atracurium 0.5 mg kg-1, and satisfactory intubating conditions were achieved earlier. "Priming" produced no significant improvement in onset time or intubating conditions. Onset times were significantly shorter with nitrous oxide-opioid anaesthesia than following thiopentone alone. Although a 0.8-mg kg-1 bolus resulted in a significant reduction in mean arterial pressure to 75% of control and was associated with a significant increase in plasma histamine concentrations, this response could be prevented by injecting the drug over 75 s. "Priming" or a 30-s injection produced no haemodynamic protection. The protection achieved by pretreatment with anti-histamines was incomplete: mean arterial pressure decreased to 83% of control.
Adolescent↗
Pharmacokinetics and pharmacodynamics of atracurium during isoflurane anesthesia in normal and anephric patients.
We compared the pharmacokinetics and pharmacodynamics of atracurium in eight normal and eight anephric patients during isoflurane anesthesia. Plasma concentrations were measured by high performance liquid chromatography after a single injection of 0.5 mg/kg, and neuromuscular effects were evaluated by the single twitch method. With regard to pharmacokinetic or pharmacodynamic parameters, we found no statistically significant differences between normal and anephric patients. We conclude that during isoflurane anesthesia, anephric patients distribute and eliminate atracurium much as normal patients do.
Anesthesia, General↗
Atracurium: clinical strategies for preventing histamine release and attenuating the haemodynamic response.
This study was designed to determine the effects of a rapid bolus dose of atracurium 0.6 mg kg-1 on arterial pressure, heart rate and plasma histamine concentration (n = 9), and to compare these values with those obtained by (a) giving the same dose of atracurium slowly (over 75 s) (n = 9), or (b) pre-treating with H1- and H2- antagonists (n = 9). The rapid (5-s) bolus dose of atracurium i.v. resulted in a significant increase in plasma histamine concentration (P less than 0.05) and was associated with a decrease in mean arterial pressure and an increase in heart rate. Administering the same dose of atracurium slowly (over 75 s) prevented the increase in plasma histamine concentration, and abolished the subsequent haemodynamic response. Pretreatment with cimetidine 4 mg kg-1 i.v. and chlorpheniramine 0.1 mg kg-1 i.v. abolished the haemodynamic response despite a moderate increase in histamine concentration (0.1 greater than P greater than 0.05).
Adolescent↗