[Clinical study of the calbogen-succinylcholine as a muscle relaxant].
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Adjuvants, Anesthesia↗
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New muscle relaxants in outpatient anesthesiology.
The ideal neuromuscular blocking drug for dental and other outpatient procedures would be nondepolarizing (therefore reversible), highly potent, have a rapid onset and short duration of action, be highly specific for the nicotinic acetylcholine receptor, be eliminated independently of renal or hepatic metabolism, and have minimal side effects such as tachycardia and histamine release. The newer neuromuscular blocking drugs vecuronium and atracurium approach this ideal much more closely than the older drugs curare, metocurine, and gallamine. Aside from considerations of slightly higher cost, the neuromuscular blocking agents of choice remain succinylcholine for rapid, short-lived paralysis, vecuronium and atracurium for relaxation of 15- to 60-minute duration and when cardiovascular stability is vital, and pancuronium for longer surgical procedures. Vecuronium and atracurium have achieved and will continue to achieve predominance in the anesthetic management of the short-procedure patient.
Anesthesia, Dental↗
Pituitary adenylate cyclase-activating peptide (PACAP), a VIP-like peptide, has prolonged airway smooth muscle relaxant activity.
Pituitary adenylate cyclase-activating peptide (PACAP), a widely distributed peptide belonging to the vasoactive intestinal peptide (VIP) family of peptides, stimulates the accumulation of cyclic adenosine monophosphate (cAMP) in many tissues, with greater potency and efficacy than VIP. We report that PACAP-38 was one-third as potent and 70% as efficacious as VIP in producing relaxation of isolated perifused guinea pig strips, although it was approximately twice as effective in stimulating cAMP accumulation. The PACAP-38-induced relaxation, however, was five to eight times as prolonged as that of VIP, and its cAMP stimulation was also more sustained. The prolonged action of PACAP-38 is probably due to its greater resistance to enzymatic degradation. The data suggest that airway relaxation is not solely dependent on the total content of cAMP in airways. PACAP-38 exhibits properties that may be useful in the management of airway constriction.
Adenylyl Cyclases↗
[Repeated injection of atracurium for muscle relaxation in abdominal surgery].
21 patients selected for abdominal surgery received intravenously after initiation of neuroleptic analgesia for intubation, 0.5 mg/kg body weight (BW) of atracurium. Relaxation was maintained by repeat doses of 0.2 mg/kg BW atracurium. Both the time of intubation and the time of giving the repeat dose depended on the electromyographically measured stimulus response to supramaximal stimulation of the ulnar nerve (Datex-NTM, "Train-of-Four" stimulation). Intubation was effected at maximal inhibition of stimulus response, on the average after 195 +/- 90 sec. The duration of clinical efficacy was 33 +/- 8 min on the average, the recovery index 13 +/- 7 min and the duration of the full effect 54 +/- 6 min. The repeat doses were administered as soon as stimulus response recovered to 25% of the original value. Up to a cumulative total dose of 1.5 mg/kg BW atracurium no extension of the duration of clinical efficacy and of the full effect was seen, but there was a prolongation of the recovery index. The "Train-of-Four" quotient during recovery of relaxation was independent of the cumulative total dose. In the dosage levels described here, atracurium hardly exercised any action on pulse rate and blood pressure.
Abdomen↗
Inspiratory pressure support reduces slowing of inspiratory muscle relaxation rate during exhaustive treadmill walking in severe COPD.
When patients with COPD walk to a state of intolerable dyspnea, there is excessive inspiratory muscle loading, as evidenced by slowing of the maximum relaxation rate of the inspiratory muscles, measured from esophageal pressure during a sniff (Sn Pes MRR). In this setting, inspiratory pressure support (IPS) delivered via an orofacial mask increases walking distance and reduces dyspnea, but the mechanism by which this benefit is achieved remains unclear. In this study we compared Sn Pes MRR after equidistant treadmill walking in six men with severe COPD (mean FEV1: 0.6 L, 22% predicted). After the free walk there was a mean slowing of Sn Pes MRR of 41% (p < 0.03). After the IPS-assisted walks, the slowing of Sn Pes MRR was 20% of baseline; this was significantly less than after the free walk (p < 0.05). Four subjects performed shorter walks; after free walks of one third and two thirds of maximum distance, the mean slowing of Sn Pes MRR was 23% and 28%, respectively. We conclude that when patients with COPD walk to exhaustion, IPS reduces slowing of inspiratory muscle MRR, and that this represents a considerable unloading of the inspiratory muscles. The magnitude of the reduction is approximately the same as reducing the distance walked by two thirds.
Aged↗
Overdose of cyclobenzaprine, the tricyclic muscle relaxant.
A case of cyclobenzaprine (Flexeril) overdose in a 31-year-old woman is presented. The treatment rendered was analogous to treatment protocols implemented for tricyclic overdose. A review of the pharmacology of cyclobenzaprine, as well as the management of patients who overdose on this drug, is presented.
Adult↗
Liver tumours and muscle relaxants. Electromyographic studies in children.
Electromyographic studies of the onset of action of tubocurarine or alcuronium were performed on eight occasions in five patients who had liver masses. There was a slow onset of action and an increased dose requirement in those with malignant disease. Normal responses were found in a patient with benign nodular hyperplasia and in another where the malignant tumour was successfully treated with chemotherapy.
Alcuronium↗
[Influence of verapamil and diltiazem on the muscle-relaxing effect of atracurium in vivo].
The interaction between atracurium and the two calcium antagonists verapamil and diltiazem were studied in rabbits. It was observed that intravenous verapamil (0.2 mg/kg) reduced by 25% and 30% respectively, the dose of atracurium required to produce a 50% or 95% of neuromuscular blockade. In contrast, intravenous diltiazem (1 mg/kg) failed to produce significant changes.
Animals↗
Plasma beta-endorphin concentrations and analgesia-muscle relaxation in the newborn infant supported by mechanical ventilation.
We evaluated the effects of pancuronium and opiates on plasma beta-endorphin concentrations in 25 infants supported by mechanical ventilation. Infants receiving opiate were randomly assigned to receive either fentanyl or morphine. There was no change in beta-endorphin concentrations after administration of pancuronium, whereas both fentanyl and morphine reduced beta-endorphin concentrations by approximately 60%.
Female↗
A non-nitrergic smooth muscle relaxant factor released from rat urinary bladder by muscarinic receptor stimulation.
PURPOSE: To study the possible release of a relaxant factor from isolated rat bladder tissue. MATERIALS AND METHODS: Thoracic aortae and urinary bladders were obtained from 55 female Sprague-Dawley rats. The bladder body was used in its original tubular shape as the donor tissue in a co-axial bioassay system, and the aorta served as acceptor tissue. RESULTS: In a co-axial bioassay system with endothelium-free, norepinephrine-contracted, rat aortic preparations mounted within urothelium-intact urinary bladder, carbachol caused a concentration-dependent relaxation, amounting to 64+/-7% (n = 10) of the induced contraction, suggesting release of a relaxing factor. The relaxant effect of carbachol was lost if the urinary bladder segment was removed. However, the relaxation was affected neither by removal of the urothelium, nor by bladder segment inversion. It was resistant to inhibition of the L-arginine/nitric oxide and cyclo-oxygenase pathways, and unaffected by beta-adrenoceptor blockade and K+ channel inhibition. The relaxation was not associated with any significant changes in the intracellular levels of cGMP or cAMP. CONCLUSION: A previously unrecognized non-adrenergic, non-nitrergic, non-prostanoid inhibitory mediator is released from the rat urinary bladder by muscarinic receptor stimulation. The physiological importance of such a factor remains to be established.
Animals↗
The effects of propofol, isoflurane and sevoflurane on vecuronium infusion rates for surgical muscle relaxation in dogs.
OBJECTIVE: To compare the constant rate infusion (CRI) of vecuronium required to maintain a level of neuromuscular blockade adequate for major surgeries, e.g. thoracotomy or laparotomy, in dogs anaesthetized with a CRI of fentanyl and either propofol, isoflurane or sevoflurane. STUDY DESIGN: Prospective, randomized, cross-over study. ANIMALS: Thirteen male beagles (age, 9-22 months; body mass 6.3-11.3 kg). MATERIALS AND METHODS: Dogs were anaesthetized with propofol (24 mg kg(-1) hour(-1) IV CRI; group P), isoflurane (1.3% end-tidal concentration; group I) or sevoflurane (2.3% end-tidal concentration; group S) with fentanyl (5 microg kg(-1) hour(-1) IV, CRI). Sixty to seventy minutes after induction of anaesthesia, vecuronium was administered at a rate of 0.4, 0.3 and 0.2 mg kg(-1) hour(-1) in groups P, I and S respectively. To determine the degree of neuromuscular block, a peripheral nerve was stimulated electrically using the train-of-four (TO4) stimulus pattern. Evoked muscle contractions were evaluated using a neuromuscular monitoring device. Once the TO4 ratio reached 0, the continuous infusion rate was decreased and adjusted to maintain a TO4 count of 1. Continuous infusion was continued for 2 hours. The infusion rate of vecuronium was recorded 20, 40, 60, 80, 100 and 120 minutes after the start of infusion. RESULTS: The mean continuous infusion rates of vecuronium during stable infusion were 0.22 +/- 0.04 (mean +/- SD), 0.10 +/- 0.02 and 0.09 +/- 0.02 mg kg(-1) hour(-1) in groups P, I and S respectively. There were statistically significant differences between the rates in groups P and I and between the rates in groups P and S. Conclusions and clinical relevance In healthy dogs, the recommended maintenance infusion rate of vecuronium is 0.2 mg kg(-1) hour(-1) under CRI propofol-fentanyl anaesthesia and 0.1 mg kg(-1) hour(-1) during CRI fentanyl-isoflurane or sevoflurane anaesthesia.
Anesthesia, General↗
Muscle relaxation with an infusion of vecuronium.
Vecuronium was administered by a continuous intravenous infusion following a bolus dose of 0.1 mg kg-1 in 10 patients. Following recovery of twitch height to 10% of control, steady state dose requirement for maintaining a 90% block was attained in an average of 15.4 min. The average dose required was 0.083 mg kg-1 h-1 or 3.27 mg m-2 h-1. Large individual variations were observed but each patient required an approximately constant dose over periods up to 4.5 h. Recovery was prompt following cessation of infusion.
Adult↗
Estimation of the analgesic muscle relaxants chlorzoxazone and diazepam in human plasma by reversed-phase liquid chromatography.
A rapid and sensitive method of extraction of human plasma containing acetaminophen, chlorzoxazone, oxyphenbutazone and diazepam along with their active metabolites was developed. The plasma samples were extracted by a solid-phase extraction procedure with theophylline as an internal standard for accurate quantitation. The reversed-phase liquid chromatographic method provided a linear ultraviolet detector response in the range 100.0-700.0 ng/ml. Recoveries greater than 95% were achieved from human plasma samples. Limits of detection of 100, 200, 150 and 250 ng/ml for acetaminophen, chlorzoxazone, oxyphenbutazone and diazepam, respectively, were obtained.
Acetaminophen↗
Rocuronium for muscle relaxation in two children with Friedreich's ataxia.
Friedreich's ataxia is a rare hereditary neurodegenerative disease caused by a defect in the gene that encodes a mitochondrial protein called frataxin. We report the use of rocuronium 0.6 mg kg(-1) in two adolescent girls with Friedreich's ataxia undergoing propofol-sufentanil-oxygen-air anaesthesia for spinal surgery. Neuromuscular transmission was monitored using acceleromyography, and onset and recovery times were recorded. The clinical duration of rocuronium was comparable to that of children without neuromuscular disease (25% recovery T(1)=44 and 24 min for patients 1 and 2 respectively).
Adolescent↗
Clinical pharmacology of muscle relaxants in patients with burns.
Pathophysiologic changes accompanying burn trauma can alter the pharmacokinetics and pharmacodynamic responses to neuromuscular relaxants. Pathophysiologic changes that can potentially affect kinetics in the hypermetabolic phase of burn injury include increased hepatic blood flow, increased glomerular filtration, and increased protein binding. Except for D-tubocurarine, the pharmacokinetics of neuromuscular relaxants relative to burn trauma have not been studied. The unbound volume of distribution, clearance, and half-life of D-tubocurarine were not significantly different from controls, but the plasma binding and renal elimination at 24 hours was increased in burn patients. The aberrant pharmacodynamic responses to neuromuscular relaxants in burn patients include the potential for lethal hyperkalemia with the administration of depolarizing relaxant, succinylcholine, and a 2.5- to 5.0-fold increase in the dose or plasma concentration requirement for nondepolarizing relaxant, including D-tubocurarine, metocurine, pancuronium, and atracurium. The altered pharmacodynamic responses are probably related to an increase in nicotinic acetylcholine receptor number. An alternative to succinylcholine to produce rapid-onset neuromuscular paralysis include the administration of 3XED95 doses of pancuronium and metocurine in combination (but recovery from paralysis is prolonged). Vecuronium and atracurium have good cardiovascular stability and faster recovery times even in high dosages in healthy patients, but the pharmacokinetics and pharmacodynamics of these drugs in patients with burns have not been fully characterized.
Burns↗
[Important pharmaceutical-chemical characteristics of the central muscle relaxant chlormezanone].
The enantinomers of chlormezanone (1) may be achieved by enantioselective HPLC separation with a yield of 98% using a OD-Daicel column. Both enantiomers bind to human serum albumin (HSA) at pH 7.4 to a range of 11-12%. Binding to the globuline fractions is much less (2-4%, equilibrium dialysis, validation by ultrafiltration). It could be demonstrated by means of 1H-NMR spectroscopy that 1 binds to HSA with the benzene ring as well as with the thiazanone ring. The velocity of racemization could be measured for the first time using a BSA column. The enantiomers undergo racemization at pH 7.4 and 37 degrees C with a halflife of approx. 20.5 h.
Chlormezanone↗
[Effects of tizanidine, a central muscle relaxant, upon spinal reflexes].
Effects of intravenous administration of tizanidine upon spinal reflexes were studied in cats anesthetized with urethane-chloralose. Both extensor and flexor monosynaptic reflexes and polysynaptic flexor reflex were inhibited by intravenous administration of tizanidine in a dose of 10-50 micrograms.kg-1. The inhibition was dose-dependent. After strychnine administration, polysynaptic flexor reflex was augmented, but the inhibition by tizanidine administration was unaffected. In spinal cats, inhibitory effect of tizanidine upon monosynaptic reflex was weaker than in intact cats. Viscero-intercostal reflex elicited by electrical stimulation of A delta afferent fibers in the greater splanchnic nerve was also inhibited by intravenous tizanidine (25 micrograms.kg-1). The degree of inhibition decreased in parallel with increase in the intensity of stimulus applied to the greater splanchnic nerve.
Animals↗
Stereochemical study of tolperisone, a muscle relaxant agent, by circular dichroism and ultraviolet spectroscopy.
The stereochemistry of tolperisone, a chiral aryl-alkyl basic ketone was investigated by means of circular dichroism (CD) and ultraviolet (UV) spectroscopy. The unusually high optical activity of tolperisone hydrochloride in the n-->pi* region is interpreted by the presence of a chiral conformer in solution. For stereochemical reasons, the C = O group and the aromatic moiety lack coplanarity by forming an inherently dissymetric chromophore, of M helicity. Similar helicity prevails in the crystal phase, according to the solid-state CD spectrum of (-)-tolperisone HCl salt. The chirality rule proposed by Snatzke for nonplanar benzoyl chromophores predicts the absolute configuration of (-)-tolperisone hydrochloride to be R, in agreement with other alpha-methyl-beta-amino-ketones.
Circular Dichroism↗