Advantages of glycopyrrolate over atropine during reversal of pancuronium block

The effects of acetylcholinesterase inhibitors on morbidity after general anesthesia and surgery

Non-depolarizing neuromuscular blocking agents are used during general anesthesia to facilitate intubation and optimize surgical conditions. When patients leave the operating room after surgery, postoperative residual neuromuscular block occurs frequently, increasing vulnerability to respiratory complications such as hypoxemia and unplanned postoperative mechanical ventilation. To restore neuromuscular transmission and skeletal muscle strength, anesthesiologists typically administer peripherally acting acetylcholinesterase inhibitors such as neostigmine. However, neostigmine's desirable effects have a narrow therapeutic range. Even at recommended dose (15-50 μg/kg), neostigmine induces nicotinic (upper airway muscle weakness leading to dysphagia and upper airway obstruction, and decreased maximum inspiratory airflow) and muscarinic (blurred vision, bronchial constriction, abdominal cramping and nausea) side effects. Recent data have questioned as to whether neostigmine reversal of neuromuscular blockade improves relevant patient outcomes such as postoperative respiratory and perioperative cardiovascular complications. A central strategy to avoid side effects of neuromuscular blocking agents is their judicious use based on quantitative monitoring of neuromuscular transmission using repetitive peripheral nerve stimulation (train-of-four ratio). Peripherally acting acetylcholinesterase inhibitors such as neostigmine should then only be administered when indicated and dosed based on results of the train-of-four ratio.

Effects of Anticholinesterase Reversal Under General Anesthesia on Postoperative Cardiovascular Complications: A Retrospective Cohort Study

BACKGROUND

The anticholinesterase neostigmine and the muscarinic inhibitor glycopyrrolate are frequently coadministered for the reversal of neuromuscular blockade. This practice can precipitate severe bradycardia or tachycardia, but whether it affects the incidence of cardiovascular complications remains unclear. We hypothesized that anticholinesterase reversal with neostigmine and glycopyrrolate versus no anticholinesterase reversal increases the risk of postoperative cardiovascular complications among adult patients undergoing noncardiac surgery with general anesthesia.

METHODS

We conducted a prespecified retrospective analysis of hospital registry data from a major health care network for patients undergoing surgery with general anesthesia from January 2007 to December 2015. The primary outcome was a composite of cardiac dysrhythmia, acute heart failure, transient ischemic attack, ischemic stroke, and acute myocardial infarction within 30 days after surgery. We performed sensitivity analyses in subgroups and propensity score adjustment and explored the association between exposure and outcome in subgroups of patients with high risk of cardiovascular complications.

RESULTS

Of the 98,147 cases receiving neuromuscular blockade, 73,181 (74.6%) received neostigmine and glycopyrrolate, while 24,966 (25.4%) did not. A total of 5612 patients (7.7%) in the anticholinesterase reversal group and 1651 (6.6%) in the control group (P < .001) experienced the primary outcome. After adjustment for clinical covariates, neostigmine and glycopyrrolate exposure was significantly associated in a dose-dependent fashion (P for trend <.001, respectively) with tachycardia (adjusted odds ratio = 2.1 [95% CI, 1.97-2.23]; P < .001) and bradycardia (adjusted odds ratio = 2.84 [95% CI, 2.49-3.24]; P < .001) but not with postoperative cardiovascular complications (adjusted odds ratio = 1.03 [95% CI, 0.97-1.1]; P = .33). We identified a significant effect modification of anticholinesterase reversal by high age, high-risk surgery, and history of atrial fibrillation (P for interaction = .002, .001, and .02, respectively). By using linear combinations of main effect and exposure-risk interaction terms, we detected significant associations between anticholinesterase reversal and cardiovascular complications toward a higher vulnerability in these patient subgroups.

CONCLUSIONS

Neuromuscular blockade reversal with neostigmine and glycopyrrolate was associated with an increased incidence of intraoperative tachycardia and bradycardia but not with 30-day postoperative cardiovascular complications. Exploratory analyses suggest that a high postoperative cardiovascular complication risk profile may modify the effects of anticholinesterase reversal toward clinical relevance.

Pharmacokinetics and related pharmacodynamics of anticholinergic drugs

The pharmacokinetics and some pharmacodynamic properties of atropine, glycopyrrolate and scopolamine are reviewed. With the development of new analytical methods for drug determination, it is now possible to measure relatively low concentrations of these drugs in biological fluids and, consequently, some new kinetic data have been collected. Following intravenous administration, a fast disappearance from the circulation is observed and due to a high total clearance value their elimination phase half-lives vary from 1 to 4 h. All these agents are nonselective muscarinic receptor antagonists, but their actions on various organ systems with cholinergic innervation show considerable diversity. The cardiovascular effects are of short duration; other peripheral muscarinic effects and CNS effects can last up to 8 h or even longer. Differing from atropine and scopolamine, glycopyrrolate as a quaternary amine penetrates the biological membranes (blood-CNS, placental barriers) slowly and incompletely, making it the drug of choice for elderly patients with coexisting diseases and for obstetric use. Similarly, its oral absorption is slow and erratic, and hence it cannot be used as an oral premedicant. Atropine, scopolamine and glycopyrrolate have a definitely faster absorption rate, when injected into the deltoid muscle compared with administration into the gluteal or vastus lateralis muscles. There appear to be significant differences in the metabolism and renal excretion of these agents. Scopolamine is apparently excreted into the urine mainly as inactive metabolites, nearly half of the atropine dose administered is recovered in the urine as the parent drug or as active metabolites and about 80% of glycopyrrolate is excreted as unchanged drug or active metabolites.(ABSTRACT TRUNCATED AT 250 WORDS)

Glycopyrrolate vs. atropine during anaesthesia for laryngoscopy and bronchoscopy

As glycopyrrolate has been reported superior to atropine with respect to reduction of salivation, stability of cardiac rate and rhythm, and recovery, a comparison of these properties of the two drugs and placebo was made in 45 patients undergoing direct laryngoscopy and 45 patients undergoing bronchoscopy, in most cases followed by mediastinoscopy. When given i.m. 30 min before anesthesia (midazolam, alfentanil, thiopentone, and suxamethonium), the two test drugs were found to be equally potent regarding the antisialogogic effect. The same increase in heart rate after the test drugs was seen before induction, and during anaesthesia heart rate rose to the same level in the placebo group as the test groups. During anaesthesia, blood pressure was lowest in the atropine group. No differences could be demonstrated with respect to cardiac arrhythmias, possibly due to the small size of the material. The present study gives no reason for preferring either drug, and only the efficacy of both test drugs in controlling airway secretions provides an argument for using any anticholinergic drug when laryngoscopy or bronchoscopy is performed under the conditions of the present study.

Do anticholinergic agents affect the occurrence of postanaesthetic nausea?

In order to establish if anticholinergic drugs might influence postoperative nausea and vomiting, 100 ASA I-II adult patients scheduled for minor orthopaedic procedures, varicose vein stripping or inguinal herniorraphy were randomised to receive, in a double-blind fashion, either a premedicant and a reversal dose of 0.003 and 0.0075 mg/kg of glycopyrrolate or 0.006 and 0.015 mg/kg of atropine, respectively. Nitrous oxide, after thiopentone induction was used for anaesthesia with fentanyl and diazepam as supplements and pancuronium for relaxation. In the recovery room, up to 2 h after surgery, 28% of the patients in the glycopyrrolate group and 8% in the atropine group experienced nausea (P = 0.017). Thereafter, the patients complained of nausea at decreased and equal frequencies in both groups. The incidence of vomiting was not statistically significantly different. Droperidol was needed, to control persistent emesis, three times more often in the glycopyrrolate than in the atropine group. It is concluded that substitution of glycopyrrolate for atropine increases the likelihood of postoperative nausea, and continued use of atropine should be considered in patients at risk of postoperative emesis.

Cardiovascular changes at antagonism of atracurium. Effects of different doses of premixed neostigmine and glycopyrronium in a ratio of 5:1

The cardiovascular changes in the 10 minutes following antagonism of an atracurium-induced block were studied in 32 patients. A 5:1 ratio combination of either 15, 35, 55 or 75 micrograms/kg neostigmine, with a corresponding dose of 3, 7, 11, or 15 micrograms/kg of glycopyrronium was used for antagonism. The least change in heart rate was with neostigmine 15 micrograms/kg with an increase of more than 15 beats/minute found in only one patient. Antagonism with 35, 55 and 75 micrograms/kg neostigmine mixture produced the greatest increase in heart rate at one minute and this was significantly different from the effect of the 15 micrograms/kg dose. Twenty out of 24 patients given the larger doses had heart rate increases in excess of 15 beats/minute and in nine patients this ranged from 30 to 52 beats/minute, representing increases of 46-80% above baseline values. Arterial pressure increases after antagonism were statistically significant in all four groups, with no between-group difference; these were clinically unimportant. When antagonising an atracurium-induced block with clinically useful doses of neostigmine, the standard 5 : 1 ratio combination with glycopyrronium will result in an initial tachycardia.

Split-dose atropine versus glycopyrrolate with neostigmine for reversal of gallamine-induced neuromuscular blockade

The effects of a split-dose of atropine sulphate versus a single dose of glycopyrrolate given with neostigmine for the reversal of gallamine-induced neuromuscular blockade were studied in 55 patients undergoing gynaecological surgery. The patients were randomized to receive either a single dose of glycopyrrolate (7 micrograms.kg-1) or two doses of atropine (8 micrograms.kg-1 each), given with an interval of 1 min. There were no differences between the two methods with respect to percentage heart rate changes, salivation or arousal time. Four patients demonstrated cardiac arhythmias in the atropine group, whereas none occurred in the glycopyrrolate group (P less than 0.05). It is concluded that a split-dose of atropine has similar chronotropic effects to a single dose of glycopyrrolate for the reversal of gallamine-induced neuromuscular blockade. However, the finding of a higher incidence of cardiac arrhythmias in the atropine group suggests that this reversal regime should be reserved for patients without cardiac disease.

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.

Glycopyrrolate compared with atropine in association with ketamine anaesthesia

Atropine and glycopyrrolate given intravenously before the induction of a ketamine anaesthesia to diminish salivary secretion were compared for their effect on psychotomimetic side-effects, awakening time and heart rate. Though atropine is a tertiary amine that crosses the blood-brain barrier, which glycopyrrolate as a quaternary ammonium compound does not, it did not increase the incidence of psychotomimetic side-effects nor did it significantly prolong the awakening time after ketamine anaesthesia. During intubation the increase in heart rate was significantly higher following atropine than following glycopyrrolate.

Glycopyrrolate during ketamine/diazepam anaesthesia. A double-blind comparison with atropine

In a double-blind study, the effects of atropine and glycopyrrolate (dosage ratio 2:1) following i.m. and i.v. administration were compared with respect to salivation, heart rate, and blood pressure before, during and after i.v. infusion anaesthesia with ketamine and diazepam for alloplastic hip or knee surgery in 30 patients above the age of 50 years. Given with the premedicant, the two drugs were equally effective in reducing salivation. A slight increase in heart rate was seen after atropine only (P less than 0.005). Increases in heart rate and blood pressure during induction of anaesthesia were similar in the two groups. A second dose of the test drug was given with neostigmine for reversal of neuromuscular blockade. Again, there were no statistically significant differences with respect to salivation, blood pressure, heart rate, nausea and/or vomiting, unpleasant dreams and arousal time.

Comparison of atropine and glycopyrronium in patients with pre-existing cardiac disease

The effects of atropine and glycopyrronium, when given intravenously with neostigmine during the reversal of neuromuscular blockade in patients with cardiovascular disease, were compared in a double blind trial. Atropine was associated with a significantly greater elevation of heart rate and rate-pressure product than glycopyrronium. This elevation was also more sustained with atropine. The entire atropine population also showed a significantly greater incidence of ST-segment depression on the electrocardiogram than that observed in those who had received glycopyrronium. Furthermore, patients with ischaemic heart disease and previous myocardial infarction who received atropine showed a significantly greater incidence of dysrhythmias than those given glycopyrronium. It is suggested that at the time of reversal of neuromuscular blockade in patients with cardiovascular disease, glycopyrronium is a more suitable agent than atropine.

Prevention of neostigmine-induced colonic activity. A comparison of atropine and glycopyrronium

Colonic intraluminal pressure was recorded in eight patients receiving either atropine 1.2 mg (n = 4) or glycopyrronium 0.6 mg (n = 4) intravenously in a randomised, double-blind fashion and followed after 5 minutes by neostigmine 2.5 mg. Estimations of total colonic activity were made from the area under the recording of intraluminal pressure. There were no significant differences in mean intraluminal pressures or total colonic activity between the two groups. It is concluded that glycopyrronium offers no advantage over atropine with respect to protection of the bowel against the effects of neostigmine.

Antagonism of d-tubocurarine-induced neuromuscular blockade with a mixture of 4-aminopyridine and neostigmine in man

The antagonistic properties of a mixture of 4-aminopyridine (4-AP) 3 mg X ml-1 and neostigmine 0.2 mg X ml-1 (in three patient groups) administered at 90 per cent d-tubocurarine block were compared with those of plain neostigmine (in three patient groups) in thirty-six patients during thiopentone-fentanyl-nitrous oxide-oxygen anaesthesia. The recovery variables included thumb twitch height, thenar e.m.g. peak-to-peak amplitude, and train-of-four ratio in response to supramaximal ulnar nerve stimulation. In addition, mean arterial pressure, heart rate, apnoea time and time to responsiveness to verbal command after nitrous oxide was turned off at 20 minutes of recovery were examined as circulatory and central nervous system responses to antagonism. The addition of 4-AP 30 mg to neostigmine 2 mg enhanced the recovery of train-of-four ratio from 54.2 +/- 5.2 to 80.2 +/- 5.2 per cent at 20 mins of antagonism (mean +/- SEM; p less than 0.01) while adding 4-AP 45 mg to neostigmine 3 mg increased the train-of-four ratio from 67.7 +/- 2.3 to 92.3 +/- 2.4 per cent (p less than 0.01) when compared with plain neostigmine. No statistically significant difference could be found between the groups in the recovery of twitch height or e.m.g. amplitude. The antagonism of d-tubocurarine block with 4-AP 30 mg plus neostigmine 2 mg was at least as effective as with neostigmine 3-4 mg. Mean arterial pressure increased in the group receiving 45 mg 4-AP plus 3 mg neostigmine.(ABSTRACT TRUNCATED AT 250 WORDS)

Atropine vs glycopyrrolate during reversal of pancuronium block in patients anaesthetized with halothane

Atropine 0.015 mg kg-1 and glycopyrrolate 0.0075 mg kg-1 were compared as antimuscarinic agents during reversal of pancuronium block with neostigmine 0.03 mg kg-1 in 30 patients anaesthetized with thiopental-N2O-halothane and undergoing minor surgery. In patients treated with atropine-neostigmine, the frequencies of bradycardia and junctional rhythm were relatively high and about the same as those reported by us previously in patients anaesthetized with thiopental-N2O-fentanyl. As in our previous study, glycopyrrolate seemed to have advantages over atropine during reversal of pancuronium block: the incidences of bradycardia and junctional rhythm were significantly less in patients treated with glycopyrrolate. Recovery from anaesthesia, as assessed by the awakening after discontinuation of N2O and halothane administration, and the incidence of postoperative nausea and vomiting, were not significantly different between the atropine and glycopyrrolate groups.

Glycopyrrolate: pharmacology and clinical use

This is a review of glycopyrrolate whose function in clinical practice is compared with that of atropine.