The evolution of spinal/epidural neostigmine in clinical application: Thoughts after two decades

New advances in clinical application of neostigmine: no longer focusing solely on increasing skeletal muscle strength

Neostigmine is a clinical cholinesterase inhibitor, that is, commonly used to enhance the function of the cholinergic neuromuscular junction. Recent studies have shown that neostigmine regulates the immune-inflammatory response through the cholinergic anti-inflammatory pathway, affecting perioperative neurocognitive function. This article reviews the relevant research evidence over the past 20 years, intending to provide new perspectives and strategies for the clinical application of neostigmine.

The Options for Neuraxial Drug Administration

Neuraxial drug administration, i.e., the injection of drugs into the epidural or intrathecal space to produce anesthesia or analgesia, is a technique developed more than 120 years ago. Today, it still is widely used in daily practice in anesthesiology and in acute and chronic pain therapy. A multitude of different drugs have been introduced for neuraxial injection, only a part of which have obtained official approval for that indication. A broad understanding of the pharmacology of those agents is essential to the clinician to utilize them in a safe and efficient manner. In the present narrative review, we summarize current knowledge on neuraxial anatomy relevant to clinical practice, including pediatric anatomy. Then, we delineate the general pharmacology of neuraxial drug administration, with particular attention to specific aspects of epidural and intrathecal pharmacokinetics and pharmacodynamics. Furthermore, we describe the most common clinical indications for neuraxial drug administration, including the perioperative setting, obstetrics, and chronic pain. Then, we discuss possible neurotoxic effects of neuraxial drugs, and moreover, we detail the specific properties of the most commonly used neuraxial drugs that are relevant to clinicians who employ epidural or intrathecal drug administration, in order to ensure adequate treatment and patient safety in these techniques. Finally, we give a brief overview on new developments in neuraxial drug therapy.

Antinociceptive action of Achillea biebersteinii methanolic flower extract is mediated by interaction with cholinergic receptor in mouse pain models

Achillea biebersteinii is a perennial aromatic herb that grows in the Mediterranean area. The leaves of this plant are used in foods as bittering and appetizing agents. In folk medicine, it is used for the treatment of stomachache and abdominal pain. In this study, the analgesic effect of A. biebersteinii methanolic flower extract was tested in three pain models, namely: writhing, tail-flick and paw-licking (formalin) tests. A. biebersteinii extract inhibited abdominal cramps produced by acetic acid. The effect of A. biebersteinii was better than that of 70 mg/kg indomethacin. In tail flick, A. biebersteinii extract increased latency at 30 min and was as effective as 100 mg/kg diclofenac sodium. In formalin test, A. biebersteinii extracts decreased paw-licking and flinching response in early and late phases. Atropine blocked the action of A. biebersteinii extract (300 mg/kg) in the late phase of formalin test as well as in writhing and tail-flick tests. GC-MS analysis revealed that ascaridole and iso-ascaridole were the main constituents of A. biebersteinii flower extract. In conclusion, this study shows for the first time that the antinociceptive effect of A. biebersteinii is mediated by the cholinergic receptor.

Intrathecal Bupivacaine with Neostigmine and Bupivacaine with Normal Saline for Postoperative Analgesia: A Cost-effective Additive

Context:

In day-to-day practice, subarachnoid block remains the most common type of anesthesia. Bupivacaine is commonly used local anesthetic of neuraxial blockade, though earlier 5% xylocaine and now ropivacaine and levobupivacaine are also used. Additives such as opioids and α₂ agonists are also used. We are using neostigmine as an additive with bupivacaine to see the duration of postoperative analgesia.

Aims:

To compare the efficacy of intrathecal hyperbaric bupivacaine with neostigmine when compared to hyperbaric bupivacaine with normal saline with regard to time of onset and duration of sensory and motor blockade, time to two-segment regression.

Settings and Design:

Randomized, double-blinded study.

Subjects and Methods:

One hundred patients admitted for lower abdominal and lower limb surgeries done under spinal anesthesia (SA) during the period of February 2015–August 2016.

Statistical Analysis Used:

Data were entered into Microsoft excel data sheet and analyzed using SPSS 22 version. Categorical data were represented in the form of frequencies and proportions. Chi-square was used as a test of significance. Continuous data were represented as a mean and standard deviation. Independent t-test was used as a test of significance to identify the mean difference between two groups.

Results:

Mean onset of sensory blockade with neostigmine group was 174.1 ± 107.1 s and in normal saline group 171 ± 35.6 s. Mean onset of motor blockade with neostigmine group was 197.4 ± 111.6 s and in normal saline group was 219.4 ± 73.2 s. Mean two-segment regression with neostigmine group was 110.6 ± 22.7 s and in normal saline group was 71.5 ± 17.1 min. Duration of analgesia with neostigmine group was 336.3 ± 54.5 min and in normal saline group was 188.8 ± 18.4 min.

Conclusions:

Intrathecal neostigmine is associated with significantly prolonged sensory, motor blockade, and effective postoperative analgesia.

Epidural Neostigmine versus Fentanyl to Decrease Bupivacaine Use in Patient-controlled Epidural Analgesia during Labor: A Randomized, Double-blind, Controlled Study

BACKGROUND

The addition of opioids to epidural local anesthetic reduces local anesthetic consumption by 20% but at the expense of side effects and time spent for regulatory compliance paperwork. Epidural neostigmine also reduces local anesthetic use. The authors hypothesized that epidural bupivacaine with neostigmine would decrease total hourly bupivacaine use compared with epidural bupivacaine with fentanyl for patient-controlled epidural analgesia.

METHODS

A total of 215 American Society of Anesthesiologists physical status II, laboring parturients requesting labor epidural analgesia consented to the study and were randomized to receive 0.125% bupivacaine with the addition of either fentanyl (2 μg/ml) or neostigmine (2, 4, or 8 μg/ml). The primary outcome was total hourly local anesthetic consumption, defined as total patient-controlled epidural analgesia use and top-ups (expressed as milliliters of 0.125% bupivacaine) divided by the infusion duration. A priori analysis determined a group size of 35 was needed to have 80% power at α = 0.05 to detect a 20% difference in the primary outcome.

RESULTS

Of 215 subjects consented, 151 patients were evaluable. Demographics, maternal and fetal outcomes, and labor characteristics were similar among groups. Total hourly local anesthetic consumption did not differ among groups (P = 0.55). The total median hourly bupivacaine consumption in the fentanyl group was 16.0 ml/h compared with 15.3, 14.6, and 16.2 ml/h in the 2, 4, and 8 μg/ml neostigmine groups, respectively (P = 0.55).

CONCLUSIONS

The data do not support any difference in bupivacaine requirements for labor patient-controlled epidural analgesia whether patients receive epidural bupivacaine with 2 to 8 μg/ml neostigmine or epidural bupivacaine with 2 μg/ml fentanyl.

A Comparison of Intrathecal Dexmedetomidine and Neostigmine as Adjuvant to Ropivacaine for Lower Limb Surgeries: A Double-blind Randomized Controlled Study

Objective:

The primary objective of this study was to compare the analgesic effects of intrathecal ropivacaine with or without neostigmine or dexmedetomidine in lower limb surgeries. Secondary objectives were to study the characteristics of block, duration of analgesia, postoperative analgesic requirement, and associated side effects.

Materials and Methods:

Seventy-five patients posted for elective orthopedic lower limb surgeries under spinal anesthesia were randomly divided into three equal groups to receive intrathecal ropivacaine 0.5% alone (Group R), with adjuvant 5 μg dexmedetomidine (Group R + D) or 50 μg neostigmine (Group R + N). Time to achieve T10 sensory block, time to 2-segment regression, duration of regression to L4, maximum modified Bromage score and duration of analgesia were noted. The incidences of adverse events such as nausea, vomiting, hypotension, bradycardia, desaturation, shivering, and itching were also noted. Statistical analysis was performed using two sample t-test for normally distributed variables and Pearson's Chi-squared test for categorical data. The level of significance was set as P < 0.05.

Results:

Quality of motor and sensory blockage was significantly better in both Group R + D and Group R + N than Group R. Mean time to achieve T10 sensory block was lowest, time taken in regression of block by 2-segments and duration of regression to L4 was longest in Group R + D and was significant when compared to other groups. Adverse effects such as nausea and vomiting were highest in Group R + N and was statistically significant as compared to other groups.

Conclusions:

Dexmedetomidine is a better intrathecal adjuvant emerged as compared to neostigmine due to faster onset of anesthesia, better intra- and post-operative analgesia and prolonged duration of motor and sensory blockade without significant increase in adverse effects.