[Non-opioid analgesics for perioperative pain therapy. Risks and rational basis for use]

5-Alkoxy-1-aryl-3-polyfluoroalkylpyrazoles with Antinociceptive Activity: Partial Agonists of TRPV1 Ion Channels

Chemoselective O-alkylation of 1-aryl-3-polyfluoroalkylpyrazol-5-oles under basic conditions resulted in a series of 5-alkoxypyrazoles (26 derivatives). They showed an acceptable ADME profile (in silico) and can be considered as drug-like. In experiments in vivo (CD-1 mice), it was found that the obtained compounds do not have toxic properties at a dose of more than 150 mg/kg (for most compounds at a dose of >300 mg/kg, and for lead compounds - >600 mg/kg). 22 Compounds from this series demonstrated from moderate to high analgesic effects (28-104 % at 1 h and 37-109 % at 2 h after administration) in vivo in the hot plate test (SD rats, 15 mg/kg, intraperitoneal (ip)). The lead compound was 4-([1-phenyl-3-(trifluoromethyl)pyrazol-5-yl]oxy)butan-1-ol, which not only increased the latent period in the hot plate test by 103 % at both measurement points but also showed a pronounced analgesic effect under conditions of capsaicin-induced nociception (CD-1 mice, 15 mg/kg, ip). According to molecular modeling, all synthesized compounds can interact with the TRPV1 ion channel. This biological target was confirmed in in vitro experiments on Chinese hamster ovary cells expressing rTRPV1. 5-Alkoxypyrazoles were partial agonists of the TRPV1 ion channel in various degree, and the most active was the same pyrazole as in in vivo tests.

Opioid Sparing Analgesics in Spine Surgery

Combinations of various nonopioid analgesics have been used to decrease pain and opioid consumption postoperatively allowing for faster recovery, improved patient satisfaction, and decreased morbidity. These opioid alternatives include acetaminophen, NSAIDs, COX-2 specific inhibitors, gabapentinoids, local anesthetics, dexamethasone, and ketamine. Each of these drugs presents its own advantages and disadvantages which can make it difficult to implement universally. In addition, ambiguous administration guidelines for these nonopioid analgesics lead to a difficult implementation of standardization protocols in spine surgery. A focus on the efficacy of different pain modalities specifically within spine surgery was implemented to assist with this standardized protocol endeavor and to educate surgeons on limiting opioid prescribing in the postoperative period. The purpose of this review article is to investigate the various opioid sparing medications that have been used to decrease morbidity in spine surgery and better assist surgeons in managing postoperative pain. Methods. A narrative review of published literature was conducted using the search function in Google scholar and PubMed was used to narrow down search criteria. The keywords “analgesics,” “spine,” and “pain” were used.

Effectiveness and safety of repetitive transcranial magnetic stimulation for the treatment of morphine dependence: A retrospective study

Morphine dependence (MD) is a very common complication because of the chronic morphine consumption. Studies suggest that repetitive transcranial magnetic stimulation (rTMS) can be used for the treatment of MD. However, there is still lacking evidence to support rTMS for MD. Thus, this retrospective study aimed to investigate the effectiveness and safety of rTMS for patients with MD.In this retrosepctive study, a total of 100 patients with MD were included, and they were divided into a rTMS group (n = 50), and a control group (n = 50). All patients in both groups received occupational therapy. In addition, patients in the rTMS group received rTMS. All patients in both groups received a total of 8 weeks treatment. The outcomes comprised of morphine craving intensity, depression, anxiety, and sleep quality, which were appraised by Visual Analogue Scale (VAS), Self-Rating Depression Scale (SDS), Self-Rating Anxiety Scale (SAS), and Pittsburgh Sleep Quality Index (PSQI), respectively. In addition, treatment-related adverse events were also considered for assessment.After 8 weeks treatment, patients in the rTMS group exerted better benefits in improving VAS (P < .01), SDS (P < .01), SAS (P < .01), and PSQI (P < .01), than patients in the control group. In addition, this study did not identify treatment-related adverse events in both groups.The findings of this study showed that rTMS treatment showed promising effectiveness on patients with MD. However, future studies should focus on warranting the present findings.

[Considerations concerning the perioperative use of metamizole]

BACKGROUND

The non-opioid analgesic metamizole (dipyrone) is approved for the treatment of severe pain and is often used in the perioperative period. As it can cause agranulocytosis, a severe adverse event, its perioperative administration is controversially discussed.

OBJECTIVE

Is there enough evidence for a high risk of metamizol-induced agranulocytosis (MIA)? What are the consequences of its perioperative use with respect to the risk profiles of alternative analgesics?

MATERIAL AND METHODS

Rapid review of the literature on the risk of MIA and adverse effects of non-opioid analgesics.

RESULTS

The incidence of MIA is estimated to be one case per million inhabitants per year. The risk seems low compared to other drugs associated with a risk of agranulocytosis, such as antithyroid drugs and ticlopidine. The risk profile of metamizole concerning hepatotoxicity, nephrotoxicity, bleeding and cardiovascular adverse effects is favorable compared to other non-opioid analgesics. None of the non-opioid analgesics are licensed to be administered intraoperatively.

CONCLUSION

The perioperative use of metamizole is possible after a thorough evaluation of the indications as it provides good analgesia with a generally favorable side effect profile and is administered intravenously. The risk of agranulocytosis is small but needs to be mentioned during patient informed consent in order to optimize early recognition. Intraoperative administration aims at reducing the expected severe postoperative pain. A documentation and justification for the evaluation of the indications are recommended.

Side effects associated with current and prospective antimigraine pharmacotherapies

INTRODUCTION

Migraine is a neurovascular disorder. Current acute specific antimigraine pharmacotherapies target trigeminovascular 5-HT1B/1D, 5-HT1F and CGRP receptors but, unfortunately, they induce some cardiovascular and central side effects that lead to poor treatment adherence/compliance. Therefore, new antimigraine drugs are being explored. Areas covered: This review considers the adverse (or potential) side effects produced by current and prospective antimigraine drugs, including medication overuse headache (MOH) produced by ergots and triptans, the side effects observed in clinical trials for the new gepants and CGRP antibodies, and a section discussing the potential effects resulting from disruption of the cardiovascular CGRPergic neurotransmission. Expert opinion: The last decades have witnessed remarkable developments in antimigraine therapy, which includes acute (e.g. triptans) and prophylactic (e.g. β-adrenoceptor blockers) antimigraine drugs. Indeed, the triptans represent a considerable advance, but their side effects (including nausea, dizziness and coronary vasoconstriction) preclude some patients from using triptans. This has led to the development of the ditans (5-HT1F receptor agonists), the gepants (CGRP receptor antagonists) and the monoclonal antibodies against CGRP or its receptor. The latter drugs represent a new hope in the antimigraine armamentarium, but as CGRP plays a role in cardiovascular homeostasis, the potential for adverse cardiovascular side effects remains latent.

Treatment of acute abdominal pain in the emergency room: a systematic review of the literature

Appropriate pain therapy prior to diagnosis in patients with acute abdominal pain remains controversial. Several recent studies have demonstrated that pain therapy does not negatively influence either the diagnosis or subsequent treatment of these patients; however, current practice patterns continue to favour withholding pain medication prior to diagnosis and surgical treatment decision. A systematic review of PubMed, Web-of-Science and The-Cochrane-Library from 1929 to 2011 was carried out using the key words of 'acute', 'abdomen', 'pain', 'emergency' as well as different pain drugs in use, revealed 84 papers. The results of the literature review were incorporated into six sections to describe management of acute abdominal pain: (1) Physiology of Pain; (2) Common Aetiologies of Abdominal Pain; (3) Pre-diagnostic Analgesia; (4) Pain Therapy for Acute Abdominal Pain; (5) Analgesia for Acute Abdominal Pain in Special Patient Populations; and (6) Ethical and Medico-legal Considerations in Current Analgesia Practices. A comprehensive algorithm for analgesia for acute abdominal pain in the general adult population was developed. A review of the literature of common aetiologies and management of acute abdominal pain in the general adult population and special patient populations seen in the emergency room revealed that intravenous administration of paracetamol, dipyrone or piritramide are currently the analgesics of choice in this clinical setting. Combinations of non-opioids and opioids should be administered in patients with moderate, severe or extreme pain, adjusting the treatment on the basis of repeated pain assessment, which improves overall pain management.

[Implementation of standardized postoperative pain therapy for orthopaedic patients. Comparison between unsystematic and standardized pain therapy]

BACKGROUND

The painless clinic and postoperative pain therapy are currently major issues in the management of surgical procedures. The aim of this study was to evaluate the benefit of a standardized pain therapy on the postoperative pain level after orthopaedic procedures.

PATIENTS AND METHODS

We investigated two different groups of patients who underwent an orthopaedic surgical procedure. Group 1 (n = 249) received a pain therapy which was based on an individual and surgery-dependent concept whereas group 2 (n = 243) was treated with a standardized pain therapy concept. The effect of the treatment was monitored with a VAS-based protocol.

RESULTS

Up to day 9 after surgery there was a significant difference between the two groups in regard to the postoperative pain. The patients of group 2 had less pain but had more unwanted side effects caused by the pain therapy during the first 3 days after surgery. Mobility and mental disposition were positively affected.

CONCLUSION

The implementation of a standardized pain therapy is successful in reducing postoperative pain. Mobility and mental disposition are also influenced positively. As a consequence the incidence of unwanted side effects is rising.

[Critical reevaluation of cyclooxygenase two inhibitors in perioperative pain therapy]

A significant increase in thromboembolic events (i.e. myocardial infarction and stroke) was demonstrated in multicenter studies after several months of treatment with cyclooxygenase 2 (cox-2) inhibitors. In February 2005, the European medical agencies (EMEA) substantially increased the number of contraindications for all cox-2 inhibitors. They are now contraindicated for patients with coronary artery disease. Furthermore, 2 out of 6 cox-2 inhibitors have been withdrawn from the market. In this review, the current state of knowledge on the use of cox-2 inhibitors in perioperative pain therapy is summarized: i) they are equally as potent as other non-opioid analgesics, ii) they decrease opioid consumption, iii) a reduction in postoperative nausea and vomiting (PONV) has not been adequately demonstrated. Regarding side-effects, it can be concluded that i) the incidence of thromboembolic events is increased in patients undergoing coronary artery bypass surgery, ii) perioperative blood loss is not affected, iii) ulcer formation is not promoted, iv) the risk for acute renal failure is probably increased to the same extent as for NSAIDs and v) severe bronchospasm can be triggered in patients with asthma and chronic obstructive pulmonary disease (COPD).

Postoperatives Schmerzmanagement

Although scientific interest in the field of pain research is unremitting and the understanding of acute pain mechanisms has eminently advanced, it is evident that clinical practice of postoperative pain management still has major deficits. Indeed, the use of regional analgesia via a catheter, e.g. epidural analgesia (EDA), or patient controlled intravenous analgesia (PCIA) has become very popular. These methods require special equipment, adequate nursing skills and professional expertise as well as the establishment of clinical procedures and an appropriate logistic setup. However, the majority of patients are not managed by EDA or PCIA and cannot be ignored due to lack of knowledge of the proper use of basic analgesic treatment. Therefore, it makes sense to establish a standardized step-concept of postoperative pain management with regular quality control integrated into a multimodal perioperative rehabilitation program.

Selektive Zyklooxygenase-2-Inhibitoren zur postoperativen Schmerztherapie

Systemic administration of analgesics is still the most widely used method for postoperative pain therapy. In the concept of balanced or multimodal analgesia non-steroidal anti-inflammatory drugs (NSAIDs) play an important role besides opioids. Their analgesic effect is based on a diminished prostaglandin synthesis by inhibition of the cyclooxygenase (COX) enzyme in the arachidonic acid metabolism. The discovery of at least two COX isoenzymes led to the development of selective COX-2 inhibitors that were hypothesized to have an improved risk-benefit-ratio compared with conventional NSAIDs. In this context the analgesic efficacy and adverse effects of selective COX-2 inhibitors for postoperative pain therapy were evaluated by reviewing the pertinent literature.