Characterization of inhibition of platelet function by paracetamol and its interaction with diclofenac in vitro

Common Medications Which Should Be Stopped Prior to Platelet-Rich Plasma Injection

Osteoarthritis (OA) is an extremely prevalent joint condition in the United States, affecting over 30 million people [...]

Home pharmacological therapy in early COVID-19 to prevent hospitalization and reduce mortality: Time for a suitable proposal

The COVID‐19 pandemic is a highly dramatic concern for mankind. In Italy, the pandemic exerted its major impact throughout the period of February to June 2020. To date, the awkward amount of more than 134,000 deaths has been reported. Yet, post‐mortem autopsy was performed on a very modest number of patients who died from COVID‐19 infection, leading to a first confirmation of an immune‐thrombosis of the lungs as the major COVID‐19 pathogenesis, likewise for SARS. Since then (June–August 2020), no targeted early therapy considering this pathogenetic issue was approached. The patients treated with early anti‐inflammatory, anti‐platelet, anticoagulant and antibiotic therapy confirmed that COVID‐19 was an endothelial inflammation with immuno‐thrombosis. Patients not treated or scarcely treated with the most proper and appropriate therapy and in the earliest, increased the hospitalization rate in the intensive care units and also mortality, due to immune‐thrombosis from the pulmonary capillary district and alveoli. The disease causes widespread endothelial inflammation, which can induce damage to various organs and systems. Therapy must be targeted in this consideration, and in this review, we demonstrate how early anti‐inflammatory therapy may treat endothelia inflammation and immune‐thrombosis caused by COVID‐19, by using drugs we are going to recommend in this paper.

The dorsal skinfold chamber: A valuable model for the in vivo evaluation of topical formulations

In this study, we introduce the mouse dorsal skinfold chamber model as a valuable approach for the in vivo evaluation of topical formulations. For this purpose, dorsal skinfold chambers were implanted into BALB/c mice. Tumor necrosis factor (TNF)-α was administered to the chamber tissue for the local induction of inflammation followed by the application of diclofenac-containing or diclofenac-free (control) gel onto the skin of the chamber backside. Intravital fluorescence microscopy was repetitively performed throughout an observation period of 24 hours to study macromolecular leakage, leucocyte-endothelial cell interactions and microhaemodynamic parameters. In addition, infiltration of the inflamed tissue with different immune cell subtypes was assessed by immunohistochemistry. In a second set of experiments, the effect of dermal application of a diclofenac-containing gel on photochemically induced thrombus formation was analysed. It was observed that macromolecular leakage, numbers of adherent leucocytes and tissue infiltrating myeloperoxidase (MPO)-positive neutrophilic granulocytes and CD68-positive macrophages were significantly reduced in dorsal skinfold chambers treated with diclofenac-containing gel when compared to controls. Moreover, the diclofenac-containing gel exerted an anti-thrombotic activity, as indicated by a significantly prolonged complete vessel occlusion time. These findings demonstrate that the mouse dorsal skinfold chamber represents a valid and versatile tool to evaluate the effects of topical formulations in vivo.

Comparative Safety and Efficacy of Two High Dose Regimens of Oral Paracetamol in Healthy Adults Undergoing Third Molar Surgery under Local Anaesthesia

This study compared the efficacy and safety of single oral doses of 60 mg/kg and 90 mg/kg paracetamol in fit young adult patients undergoing third molar extractions. The study was a randomised, blinded, crossover design on 20 young, fit adults. Paracetamol was administered 30 minutes prior to the surgical extraction of the teeth, which was done under intravenous sedation and local anaesthesia. There were no clinically or statistically significant differences in the pain scores between 60 mg/kg or 90 mg/kg doses until the intake of rescue analgesics. There was a reduction in factor VII activity with 90 mg/kg dose compared to 60 mg/kg dose. It may be concluded that the 90 mg/kg dose, though safe, does not offer any advantages over 60 mg/kg dose of paracetamol in young fit adults undergoing third molar surgery.

Donor Hepatectomy Surgery using Ketamine to Compliment Analgesia and Reduce Morbidity - a Retrospective Chart Review Investigation

Objective

Inferior and limited analgesic options/techniques during living donor hepatectomy surgery can result in pain and risks of morbidity, opioid-related adverse events (AEs), predisposition to the development of chronic pain and concerns of potential narcotic abuse. Traditional analgesia uses unimodal intravenous opioids that can cause significant side effects. Ketamine provides analgesia and may be opioid sparing, but use in living-donor hepatectomy has not been studied.

Methods

Following human investigation committee approval and informed written consent, 47 liver donor patients over a 5-year period scheduled for surgery were categorized into one of three groups: 24 patients received no ketamine (Group 1), 9 received only intraoperative ketamine (Group 2) and 14 patients received intraoperative plus postoperative ketamine (Group 3). Subjects had access to opioid patient-controlled analgesia (PCA). Chart reviews (including operating room and intensive care unit) were collected and analysed for morphine consumption, pain-intensity scores, opioid-sparing effects, AEs of analgesics and for evidence of ketamine side effects on donor hepatectomy patients.

Results

There were no differences in patient demographics. Living donor hepatectomy patients receiving intraoperative ketamine that was continued postoperatively consumed fewer morphine-equivalents and had lower median pain scores than subjects from the other two groups. Ileus occurred in those not receiving ketamine, pruritus was lowest in Group 3, and there was no evidence or reports of ketamine-associated AEs.

Conclusion

Perioperative ketamine for donor hepatectomy patients could safely provide improved analgesia and be opioid sparing when compared to PCA opioids alone, and there is no evidence of ketamine-related AEs at the dose and delivery methods described here during partial liver donation surgery.

Meloxicam and diclofenac do not change VEGF and PDGF-ABserum levels of platelet-rich plasma

BACKGROUND/AIM

Platelet-rich plasma (PRP) application has gained widespread interest for musculoskeletal injuries. Nonsteroidal antiinflammatory drugs are frequently used in sports medicine before and/or after PRP application. Our study seeks to determine whether serum levels of platelet-derived growth factor-AB (PDGF-AB) and vascular endothelial growth factor (VEGF) levels of PRP would be affected by nonsteroidal antiinflammatory drugs.

MATERIALS AND METHODS

Two different final concentrations of diclofenac (0.5 μg mL^-1 and 2.5 μg mL^-1), meloxicam (0.8 μg mL^-1 and 2.0 μg mL^-1), and acetylsalicylic acid (final concentration 450 μm) were obtained in separate tubes with PRPs prepared from 20 healthy male volunteers. Medicine-free PRP was the control group. Growth factors were measured using ELISA.

RESULTS

PDGF-AB and VEGF serum levels did not change with diclofenac, meloxicam, or acetylsalicylic acid addition. PDGF-AB and VEGF serum levels correlated with each other.

CONCLUSION

Diclofenac, meloxicam, and acetylsalicylic acid did not affect PDGF-AB and VEGF serum levels.

Laparoscopic surgery: a narrative review of pharmacotherapy in pain management

Laparoscopic surgery is widespread, and an increasing number of surgeries are performed laparoscopically. Early pain after laparoscopy can be similar or even more severe than that after open surgery. Thus, proactive pain management should be provided. Pain after laparoscopic surgery is derived from multiple origins; therefore, a single agent is seldom sufficient. Pain is most effectively controlled by a multimodal, preventive analgesia approach, such as combining opioids with non-opioid analgesics and local anaesthetics. Wound and port site local anaesthetic injections decrease abdominal wall pain by 1-1.5 units on a 0-10 pain scale. Inflammatory pain and shoulder pain can be controlled by NSAIDs or corticosteroids. In some patient groups, adjuvant drugs, ketamine and α2-adrenergic agonists can be helpful, but evidence on gabapentinoids is conflicting. In the present review, the types of pain that need to be taken into account while planning pain management protocols and the wide range of analgesic options that have been assessed in laparoscopic surgery are critically assessed. Recommendations to the clinician will be made regarding how to manage acute pain and how to prevent persistent postoperative pain. It is important to identify patients at the highest risk for severe and prolonged post-operative pain, and to have a proactive strategy in place for these individuals.

Autologous Platelet-Rich Plasma Preparations: Influence of Nonsteroidal Anti-inflammatory Drugs on Platelet Function

Background

Autologous platelet-rich plasma (PRP) has been widely used for the treatment of sports injuries. It has been associated with improved healing and regeneration of soft tissues in elite athletes. Athletes are commonly receiving nonsteroidal anti-inflammatory drugs (NSAIDs). As yet, the effect of these drugs on platelet function in PRP formulations has not been taken into consideration.

Hypothesis

The function of platelets in PRP produced under the influence of NSAIDs is inhibited and may lessen a possible healing effect on the site of injury.

Study Design

Controlled laboratory study.

Methods

PRP was collected from patients receiving NSAIDs after elective orthopaedic surgery, and platelet function was evaluated using light transmission aggregometry (LTA). Results were compared with those obtained from healthy volunteers without a history of NSAID intake during the previous 2 weeks. Two different systems for blood collection and PRP production (Arthrex ACP double-syringe system and standard 4.5-mL sodium citrate blood collection tubes) were used and compared regarding the quality of PRP that was produced.

Results

For both groups, the baseline platelet counts of whole blood and the platelet counts of PRP formulations were found to be in the normal range. Both collection systems for PRP produced comparable results without significant differences between the groups. Platelet function testing with LTA revealed significantly impaired platelet aggregation in both PRP preparations, obtained from patients taking NSAIDs, irrespective of the type of NSAID (P < .001). All subjects from the control group showed normal platelet aggregation patterns when tested with LTA.

Conclusion

Autologous PRP produced from subjects after NSAID medication shows significantly impaired platelet function and may result in lower quality regarding the content of bioactive compounds.

Clinical Relevance

If required, the administration of NSAIDs should be performed after blood collection for preparation of autologous PRP; otherwise, the therapeutic effect may be limited.

The modern pharmacology of paracetamol: therapeutic actions, mechanism of action, metabolism, toxicity and recent pharmacological findings

Paracetamol is used worldwide for its analgesic and antipyretic actions. It has a spectrum of action similar to that of NSAIDs and resembles particularly the COX-2 selective inhibitors. Paracetamol is, on average, a weaker analgesic than NSAIDs or COX-2 selective inhibitors but is often preferred because of its better tolerance. Despite the similarities to NSAIDs, the mode of action of paracetamol has been uncertain, but it is now generally accepted that it inhibits COX-1 and COX-2 through metabolism by the peroxidase function of these isoenzymes. This results in inhibition of phenoxyl radical formation from a critical tyrosine residue essential for the cyclooxygenase activity of COX-1 and COX-2 and prostaglandin (PG) synthesis. Paracetamol shows selectivity for inhibition of the synthesis of PGs and related factors when low levels of arachidonic acid and peroxides are available but conversely, it has little activity at substantial levels of arachidonic acid and peroxides. The result is that paracetamol does not suppress the severe inflammation of rheumatoid arthritis and acute gout but does inhibit the lesser inflammation resulting from extraction of teeth and is also active in a variety of inflammatory tests in experimental animals. Paracetamol often appears to have COX-2 selectivity. The apparent COX-2 selectivity of action of paracetamol is shown by its poor anti-platelet activity and good gastrointestinal tolerance. Unlike both non-selective NSAIDs and selective COX-2 inhibitors, paracetamol inhibits other peroxidase enzymes including myeloperoxidase. Inhibition of myeloperoxidase involves paracetamol oxidation and concomitant decreased formation of halogenating oxidants (e.g. hypochlorous acid, hypobromous acid) that may be associated with multiple inflammatory pathologies including atherosclerosis and rheumatic diseases. Paracetamol may, therefore, slow the development of these diseases. Paracetamol, NSAIDs and selective COX-2 inhibitors all have central and peripheral effects. As is the case with the NSAIDs, including the selective COX-2 inhibitors, the analgesic effects of paracetamol are reduced by inhibitors of many endogenous neurotransmitter systems including serotonergic, opioid and cannabinoid systems. There is considerable debate about the hepatotoxicity of therapeutic doses of paracetamol. Much of the toxicity may result from overuse of combinations of paracetamol with opioids which are widely used, particularly in USA.

What do we (not) know about how paracetamol (acetaminophen) works?

WHAT IS KNOWN AND BACKGROUND

Although paracetamol (acetaminophen), N-(4-Hydroxyphenyl)acetamide, is one of the world's most widely used analgesics, the mechanism by which it produces its analgesic effect is largely unknown. This lack is relevant because: (i) optimal pain treatment matches the analgesic mechanism to the (patho)physiology of the pain and (ii) modern drug discovery relies on an appropriate screening assay.

OBJECTIVE

To review the clinical profile and preclinical studies of paracetamol as means of gaining insight into its mechanism of analgesic action.

METHODS

A literature search was conducted of clinical and preclinical literature and the information obtained was organized and reviewed from the perspective of its contribution to an understanding of the mechanism of analgesic action of paracetamol.

RESULTS

Paracetamol's broad spectrum of analgesic and other pharmacological actions is presented, along with its multiple postulated mechanism(s) of action. No one mechanism has been definitively shown to account for its analgesic activity.

WHAT IS NEW AND CONCLUSION

Further research is needed to uncover the mechanism of analgesic action of paracetamol. The lack of this knowledge affects optimal clinical use and impedes drug discovery efforts.

Acetaminophen, phenacetin and dipyrone do not modulate pressor responses to arachidonic Acid or to pressor agents

In contrast to nonsteroidal anti-inflammatory drugs (NSAIDs), the nonopioid analgesics phenacetin, acetaminophen and dipyrone exhibit weak anti-inflammatory properties. An explanation for this difference in pharmacologic activity was provided by the recent discovery of a new cyclooxygenase isoform, cyclooxygenase (COX)-3, that is reported to be inhibited by phenacetin, acetaminophen and dipyrone. However, COX-3 was found to be a spliced variant of COX-1 and renamed COX-1b. Although recent studies provide evidence for the existence of this new COX isoform, it is uncertain whether this COX-3 (COX-1b) isoform, or putative acetaminophen-sensitive pathway, plays a role in the generation of vasoactive prostaglandins. NSAIDs increase systemic blood pressure by inhibiting the formation of vasodilator prostanoids. Angiotensin II, norepinephrine and other vasoconstrictor agents have been reported to release prostaglandins. It is possible that this acetaminophen-sensitive pathway also modulates pressor responses to these vasoconstrictor agents. Therefore, the purpose of the present study was to determine whether this acetaminophen-sensitive pathway plays a role in the generation of vasoactive products of arachidonic acid or in the modulation of vasoconstrictor responses in the pulmonary and systemic vascular bed of the intact-chest rat. In the present study, the nonopioid analgesics did not attenuate changes in pulmonary or systemic arterial pressure in response to injections of the prostanoid precursor, arachidonic acid, to the thromboxane A(2) mimic, U46619, or to angiotensin II or norepinephrine. The results of the present study do not provide evidence in support of a role of a functional COX-3 (COX-1b) isoform, or an acetaminophen-sensitive pathway, in the generation of vasoactive prostanoids or in the modulation of responses to vasoconstrictor hormones in the intact-chest rat.

Influence on platelet aggregation of i.v. parecoxib and acetaminophen in healthy volunteers

BACKGROUND

Acetaminophen (paracetamol) alone or in combination with other analgesics is widely used for postoperative analgesia. While acetaminophen and non-steroidal anti-inflammatory drugs inhibit platelet function, the cyclooxygenase-2 (COX-2) selectively inhibiting coxibs show no interference with platelet function. The authors studied the effect of a combination of i.v. parecoxib and acetaminophen on platelet function in healthy volunteers.

METHODS

Eighteen healthy, male volunteers (22-33 yr) received i.v. acetaminophen 1 g, parecoxib 40 mg+acetaminophen 1 g or placebo in a double-blind, crossover study. Platelet function was assessed by photometric aggregometry and by measuring the release of thromboxane B(2). Plasma acetaminophen concentrations were measured by high-performance liquid chromatography.

RESULTS

Platelet aggregation (median area under the curve) triggered with arachidonic acid 500 microM was 24.6, 3.9 and 4.2x10(3) area units (P=0.02, all groups) after placebo, acetaminophen and parecoxib+acetaminophen, respectively. Inhibition of platelet aggregation showed no difference between acetaminophen alone and the combination (P=0.82). Aggregation triggered with arachidonic acid 750 or 1000 microM, adenosine diphosphate (ADP) 1.5 or 3 microM, or epinephrine 5 microM showed no differences between the groups. Release of thromboxane B(2) in response to ADP was inhibited similarly by both acetaminophen and the combination. Plasma acetaminophen concentrations were similar after acetaminophen and the combination.

CONCLUSIONS

Acetaminophen and parecoxib showed no interaction in inhibiting platelet function. In combination they cause a mild degree of COX-1 inhibition corresponding to that of acetaminophen alone.