Sedation and Restraint for Standing Procedures
Michele Barletta, Jane Quandt, Rachel Reed in Equine Anesthesia and Pain Management, 2023
Mechanism of action. Bind to opioid receptors in the CNS and peripheral organs.Opioid receptors include mu (μ), kappa (κ), and delta (δ) receptors.Alterations in autonomic tone.Increases in dopamine release/brain dopamine receptor sensitivity. Behavioral changes.Increased locomotor activity.Inhibition of ascending transmission of nociception from the dorsal horns of the spinal cord.Activation of descending pain control circuits from the midbrain.
Pharmacotherapy of Neurochemical Imbalances
Sahab Uddin, Rashid Mamunur in Advances in Neuropharmacology, 2020
Peptides, which bind to opioid receptors, are called opioid peptides. Opioid peptides are also called opioid neuropeptides or opioid neuromodulators. Opioid receptors are the membrane proteins located in nerve endings in brain and GIT. Opioid receptors are of three types: µ, κ, and δ. These proteins are called opioid receptors because of their affinity toward the opiate or morphine, which are derived from opium. Opiate and morphine act by binding with the receptor proteins (opioid receptors) for the natural neuropeptides. Natural neuropeptides are called endogenous opioid peptides. Endogenous opioid peptides have opiate like activity and inhibit the neurons in the brain involved in pain sensation (Froehlich, 1997). Opioid peptides are of three types:
Consciousness, Sleep and Hypnosis, Meditation, and Psychoactive Drugs
Mohamed Ahmed Abd El-Hay in Understanding Psychology for Medicine and Nursing, 2019
Opiates are substances derived from the opium poppy that exert a strong pain-relieving effect and produce feelings of euphoria, e.g., morphine and codeine. Opiates act on specific receptors: mu (μ), kappa (κ), and sigma (σ). Mu receptors appear most important in analgesia (μ1), and respiratory depression and physical dependence (μ2) effects. These findings have led to the development of drugs that operate by modulating the opioid receptors. There are two basic types of drugs acting on opiate receptors: agonists and antagonists. Agonist drugs bind to the opioid receptors to produce a feeling of pleasure and thereby reduce the craving for opiates, but they cause less psychological and physiological impairment than the opiates. Antagonists block the receptors so that the opiates cannot gain access to them.
Short-acting versus long-acting opioids for pediatric postoperative pain management
Published in Expert Review of Clinical Pharmacology, 2023
Yun Han Chen, Senthilkumar Sadhasivam, Spencer DeMedal, Mihaela Visoiu
Since methadone acts on mu-opioid receptors, it has similar side effects to other opioids, including reduced gastrointestinal motility, respiratory depression, nausea, and vomiting. While it can trigger histamine release, it is not associated with hypotension, although bradycardia has been anecdotally reported in an infant receiving methadone [60,61]. There is a more significant concern with the association of methadone and QTc prolongation as it can progress to potentially fatal arrhythmias such as torsades de pointes (TdP). These are thought to be related to methadone delaying repolarization by antagonizing the delayed rectifier potassium ion channel [62–66]. While this topic has received significant attention in adults, currently, there is limited data on children. Studies have shown that while QTc prolongation was longer in pediatric patients receiving methadone than their baseline electrocardiogram. No TdP or sudden cardiac death was documented. Risk factors in adults were also not associated with QTc prolongation in children [67,68].
Rationale, evidence, and steps for implementation of medication for opioid use disorder treatment programs in HIV primary care settings
Published in AIDS Care, 2023
Marisa Brizzi, Sarah B. Green
Naltrexone is a pure opioid antagonist that works by blocking effects of opioids through competitive binding at opioid receptor sites (Substance Abuse and Mental Health Services Administration, 2016). It is available as an oral tablet and extended-release injectable. Naltrexone has demonstrated improvements in rates of HIV virologic suppression with demonstrated safety and efficacy in patients with HIV, including HIV/HCV coinfected patients (Springer et al., 2018; Korthuis et al., 2017; Fanucchi et al., 2019). Important limitations to naltrexone include the immediate precipitation of severe opioid withdrawal symptoms if complete detoxification has not occurred. Additionally, up-regulation of opioid receptors with continued use may increase the risk of overdose with subsequent opioid exposure (Substance Abuse and Mental Health Services Administration, 2016).
The possible role of pedunculopontine tegmental nucleus (PPT) opioid receptors in the cardiovascular responses in normotensive and hemorrhagic hypotensive rats
Published in Clinical and Experimental Hypertension, 2022
Mohammad Naser Shafei, Omid Fakharzadeh Moghaddam, Vida Alikhani, Reza Mohebbati
It has been shown that the PPT has three types of neurons, and opioids by hyperpolarization of these types of neurons contribute to hypotension. In addition to direct projection to the RVLM, the PPT neurons were identified to project to other areas aimed at regulating blood pressure, including the vlPAG area (26). In addition, the projection of opioids from PPT is proposed to be polysynaptic and PPT-PAG-RVLM mediated because of the inhibitory effect of the vlPAG on blood pressure (30). We suggest that opioid receptors are involved in this effect. However, it requires to be further studied in the future. The effect of Ach on BP in the PPT is probably negotiated by muscarinic receptor (31). Muscarinic receptors are critical receptors of the brain cholinergic system, and the cardiovascular effects induced by muscarinic receptors have been demonstrated in numerous experiments (18,31,32). Therefore, muscarinic receptors in the PPT (33) may approve this theory.
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