💊أدوي العصبي 16
#Pharmacology_of_CNS 16
#CNS
#Opioids
مواضيع الفصل دا هي
✔️OPIOID RECEPTORS
✔️OPIOID AGONISTS
✔️PARTIAL AGONISTS AND MIXED
AGONIST–ANTAGONISTS
✔️OTHER ANALGESICS
✔️ANTAGONISTS
حانتكلم عن اول موضوعين والباقي حا يكون في البوست الجاي ان شاء الله
💠Management of pain is one of clinical medicine’s greatest challenges.
💠All opioids act by binding to specific opioid receptors in the CNS to produce effects that mimic the action of endogenous peptide neurotransmitters (for example, endorphins, enkephalins,and dynorphins).
💠على الرغم من انو ليها تاثيرات كتيرة لكن الغرض الأساسي البتستخدم فيو هو تسكين الالم بس للاسف كتير منها
led to abuse of those agents with euphoric properties.
✔️OPIOID RECEPTORS
🔘The major effects of the opioids are mediated by three receptor families, which are commonly designated as μ (mu), κ (kappa), and δ (delta).
🔘The analgesic properties of the opioids are primarily mediated by the μ receptors
🔘 All three opioid receptors are members of the G protein–coupled
receptor family and inhibit adenylyl cyclase
✔️OPIOID AGONISTS
♻️Morphine [MOR-feen] is the major analgesic drug contained in crude
opium and is the prototype strong μ receptor agonist
✅Morphine
🔷Actions
🔹Analgesia: Morphine and other opioids cause analgesia (relief of pain without the loss of consciousness) and relieve pain both by raising the pain threshold at the spinal cord level and, more
importantly, by altering the brain’s perception of pain.
🔹Euphoria: Morphine produces a powerful sense of contentment and well-being
🔹Respiration: Morphine causes respiratory depression by reduction of the sensitivity of respiratory center neurons to carbon dioxide. Respiratory depression is the most common cause of death in acute opioid overdoses.
🔹Depression of cough reflex: Both morphine and codeine have antitussive properties.The receptors involved in the antitussive action appear to be different from those involved in analgesia
🔹Miosis: The pinpoint pupil characteristic of morphine use results from stimulation of μ and κ receptors.
🔹Emesis: Morphine directly stimulates the chemoreceptor trigger zone in the area postrema that causes vomiting.
🔹GI tract:morphine and other opioids produce constipation
🔹Cardiovascular: Morphine has no major effects on the blood pressure or heart rate at lower dosages. With large doses,hypotension and bradycardia may occur.
🔹Histamine release: Morphine releases histamine from mast cells causing urticaria, sweating, and vasodilation. Because itcan cause bronchoconstriction, morphine should be used with caution in patients with asthma.
🔹Hormonal actions: Morphine increases growth hormone release and enhances prolactin secretion. It increases antidiuretic hormone and leads to urinary retention.
🔹Labor: Morphine may prolong the second stage of labor by transiently decreasing the strength, duration, and frequency of uterine contractions.
🔷Pharmacokinetics
🔹Because significant first-pass metabolism of morphine occurs in the liver, intramuscular, subcutaneous, and IV injections produce the most reliable responses
🔹It is important to note that morphine has a linear pharmacokinetic profile that allows dosing to be more predictable and more flexible
🔹Morphine rapidly enters all body tissues,including the fetuses of pregnant women
🔹Only a small percentage of morphine crosses the blood–brain barrier, because morphine is the least lipophilic of the common opioids
🔹Morphine is conjugated with glucuronic acid in the liver,The conjugates are excreted primarily in urine, with small quantities appearing in bile.
🔷Adverse effects
🔹Many adverse effects are common across the entire opioid class. With most μ agonists, severe respiratory depression can occur and may result in death from acute opioid overdose.
🔹Morphine should be used with caution in patients with asthma,liver disease, or renal dysfunction.
✅Codeine
🔘Codeine is a naturally occurring opioid that is a weak analgesic compared to morphine. It should be used only for mild to moderate pain.
💊أدويه الجهاز العصبي 17
#Pharmacology_of_CNS 17
#CNS
#Opioids
باقي لينا ٣ نقاط ما اتكلمنا عنها بالنسبة لل Opioids هي👇
✔️PARTIAL AGONISTS AND MIXED
AGONIST–ANTAGONISTS
✔️OTHER ANALGESICS
✔️ANTAGONISTS
✔️PARTIAL AGONISTS AND MIXED
AGONIST–ANTAGONISTS
🔘Partial agonists bind to the opioid receptor, but have less intrinsic activity than full agonists
🔘Drugs that stimulate one receptor but block another are termed mixed agonist–antagonists
✅Buprenorphine
🌀Buprenorphine is classified as a partial agonist, acting at the μ receptor.
🌀Buprenorphine tablets are indicated for the treatment of opioid dependence and are also available in a combination product containing buprenorphine and naloxone. Naloxone was added to prevent the abuse of buprenorphine via IV administration.
🌀Buprenorphine is metabolized by the liver and excreted in bile and urine
✅Pentazocine
🌀Pentazocine acts as an agonist on κ receptors and is a weak antagonist at μ and δ receptors.
🌀It may be administered either orally or parenterally. Pentazocine produces less euphoria compared to morphine. In higher doses, the drug causes respiratory depression and decreases the activity of the GI tract.
🌀Despite its antagonist action, pentazocine does not antagonize the respiratory depression of morphine, but it can precipitate a withdrawal syndrome in a morphine abuser.
🌀Pentazocine should be used with caution in patients with angina or coronary artery disease, since it can increase systemic and pulmonary arterial pressure and, thus, increase the work of the heart.
✅Nalbuphine and butorphanol
🌀Nalbuphine and butorphanol are mixed opioid agonist–antagonists.
🌀Butorphanol is available in a nasal formulation that has been used for severe headaches, but has also been associated with abuse
🌀Nalbuphine does not affect the heart or increase blood pressure, in
contrast to pentazocine and butorphanol
✔️OTHER ANALGESICS
✅Tapentadol
🌀Tapentadol, a centrally acting analgesic, is an agonist at the μ opioid receptor and an inhibitor of norepinephrine reuptake.
🌀Tapentadol is mainly metabolized to inactive metabolites via glucuronidation, and it does not inhibit or induce the CYP450 enzyme system
🌀Tapentadol should be avoided in patients who have received MAOIs within the last 14 days.
✅Tramadol
🌀Tramadol is a centrally acting analgesic that binds to the μ opioid receptor
🌀 it weakly inhibits reuptake of norepinephrine and serotonin.
🌀Its respiratory depressant activity is less than that of morphine.
🌀Overdose or drug–drug interactions with medications, such as SSRIs, MAOIs, and tricyclic antidepressants, can lead to toxicity manifested by CNS excitation and seizures.
🌀As with other agents that bind the μ opioid receptor, tramadol has been associated with misuse and
abuse.
✔️ANTAGONISTS
💠The opioid antagonists bind with high affinity to opioid receptors, but fail to activate the receptor-mediated response
✅Naloxone
🌀Naloxone is used to reverse the coma and respiratory depression of opioid overdose
🌀Within 30 seconds of IV injection of naloxone,the respiratory depression and coma characteristic of high doses of morphine are reversed, causing the patient to be revived and alert.
🌀Naloxone has a half-life of 30 to 81 minutes
🌀treated and recovered may lapse back into respiratory depression. Naloxone is a competitive antagonist at μ, κ, and δ receptors, with a 10-fold higher affinity for μ than for κ receptors
✅Naltrexone
🌀Naltrexone has actions similar to those of naloxone. It has a longer duration of action than naloxone, and a single oral dose of naltrexone blocks the effect of injected heroin for up to 24 hours.
🌀Although it may also be beneficial in treating chronic alcoholism by an unknown mechanism, benzodiazepines and clonidine are preferred.
🌀Naltrexone can lead to hepatotoxicity
🅿️بكدا نكون خلصنا الفصل دا. المرة الجاية حا ندخل في Drugs of Abuse
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