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Questions and Answers
What is a crucial physiological effect of morphine that can lead to respiratory arrest in patients?
What is a crucial physiological effect of morphine that can lead to respiratory arrest in patients?
Which of the following effects is associated with morphine's action on smooth muscles in the gastrointestinal tract?
Which of the following effects is associated with morphine's action on smooth muscles in the gastrointestinal tract?
In patients with severe head injury, what is the primary reason morphine is contraindicated?
In patients with severe head injury, what is the primary reason morphine is contraindicated?
What effect does morphine have on the biliary system?
What effect does morphine have on the biliary system?
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Which statement correctly describes the effect of morphine on the urinary system in patients with benign prostatic hyperplasia?
Which statement correctly describes the effect of morphine on the urinary system in patients with benign prostatic hyperplasia?
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Which opioid receptor family is associated with the highest analgesic effects and is primarily targeted by strong agonists like morphine?
Which opioid receptor family is associated with the highest analgesic effects and is primarily targeted by strong agonists like morphine?
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What differentiates partial agonists like pentazocine from full agonists such as morphine in terms of receptor activation?
What differentiates partial agonists like pentazocine from full agonists such as morphine in terms of receptor activation?
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Which of the following statements correctly describes the action of opioids on the central nervous system?
Which of the following statements correctly describes the action of opioids on the central nervous system?
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Which of the following best describes the classification of codeine within the opioid classification system?
Which of the following best describes the classification of codeine within the opioid classification system?
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Which endogenous opioid peptide is NOT included in the complex pain inhibition system described?
Which endogenous opioid peptide is NOT included in the complex pain inhibition system described?
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Study Notes
General Pharmacology of Narcotic Analgesics
- Analgesics relieve pain and are classified as narcotic (central action) or non-narcotic (peripheral action).
- Narcotics induce sedation and drowsiness; morphine is the prototype derived from opium poppy.
- Opioids are natural opioids, including morphine and codeine.
- Opioid receptors include mu, kappa, delta, and sigma, influencing pain perception and drug binding specificity.
- Opioid receptors are inhibitory G-protein coupled, leading to decreased cAMP levels and cellular hyperpolarization.
Pharmacology of Morphine
- Acts as a central depressant, altering pain perception and inducing drowsiness.
- Causes respiratory depression, especially risky in COPD and asthma patients.
- Exhibits antitussive effects by inhibiting the cough center.
- Notable for pinpoint pupils (miosis), which is a classic sign of overdose.
- Can cause nausea and vomiting due to stimulation of the chemoreceptor trigger zone.
Distribution and Pharmacokinetics
- Morphine undergoes first-pass metabolism; routes include intramuscular, intravenous, subcutaneous, buccal, and transdermal.
- It crosses the placenta, potentially affecting fetal respiration.
- Metabolized primarily in the liver; active metabolite is morphine-6-glucuronide, while morphine-3-glucuronide is inactive.
- The half-life is approximately 2 hours, and effects last 4-6 hours.
Clinical Uses
- Effective for severe pain relief (visceral and somatic), anxiety relief in critical conditions, and cough suppression (codeine preferred).
- Used in premedication for surgery and to alleviate dyspnea in acute left ventricular failure.
Adverse Effects and Contraindications
- Common side effects: respiratory depression, vomiting, hypotension, and urinary retention.
- Contraindicated in head injuries, severe liver disease, diverticulitis, and during labor.
Opioid Dependence and Tolerance
- Tolerance primarily develops to respiratory depression, analgesia, and euphoria, with less effect on miosis.
- Treatment includes gradual withdrawal, substitution with methadone, or clonidine for withdrawal syndromes.
Opioids Poisoning
- Symptoms include coma, slow shallow respiration, and pinpoint pupils.
- Treated initially with respiratory support and administration of Naloxone, a pure opioid antagonist.
Pharmacology of Other Members
- Pethidine (Meperidine): Used for severe pain, causes less constipation, not useful for cough suppression.
- Methadone: Less sedating, long half-life, used in analgesia and opioid dependence treatment.
- Diamorphine (Heroin): Highly addictive, most potent opioid.
- Fentanyl: Used for general anesthesia, potent and fast-acting.
- Codeine: Milder analgesic, effective for cough and mild pain, converted less than 10% to morphine in the body.
- Dextropropoxyphene and Tramadol: Used for pain, less addictive potential compared to strong opioids.
Opioid Antagonists
- Naloxone: Fast-acting opioid antagonist, used in overdose cases; reverses respiratory depression.
- Naltrexone: Longer-acting antagonist, can be taken orally; used for dependence and to decrease alcohol craving.
- Nalorphine: Functions as an antagonist and partial agonist, depending on the context of use.
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Description
Test your knowledge on the pharmacology of narcotic analgesics, including topics such as morphine and opioids dependence. This quiz covers the general pharmacology, various members of opioids, and their antagonists. Prepare yourself for questions on opioid poisoning and more!
