Podcast
Questions and Answers
What effect do opioid analgesics have on consciousness?
What effect do opioid analgesics have on consciousness?
- They only relieve pain during sleep.
- They provide pain relief without affecting consciousness. (correct)
- They induce complete loss of consciousness.
- They cause hallucinations and confusion.
Which of the following correctly defines narcotics?
Which of the following correctly defines narcotics?
- Drugs that produce drowsiness or stupor along with analgesia. (correct)
- Drugs that provide immediate relief from anxiety.
- Drugs that are used exclusively for surgical anesthesia.
- Drugs that enhance alertness and cognitive function.
Which of the following is NOT classified as an opioid analgesic?
Which of the following is NOT classified as an opioid analgesic?
- Papaverine
- Acetaminophen (correct)
- Morphine
- Codeine
Opiates are primarily derived from which source?
Opiates are primarily derived from which source?
What potential issue is associated with opioid analgesics?
What potential issue is associated with opioid analgesics?
Which of the following terms describes endogenous peptides with opioid-like activity?
Which of the following terms describes endogenous peptides with opioid-like activity?
Which drug is used specifically for trigeminal neuralgia?
Which drug is used specifically for trigeminal neuralgia?
What characteristic is true of narcotics?
What characteristic is true of narcotics?
What is a significant reason why morphine cannot treat itching?
What is a significant reason why morphine cannot treat itching?
What effect does morphine have on the respiratory center?
What effect does morphine have on the respiratory center?
Which gastrointestinal effect is caused by morphine?
Which gastrointestinal effect is caused by morphine?
What therapeutic use of morphine is appropriate in the case of acute pulmonary edema?
What therapeutic use of morphine is appropriate in the case of acute pulmonary edema?
What is a central effect of morphine that can lead to clinical challenges?
What is a central effect of morphine that can lead to clinical challenges?
Which of the following effects is attributed to vagal stimulation due to morphine administration?
Which of the following effects is attributed to vagal stimulation due to morphine administration?
In which scenario is it beneficial to combine morphine with atropine?
In which scenario is it beneficial to combine morphine with atropine?
Severe miosis is a potential indicator of what condition related to morphine usage?
Severe miosis is a potential indicator of what condition related to morphine usage?
Which receptor interactions are primarily responsible for the analgesic effects of opioids?
Which receptor interactions are primarily responsible for the analgesic effects of opioids?
What pharmacokinetic property affects the oral bioavailability of morphine?
What pharmacokinetic property affects the oral bioavailability of morphine?
What is one physiological effect caused by interaction with μ-receptors?
What is one physiological effect caused by interaction with μ-receptors?
What role does the activation of descending inhibitory pathways play in opioid action?
What role does the activation of descending inhibitory pathways play in opioid action?
What is the primary method of excretion for morphine metabolites?
What is the primary method of excretion for morphine metabolites?
Which effect is NOT associated with the pharmacological actions of morphine?
Which effect is NOT associated with the pharmacological actions of morphine?
What neurotransmitter's release is decreased due to the psychic effect of morphine?
What neurotransmitter's release is decreased due to the psychic effect of morphine?
Which property is characteristic of the analgesic effect of morphine?
Which property is characteristic of the analgesic effect of morphine?
Morphine has an effect on peripheral inflamed tissue that can help alleviate symptoms.
Morphine has an effect on peripheral inflamed tissue that can help alleviate symptoms.
The mechanism by which morphine causes respiratory center depression involves increasing the rate of carbon dioxide removal from the body.
The mechanism by which morphine causes respiratory center depression involves increasing the rate of carbon dioxide removal from the body.
Morphine can be used to manage acute pulmonary edema effectively due to its anxiolytic properties and venodilation effects.
Morphine can be used to manage acute pulmonary edema effectively due to its anxiolytic properties and venodilation effects.
Bradycardia caused by morphine is primarily the result of increased sympathetic stimulation.
Bradycardia caused by morphine is primarily the result of increased sympathetic stimulation.
Morphine is effective in treating colic when combined with atropine because both drugs are spasmogenic.
Morphine is effective in treating colic when combined with atropine because both drugs are spasmogenic.
A therapeutic effect of morphine is a prolonged labor due to its stimulation of uterine activity.
A therapeutic effect of morphine is a prolonged labor due to its stimulation of uterine activity.
Histamine release as a side effect of morphine can contribute to orthostatic hypotension.
Histamine release as a side effect of morphine can contribute to orthostatic hypotension.
Miosis, the constriction of the pupils, is a common indicator of morphine overdose.
Miosis, the constriction of the pupils, is a common indicator of morphine overdose.
Opioids interact with five major receptors identified as μ, δ, κ, ρ, and σ.
Opioids interact with five major receptors identified as μ, δ, κ, ρ, and σ.
Morphine exhibits a 50% bioavailability when taken orally due to the first-pass effect.
Morphine exhibits a 50% bioavailability when taken orally due to the first-pass effect.
The chief mechanism by which opioid analgesia occurs is through the activation of μ and δ receptors resulting in a decrease in substance-P release.
The chief mechanism by which opioid analgesia occurs is through the activation of μ and δ receptors resulting in a decrease in substance-P release.
Consciousness is significantly impaired while under the analgesic effect of morphine.
Consciousness is significantly impaired while under the analgesic effect of morphine.
The metabolism of morphine occurs mainly through hydroxylation in the liver.
The metabolism of morphine occurs mainly through hydroxylation in the liver.
Euphoria resulting from morphine's action is linked to increased norepinephrine release in certain areas of the CNS.
Euphoria resulting from morphine's action is linked to increased norepinephrine release in certain areas of the CNS.
The renal system plays a minimal role in the excretion of morphine, with only 10% expelled through urine.
The renal system plays a minimal role in the excretion of morphine, with only 10% expelled through urine.
κ-receptor interaction significantly contributes to euphoria associated with opioid use.
κ-receptor interaction significantly contributes to euphoria associated with opioid use.
Opioids are drugs that induce complete loss of consciousness while providing pain relief.
Opioids are drugs that induce complete loss of consciousness while providing pain relief.
Opiates are solely synthetic drugs that do not derive from the opium plant.
Opiates are solely synthetic drugs that do not derive from the opium plant.
Narcotics are classified as legal substances and have no medical implications.
Narcotics are classified as legal substances and have no medical implications.
Endorphins and enkephalins are examples of exogenous peptides with opioid-like activity.
Endorphins and enkephalins are examples of exogenous peptides with opioid-like activity.
Dipyron is classified as an opioid analgesic.
Dipyron is classified as an opioid analgesic.
Physical dependence on opioid analgesics can occur due to their regular use.
Physical dependence on opioid analgesics can occur due to their regular use.
The term 'opioid' specifically refers to drugs derived from the opium plant.
The term 'opioid' specifically refers to drugs derived from the opium plant.
Carbamazepine is used primarily for migraine treatment.
Carbamazepine is used primarily for migraine treatment.
What distinguishes opioid analgesics from non-opioid analgesics in terms of their mechanism of action?
What distinguishes opioid analgesics from non-opioid analgesics in terms of their mechanism of action?
How do endogenous peptides like endorphins influence pain management in comparison to exogenous opioid drugs?
How do endogenous peptides like endorphins influence pain management in comparison to exogenous opioid drugs?
In what context might the use of narcotics be legally justified despite their addictive potential?
In what context might the use of narcotics be legally justified despite their addictive potential?
What are the physiological effects of morphine that contribute to its analgesic properties aside from pain relief?
What are the physiological effects of morphine that contribute to its analgesic properties aside from pain relief?
How does the pharmacokinetic property of first-pass metabolism affect morphine’s bioavailability?
How does the pharmacokinetic property of first-pass metabolism affect morphine’s bioavailability?
What role do opioid receptors play in the therapeutic effects of both natural and synthetic opioids?
What role do opioid receptors play in the therapeutic effects of both natural and synthetic opioids?
Identify a specific condition that carbamazepine is used to treat and explain why it is suitable for that purpose.
Identify a specific condition that carbamazepine is used to treat and explain why it is suitable for that purpose.
What physiological mechanism is primarily responsible for the respiratory depression seen with morphine administration?
What physiological mechanism is primarily responsible for the respiratory depression seen with morphine administration?
How does morphine's vagal stimulation contribute to bradycardia?
How does morphine's vagal stimulation contribute to bradycardia?
Explain why morphine cannot effectively treat itching.
Explain why morphine cannot effectively treat itching.
What are the implications of severe miosis in morphine overdose?
What are the implications of severe miosis in morphine overdose?
Discuss the impact of morphine on the gastrointestinal system, specifically regarding constipation.
Discuss the impact of morphine on the gastrointestinal system, specifically regarding constipation.
Describe the therapeutic rationale for combining morphine with atropine in severe colic.
Describe the therapeutic rationale for combining morphine with atropine in severe colic.
How does morphine's mechanism of venodilation benefit patients with acute pulmonary edema?
How does morphine's mechanism of venodilation benefit patients with acute pulmonary edema?
What central nervous system effect of morphine can lead to vomiting in patients?
What central nervous system effect of morphine can lead to vomiting in patients?
What receptors do opioids primarily interact with to produce analgesia?
What receptors do opioids primarily interact with to produce analgesia?
How is morphine metabolized in the body?
How is morphine metabolized in the body?
Why is morphine's effect on the respiratory center critical for patient monitoring?
Why is morphine's effect on the respiratory center critical for patient monitoring?
What is the significance of kappa-receptor interaction in opioid action?
What is the significance of kappa-receptor interaction in opioid action?
What effect does morphine have on gastrointestinal motility?
What effect does morphine have on gastrointestinal motility?
What is the bioavailability of orally administered morphine, and what causes this limitation?
What is the bioavailability of orally administered morphine, and what causes this limitation?
What are the primary pathways through which morphine exerts its analgesic effects?
What are the primary pathways through which morphine exerts its analgesic effects?
Describe the renal excretion profile of morphine metabolites.
Describe the renal excretion profile of morphine metabolites.
What potential effects can the psychic component of morphine have on patients?
What potential effects can the psychic component of morphine have on patients?
Ana ______ are drugs that relieve or decrease pain sensations.
Ana ______ are drugs that relieve or decrease pain sensations.
________ analgesics are drugs that decrease pain sensation without loss of consciousness.
________ analgesics are drugs that decrease pain sensation without loss of consciousness.
_______ are drugs derived from the opium plant.
_______ are drugs derived from the opium plant.
Narcotics produce narcosis, meaning marked impairment, but not complete loss of ________.
Narcotics produce narcosis, meaning marked impairment, but not complete loss of ________.
Endorphins and enkephalins are examples of ________ peptides with opioid-like activity.
Endorphins and enkephalins are examples of ________ peptides with opioid-like activity.
Carbamazepine is a drug used specifically for ________ neuralgia.
Carbamazepine is a drug used specifically for ________ neuralgia.
Narcotics are usually ________, meaning they can lead to physical dependence.
Narcotics are usually ________, meaning they can lead to physical dependence.
The ________ classification of analgesics includes NSAIDs and antipyretics.
The ________ classification of analgesics includes NSAIDs and antipyretics.
Morphine can treat all types of pain except ___.
Morphine can treat all types of pain except ___.
Euphoria can be produced by large doses of morphine, whereas ___ can result in dysphoria.
Euphoria can be produced by large doses of morphine, whereas ___ can result in dysphoria.
Severe miosis is indicative of ___ doses of morphine.
Severe miosis is indicative of ___ doses of morphine.
Morphine depresses the respiratory center which leads to ___ retention.
Morphine depresses the respiratory center which leads to ___ retention.
Morphine is used as an adjuvant in ___ to achieve long lasting analgesia.
Morphine is used as an adjuvant in ___ to achieve long lasting analgesia.
The combination of morphine and atropine is effective for treating severe ___.
The combination of morphine and atropine is effective for treating severe ___.
One of the cardiovascular effects of morphine is ___ due to histamine release.
One of the cardiovascular effects of morphine is ___ due to histamine release.
The therapeutic use of morphine for acute pulmonary edema includes decreasing ___ and anxiety of the patient.
The therapeutic use of morphine for acute pulmonary edema includes decreasing ___ and anxiety of the patient.
Opioids such as morphine interact with three major receptors: μ, δ, and ______.
Opioids such as morphine interact with three major receptors: μ, δ, and ______.
The primary site of opioid receptor concentration is the dorsal horn of the ______.
The primary site of opioid receptor concentration is the dorsal horn of the ______.
The analgesic effect of morphine is greater when administered ______.
The analgesic effect of morphine is greater when administered ______.
Analgesia from opioids results from direct activation of μ and ______ receptors.
Analgesia from opioids results from direct activation of μ and ______ receptors.
The metabolism of morphine occurs in the ______ by conjugation.
The metabolism of morphine occurs in the ______ by conjugation.
Morphine facilitates the decrease of ______ release in the spinal cord, contributing to its analgesic effect.
Morphine facilitates the decrease of ______ release in the spinal cord, contributing to its analgesic effect.
Opioid analgesics cause respiratory ______ as one of their significant side effects.
Opioid analgesics cause respiratory ______ as one of their significant side effects.
One of the pharmacological effects of morphine includes decreased gastrointestinal ______.
One of the pharmacological effects of morphine includes decreased gastrointestinal ______.
Match the following effects of morphine with their corresponding mechanisms:
Match the following effects of morphine with their corresponding mechanisms:
Match the therapeutic uses of morphine with their reasons:
Match the therapeutic uses of morphine with their reasons:
Match the side effects of morphine with their causing mechanisms:
Match the side effects of morphine with their causing mechanisms:
Match the physiological effects of morphine with their clinical significance:
Match the physiological effects of morphine with their clinical significance:
Match the conditions treated with morphine to their effects:
Match the conditions treated with morphine to their effects:
Match the types of pains with the appropriate characteristic regarding morphine's action:
Match the types of pains with the appropriate characteristic regarding morphine's action:
Match the opioid related terms with their appropriate definitions:
Match the opioid related terms with their appropriate definitions:
Match the side effects of morphine with their consequences:
Match the side effects of morphine with their consequences:
Match the following drugs with their classifications:
Match the following drugs with their classifications:
Match the following classes of analgesics with their characteristics:
Match the following classes of analgesics with their characteristics:
Match the following terms with their descriptions:
Match the following terms with their descriptions:
Match the following specific conditions with their corresponding drugs:
Match the following specific conditions with their corresponding drugs:
Match the following opioid-related concepts with their meanings:
Match the following opioid-related concepts with their meanings:
Match the following opioids with their natural or synthetic categorization:
Match the following opioids with their natural or synthetic categorization:
Match the following side effects with their potential causes from opioids:
Match the following side effects with their potential causes from opioids:
Match the following terms with their associated physiological processes:
Match the following terms with their associated physiological processes:
Match the opioid receptors with their primary effects:
Match the opioid receptors with their primary effects:
Match the pharmacokinetic properties of morphine with their descriptions:
Match the pharmacokinetic properties of morphine with their descriptions:
Match the effects of morphine with their corresponding actions:
Match the effects of morphine with their corresponding actions:
Match the opioid drug types with their classifications:
Match the opioid drug types with their classifications:
Match the pharmacological actions of morphine with the adverse effects:
Match the pharmacological actions of morphine with the adverse effects:
Match the terms related to opioid pharmacodynamics with their definitions:
Match the terms related to opioid pharmacodynamics with their definitions:
Match the pathways influenced by morphine with their implications:
Match the pathways influenced by morphine with their implications:
Match the key points about morphine with their descriptions:
Match the key points about morphine with their descriptions:
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Study Notes
Analgesics
- Drugs that relieve or decrease pain sensations.
- Classified into various categories including opioids, NSAIDs, and antipyretics.
Opioid Analgesics
- Decrease pain sensation without loss of consciousness; can induce physical dependence.
- Opiates are derived from the opium plant (Papaver somniferum), including morphine, codeine, and papaverine.
- Opioids exhibit morphine-like activity.
- Opiopeptins are endogenous peptides (e.g., endorphins, enkephalins) with opioid-like effects.
- Narcotics cause drowsiness or stupor, alongside analgesia but not full loss of consciousness; often addictive.
Mechanism of Action
- Opioids interact with three main receptors: μ (mu), δ (delta), and κ (kappa), concentrated in the spinal cord's dorsal horn.
- μ-receptor interaction leads to analgesia, respiratory depression, sedation, euphoria, and decreased gastrointestinal motility.
- κ-receptor role in analgesia is less clear but may inhibit substance P release in pain transmission.
Morphine
- Good oral absorption but lower bioavailability (25%) due to the first-pass effect; greater analgesic effect when administered parenterally.
- Half-life (t½) is 4-5 hours; metabolized in the liver with renal (90%) and bile (10%) excretion.
Pharmacological Effects
- Produces dose-dependent analgesia without loss of consciousness and can reduce anxiety.
- Analgesia mechanism: activation of μ and δ receptors in the spinal cord and higher centers, leading to reduced pain transmission.
- Euphoria and miosis (constricted pupils) may occur, with severe miosis indicative of toxicity.
- Causes respiratory depression leading to CO2 retention and increased intracranial pressure.
- Other effects include cough suppression, nausea and vomiting due to stimulation of the chemoreceptor trigger zone.
Cardiovascular Effects
- Orthostatic hypotension due to histamine release and vagal stimulation.
- Bradycardia from vagal nerve stimulation.
Smooth Muscle Effects
- Bronchoconstriction due to vagal stimulation and histamine release.
- Constipation from decreased gastrointestinal peristalsis and increased water absorption.
- Can cause sphincter spasms, increase biliary pressure, and prolong labor.
Therapeutic Uses
- Effective for severe pain management, such as in acute myocardial infarction, cancer, and surgical procedures.
- Treats acute pulmonary edema by reducing stress and venous return.
- Used in anesthesia for prolonged analgesia and as an adjunct to anesthetic agents.
- Designed for severe colic when combined with anti-spasmodic agents like atropine.
Analgesics
- Drugs that relieve or decrease pain sensations.
- Classified into various categories including opioids, NSAIDs, and antipyretics.
Opioid Analgesics
- Decrease pain sensation without loss of consciousness; can induce physical dependence.
- Opiates are derived from the opium plant (Papaver somniferum), including morphine, codeine, and papaverine.
- Opioids exhibit morphine-like activity.
- Opiopeptins are endogenous peptides (e.g., endorphins, enkephalins) with opioid-like effects.
- Narcotics cause drowsiness or stupor, alongside analgesia but not full loss of consciousness; often addictive.
Mechanism of Action
- Opioids interact with three main receptors: μ (mu), δ (delta), and κ (kappa), concentrated in the spinal cord's dorsal horn.
- μ-receptor interaction leads to analgesia, respiratory depression, sedation, euphoria, and decreased gastrointestinal motility.
- κ-receptor role in analgesia is less clear but may inhibit substance P release in pain transmission.
Morphine
- Good oral absorption but lower bioavailability (25%) due to the first-pass effect; greater analgesic effect when administered parenterally.
- Half-life (t½) is 4-5 hours; metabolized in the liver with renal (90%) and bile (10%) excretion.
Pharmacological Effects
- Produces dose-dependent analgesia without loss of consciousness and can reduce anxiety.
- Analgesia mechanism: activation of μ and δ receptors in the spinal cord and higher centers, leading to reduced pain transmission.
- Euphoria and miosis (constricted pupils) may occur, with severe miosis indicative of toxicity.
- Causes respiratory depression leading to CO2 retention and increased intracranial pressure.
- Other effects include cough suppression, nausea and vomiting due to stimulation of the chemoreceptor trigger zone.
Cardiovascular Effects
- Orthostatic hypotension due to histamine release and vagal stimulation.
- Bradycardia from vagal nerve stimulation.
Smooth Muscle Effects
- Bronchoconstriction due to vagal stimulation and histamine release.
- Constipation from decreased gastrointestinal peristalsis and increased water absorption.
- Can cause sphincter spasms, increase biliary pressure, and prolong labor.
Therapeutic Uses
- Effective for severe pain management, such as in acute myocardial infarction, cancer, and surgical procedures.
- Treats acute pulmonary edema by reducing stress and venous return.
- Used in anesthesia for prolonged analgesia and as an adjunct to anesthetic agents.
- Designed for severe colic when combined with anti-spasmodic agents like atropine.
Analgesics
- Drugs that relieve or decrease pain sensations.
- Classified into various categories including opioids, NSAIDs, and antipyretics.
Opioid Analgesics
- Decrease pain sensation without loss of consciousness; can induce physical dependence.
- Opiates are derived from the opium plant (Papaver somniferum), including morphine, codeine, and papaverine.
- Opioids exhibit morphine-like activity.
- Opiopeptins are endogenous peptides (e.g., endorphins, enkephalins) with opioid-like effects.
- Narcotics cause drowsiness or stupor, alongside analgesia but not full loss of consciousness; often addictive.
Mechanism of Action
- Opioids interact with three main receptors: μ (mu), δ (delta), and κ (kappa), concentrated in the spinal cord's dorsal horn.
- μ-receptor interaction leads to analgesia, respiratory depression, sedation, euphoria, and decreased gastrointestinal motility.
- κ-receptor role in analgesia is less clear but may inhibit substance P release in pain transmission.
Morphine
- Good oral absorption but lower bioavailability (25%) due to the first-pass effect; greater analgesic effect when administered parenterally.
- Half-life (t½) is 4-5 hours; metabolized in the liver with renal (90%) and bile (10%) excretion.
Pharmacological Effects
- Produces dose-dependent analgesia without loss of consciousness and can reduce anxiety.
- Analgesia mechanism: activation of μ and δ receptors in the spinal cord and higher centers, leading to reduced pain transmission.
- Euphoria and miosis (constricted pupils) may occur, with severe miosis indicative of toxicity.
- Causes respiratory depression leading to CO2 retention and increased intracranial pressure.
- Other effects include cough suppression, nausea and vomiting due to stimulation of the chemoreceptor trigger zone.
Cardiovascular Effects
- Orthostatic hypotension due to histamine release and vagal stimulation.
- Bradycardia from vagal nerve stimulation.
Smooth Muscle Effects
- Bronchoconstriction due to vagal stimulation and histamine release.
- Constipation from decreased gastrointestinal peristalsis and increased water absorption.
- Can cause sphincter spasms, increase biliary pressure, and prolong labor.
Therapeutic Uses
- Effective for severe pain management, such as in acute myocardial infarction, cancer, and surgical procedures.
- Treats acute pulmonary edema by reducing stress and venous return.
- Used in anesthesia for prolonged analgesia and as an adjunct to anesthetic agents.
- Designed for severe colic when combined with anti-spasmodic agents like atropine.
Analgesics
- Drugs that relieve or decrease pain sensations.
- Classified into various categories including opioids, NSAIDs, and antipyretics.
Opioid Analgesics
- Decrease pain sensation without loss of consciousness; can induce physical dependence.
- Opiates are derived from the opium plant (Papaver somniferum), including morphine, codeine, and papaverine.
- Opioids exhibit morphine-like activity.
- Opiopeptins are endogenous peptides (e.g., endorphins, enkephalins) with opioid-like effects.
- Narcotics cause drowsiness or stupor, alongside analgesia but not full loss of consciousness; often addictive.
Mechanism of Action
- Opioids interact with three main receptors: μ (mu), δ (delta), and κ (kappa), concentrated in the spinal cord's dorsal horn.
- μ-receptor interaction leads to analgesia, respiratory depression, sedation, euphoria, and decreased gastrointestinal motility.
- κ-receptor role in analgesia is less clear but may inhibit substance P release in pain transmission.
Morphine
- Good oral absorption but lower bioavailability (25%) due to the first-pass effect; greater analgesic effect when administered parenterally.
- Half-life (t½) is 4-5 hours; metabolized in the liver with renal (90%) and bile (10%) excretion.
Pharmacological Effects
- Produces dose-dependent analgesia without loss of consciousness and can reduce anxiety.
- Analgesia mechanism: activation of μ and δ receptors in the spinal cord and higher centers, leading to reduced pain transmission.
- Euphoria and miosis (constricted pupils) may occur, with severe miosis indicative of toxicity.
- Causes respiratory depression leading to CO2 retention and increased intracranial pressure.
- Other effects include cough suppression, nausea and vomiting due to stimulation of the chemoreceptor trigger zone.
Cardiovascular Effects
- Orthostatic hypotension due to histamine release and vagal stimulation.
- Bradycardia from vagal nerve stimulation.
Smooth Muscle Effects
- Bronchoconstriction due to vagal stimulation and histamine release.
- Constipation from decreased gastrointestinal peristalsis and increased water absorption.
- Can cause sphincter spasms, increase biliary pressure, and prolong labor.
Therapeutic Uses
- Effective for severe pain management, such as in acute myocardial infarction, cancer, and surgical procedures.
- Treats acute pulmonary edema by reducing stress and venous return.
- Used in anesthesia for prolonged analgesia and as an adjunct to anesthetic agents.
- Designed for severe colic when combined with anti-spasmodic agents like atropine.
Analgesics
- Drugs that relieve or decrease pain sensations.
- Classified into various categories including opioids, NSAIDs, and antipyretics.
Opioid Analgesics
- Decrease pain sensation without loss of consciousness; can induce physical dependence.
- Opiates are derived from the opium plant (Papaver somniferum), including morphine, codeine, and papaverine.
- Opioids exhibit morphine-like activity.
- Opiopeptins are endogenous peptides (e.g., endorphins, enkephalins) with opioid-like effects.
- Narcotics cause drowsiness or stupor, alongside analgesia but not full loss of consciousness; often addictive.
Mechanism of Action
- Opioids interact with three main receptors: μ (mu), δ (delta), and κ (kappa), concentrated in the spinal cord's dorsal horn.
- μ-receptor interaction leads to analgesia, respiratory depression, sedation, euphoria, and decreased gastrointestinal motility.
- κ-receptor role in analgesia is less clear but may inhibit substance P release in pain transmission.
Morphine
- Good oral absorption but lower bioavailability (25%) due to the first-pass effect; greater analgesic effect when administered parenterally.
- Half-life (t½) is 4-5 hours; metabolized in the liver with renal (90%) and bile (10%) excretion.
Pharmacological Effects
- Produces dose-dependent analgesia without loss of consciousness and can reduce anxiety.
- Analgesia mechanism: activation of μ and δ receptors in the spinal cord and higher centers, leading to reduced pain transmission.
- Euphoria and miosis (constricted pupils) may occur, with severe miosis indicative of toxicity.
- Causes respiratory depression leading to CO2 retention and increased intracranial pressure.
- Other effects include cough suppression, nausea and vomiting due to stimulation of the chemoreceptor trigger zone.
Cardiovascular Effects
- Orthostatic hypotension due to histamine release and vagal stimulation.
- Bradycardia from vagal nerve stimulation.
Smooth Muscle Effects
- Bronchoconstriction due to vagal stimulation and histamine release.
- Constipation from decreased gastrointestinal peristalsis and increased water absorption.
- Can cause sphincter spasms, increase biliary pressure, and prolong labor.
Therapeutic Uses
- Effective for severe pain management, such as in acute myocardial infarction, cancer, and surgical procedures.
- Treats acute pulmonary edema by reducing stress and venous return.
- Used in anesthesia for prolonged analgesia and as an adjunct to anesthetic agents.
- Designed for severe colic when combined with anti-spasmodic agents like atropine.
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