CNS and Analgesics Quiz
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Questions and Answers

What physiological effect is not attributed to kappa (κ) receptors?

  • Miosis
  • Constipation (correct)
  • Sedation
  • Spinal analgesia

    • Which of the following is a significant side effect associated with opioid use?

  • Hyperactivity
  • Increased respiration
  • Constipation (correct)
  • Vasodilation

    • Which of the following effects is specifically linked to kappa (κ) receptors?

  • Respiratory depression
  • Tolerance development
  • Analgesia in peripheral tissues
  • Miosis (correct)

    • What is a characteristic of kappa (κ) receptor activation?

    <p>Sedation</p> Signup and view all the answers

    Which condition is a result of opioid use due to kappa (κ) receptor action?

    <p>Analgesia</p> Signup and view all the answers

    What is naloxone primarily classified as?

    <p>A pure narcotic antagonist</p> Signup and view all the answers

    How does the duration of action of naltrexone compare to naloxone?

    <p>Naltrexone has a longer duration of action</p> Signup and view all the answers

    Which of the following properties does naloxone NOT exhibit?

    <p>Morphine-like properties</p> Signup and view all the answers

    Which statement accurately describes naltrexone?

    <p>It can be taken orally and has a prolonged effect</p> Signup and view all the answers

    What is one key distinction between naloxone and naltrexone?

    <p>Naloxone acts quickly, whereas naltrexone has a longer duration of action</p> Signup and view all the answers

    What is the primary effect of inhibiting T-type Ca2+ channels?

    <p>Decreased neuronal excitability</p> Signup and view all the answers

    Which of the following is NOT a medication used in the context of epilsepy treatment?

    <p>Nifedipine</p> Signup and view all the answers

    Which mechanism is primarily involved in the action of Phenobarbital?

    <p>Enhancement of GABA activity</p> Signup and view all the answers

    What is a common side effect of long-term use of Primidone?

    <p>Psychiatric disturbances</p> Signup and view all the answers

    In what clinical scenario would inhibition of T-type Ca2+ channels be particularly beneficial?

    <p>Generalized absence seizures</p> Signup and view all the answers

    What is the primary mechanism of action for Carbamazepine?

    <p>Use-dependent blockade of Na+ channels</p> Signup and view all the answers

    How does the structural relationship of Carbamazepine affect its classifications?

    <p>It is structurally related to tricyclic antidepressants</p> Signup and view all the answers

    What effect does the mechanism of action of Carbamazepine have on neuron behavior?

    <p>Reduces cell excitability</p> Signup and view all the answers

    Which of the following is NOT a characteristic of Carbamazepine?

    <p>It is chemically related to benzodiazepines</p> Signup and view all the answers

    Which statement accurately describes the action of Carbamazepine on sodium channels?

    <p>It has a use-dependent blockade effect</p> Signup and view all the answers

    What characterizes Stage I of anaesthesia?

    <p>Patient experiences loss of sensation but remains alert.</p> Signup and view all the answers

    During which stage of anaesthesia does CNS excitation occur?

    <p>Stage II: Excitement</p> Signup and view all the answers

    Which of the following is NOT a characteristic of Stage II anaesthesia?

    <p>Loss of sensation</p> Signup and view all the answers

    What happens to blood pressure during Stage II of anaesthesia?

    <p>It may become irregular.</p> Signup and view all the answers

    Which stage of anaesthesia is characterized by a combination of alertness and loss of sensation?

    <p>Stage I: Analgesia</p> Signup and view all the answers

    What is the primary mechanism of action of zolpidem?

    <p>Binding to the BZ receptor family</p> Signup and view all the answers

    Which neurotransmitter does zolpidem primarily affect in its action?

    <p>GABA</p> Signup and view all the answers

    What effect does zolpidem have on neuronal activity?

    <p>Facilitation of GABA-mediated inhibition</p> Signup and view all the answers

    Zolpidem is classified as which type of drug?

    <p>Hypnotic</p> Signup and view all the answers

    Which of the following best describes zolpidem's binding specificity?

    <p>Selective binding to a subset of BZ receptors</p> Signup and view all the answers

    Study Notes

    Central Nervous System (CNS)

    • The CNS consists of the brain and spinal cord
    • It integrates information received from, and coordinates and influences the activity of, all parts of the bodies of bilaterally symmetric animals

    Drugs Acting on CNS

    • Analgesics
      • Relieve pain
      • Two main groups:
        • Opioid (Narcotic) Analgesics:
          • Most powerful
          • Relieve pain except itching
          • Can produce addiction
          • Examples: Morphine and codeine
        • Non-opioid Analgesics (analgesics- antipyretics):
          • Mild analgesics
          • Effective for certain types of pain (e.g., headache, toothache)
          • Not addictive
          • Example: NSAIDs (e.g., salicylates, paracetamol)
    • Narcotic Analgesics
      • Derived from opium alkaloids
      • Few are used clinically
      • Example: Morphine (8-15mg by injection)

    Pharmacological Actions of Morphine (CNS)

    • Centers Depressed by Morphine
      • Cortical pain center
      • Respiratory center
      • Cough center
      • Inhibition of the polysynaptic spinal reflexes
      • Inhibition of the vasomotor center (in large doses)
    • Centers Stimulated by Morphine
      • Vomiting center (CTZ in medulla) leading to nausea and vomiting
      • Occulomotor center
      • Stimulation of monosynaptic spinal reflexes (stretch reflex)
      • Release of antidiuretic hormone (ADH) from the posterior pituitary
      • Stimulation of cardiovagal center leading to slow and full pulse
    • Opioid Receptors
      • Several types (mu (μ), kappa (к), delta (δ))
      • Found in the nervous system and other tissues
      • Mu (μ) receptors: Supraspinal analgesia, euphoria, sedation, respiratory depression, physical dependence, constipation, miosis
      • Kappa (к) receptors: Spinal analgesia, miosis, sedation
      • Delta (δ) receptors: Supraspinal analgesia

    Tolerance

    • Failure of responsiveness to a usual dose of the drug
    • Develops to the analgesic and respiratory depressant actions of Morphine after 10-14 days

    Therapeutic Uses of Morphine

    • Powerful analgesic for severe pain
    • Pre-anesthetic medication (10-15mg subcutaneously or IM one hour before general anesthesia)
    • Alleviating dyspnea
    • Certain cases of severe cough (e.g., cancer of the bronchial tree)
    • Certain cases of severe diarrhea (after removing the poison causing the diarrhea)

    Codeine (Methyl Morphine)

    • Less potent
    • Produces constipation
    • Nausea and vomiting are less
    • Less addiction
    • Uses: cough suppressant, analgesic with aspirin and paracetamol

    Synthetic Morphine Derivatives

    • Heroin (Diacetylmorphine)
    • Pethidine
    • Fentanyl
    • Methadone
    • Loperamide (Imodium) and diphenoxylate

    Opioid Antagonists

    • Nalorphine (partial agonist at mu receptors, partial antagonist at delta and kappa receptors)
    • Naloxone (pure antagonist at all opioid receptors)
    • Naltrexone (longer duration of action than naloxone)
    • Therapeutic Uses: Treatment of acute morphine poisoning. Diagnosis of opium addiction.

    Sedative-Hypnotic Drugs

    • Benzodiazepines (BZs): most widely used anxiolytic drugs
      • Mechanism of Action: Potentiate GABA-ergic inhibition, increasing GABA receptor affinity for GABA, leading to enhanced hyperpolarization and neuronal inhibition
      • Pharmacological Actions: Reduction of anxiety, sedation, induction of sleep, muscle relaxation, anticonvulsant effects
      • Classification: Short-acting (triazolam), Intermediate-acting (alprazolam), Long-acting (diazepam)
    • Zolpidem
      • Mechanism of action: Binds selectively to a subset of BZs receptors, facilitating GABA-mediated neuronal inhibition
    • Barbiturates
      • Non-selective CNS depressants, ranging from sedation to hypnosis and unconsciousness
      • Mechanism of action: Facilitate GABA action at multiple sites, activating GABA receptors and prolonging chloride channel opening, increasing neuronal membrane hyperpolarization

    CNS Stimulants

    • Stimulation of CNS can be produced in humans by substances with few clinical uses, but some are drugs of abuse
    • Categories: Convulsants and respiratory stimulants, Psychomotor stimulants, Psychotomimetic drugs (hallucinogens)
    • Examples of analeptics: Nikethamide, Doxapram

    Methylxanthines

    • Include theophylline (tea), theobromine (cocoa), and caffeine (highest concentration in coffee, tea, cola drinks, chocolate, candy)
    • Mechanism of action: Translocation of extracellular calcium, inhibition of phosphodiesterase leading to increased cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP)
    • Therapeutic Uses: Combination with salicylates to relieve simple headache, with ergotamine to relieve migraine, stimulate depressed CNS in alcohol ingestion, bronchial asthma, biliary colics, congestive heart failure, cardiac edema

    Anti-Epileptic Drugs

    • Carbamazepine: Use-dependent blockade of Na+ channels, suppressing repetitive neuronal firing, reduces propagation of abnormal impulses, attenuates action and release of glutamate
    • Phenytoin (diphenylhydantoin): Use-dependent blockade of Na+ channels, blockade of L-type Ca2+ channels, potentiation of GABA action at GABAA receptors
    • Lamotrigine: Use-dependent inhibition of neuronal Na+ channels, interferes with synthesis of glutamate and aspartate, reduces glutamate release (possibly through inhibition of voltage-sensitive Ca2+ channels)
    • Sodium valproate: Use-dependent blockade of Na+ channels, potentiation of GABA by enhanced synthesis and release (with reduced degradation), attenuation of the excitatory action of glutamate

    General Anesthetics

    • General anaesthesia: state of loss of sensation, controllable reversible loss of consciousness, skeletal muscle relaxation
    • Stages: I (analgesia), II (excitement), III (surgical anesthesia), IV (medullary paralysis)
    • Classification: Inhaled volatile agents (hydrocarbons), IV anesthetic drugs

    Local Anesthetics

    • Definition: Agent that interrupts pain impulses in a specific region without loss of consciousness
    • Mechanism of action: Block nerve conduction by interacting directly with receptors on neuronal Na+ channels, inhibiting Na+ ion influx; impairing propagation of action potential
    • Factors affecting onset, intensity, and duration: Lipid solubility (lipophilic more potent), Protein binding (higher binding = longer action), pKa (pH at which 50% is ionized; closer pH and pKa = faster onset)

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    Drugs Acting On Central Nervous System PDF

    Description

    Explore the intricate workings of the central nervous system as well as the effects of various drugs that act upon it, focusing on analgesics. This quiz covers the classification of analgesics, including opioid and non-opioid types, with specific emphasis on their pharmacological actions. Test your knowledge on the impact of these substances on the brain and spinal cord.

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