Focused Review Drugs

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Questions and Answers

Which of the following receptors are primarily associated with euphoria and pain relief?

Kappa (κ) receptors

Sigma (σ) receptors

Delta (δ) receptors

Mu (μ) receptors (correct)

What characterizes the metabolization of methadone compared to other opioids?

It has a long half-life and not converted into active metabolites. (correct)

It is metabolized primarily in the stomach.

It is rapidly converted into multiple active metabolites.

It is dependent on the enzyme CYP2D6 for its effects.

Which opioid is metabolized rapidly into morphine and has a half-life of approximately 30 minutes?

Methadone

Heroin (correct)

Codeine

Fentanyl

Which receptors are primarily involved in contributing to feelings of dysphoria?

Kappa (κ) receptors Signup and view all the answers

What is the main enzyme involved in the metabolization of codeine into morphine?

CYP2D6 Signup and view all the answers

What is primarily responsible for fentanyl's analgesic effects?

Only the parent drug without active metabolites Signup and view all the answers

Which of the following opioids is associated with inactive metabolites after liver metabolism?

Fentanyl Signup and view all the answers

Which receptor type is no longer considered part of the opioid system?

Sigma (σ) receptors Signup and view all the answers

Which opioid receptor is least associated with the emotional regulation of pain?

Sigma receptors Signup and view all the answers

What is a common side effect associated with mu (μ) receptor activation from opioid use?

Respiratory depression Signup and view all the answers

How does serotonin release affect pain transmission in the context of opioid action?

It inhibits the release of substance P. Signup and view all the answers

Which of the following is a major concern related to opioid use due to its effects on the CNS?

Respiratory depression affecting breathing rates Signup and view all the answers

Which opioid is metabolized to have long-lasting effects with a half-life of 36–48 hours?

LAAM Signup and view all the answers

What differentiates kappa (κ) receptors from mu (μ) receptors in terms of their effects?

Kappa receptors primarily induce sedation rather than euphoria. Signup and view all the answers

What effect does opioid use have on sex hormones?

Suppresses sex hormone levels in both sexes Signup and view all the answers

The phenomenon of miosis, or pupillary constriction, caused by opioids is believed to involve which mechanism?

Activation of opioid receptors affecting the parasympathetic nervous system Signup and view all the answers

Which CNS effect of opioids may initially lead to nausea and vomiting?

Excitation of the vomiting center Signup and view all the answers

Which receptors do opioids predominantly act upon to block incoming pain signals?

Mu, Delta, and Kappa receptors Signup and view all the answers

What type of sedative effect do opioids provide that can lead to drowsiness?

CNS depression leading to sedation Signup and view all the answers

Which of the following statements about opioid metabolites is true?

Opioids generally do not have significant effects from their metabolites. Signup and view all the answers

Which receptor is primarily implicated in the feeling of euphoria associated with opioid use?

Delta receptors Signup and view all the answers

Which of the following symptoms is NOT commonly associated with the psychological effects of opioids?

Decreased muscle tone Signup and view all the answers

What is the mechanism by which opioids induce dysphoria in first-time users?

Mediation by Sigma receptors Signup and view all the answers

What effect does reduced peristalsis have on the gastrointestinal system when opioids are used?

Fecal dehydration Signup and view all the answers

Which side effect does NOT develop tolerance when using opioids?

Constipation Signup and view all the answers

What is the likely reason behind decreased concentration in opioid users?

Induction of sleepiness Signup and view all the answers

How quickly does rapid tolerance to opioids develop with daily use?

8-10 days Signup and view all the answers

Which of the following is a direct effect of opioids on emotional pain?

Dulls emotional distress Signup and view all the answers

What happens to opioid consumption as tolerance develops?

It increases tenfold Signup and view all the answers

Which of the following describes the physiological effect caused by opioids that relates to digestion?

Decreased muscle tone Signup and view all the answers

What role do Cytochrome P450 enzymes play in opioid tolerance?

They increase in number, leading to faster clearance of opioids. Signup and view all the answers

How does pharmacodynamic tolerance primarily affect mu receptors?

They undergo downregulation or desensitization. Signup and view all the answers

What is the effect of cross-tolerance between opioids and alcohol?

Tolerance to one reduces sensitivity to the other. Signup and view all the answers

During opioid withdrawal, when do symptoms typically peak?

36-72 hours after the last use. Signup and view all the answers

Which of the following is a characteristic of physical tolerance to opioids?

It can develop within 2 weeks of daily use. Signup and view all the answers

What immediate withdrawal symptoms are likely to occur after the last opioid dose?

Restlessness, agitation, and yawning. Signup and view all the answers

What physiological changes may occur during opioid withdrawal?

Tearing, runny nose, and increased anxiety. Signup and view all the answers

Which aspect of opioid use contributes significantly to the development of physical tolerance?

Increased metabolism of opioids. Signup and view all the answers

What is a common withdrawal symptom that occurs after opioid cessation?

Intense cravings and muscle pain. Signup and view all the answers

Which receptor type is predominantly involved in producing analgesic effects from opioids?

Mu receptors. Signup and view all the answers

Study Notes

Mu (μ) Receptors

Main target of opiates like morphine and heroin
Responsible for pain relief, euphoria, and sedation
Can cause respiratory depression and dependence

Kappa (κ) Receptors

Contribute to pain relief, but effects are less intense than mu receptors
Can cause dysphoria (unease or discomfort) instead of euphoria
Associated with some hallucinatory effects in certain drugs

Delta (δ) Receptors

Play a role in modulating pain and mood
May contribute to reducing anxiety or depression, but less studied

Sigma (σ) Receptors

Originally thought to be part of the opioid system, now considered non-opioid
Associated with psychedelic effects and responses to some drugs like PCP

Opioids: Metabolization

Many opioids are inactive until metabolized in the liver
Rapid metabolization, except for some synthetic opioids with extended durations
Key Opioids and Metabolism:
- Heroin: Rapidly metabolized to morphine (active form), half-life ~30 minutes
- Codeine: Metabolized to morphine and other active metabolites, primarily by CYP2D6
- Methadone: Slow metabolism, prolonged effects, half-life 10-25 hours, primarily metabolized by CYP3A4 and CYP2B6; methadone itself is the primary active metabolite

Opioids: CNS Effects

Analgesic effects:
- Opioids block incoming pain signals in the spinal cord
- Increase activity in the periaqueductal gray area (PAG), which sends signals to the raphe nuclei
- Stimulate serotonin release, triggering enkephalins or dynorphins, blocking pain transmission to axons
Emotional regulation of pain:
- Opioids reduce aversive emotional experience of pain, mediated by opioid receptors in the limbic system and frontal lobe
CNS depression:
- Respiratory depression is a primary concern in overdose
- Cough suppression

Opioids: Effects on the Body

Eye effects: pupillary constriction (miosis)
Gastrointestinal effects:
- Reduced peristalsis (slower movement of material)
- Decreased muscle tone (further slowing digestion)
- Constipation, fecal dehydration
Psychological effects:
- Euphoria: mediated by Delta receptors, indirectly activating dopaminergic neurons projecting to the nucleus accumbens
- Dysphoria: can be chronic, associated with sigma receptors
- Decreased concentration: sedative effects lead to reduced mental alertness
- Dulling of emotional pain: mu receptors in the limbic system and frontal lobe mediate this effect

Opioids: Tolerance and Dependence

Tolerance development
- Effects such as respiratory depression and analgesia develop tolerance
Types of Tolerance:
- Intermittent use: sporadic use, minimal tolerance development
- Regular use: tolerance develops with extended time. Daily use, rapid development of tolerance (8-10 days), consumption increases significantly
Tolerance mechanisms:
- Pharmacokinetic: enzyme increase (Cytochrome P450 enzymes like CYP3A4, CYP2D6, CYP2B6) leading to faster clearance of the drug
- Pharmacodynamic: receptor changes (mu receptors primarily responsible for analgesia and euphoria undergo downregulation or desensitization with prolonged use); Delta and Kappa receptors can also experience changes
- Cross-tolerance: tolerance to one opioid can reduce sensitivity to other opioids

Opioids: Dependence

Withdrawal symptoms, including restlessness, agitation, yawning, fever, chills, deep sleep followed by cramps, limb twitching, and profuse sweating, peak symptoms (36-72 hours), ceases in 5-10 days.
Physical and psychological dependence
Harder to treat

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Description

Explore the types of opioid receptors including Mu, Kappa, Delta, and Sigma, and their roles in pain relief and effects. This quiz also covers the metabolization of opioids and their active forms. Test your understanding of these critical components in pharmacology and their implications on health.