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CNS Pharma > Slides 3 > Flashcards

Slides 3 Flashcards

1
Q

What is the Tolerance and physical dependence of the Opioids?

A

Tolerance: Gradual loss in effectiveness due to repeated administration of morphine (and others).
= To reproduce the original response, a larger dose is needed.

• Along with tolerance, physical dependence develops.

Physical dependence: A characteristic withdrawal or abstinence syndrome when a drug is stopped or an antagonist is administered

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2
Q

The mechanism of physical dependence is poorly understood, but may be due to any of the following:

A

1) Down regulation of μ receptors.

2) δ opioid receptors function as an
independent component in the maintenance of tolerance.

3) Receptor uncoupling: a dysfunction of structural interactions between the μ receptor and G proteins, second messenger systems, and their target ion channel.

4) NMDA type glutamate receptor, because its antagonist ketamine
can block the development of tolerance.

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3
Q

Organ System CNS Effects of Opioids:

A

1) Analgesia: Sensory and affective (emotional) components.

2) Euphoria: After IV administration of
morphine, patients or users experience a pleasant floating sensation with lessened anxiety or distress.

• Sometimes dysphoria occurs, which is an unpleasant state characterized by restlessness and malaise

3) Sedation: Drowsiness and clouding of mentation, with little or no amnesia.

• Sleep is induced more in the elderly than the young, but the patient is easily aroused from this sleep.

4) Respiratory depression: They inhibit brainstem respiratory center = Increase in alveolar PCO2 and depressed response to a carbon dioxide challenge.
5) Cough suppression: may lead to accumulation of secretions in the airway with obstruction and atelectasis.
6) Miosis: Constriction of the pupil even in highly tolerant addicts.
7) Truncal rigidity: Results from an action at supraspinal level.
8) Nausea and vomiting
9) Temperature

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4
Q

Organ System Peripheral Effects of Opioids in the Cardiovascular system?

A

1) Most opioids produce bradycardia.
2) Meperidine (pethidine) has antimuscarinic action and can produce tachycardia.
3. Hypotension due to vasodilation (attributed to depression of the vasomotor center and release of histamine).

• Hypotension is especially important in the stressed heart and in the presence of hypovolemia.

4) Cerebral vasodilation is associated with respiratory depression and accumulation of CO2 leading to increased cerebral blood flow and elevation in intracranial pressure.

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5
Q

Organ System Peripheral Effects of Opioids in the GIT ?

A

1) Constipation as a result of an effect on the enteric nervous system and CNS.

2) Stomach motility decreases but tone
increases and gastric acid secretion decreases.

3) Small intestine tone is increased but the amplitude of nonpropulsive contrations is markedly decreased.

4) Large intestine propulsive contractions decrease but tone is increased = delays the
passage of fecal mass and allows increased absorption of water = constipation (is the basis for their use in treatment of diarrhea).

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6
Q

Organ System Peripheral Effects of Opioids in the Biliary tract?

A
  1. Contract biliary smooth muscle = biliary colic.
  2. Contraction of the sphincter of Oddi = reflux of biliary and pancreatic secretions and elevated plasma amylase and lipase levels.
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7
Q

Organ System Peripheral Effects of Opioids in the Uterus?

A

• May prolong labor.

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8
Q

Organ System Peripheral Effects of Opioids in the Renal system?

A
  1. Depression of renal function due to reduction in renal blood flow.
  2. Antidiuretic effect.
  3. Enhance renal tubular sodium reabsorption.
  4. Ureteral, bladder and sphincter tone are increased = urinary retention.

• Renal colic caused by a renal stone is made worse.

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9
Q

Organ System Peripheral Effects of Opioids in the Neuroendocrine?

A

Stimulate the release of ADH, prolactin, somatotropin but inhibit the release of LH.

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10
Q

Organ System Peripheral Effects of Opioids in the Pruritus?

A

Flushing and warming of the skin, sweating and itching at therapeutic doses probably due both to central effect and release of histamine.

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11
Q

What are the Therapeutic Uses of Opioids

A
  1. Analgesia: Severe, constant pain is usually relieved by opioids; whereas sharp, intermittent pain is NOT effectively controlled.
  • Effective for pain of cancer.
  • May make the pain of renal and biliary colic worse (increase smooth muscle tone)
  1. Acute pulmonary edema:
  • Reduce anxiety by reducing perception of the shortness of breath.
  • Reduction of preload and afterload.
  • Particularly useful for pain of MI associated with pulmonary edema.
  1. Cough suppression at doses lower than those needed to produce analgesia.
  2. Diarrhea:
  • Can control all kinds of diarrhea.
  • Diarrhea due to infection should be treated with the appropriate antibiotic.
  1. Shivering: meperidine has the most
    pronounced reduction of shivering through an action on subtypes of α2
    adrenoceptors.
  2. Anesthesia: as premedications and
    intraoperatively to reduce pain.
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12
Q

What are the Routes of administration for the Opioids?

A
  1. IV
  2. PO
  3. PR
  4. Transdermal
  5. Intranasal
  6. buccal
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13
Q

What are the Adverse Effects of the Opioids?

A
  1. Behavioral restlessness, tremulousness, and hyperactivity.
  2. Respiratory depression.
  3. Nausea and vomiting.
  4. Increased intracranial pressure
  5. Postural hypotension.
  6. Constipation
  7. Urinary retention.
  8. Itching and urticaria.
  9. Tolerance and dependence:
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14
Q

Explain the following Tolerance in the Opioids:

When it Begins , Its Development doses , the degree of tolerance can be , and what it can affect

A
  • Begins with the first dose but becomes clinically manifest after 2-3 weeks of frequent exposure to ordinary doses.
  • Develops most readily with large doses given at short intervals, and is minimized by giving small doses with long intervals.
  • The degree of tolerance can be as great as 35-fold.

• Can affect analgesic, sedative and respiratory depressant effect; in addition to antidiuretic, emetic and hypotensive effect but NOT miotic,
convulsant and constipating actions

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15
Q

Fill in the Blank :

• Tolerance may develop to agents with ___, but to a lesser extent than to _____.

A

Mixed agonist/antagonist effect; agonists.

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16
Q

True or False:
The rates at which tolerance appears and disappears, as well as the degree of tolerance, may differ among different opioids and among
individuals using the same drug.

A

True

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17
Q

True or False:
Tolerance does develop to the antagonist action of mixed agents or to those of pure antagonists.

A

False

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18
Q

What is Cross-tolerance (Explain in detail) ?

A

Characteristic of opioids (for
those with pure μ receptor agonist activity primarily).

• It affects analgesic, euphorient, sedative, and respiratory depressant actions; which can be
partial or incomplete.

• This led to the concept of “opioid rotation” for treatment of cancer pain.

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19
Q

True of false:

• Ketamine (NMDA-receptor antagonist)
improves opioid tolerance

A

True

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20
Q

True of false:

The use of drugs with δ receptor antagonist action and μ receptor agonist action may produce more tolerance.

A

False

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21
Q

What are the signs and symptoms of withdrawal in the Physical dependence?

A

Rhinorrhea, lacrimation, yawning, chills, piloerection (goosebumps), hyperventilation, hyperthermia, mydriasis, muscular aches, vomiting, diarrhea, anxiety, and hostility.

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22
Q

What is used to suppress these signs and symptoms of the Physical dependence?

A

Administration of an opioid

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23
Q

What does The time of onset, intensity and duration of

abstinence syndrome depend on in the Physical dependence?

A

depend on the drug used and its half-life.

24
Q

When does withdrawal signs usually start With morphine and heroin in the Physical dependence?

A

withdrawal signs usually start 6-10 hours after the last dose, peaks in 36-48 hours, and most of the effects
gradually disappear by the 5th day.

25
Q

When does withdrawal signs usually start With meperidine in the Physical dependence?

A

withdrawal subsides in 24 hours.

26
Q

When does withdrawal signs usually start With methadone in the Physical dependence?

A

several days are needed to reach the peak, but it may last up to 2 weeks, and is associated with less intense immediate syndrome, and this is the basis for its use to
treat heroin addicts.

27
Q

What occurs After abstinence syndrome subsides?

A

tolerance also disappears, but craving (ملحة رغبة (for

opioids may persist for many months.

28
Q

write the times that A transient explosive syndrome – antagonist precipitated withdrawal occurs , peaks , and subsides ?

A

occurs within 3 min, peaks in 10-20 min and subsides after 1 hour.

29
Q

What happens In case of mixed agents?

A

withdrawal syndrome occurs after repeated administration and sudden withdrawal but is different: anxiety, loss of appetite and weight, tachycardia, chills,
increase in body temperature and abdominal cramps

30
Q

Explain the Psychologic dependence of the Opioids:

A
  • After IV administration, euphoria, indifference to stimuli and sedation tend to promote their compulsive use.
  • Addicts experience an abdominal effect similar to intense sexual orgasm.
  • These factors constitute the primary reasons for opioid abuse liability and are strongly reinforced by development of physical dependence.
31
Q

What are the Contraindications And Cautions of the Opioids?

A
  1. Use of pure agonist + weak partial agonist may diminish analgesia.
  2. May increase intracranial pressure in patients with head injury = Death.
  3. Use in pregnancy = physical dependence in fetus followed by withdrawal syndrome after delivery.
  4. Patients with impaired pulmonary function = acute respiratory failure.
  5. Impaired renal and/or hepatic function = prolong half-life of elimination.
  6. Addisons’s disease and hypothyroidism = prolonged and exaggerated response.
32
Q

What happens when a drug-group of Sedative-hypnotics Interact with Opioids ?

A

Increased central nervous system depression , particularly respiratory depression

33
Q

What happens when a drug-group of Antipsychotic tranquilizers Interact with Opioids ?

A

Increased sedation. Variable effects on respiratory depression. Accentuation of cardiovascular effects (anti-muscarinic and a-blocking actions)

34
Q

What happens when a drug-group of MAO inhibitors Interact with Opioids ?

A

Relative contraindication to all opioid analgesics because of the high incidence of the hyperpyrexic coma; hypertension has also been reported

35
Q

Of the other drug-groups is Tramadol, explain its effects and what exactly its used for :

A
  • Centrally acting analgesic.
  • It is a weak μ receptor agonist – partially antagonized by naloxone.
  • Adverse effects include seizures, nausea, dizziness, serotonin syndrome
  • No significant effects on respiration or cardiovascular system.
  • Can be used as adjunct with pure agonists in treatment of chronic neuropathic pain.
  • It has a weak dependence potential if used over weeks to months. There is a higher risk in drug abusers and Medical staff.
36
Q

Name the receptors which the Naloxone, Naltrexone, Nalmefene have high affinity for :

A

μ receptors

37
Q

Name the receptors which the Naloxone, Naltrexone, Nalmefene have low affinity for :

A

δ and κ receptors

38
Q

How is Naloxone given , what is its duration of action, and what is its major metabolite?

A

usually given by injection and have a
short duration of action (1-2 hours). The major
metabolite is the glucuronide conjugate.

39
Q

When is Naltrexone well absorbed , what is its half-life and what is its duration of action

A

is well absorbed after oral administration but may undergo first pass metabolism. Its half life is ~ 10 hours and duration of action up to 48 hours.

40
Q

What is Nalmefene’s half-life?

A

Its half life is ~ 8-10 hours.

41
Q

Of the Opioid Antagonists we have the Pharmacodynamics, write what you know about these

A
  • The are inert in the absence of an agonist.
  • Naloxone when given to a morphine addict, it completely and dramatically reverses the opioid effects within 1-3 minutes.
  • It normalizes respiration, level of consciousness, pupil size, bowel activity and awareness of pain.
  • In dependent subjects who appear normal while taking opioids, they precipitate an abstinence syndrome.
  • Major application of naloxone is in opioid overdose.
  • Longer-acting antagonists are used in addicts treatment programs.
  • No tolerance to their action occurs.
42
Q

of the Opioid Mixed Agonist-Antagonist we have Buprenorphine, write what you know about it

A

• Long-acting derivative.
• It is a partial μ-receptor agonist (low
intrinsic activity) and an antagonist at the δ and κ receptors.
• It can antagonize the action of more
potent μ agonists such as morphine.
• Slowly dissociates from μ receptors.
Thus, it is resistant to naloxone reversal.
• It is as effective as methadone for the
management of opioid withdrawal and
detoxification.
• In contrast to methadone, high-dose
administration of buprenorphine results in a μ-opioid antagonist action, limiting its analgesia and respiratory depression.
• Can depress respiration if combined by CNS depressants, or if given IV.
• Psychotomimetic effects, with
hallucinations, nightmares, and anxiety, have been reported.
• Undergoes first-pass metabolism.
• May be administered sublingual.

43
Q

of the Opioid Mixed Agonist-Antagonist we have Nalbuphine, write what you know about it

A
  • Nalbuphine is a strong κ-receptor agonist and a partial μ-receptor antagonist.
  • It is given parenterally.
  • Respiratory depression may be resistant to naloxone reversal due to its greater affinity for the receptor than naloxone.
44
Q

Sedation is less frequent with:

A

1) Meperidine

2) Fentanyl

45
Q

Which drugs are used for cough suppression?

A

1) Codeine

2) Dextromethorphan

46
Q

What is a sign of opioid overdose or abuse?

A

Miosis

47
Q

Miosis is mediated by ___, and is blocked by:

A

Parasympathetic pathways;

1) Opioid antagonists
2) Atropine

48
Q

What does truncal rigidity do?

A

It reduces thoracic compliance and interferes with ventilation.

49
Q

How can truncal rigidity be overcome?

A

By opioid antagonists

50
Q

How do opioids cause nausea and vomiting?

A

By stimulation of the brainstem chemoreceptor- trigger zone (CRTZ).

51
Q

What does the brainstem chemoreceptor- trigger zone (CRTZ) contain?

A

A vestibular component

52
Q

Hyperthermia is produced by __, while Hypothermia is produced by ___.

A

μ receptor agonists; κ receptor agonists

53
Q

What can lead to postural hypotension?

A

1) Bradycardia

2) Hypovolemia

54
Q

Where do opioid receptors exist in high density?

A

In the GIT

55
Q

What is the mechanism of action for Tramadol?

A

1) Predominantly blockade of serotonin reuptake.

2) Inhibits norepinephrine reuptake

CNS Pharma (7 decks)

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