ANALGESICS - DETAILS. 106 good questions, nicely answered!

What is the role of Naltrexone in maintenance therapy for addicts?

Naltrexone is oral and long acting, used in maintenance therapy in treatment programs for addicts. It blocks the euphoric effects of opioids, resulting in loss of the desire to take the drug.

What is the dosage and administration method for Naloxone in emergencies?

Naloxone is administered I.V and is short acting, therefore used in emergencies at a dosage of 0.1 – 0.4mg I.V.

When should Naltrexone be given to avoid withdrawal syndrome?

Naltrexone should be given after complete detoxification; otherwise, it would precipitate a withdrawal syndrome.

What is one use of Naloxone related to opioid toxicity?

Naloxone is used for acute opioid toxicity. It is repeated as necessary to avoid relapse into coma since its duration of action is shorter than that of opioids.

What are the advantages of partial opioid agonists over pure agonists?

Less addiction.
Respiratory depression is not increased by increasing the dose (ceiling effect) due to their antagonist effect.

How does Naloxone help in cases of asphyxia neonatorum?

In asphyxia neonatorum due to morphine administration during labour, Naloxone reverses respiratory depression in the newborn.

What is Diacetylmorphine converted to in the CNS?

Diacetylmorphine is converted to Morphine in the CNS.

What is Buprenorphine classified as, and how does it compare to Morphine?

Partial opioid agonist.
Long acting and more potent than Morphine.

Describe the onset and duration of Heroin and its implications.

Heroin has a rapid onset as it crosses the Blood-Brain-Barrier better than Morphine. Its short duration increases the risk of drug abuse and is not used clinically in most countries.

How does Pethidine differ from Morphine in terms of potency?

Pethidine is less potent compared to Morphine.

What is Methadone used for in opioid addiction treatment?

Methadone is used for the Treatment of Opioid addicts (Detoxification and maintenance). It is orally active with long duration of action. Gradual withdrawal of Methadone is associated with less severe and smoother withdrawal symptoms.

What are the characteristics of Fentanyl in terms of potency and duration?

Fentanyl is more potent than Morphine with rapid onset and short duration.

How does Methadone function as an analgesic?

Methadone serves as an Analgesic with efficacy equal to Morphine in severe chronic pain. It is orally active with long duration of action, making it effective for pain management.

What are the spasmogenic effects of Pethidine compared to Morphine?

Pethidine is less spasmogenic, causing less biliary spasm, less constipation, and less urine retention due to its short duration of action.

What are the symptoms of acute morphine toxicity?

Symptoms include coma, respiratory depression, and pin-point pupil.

What are the uses of Fentanyl as an analgesic and in anesthesia?

Analgesic in severe pain.
Anaesthesia (safe in cardiovascular surgery).
Combined with Droperidol (neuroleptic) to induce neurolept-analgesia or neurolept-anaesthesia.

How does Pethidine affect respiratory depression in neonates?

Pethidine causes less respiratory depression in neonates due to its short duration of action.

Why is Pethidine preferred during labor?

Pethidine does not delay labor and is preferred during labor with less risk of Asphyxia neonatorum.

How is premedication administered before an operation?

Premedication is administered by subcutaneous or intramuscular injection, up to 10 mg, 60–90 minutes before operation. For a child, by intramuscular injection, 150 micrograms/kg Patient controlled analgesia (PCA).

What is the treatment for acute morphine toxicity?

Treatment involves:

Support respiration.
Opioid antagonist: Naloxone I.V, repeated when necessary, an antidote.
Gastric lavage.

What is the initial dosing for a child aged 2–12 years?

CHILD 2–12 years initially 200 micrograms/kg every 4 hours.

What atropine-like actions does Pethidine have?

Pethidine has atropine-like actions, including dry mouth, blurring of vision, and tachycardia.

What is the dosing for myocardial infarction?

Myocardial infarction is treated by slow intravenous injection (2 mg/minute), 10 mg followed by a further 5–10 mg if necessary. For elderly or frail patients, reduce dose by half.

How often should a child aged 12–18 years receive their dose?

CHILD 12–18 years initially 2.5–10 mg every 4 hours.

What is the initial dosing for acute pain by subcutaneous injection?

Subcutaneous injection is not suitable for oedematous patients. It is used for acute pain management.

Describe the dosing for acute pulmonary oedema.

Acute pulmonary oedema is treated by slow intravenous injection (2 mg/minute) 5–10 mg. For elderly or frail patients, reduce dose by half.

What is the method of administration mentioned?

By slow intravenous injection.

What are the administration routes for Morphine and its metabolism characteristic?

Morphine can be administered via IV, IM, SC, and Oral routes. It undergoes extensive first-pass metabolism.

How is acute pain managed by intramuscular injection in elderly or frail patients?

Initially 10 mg, but for elderly or frail patients, 5 mg every 4 hours (or more frequently during titration) adjusted according to response.

How is chronic pain managed according to the document?

Chronic pain is managed by mouth or by subcutaneous injection or by intramuscular injection. Initially 5–20 mg every 4 hours, adjusted according to response. By rectum, initially 15–30 mg every 4 hours, adjusted according to response.

What is the initial dosing for neonates with acute pain?

Neonates are initially given 100 micrograms/kg every 6 hours, adjusted according to response.

What is the classification of Codeine under opioid analgesics?

Codeine is classified as a moderate opioid analgesic and is used as an antitussive.

What is the initial dose for elderly or frail patients?

Initially 2.5 mg (reduce dose in ELDERLY or frail) every 4 hours (or more frequently during titration).

How is Morphine used in anesthesia, and why is it considered safer?

Morphine is used in anesthesia and is considered safer in cardiovascular surgery.

What is the initial dosing for a neonate?

NEONATE initially 40–100 micrograms/kg every 6 hours.

What are the pure agonists classified under strong opioid analgesics?

Pure agonists under strong opioid analgesics include:

Morphine
Fentanyl
Methadone
Pethidine
Heroin

How is Propoxyphene classified and used?

Propoxyphene is classified as a weak opioid analgesic. It is taken orally and is combined with Paracetamol for mild to moderate pain.

What is the dosing for a child aged 1–6 months with acute pain?

A child aged 1–6 months is initially given 100–200 micrograms/kg every 6 hours, adjusted according to response.

How is the dosing for a child aged 1–6 months structured?

CHILD 1–6 months initially 100–200 micrograms/kg every 6 hours.

What can result from the interaction of opioids with other CNS depressants?

Opioids can cause additive CNS depression when combined with other CNS depressants such as sedative-hypnotics, alcohol, antidepressants, and antipsychotics.

Which partial agonist is mentioned under strong opioid analgesics, and what are its characteristics?

Buprenorphine is a partial agonist under strong opioid analgesics. It is less addictive and causes less respiratory depression.

Describe the use of Morphine in myocardial infarction and acute pulmonary edema.

In myocardial infarction and acute pulmonary edema, Morphine decreases pain and anxiety, acts as an arteriolodilator and venodilator, reducing venous congestion and pulmonary edema.

How is acute pain managed in children aged 6 months to 2 years?

Children aged 6 months to 2 years are initially given 100–200 micrograms/kg every 4 hours.

What are the effects of combining Pethidine with MAOIs?

Combining Pethidine with MAOIs results in hyper-pyrexic coma, respiratory depression, and convulsions.

What are the contraindications of opioids related to abdominal conditions?

Acute undiagnosed abdomen is a contraindication for opioids because they can mask pain. Biliary colic is another contraindication as opioids increase intra-biliary pressure and aggravate the colic.

What is the initial dosing for a child aged 6 months to 12 years?

CHILD 6 months–12 years initially 100–200 micrograms/kg every 4 hours, adjusted according to response.

What are some adverse effects of opioids related to sedation and dependence?

Sedation and narcosis.
Drug dependence.
Respiratory depression.
Nausea and vomiting.

How do opioids affect patients with head injuries?

Opioids cause respiratory depression leading to increased CO2, resulting in cerebral vasodilatation with increased intracranial tension, making head injury a contraindication.

What are the effects of opioids on the eyes and gastrointestinal system?

Miosis.
Constipation and urine retention.
Biliary spasm.

What are the therapeutic uses of opioids as analgesics?

Opioids are used as analgesics in:

Acute pain (trauma).
Chronic dull pain (visceral).
Post-operative pain and cancer pain.

Why are opioids contraindicated in bronchial asthma?

Opioids are contraindicated in bronchial asthma because they cause histamine release, which can exacerbate the condition.

Which opioids are used for anesthesia?

Opioids used for anesthesia include Morphine or Fentanyl.

What is the effect of stimulating the oculomotor nucleus by opioids?

Stimulation of the oculomotor nucleus produces miosis. This is one of the stimulatory effects of opioids.

How do opioids affect blood pressure and respiratory function in newborns?

Hypotension, itching, and bronchospasm (due to Histamine release).
Delay labor and Asphyxia neonatorum (Respiratory depression in the newborn).

What is the effect of opioids on patients with an enlarged prostate?

Opioids decrease motility of the bladder wall and cause urine retention, making them contraindicated for patients with an enlarged prostate.

How do opioids affect the CTZ?

Stimulation of CTZ by opioids produces nausea and vomiting. This is part of the stimulatory effects of opioids.

What diagnostic challenges can opioids cause?

Mask the diagnosis of acute abdomen (mask pain).

How do opioids help in myocardial infarction and acute pulmonary edema?

In myocardial infarction and acute pulmonary edema, Morphine decreases pain and anxiety, acts as an arteriolar and venodilator, and decreases venous congestion and pulmonary edema.

Why are extremes of age, hypothyroidism, and liver dysfunction contraindications for opioids?

Extremes of age, hypothyroidism, and liver dysfunction are contraindications due to decreased opioid metabolism, which can lead to adverse effects.

What are the inhibitory effects of opioids on the vasomotor centre?

The vasomotor centre is affected by opioids, causing venular and arterial dilatation.

Which opioids are used as antitussives?

Codeine and Dextromethorphan are used as antitussives.

What effects do Mu receptors mediate in opioids?

Mu receptors mediate most of the effects of opioids: Analgesia, Sedation, Euphoria, Dependence, Respiratory depression, inhibition of GIT motility.

What is the effect of opioids on smooth muscle tone and peristalsis?

Opioids increase smooth muscle tone but inhibit peristalsis, leading to constipation. This is a stimulatory effect.

What effects do Kappa receptors mediate in opioids?

Kappa receptors mediate spinal analgesia, sedation, and dysphoria.

How do opioids affect respiration?

Opioids cause respiratory depression.

How do opioids affect the release of ADH?

Stimulation of the release of ADH is one of the stimulatory effects of opioids.

How do opioids activate receptors and what is the result?

Opioids activate receptors directly or through endogenous opiopeptides, resulting in neuronal inhibition by:

Inhibition of calcium entry, decreasing release of excitatory neurotransmitters e.g. Substance-P.
Stimulation of potassium outflux, causing hyperpolarization of neuronal membrane.

Why are Loperamide or Diphenoxylate used as anti-diarrheals instead of Morphine?

Loperamide or Diphenoxylate are used as anti-diarrheals because they are less addictive than Morphine.

What is the effect of opioids on the cough centre?

Opioids cause inhibition of the cough centre.

What types of receptors are mu, kappa, and delta in the mechanism of action of opioids?

Mu, kappa, and delta are G-protein coupled receptors present in the CNS and periphery (e.g., GIT). They play a role in the mechanism of action of opioids.

What are the effects of histamine release due to opioids?

Histamine release produces hypotension, itching, and bronchospasm. These are stimulatory effects of opioids.

What are opioid/narcotic analgesics?

Drugs that mimic the effect of Morphine. They include plant-derived, synthetic, and endogenous sources. Plant: Morphine, Codeine. Synthetic: Fentanyl, Methadone, Pethidine, Heroin. Endogenous: Endorphins, Encephalins, Dynorphins.

How do opioids affect the uterine muscle?

Opioids cause inhibition of uterine muscle.

How do opioids affect pain perception and emotional response?

Opioids decrease pain perception and emotional response to pain by stimulating receptors in:

Afferent pain conducting fibers
Spinal cord (spinal analgesia)
Thalamus, brain stem, cerebral cortex (supra-spinal analgesia)
Limbic system

To which effects of opioids does tolerance develop?

Tolerance develops to all effects except constipation and miosis. This is part of the stimulatory effects of opioids.

Name five opioid analgesics listed.

Five opioid analgesics listed are:

Morphine
Codeine
Fentanyl
Methadone
Pethidine

What are the plant sources of opioid analgesics?

Morphine and Codeine are natural products of the Opium poppy. They are plant-derived sources of opioid analgesics, mimicking the effect of Morphine.

What is the role of the limbic system in the action of opioids?

The limbic system decreases the emotional response to pain and induces euphoria. Patients may still feel pain, but the feeling is not unpleasant.

What are the synthetic sources of opioid analgesics?

Synthetic sources include Fentanyl, Methadone, Pethidine, and Heroin. These drugs mimic the effect of Morphine and are classified as opioid analgesics.

What is Reye's syndrome associated with in children?

Reye’s syndrome is associated with encephalopathy and liver damage in children with fever due to viral infection.

What are the endogenous sources of opioid analgesics?

Endogenous sources include Endorphins, Encephalins, and Dynorphins. These are opiopeptides released in the body, acting on opioid receptors and producing Morphine-like effects.

What adverse effect is linked to an anti-platelet effect?

Increased bleeding tendency is linked to an anti-platelet effect.

What are the gastro-intestinal side effects mentioned?

Dyspepsia, gastritis, ulceration with risk of hemorrhage.
Due to direct irritant effect on the mucosa and decreased protective PGs.

What is the dosage for the anti-platelet effect?

The dosage for the anti-platelet effect is 150 (75 – 325) mg/day.

What causes renal damage (Analgesic nephropathy)?

Due to decreased renal vasodilator PGs.

What is the dosage for analgesic and antipyretic effects?

The dosage for analgesic and antipyretic effects is 300 mg, 1-2 tablets when necessary.

What is the antiplatelet effect of aspirin?

Inhibition of COX enzyme in platelets results in inhibition of TXA2 synthesis and inhibition of platelet aggregation.
Used for prophylaxis against CHF, ischemic attacks, myocardial infarction, and unstable angina.

What are the hypersensitivity reactions listed?

Asthma especially in asthmatics.
Aspirin diverts arachidonate metabolism from cyclo-oxygenase to lipoxygenase (Lox) pathway increasing chemotactic LTB4 and spasmogenic LTs.

What is the dosage for anti-inflammatory effects?

The dosage for anti-inflammatory effects is 4 grams/day.

How does hyper-uricemia occur in patients with Gout?

In low doses, competes with uric acid for excretion in renal tubules.

What is the anti-inflammatory effect of Acetyl Salicylic acid (Aspirin)?

Acetyl Salicylic acid decreases vasodilator PGE2 and PGI2, thus reducing the vasodilatation and edema of inflammation.

What is the mechanism of action of Acetyl Salicylic acid (ASA) or Aspirin?

Acetyl Salicylic acid (ASA) or Aspirin is the prototype of NSAIDs, inhibiting both COX-1 and COX-2 enzymes, hence inhibiting prostaglandins.

What is the anti-oxidant effect of Aspirin?

Aspirin has an anti-oxidant effect as a free radical scavenger. It is used for Rheumatic fever and Rheumatoid arthritis.

What are Cyclo-oxygenase (COX) enzymes responsible for?

Cyclo-oxygenase (COX) Enzymes are responsible for:

Conversion of Arachidonic acid to Prostaglandin (PG) and Thromboxane-A2 production.

Name two selective COX-2 inhibitors mentioned and their usage status.

Celecoxib and Rofecoxib (no longer used), Meloxicam (in use) are selective COX-2 inhibitors.

How does Aspirin relieve pain in disease conditions?

Aspirin relieves pain in many other disease conditions, providing therapeutic benefits beyond its anti-inflammatory and anti-oxidant effects.

What are the three types of Cyclo-oxygenase (COX) enzymes?

There are three types:

COX-1 present in tissues for production of protective PGs in GIT and Kidney.
COX-2 is inducible (formed during inflammation).
COX-3 in the CNS.

Describe the action of Paracetamol and its safety in PUD.

Paracetamol is an Analgesic-Antipyretic with no anti-inflammatory action, inhibits COX-3, hence it's safe in PUD.

What do you understand by NSAIDS (Non Steroids Anti-inflammatory Drugs)?

NSAIDS are Non Steroids Anti-inflammatory Drugs used to reduce inflammation and relieve pain. They are commonly used for conditions like arthritis and other inflammatory disorders.

What are the two main classifications of analgesics?

Non-Opioid analgesics: Used in mild to moderate pain.
- Non-Steroidal Anti-inflammatory drugs
- Paracetamol
Opioid analgesics: Used in moderate to severe pain.
- Morphine
- Synthetic Opioids.

What do you understand by Adjuvant therapy?

Adjuvant therapy is a treatment given in addition to the primary therapy to maximize its effectiveness. It is often used in cancer treatment to enhance the efficacy of the main treatment.

What effect do opiates have on Ca2+ influx and nociceptor action potentials?

Opiates decrease Ca2+ influx, leading to a decrease in the duration of nociceptor action potentials and a decreased release of transmitters.

What do you understand by Narcotic Analgesics therapy?

Narcotic Analgesics therapy involves the use of narcotic drugs to relieve severe pain. These drugs work by binding to opioid receptors in the brain to reduce the perception of pain.

What happens when nociceptors are activated?

Activation of nociceptors releases glutamate and neuropeptides from sensory terminals, depolarizing and activating projection neurons.

How do opiates affect the membrane of neurons?

Opiates hyperpolarize the membrane of neurons by activating K+ conductance.

What are the components of pharmacological management of pain?

NSAIDS
Narcotic analgesic
Adjuvants to Analgesics (neuro pain)

ANALGESICS - DETAILS

106 important questions on ANALGESICS - DETAILS