Opiods Flashcards
What are opioids
These are narcotic analgesics
Where in the body are opioid receptors more concentrated?
Limbic system
Thalamus
Hypothalamus
Striatum
Reticular Activating System
Midbrain
Substantia Gelatinosa of spinal cord
Nerve plexus of intestines
What are the five species of opioid receptors?
Mu, Delta, Kappa, sigma, epsilon
What are the two general mechanisms of analgesic action
Supraspinal
Spinal
What are the sites of action of analgesics in the Supraspinal system
PeriAqueductal gray (found in the midbrain)
What are the sites of action of analgesics in the Spinal system
The site of action is receptors in the Substantia Gelatinosa region of the spinal cord (upper dorsal portion of spinal cord)
What are the general effects of morphine on the central nervous system?
Morphine has both depressive and stimulatory effects
What are the signs of depressive effects that morphine has on central nervous system?
Analgesia.
Sedation.
Mood changes.
Alveolar hypo ventilation
What are the stimulatory effects that morphine has on the central nervous system?
Pupillary constriction
Nausea and vomiting
Hyperactive spinal reflexes.
Convulsions
Why is morphine not a good anesthetic agent but a good analgesic?
This is because morphine and other. Agonist are selective analgesics because they can produce profile so with no effect on other sensory modalities i.e. unconsciousness.
True or false morphine is a complete anesthetic agent
False it is not a complete anesthetic agent. It has poor anesthetic properties.
How does morphine cause alveolar hypo ventilation?
This is a result of the direct action of morphine on respiratory centers in the brainstem.
The respiratory rate is diminished, and minute volume is reduced
When does the maximum respiratory effect of morphine occur with an IV dose versus an IM dose?
It occurs 5 to 10 minutes after an IV dose and between 30 and 60 minutes after an IM dose
True or false morphine is contraindicated in patients with respiratory insufficiency
True
In relation to the eyes, list one side effect of morphine
Pupillary constriction
Pinpoint pupils are the hallmark of an overdose of morphine
What causes miosis in morphine use?
Miosis is due to the stimulation of parasympathetic component of the third cranial nerve nucleus (Edinger- Westphal)
How does morphine cause, nausea and vomiting?
It directly stimulates the chemo receptor trigger zone at the Medulla
(Delayed SE, potentiated by ambulation)
What causes truncal rigidity with morphine administration?
Hyperactive spinal reflexes
Convulsions are usually a rare side effect of morphine when do they occur
With extremely high doses of morphine
What is the effect of morphine on the cardiovascular system?
It causes a dependent bradycardia by direct stimulation of the vagus nucleus however, it does not depress myocardial contractility
How can morphine cause orthostatic hypotension?
Morphine causes vasodilation of peripheral vessels, such as arteries and veins, and during the ambulatory patient orthostatic, hypertension can occur due to pooling of blood, in the more peripheral vessels from the vessels in the brain.
List two respiratory contraindications for morphine
Patients with asthma, or bronchitis, having an acute episode of bronchospasm
Why is morphine contraindicated in patients with asthma and bronchitis?
This is because morphine causes a histamine release which causes bronchoconstriction , and this can exacerbate bronchospasms experienced by patients with asthma and bronchitis
What is the effect of morphine on the physiology of the gastrointestinal tract?
Morphine stimulates, the smooth muscle of the G.I. tract but propulsive peristalsis is diminished and segmental tonic contraction is increased
What are the effects of morphine on the gastrointestinal tract?
Constipation.
Biliary colic in patients with gallbladder disease
How can morphine cause biliary colic in patients with gallbladder disease?
This is as a result of spasm of OD sphincter, and an increase in pressure in the biliary tree
How can you reverse the spasm of the gall bladder sphincter in patients with gall disease who are being treated with morphine?
This can be reserve first with administration of naloxone or nitroglycerin
Often times patients with gallbladder disease, who are being treated with morphine will get a sudden onset of pain, and that can be confused with acute myocardial ischemia which drug can relieve only morphine induced biliary colic, and which drug will relieve the pain of the morphine induced vary and the pain of myocardial ischemia
Naloxone will relieve morphine induced biliary colic
Nitroglycerin will relieve morphine induce, the biliary colic, and the pain of myocardial ischemia
What is the effect of morphine on the genito urinary tract?
It can cause spasm of the bladder, sphincter and lead to urinary retention
What is the effect of morphine on the intracranial pressure?
Morphine can cause hypercapnia, which can increase cerebral blood flow and cause rise and intracranial pressure in patients with intracranial space occupying lesions
Define tolerance
Tolerance to a drug is characterized by the need for increasing doses, to obtain the same therapeutic effect after repeated exposure
Tolerance to morphine is reversible when does sensitivity to therapeutic dose return to normal for a person with increased tolerance?
Returns to normal after an abstinence of one to two weeks
What is addiction?
Addiction is a state of psychological and physical dependence that manifest itself in the withdrawal syndrome
When do the signs of withdrawal of an opioid appear in long-term addict?
8hrs after the last dose
Peaks is 48-72 hours
Runs a 5-10 day course
What are the signs and symptoms of opioid withdrawal syndrome?
Lacrimation, rhinorrhea, diaphoresis, vomiting and diarrhea, incessant, yawning, goosebumps, dilated pupils, hypertension, tachycardia, abdominal cramps, muscle aches
Which drug is known to counteract the emetic effects of morphine, but potentiates, its analgesic, sedative and respiratory depressant effects
Phenothiazines (chlorpromazine)
True or false allergic reactions to morphine are very common
False
Wheels and itch at the site of injection are local reactions to histamine release, and should not be considered sign of true allergy
What is the difference between nociceptive and neuropathic pain?
Nociceptive pain is the results of stimulation of nose, receptors by noxious stimuli, whilst neuropathic pain is the result of dysfunction of the nervous system
What are the two afferent nerve fibers that conduct pain stimuli?
Small myelinated- A delta fibers : sharp pain
and
Unmyelinated C Delta fibers : dull pain
What is the oral dose of morphine?
5 - 20 mg every 4 hrs
What is the intramuscular dose of morphine?
0.1-0.2 mg/kg every 4 hrs
True or false morphine is particularly effective for sharp, superficial pain less effective for visceral pain
False
Morphine is particularly effective for visual pain and less effective for sharp superficial pain
What drug can you administer to reverse meiosis seen as a side effect of morphine administration?
Meiosis occurs in morphine administration due to stimulation of the Edinger Westfall nucleus, and can be reversed by using atropine
What could be the possible cause of morphine poor anesthetic effect?
Morphine is poorly, lipid soluble, and only a small fraction of a given dose, crosses the blood brain barrier to act as an opioid receptor
What is the main pathway for elimination of morphine?
Conjugation in the liver with glucuronic acid
Excretion of water soluble, metabolites by the kidneys
90% excreted in urine
10% excreted in bile and appears as faeces
How much more potent is diamorphine than morphine
Twice (x2)
Dimorphine is commonly used to treat what kind of pain and in want dose?
Dyspnoea associated with pulmonary edema at 2.5 - 10 mg
Which opioid produces the greatest degree of euphoria and subsequently, has become a drug of abuse?
Diamorphine
How much less potent is codeine to morphine?
10x less
What are the common uses of codeine?
Antitussive
Ant diarrhea
Hypnotic.
Anxiolytic
What is the dose given for IV fentanyl
1.5 µg per kilogram
What is the duration of analgesic action of fentanyl?
30mins
What is the use of Alfentanil
It is given in incremental doses to supplement inhalational anesthesia, or in a continuous infusion together with an intravenous anesthetic in total intravenous anesthesia
How much more potent is fentanyl than morphine and how much more potent is it than fentanyl?
Sufentanil is 100 times more potent than morphine and 10 times more potent than fentanyl 
Which opioid is widely used as an oral analgesic
Codeine
List 3 groups of analgesics
Acetominophen
NSAIDS
OPIOIDS
What are the 3 steps to pain management
Step 1: non-opioid: acetaminophen or NSAIDS
Step2: weak opioid: Codeine, Tramadol
Step 3 : strong opioid: Morphine, Oxycodone, Fentanyl
List two examples of Acetaminophen drugs
Tylenol
Panadol (paracetamol)
What type of pain is acetaminophen used for
Acute Mild pain
What is a side effect of acetaminophen
Liver toxicity in high doses
List 4 NSAIDS
Aspirin
Diclofenac
Ibuprofen
Naproxen
NSAIDS are used to manage what type of pain?
Mild- Moderate
What is the moa of NSAIDs
Cox 1 & Cox 2 inhibitor
Reducing pro inflammatory and prostaglandin synthesis
List 5 complications or side effects of NSAIDs
Gastric Ulcer
Decreased Renal Perfusion
Photosensitivity
Premature closure of ductus arteriosus in pregnancy
CI in dengue due to reduced platelet count
List 3 examples of oral opioids
Codeine
Oxycodone
Morphine
List 3 examples of parentéral opioids
Morphine
Hydromorphone
Fentanyl
Opioids are used in the management of what type of pain?
Moderate acute pain (oral)
Moderate- severe acute pain (parenteral)
What is the moa of opioids
Dampens nociceptive transmission between 1st and 2nd order neurons in the dorsal horn
List 8 SEs of opioids
(HECK OF A DREAM)
H- histamine release
E- emesis
C- CVS (hypotension)
D- depression of cough reflex, decreased GI motility, depression of CNS = analgesia
R- respiratory depression
E- euphoria
A- analgesia
M- miosis
List 7 Opioid Agonists
Codeine
Morphine
Oxycodone
Fentanyl
Remifentanil
Methadone
Pethidine
What is the dose given for Codeine
15-30mg PO
What is the dose given for Meperidine for postoperative shivering
20-25mg
Which drug is commonly used to treat post operative shivering
meperidine 20-25mg
What is the dose given for Morphine IM and IV
IM- 0.1-0.2mg/kg q4hr
IV- 0.2-0.3 mg/kg
What is the dose given for Fentanyl
2-3 micrograms/kg IV
What is the dose given for Pethidine
0.5-1mg/kg
List 3 opioids with a rapid onset of action
Fentanyl (<5mins)
Remifentanil (1-3mins)
Pethidine (<5mins)
What is the onset of action of Morphine?
5-10mins
What is the onset of action of Codeine?
30-60mins
What is the duration of action of Codeine?
4-6hrs
What is the duration of action of Morphine?
2-4hrs
What is the duration of action of Oxycodone (controlled release)?
8-12 hrs
What is the duration of action of Fentanyl?
0.5-1hr
What is the duration of action of Remifentanil
<10mins
What is the duration of action of Pethidine?
2-3hrs
What is the effect of codéine on BP
Significant decrease in BP
Why isn’t Meperidine commonly used for pain management?
Due to potential toxicity compared with other opioids
Contraindications for Meperidine
MAOI (antidepressant) use
What is the effect of Morphine on the CVS
Decreased BP
What are the main uses for Codeine
Post operative pain
Antitussive
Anti diarrheal
Anxiolytic
Morphine is mainly used to manage what type of pain?
Visceral Pain
(Less effective for sharp superficial pain)
What is the main side effect seen in Fentanyl with high doses?
Transient muscle rigidity
What is the effect of fentanyl on BP
No significant effect
What type of pain is Fentanyl used to manage?
Pain associated with minor surgery
High doses of what opioid is used to obtund the CVS effects of Laryngoscopy
Fentanyl
When is Remifentanil used ?
During induction and maintenance of anaesthesia
What is the effect of Remifentanil on BP
Reduces BP
What is the most common use for Meperidine?
Slow weaning programmed for Opioid Addicts
Pethidine is commonly used in the management of what pain?
Pain during labour
What is the effect of Pethidine on CVS
Inc. BP
Inc. HR initially
Followed by a fall after 10-15 mins
What are some contraindications for Pethidine use?
Use with MAOI (antidepressants) leading to coma , convulsions, hyperpyrexia
What is patient controlled analgesia?
This involves the use of computerized pumps that can deliver a constant infusion and bolus breakthrough doses of parentally administered opioid analgesics under the patient’s control
What are the most common drugs used in PCA - patient controlled analgesia
Morphine
Hydromorphone
List 4 advantages of PCA
- improved patient satisfaction
- fewer side effects
- accommodates patient variability
- accommodates changes in opioid requirements
List 2 opioid antagonists
Nalaxone
Naltrexone
Between nalaxone and naltrexone (opioid antagonists) which is long acting and which is short acting?
Nalaxone is short acting (repeated doses may have to be given since the half life is shorter than the half life or morphine- so when Nalaxone wears off the effects of the opioid may return is a second dose is not administered)
Naltrexone is long acting
