Drugs for Pain Flashcards
List 3 types of anesthesia.
- General: inhaled or intravenous
- Local: administered through injection or by topical administration
- Regional: involves numbing a large area of the body - spinal anesthesia
Novacane is an example of a _____ anesthetic.
Local
List 7 characteristics of an IDEAL general anesthetic .
- Loss of consciousness/ sensation
- Analgesia
- Amnesia
- Skeletal muscle relaxation
- Inhibition of sensory/ autonomic reflexes
- Rapid onset
- Non-toxic
An ideal general anesthetic should achieve desired effect WITHOUT producing what 4 conditions?
- Hypoxia
- Laryngospasm
- Excessive tracheobronchial secretions
- Depressed respirations
True or False: There is a single anesthetic that can achieve the desired anesthetic effect on its own.
FALSE
There is no one drug that can achieve the desired effect on its own. NEED BALANCED ANESTHESIA
What is balanced anesthesia?
Involves giving several different medications in small amounts to produce desired effects while minimizing toxic effects.
What are the 4 stages of anesthesia?
- Analgesia
- Delirium
- Surgical anesthesia
- Cardiovascular/ respiratory collapse
______ can occur as a result of a patient falling too deep into surgical anesthesia.
Cardiovascular and respiratory distress
List 6 drugs/considerations given as premedication prior to anesthesia.
- Sedation-benzodiazepine/ barbiturate
- Analgesia: opioids
- Antiemesis: promethazine (anti-vomiting drug)
- Infection control: usually a single injection within an hour of the start of surgery
- Disease-modifying agents: e.g. pretreatment with bronchodilators for COPD
- Withhold certain drugs like oral diabetic drugs to avoid hypoglycemia
What are 2 theories that may explain the mechanism of action of inhaled anesthetics?
- Molecules of gas dissolve in the neuronal membrane causing the membrane to expand impeding the opening of ion channels (so no AP can occur)
- Probably act differently in different neural tissues and affect a variety of ion channels. Anesthetic-sensitive potassium (K+) channel is understudy
What 2 effects can inhaled anesthetics have on the cardiovascular system?
- Most decrease arterial pressure
2. Depress contractility producing reflex tachycardia
What 2 effects can inhaled anesthetics have on the pulmonary system?
- Decrease RR
2. Decreased mucociliary function
What 2 effects can inhaled anesthetics have on the central nervous system?
- Decrease metabolic rate
2. Increased cerebral blood flow
What 2 effects can inhaled anesthetics have on the renal and hepatic systems?
- Renal: decrease glomerular filtration rate
2. Hepatic: decrease blood flow
Inhaled anesthetics can induce ________.
Malignant Hyperthermia
What are 4 symptoms associated with malignant hyperthermia?
- Excessive muscular rigidity
- Producing high BP
- Tachycardia
- Fast rise in fever
List 3 treatments used to treat malignant hyperthermia.
- Dantrolene
- Lidocaine
- Cooling blanket
_____ is an ultra-short acting barbituate (IV anesthesia). This drug is often replaced with ____.
Thiopental
Propofol
What is the MOA of IV anesthesia? (4)
Binds to GABAa gated Chloride Channels
- Induce anesthesia
- Produce hypnosis
- Anesthesia without analgesia.
What is the dosing of IV anesthesia?
- IV injection
2. Rapidly taken up by brain (30 sec) short duration (10 min) due to redistribution in fat
List 5 ADRs associated with IV anesthesia.
- Hangover due to lipid solubility
- Respiratory depression
- Bronchospasm
- Laryngospasm
- Reflex tachycardia
IV anesthetic drugs may need to be given with _____. Why?
Opioids
Why?: Anesthetics may not produce analgesia, which is why you need an opioid to relieve the pain.
Large doses of _____ can induce anesthesia while maintaining a good _____ but impairing ______.
IV Opioids
Cardiovascular profile
Ventilation (depress RR)
____ are too slow in onset but can provide basal level of sedation for maintenance of anesthesia
Benzodiazepines
What drug, given 30-60 min before surgery, can be used to produce anterograde amnesia?
Midazolam with an anxiolytic
______ may be given to inhibit any movement especially for delicate surgical procedures.
Neuromuscular blocker
List 3 TRUE IV anesthetics.
- Etomidate
- Ketamine
- Propofol
List 4 characteristics of Etomidate.
- Min. changes in CVS/ respiratory function
- Rapid induction(within 60 seconds)
- Can produce skeletal muscle movements
- Produces nausea and vomiting
List 4 ADRs associated with the use of ketamine.
- Dissociative anesthesia
- HTN
- Tachycardia
- Emergence phenomena
What 3 symptoms make up emergence phenomena ?
- Visual hallucinations
- Vivid dreams
- Thrashing
Propofol causes global CNS _____ through agonist actions on _____.
Depression
GABAa
List 4 characteristics of Propofol.
- Lowers BP without myocardial depression
- Lowers intracranial pressure
- Good anti-emetic action
- Used for same day surgery and examinations (colonoscopy)
General anesthetics depress ______ in the airways leading to pooling of mucus. List 3 PT interventions used to treat this.
Mucociliary clearance
- Breathing exercises
- Coughing
- Proper guarding with ambulation
What is the difference between regional and local anesthesia?
- Regional: administration of local agent and includes IV regional block/epidural or spinal administration
- Local: topical anesthesia, infiltration anesthesia, peripheral nerve block
List 3 advantages of local anesthesia.
- Quick recovery
- Pt remains conscious
- Does not interfere with cardiovascular, respiratory, and renal function
List 2 disadvantages of local anesthesia.
- Incomplete analgesia
2. Time to achieve anesthesia
What is the MOA of local anesthetics? What is an indication for the use of local anesthetics?
MOA: Block sodium channels: Smaller C fibers are affected first, then type A delta
- Indication: Pain relief for local surgery (suture repair/ dental work)
True or False: Local anesthetics RARELY produce ADRs.
TRUE
List 4 ADRs associated with low dose local anesthetics.
- Sleepiness
- Light-headedness
- Visual/auditory disturbances
- Restlessness
List 2 ADRs associated with high dose local anesthetics.
- Neurotoxicity
2. Produce generalized excitation followed by profound CNS depression
List 6 pain mediating substances that are released following tissue injury to stimulate afferent receptors/neurons.
- K+
- Serotonin
- Histamine
- Bradykinin
- Prostaglandins
- Leukotrienes
Pain Transmission
REFER TO DIAGRAM ON SLIDE 16 (IMPORTANT)
List 4 characteristics of opioids.
- Any substance that relieves pain
- Acts on Mu receptor
- Action is reversed by naloxone
- Mimic endogenous opioids, endorphins, and enkephalins
List the 3 classes of opioid receptors.
- Mu
- Delta
- Kappa
List 7 probable effects of stimulating Mu opioid receptors.
- Produces analgesia euphoria
- Associated with respiratory depression
- bradycardia
- Emesis
- Constipation
- Sedation
- Meiosis
List 3 probable effects of stimulating delta opioid receptors.
- Produces analgesia, euphoria (but less than Mu), 2. Sedation
- Decreased GI motility, respiratory
List 6 probable effects of stimulating kappa opioid receptors.
- Produces analgesia
- Sedation
- Dyspnea
- Dependence
- Dysphoria
- Inhibition of ADH release
All opioid receptors open ____ channels causing hyperpolarization and a decrease in ________.
Potassium
Nerve transmission
What is inhibited when hyperpolarization occurs as a result of opioid receptors opening potassium channels?
Inhibit the opening of calcium channels inhibiting release of substance P
Opioids are involved in the _____ systems to produce euphoria.
Mesolimbic dopamine system
What is the MOA of strong agonists like morphine/heroine?
Binds to mu and Kappa receptors.
List 4 effects associated with strong agonists (morphine/ heroine).
- Analgesia
- Sedation
- Euphoria (80%)
- Dysphoria (20%)
List 7 indications for the use of strong agonists (morphine).
- Acute pain
- HF-due to peripheral vasodilation
- MI (to reduce cardiac workload)
- Cough
- Antidiarrheal effect
- Acute pulmonary edema
- Anesthesia
List 3 benefits of strong agonists (morphine).
- Pain relief
- Cough suppression
- Arterial vasodilator in HF and MI
List 7 ADRs associated with the use of strong agonists (morphine).
sleepiness •vomiting (chemoreceptor trigger zone in medulla) •increased sweating •hypotension & bradycardia •depressed respiration: most common reason for death •constipation •urinary retention •frictopathia (from release histamine)
______ is a mild to moderate agonist for moderate pain.
Codeine
List 2 characteristics of codeine.
- Binds to mu and kappa receptors but with reduced affinity
- Produces same level of constipation and respiratory depression as morphine
Tramadol oral opioid that blocks reuptake of ____ and ____. It can cause addiction.
Norepinephrine
5HT (serotonin)
How is patient controlled analgesia administered?
Allows the patient to self administer the drug on an as needed basis usually with a preprogrammed continuous infusion pump
What are 2 advantages of using patient controlled transdermal fentanyl patch using iontophoresis?
- No tubing
2. Improved mobility for patients
Why is fixed interval administration more effective than dosing on demand?
Keeps the pain from building up
_____ has large first-pass effect compared to oral codeine and oxycodone therefore preferred route of administration of morphine is ____.
Morphine
IV
Once absorbed, opioids distributed to ______ and accumulate in ______.
Distributed to highly perfused tissues (brain)
Accumulate in fatty tissue
List 2 opioid metabolizing enzymes.
- CYP3A4 P450 metabolize fentanyl producing non-active metabolites
- CYP2D6 P450 metabolizes oxycodone and hydrocodone producing active metabolites with greater affinity
What is tolerance? When does it typically begin?
- Develops quickly and patient must continually administer a higher dose to get the same effect.
- Begins after the first administration and often an increase in dose is needed in just 2-3 weeks
What is physical dependence? List 13 sxs a patient may experience as a result of withdrawal.
Implies that when drug is withdrawn
- Anxiety
- Irritability
- Hot flashes alternating with chills
- Body aches
- Runny nose
- Diarrhea
- Shivering
- Gooseflesh
- Stomach cramps
- Insomnia
- Sweating
- Tachycardia
- Nausea
- Yawning.
What is addiction?
Deliberately seeking out a drug for its mood-altering abilities
How is withdrawal treated?
- methadone or buprenorphine and/or naltrexone
2. Once patient is stabilized on these, the dose is reduced 5-10% every 1-2 weeks
What is methadone?
Synthetic opioid that blocks heroin from binding to the receptor and prevents withdrawal symptoms
True or False: Methadone does not produce euphoria.
TRUE
What is the half-life of methadone?
Longer half-life, 1-2 days compared to 4-6 hours for heroin
List 2 risks associated with using methadone.
- Prolong QT interval and arrhythmias
2. When combined with a serotonin reuptake inhibitor, may cause serotonin syndrome
True or False: Withdrawal from long-acting opioid is much easier than withdrawal from a short-acting opioid
TRUE
What is the MOA of buprenorphine?
Binds to m receptor but has lower efficacy than the other opioids, also agonist at delta receptor but antagonist at Kappa receptor
What happens when heroin is injected on top of buprenorphine?
Produces less euphoria since there are less free receptors to bind heroin
Buprenorphine is used to prevent withdrawal from ______ opioids.
Long-acting opioids
What is the difference between naltrexon and naloxone (morphine antagonists)?
Naltrexone is similar but has a longer duration of action (t1/2 = 10 hrs)and can be used after detox to help reduce patient’s cravings
When should therapy be scheduled in patients taking opioids?
Schedule therapy when opioid has nearly reached its peak action so that the patient can cooperate but still be able to accurately report pain
Opioids should be prescribed at the lowest possible dose and for ___ days for acute pain and then re-evaluate.
3 days
What tool can be used to assist the prescriber in determining risk for deviant behavior by patients who will be receiving opioids for chronic pain?
Screener and Opioid Assessment for Patients with Pain-Revised (SOAPP-R)