Drugs For Treating Pain Flashcards
Pain: a unpleasant _____ and _____ experience associated with or resembling that associated with actual or potential ______ damage or described in terms of such damage.
- sensory
- emotional
- tissue
What is the difference between acute and chronic pain?
- acute: up to 6 months? 6 weeks with acute injury
- chronic: 3-6+ months
Describe the 3 types of pain:
- nociceptive: pain that we can link to somatic or visceral stimulation.
- inflammatory: can stimulate pain receptors
- pathological: pain that is not from a injury source. Can be emotional or psychological component or issues in processing sensation.
Describe analgesics:
- drugs used to alleviate (reduce or eliminate) pain
- does not cause loss of consciousness
Describe opiates:
- drugs that are obtained from the opium poppy
- naturally occurring drug
- main form: morphine
Describe opioids:
- broader term referring to drugs with similar effects as opiates
- can be synthetic and semi-synthetic
Describe narcotics:
- any controlled substance in legal context
- primary categories: schedule 1 and 2. Illegal to produce, distribute, or administer.
Describe narcotic analgesic:
- another term referring to opioids
- relieves pain and produces a state of drowsiness or sleep. Can affect consciousness.
- pain relievers that have an abuse potential
Give examples of types of drugs for treating pain:
- NSAIDs and corticosteroids
- Acetaminophen (non opioid analgesics)
- opioids
- topical analgesics
- topical and local anesthetics
- caffeine
- anti-depressants and anti-convulsants
Outside of North America, Acetaminophen is called….
Paracetamol
Describe the potential therapeutic effects of acetaminophen.
- analgesic and antipyretic
- not anti-inflammatory or anti-platelet
Acetaminophen does not affect what organs/structures?
- does not cause stomach irritation or ulcers
- does not affect platelet function
- does not affect kidney function
Acetaminophen is available in what forms?
- tablets, capsules
- chewable tablets
- suppositories
- elixirs, suspensions
- IV
What is the difference between tablets, capsules, and caplets?
- capsule can be broken open, has gelatin outer component with powder or liquid inside of it.
- tablet = round
- caplet = oval or rectangle
When would you use suppositories?
If someone is vomiting a lot
What is the difference between elixirs and suspensions?
- elixirs: liquid form (syrup), contains sugar to make it more palatable.
- suspensions: liquid that has beads in it that contain the medication. Usually administered to infants.
Describe the pharmacokinetics of acetaminophen.
- generally taken orally = goes through first pass
- readily and completely absorbed from GI tract
- half-life around 2 hours. Usually taken every 4-6 hours.
- metabolized by liver and metabolites are excreted in urine.
Indications for acetaminophen:
- mild to moderate pain
- fever
Describe the dosing of acetaminophen.
- typically 325 - 500 mg.
- Tylenol arthritis has 650 mg in a extended/controlled release form. Has different dosing schedule, usually every 12 hours.
- 4000 mg max daily dose
- 1000 mg max dose at 1 time in adults.
- ceiling effect
What is the ceiling effect?
If you take more than the recommended amount, there is no additional benefit seen and you are more at risk of adverse effects.
Describe the biggest adverse effect from acetaminophen.
- hepatotoxicity (liver toxicity)
- amount of acetaminophen exceeds the ability of the liver to metabolize it completely
- toxic metabolite accumulates and reacts with components of the liver cells
- symptoms: nausea, vomiting, drowsiness, abdominal pain
- evidence of hepatotoxicity is evident 2-4 days after overdose
- people often unknowingly take products that have acetaminophen in them (combination products)
Describe drug interactions with acetaminophen.
- alcohol: increases production of toxic metabolite of acetaminophen. Chronic alcohol consumption compromises liver.
- warfarin (anti-coagulant): even though acetaminophen is not an anti-platelet drug, it can inhibit warfarin medication and increase bleeding time
Medications often mixed with acetaminophen:
- caffeine: assumed to be utilized because it speeds up metabolism of acetaminophen so that it works faster. Migraine meds have this. Caffeine itself may also have an effect on decreasing pain.
- codeine
2 types of opioids:
- endogenous (body produces its own): endorphins
- exogenous (produced outside of the body)
Name the opioid receptors found primarily in CNS, PNS, and GI tract.
- Mu (Mu opioid receptors - MOR): associated with analgesics and euphoria. Respiratory depression is a risk.
- Kappa: associated with analgesics, sedative and dysphoria (not as good as Mu)
- Delta: associated with sedative
If a medication goes through the first pass effect, they need to take a ______ dose if taking oral form vs parenteral form.
Larger
Describe pharmacodynamics and pharmacokinetics of opioids.
- absorption: most opioids absorbed well. Oral needs larger dose.
- distribution: opioid molecules bind to plasma that circulates. Reaches brain, liver, lungs, kidney.
- frequently administer prescriptions accumulates in adipose and muscle tissue.
- metabolism: extensive first-pass in liver
- excretion: primarily through urine
Indications for opioids:
- moderate to severe pain
- cough suppression (cough syrup with codeine - because of depression of respiratory system)
- diarrhea (opioids associated with constipation)
Adverse effects of opioids
- respiratory depression
- constipation
- sedation/drowsiness
- orthostatic hypotension
- miosis (pin point pupils)
- urinary retention
- nausea and vomiting
- tolerance
- dependence
- addiction
What is the difference between tolerance, dependence, and addiction?
- tolerance: as you take it, you develop tolerance and require more to get the same effect.
- dependence: physical response. Withdrawal.
- addiction: broad term that includes psychological response
Abrupt withdrawal of opioids causes:
- abstinence syndrome
- early presentation of tremors, sweating, irritability etc.
Drug interactions with opioids:
- CNS depressants (since opioids are also a depressant, causes excessive CNS depression and respiratory depression): ex. benzodiazepines, alcohol, cannabis.
- caffeine (stimulant)
Routes of administration for opioids:
- oral
- parenteral (non GI forms. Primarily injection - IV, subcutaneous, intranasal, intraspinal, intramuscular)
Describe the indications for morphine:
- moderate to severe pain
- constant, dull pain relieved at lower doses than sharp, intermittent pain
- decrease anxiety and distress
- causes drowsiness
Describe codeine and what it is used for.
- codeine = opiate and opioid
- biotransformed, activated into morphine
- less potent than morphine
- mild to moderate pain
- antitussive (aka cough suppressant)
- often used in combination
What are the 4 types of prescription Tylenol?
Tylenol 1: acetaminophen (300 mg) + codeine (8 mg) + caffeine (15 mg)
Tylenol 2: acetaminophen (300 mg) + codeine (15 mg) + caffeine (15 mg)
Tylenol 3: acetaminophen (300 mg) + codeine (30 mg) + caffeine (15 mg)
Tylenol 4: acetaminophen (300 mg) + codeine (60 mg)
Describe meperidine.
- aka Demerol
- opioid
- shorter duration
- adverse effects: tremor, muscle twitching, seizures
- do not use with monoamine oxidase inhibitors (used to treat depression)
Describe oxycodone.
- available in controlled-release form (OxyContin), larger dose
- generally suggested to take oxycodone. Only prescribed OxyContin if it is long term chronic pain but should not be the first line of defence.
- those that are addicted often seek out OxyContin and crush the drug to get the high dose faster.
Percocet is made up of _____ + ______.
- oxycodone
- acetaminophen
Vicodin is made up of _______ + ______.
- hydrocodone
- acetaminophen
Describe methadone.
- longer duration of action
- good oral absorption
- used as analgesic
- opioid, but used to prevent withdrawal syndrome in heroin addicts during treatment
Describe fentanyl
- 100x more potent than morphine
- available parenterally as an adjunct to anesthesia (used in medicine with Sx for sedation and pain)
- available as a transdermal patch for chronic, severe pain in opioid tolerant patients.
- Is manufactured on the street and cut into other drugs because it is cheap and highly addictive
What is car-fentanyl?
- not supposed to be used in humans
- used as a tranquilizer for large animals
- 100x more potent than fentanyl
- some drugs are being laced with car-fentanyl
What is a opioid antagonist?
Naloxone
Describe tramadol
- was initially considered an opioid but with lower risk of respiratory depression, physical dependence, and addiction.
- with further research, it is now considered a opioid and is a schedule 1 controlled substance.
How can opioid analgesics be used appropriately?
- should not be the first routine therapy for chronic pain
- measurable goals of pain and function should be set
- discuss the benefits/risks and nonopioid options
- prescribe only immediate release opioids for acute pain
- start low and go slow. Prescribe no more than needed
- do not prescribe extended-release or long-acting opioids for acute pain
- follow up and reevaluate risk of harm. Reduce dose or taper and discontinue if needed.
Describe topical analgesics.
- salicylates and/or menthol, camphor, capsaicin
- counterirritants (stimulates something other than what is injured - similar to gate control theory)
- rubefacient effect - localized vasodilation resulting in redness and warmth
- adverse effects: skin reactions or burns if wrapping on top
What are salicylates?
- aspirin (do not use with those with aspirin sensitivity)
- some anti-inflammatory component
Name a natural topical analgesic:
- mustard powder
- natural form of a counter irritant that creates warmth
- some people use mustard powder with water to heat an area, but can get too warm
Describe topical anesthetics:
- decrease sensation (including pain, has numbing effect)
- lasts a max of 30 min
- short term relief at the site on the surface of skin or mucous membranes
- some absorption into bloodstream
What are the different ways to apply topical anesthetics?
- solutions
- sprays
- gels
- ointments
Uses for topical anesthetics:
- sunburn
- minor burns
- insect bites (calamine lotion)
- poison ivy
- hemorrhoids
- sore throat
- dental/oral irritation (oragel)
- minor sport injuries
- emla = topical cream before dermatology procedures
Adverse effects of topical anesthetics:
- skin irritation
- burning
- dermatitis
Most topical anesthetics end in ____.
_____caine (ex. Lidocaine, benzocaine)
How does local anesthetics work?
- locally inhibits nerve impulse transmission
- also cause diminished perception of hot, cold, and touch
- acts quickly, can last up to 4 hours
- typically through injection
- affects only the localized area
Uses for local anesthetics:
- dental procedures
- minor Sx
- diagnostic procedures: injecting nerve or joint to see what is causing pain
Local anesthetics can be used in conjunction with _______ to make it last longer.
Vasoconstrictors
Adverse effects of local anesthetics:
- few adverse effects
- high blood concentration can cause heart block and cardiac arrest
- rarely allergic reactions
- local anaesthetic toxicity: if someone has too much of it, it can result in a spike in activity in CNS, then a sudden drop.
What can ATs do in terms of pain medications?
- understand analgesics
- prioritize non pharmacological and non opioid pharmacological therapy
- start slow with OTC before prescription
- incorporate patient rated outcomes
- monitor athletes, know warning signs of abuse, misuse and dependence
- make sure opioids are used under the direction of a physician
- know how to use naloxone
