Treatment of Pain Flashcards
Pain is difficult to catch up with; (…) are more effective when given (…) pain increases
- analgesics
- before
What is the chemical name for acetaminophen and the abbreviation?
- N-acetyl-para-aminophenol
- APAP
What is the mechanism of action of acetaminophen?
- not full understood
- possibly blocks central (not peripheral) prostaglandin production
What are the uses of acetaminophen?
- antipyretic
- analgesic
What are the different formulations of acetaminophen?
- oral: capsule, tablet (chewable and ER), elixir, gel, liquid, solution, suspension, syrup, sachet (tear open and put into water)
- rectal suppository
- IV
What are the advantages to using acetaminophen vs other pain medications?
- no GI irritation
- almost no allergy
- no bleeding issues
- very safe at usual doses (TI approx. 10)
- safe in pregnancy
What are the disadvantages of using acetaminophen vs other pain medications?
- poor anti-inflammatory action (treats pain/reduces fever but no inflammation)
What are the side effects associated with acetaminophen use?
- methemoglobinemia, leukopenia rare (hemoglobin abnormal; cyanosis in babies)
- liver toxicity due to metabolite accumulation (more concerned about)
What is the 2nd most common cause of liver disease that requires transplant?
liver toxicity due to acetaminophen use
What are the different metabolite forms of acetaminophen?
- sulfate form
- glucuronide form
- N-acetyl-p-benzoquinone imine (NAPQI)
What is acetaminophen normally metabolized by?
glucuronidation and sulfation with minor CYP2E1
In acetaminophen, (…) is overwhelmed and metabolism shifts to (…), producing the toxic metabolite (…)
- phase II
- phase I
- NAPQI
Describe the steps of normal acetaminophen metabolism and what happens when an overdose of acetaminophen occurs.
- acetaminophen is mainly metabolized through glucuronidation and sulfation (phase II) with a little being metabolized by CYP2E1 (oxidation/CYP450)
- when overdose occurs, there isn’t enough molecules for glucuronidation and sulfation to occur so more acetaminophen goes through CYP2E1 (phaseI) to be converted to NAPQI, which is toxic
- usually the small amt of NAPQI is detoxified/eliminated by glutathione conjugation, but there is only a certain amount of this to allow it to occur
- so in overdose, glutathione conjugation is overwhelmed from the large amount of NAPQI and NAPQI remains in the system to interact with cellular macromolecules and cause toxicity
Toxic chronic doses of acetaminophen can occur when taken over time in a period longer than (…)
4 hours
A normal dose of acetaminophen is (…) in patients with liver impairment
toxic
What are risk factors for toxicity with acetaminophen? Explain each.
- malnutrition (decreased glutathione)
- chronic alcohol ingestion (induces 2E1)
- concomitant use of drugs that are CYP2E1 inducers
- young, febrile children (usually less serious, not intentional OD so severity will be less)
- Describe adult acetaminophen OD?
- Describe child acetaminophen OD?
- more severe, more fatal
- more frequent, less severe
Anything that induces (…) will facilitate acetaminophen to be converted to (…) causing toxicity
- 2E1
- NAPQI
What are the different phases of acetaminophen toxicity?
- phase 1: up to 24 hours after intake
- phase 2: 18-72 hours later
- phase 3: 72-96 hours later
- phase 4: 4 days to 3 weeks later
What are the symptoms associated with each phase of acetaminophen toxicity?
- phase 1: GI upset or no symptoms at all
- phase 2: RUQ pain +/- tenderness (liver); continued or new onset of GI issues
- phase 3: all of the above continue; hepatic dysfunction begins
- phase 4: resolution of symptoms and organ failure, if patient survives; complete resolution of hepatic damage may take months
What is associated with hepatic dysfunction (acetaminophen toxicity)?
- coagulopathy
- jaundice/encephalopathy
- hypoglycemia (failing liver doesn’t product a lot of sugar)
What are ways you can treat acetaminophen toxicity?
- activated charcoal (if ingestion occurred w/in an hour and patient is stable)
- n-acetylcysteine/NAC (acetadote) - always use in overdose situations w/ acetaminophen
- How does n-acetylcysteine work in acetaminophen toxicity?
- What are the regimens for it?
- Which may be more effective in what time frames?
- provides cysteine group for glutathione synthesis (so NAPQI can be detoxified/eliminated)
regimens: - 72-hour oral or 21-hour IV
- oral mixed w/soda or juice and chilled
effectiveness: - oral may be more effective for pts presenting > 18 hours after ingestion
- IV is more effective for pts presenting within 12 hours
What is the revised Rumack-Matthew Nomogram for the Acute Ingestion of Acetaminophen? (what it is used for)
- used to interpret serum concentrations of acetaminophen in relation to time since ingestion measured from ingestion of first dose, in order to assess potential hepatotoxicity
- acute = under 24 hours
- NAC administration to any patient with a blood level above the treatment line
- above treatment line: treat them; below treatment line: don’t treat them
What are the different formulations of acetaminophen and associated doses?
- regular strength: 325 mg
- extra strength: 500 mg
- arthritis formula: 650 mg
- PM or nighttime formulations: tylenol PM contains (per tablet) 500 mg acetaminophen, 25 mg diphenhydramine (benedryl)
- excedrin: APAP 250 mg, ASA 250 mg (aspirin), 65 mg caffeine
What is the max daily dose of acetaminophen in children/adults?
- children: 75 mg/kg/day and no more than 4000 mg
- adults: 4000 mg
What is the minimum hepatotoxic single dose of acetaminophen in children/adults?
- children: 150 mg/kg
- adults: 7.5-10 grams
Describe the arachidonic acid pathway.
- phospholipids are found in cells
- when cellular injury occurs, phospholipase A2 becomes active, releasing arachidonic acid into the system
- COX-1 enzyme can convert arachidonic acid into prostaglandins (PG) for GI mucosal protection and thromboxane (TXA) for platelet aggregation and vasoconstriction
- this pathway is constitutive so it is always on doing something, it just becomes enhanced in cellular injury situations
- COX-2 enzyme can convert arachidonic acid into prostaglandins (PG) to aid in pain, inflammation, fever, uterine contraction, vasodilation, and inhibition of platelet aggregation (decreased clotting)
- this pathway is inducible so it needs to be turned on
- LOX enzyme converts arachidonic acid to leukotrienes
Corticosteroids can inhibit the enzymes associated with the (…) pathway, decreasing the amount of (…) produced
- arachidonic acid pathway
- prostaglandins, TXA, and leukotrienes
- Cortisol is a (…). Describe this.
- Cortisol enhances the (…) response
- It stimulates the (…) leading to (…)
- Cortisol decreases (…) which can (…) response
- Cortisol can stabilize (…) which can (…)
- endogenous glucocorticoid - “gluco:” increase blood sugar via catabolism of protein and subsequent conversion into sugars and fats; gluconeogenesis
- enhances the sympathetic(stress) response
- stimulates the CNS leading to irritability, insomnia
- decreases WBCs which can lower the immune response
- stabilize intracellular lysosomes which can decrease cell injury
What is the MOA of cortisol?
- inhibits synthesis of histamine, kinins, and prostaglandins (inhibit phospholipase A2)
- decrease inflammation and allergy (there are steroidal anti-inflammatory products)
In fight/flight situations, the body releases (…) for energy
cortisol (increases blood sugar)
- The body doesn’t know the difference between (…) cortisol
- You shouldn’t have cortisol released for (…)
- endogenous and exogenous cortisol
- extended periods of time
- What is a prototypical agent glucocorticoids/cortisol?
- This mimics the actions of (…)
- What does this inhibit?
- prednisolone (active form)/prednisone (inactive form) - and every agent after
- mimics the actions of cortisol
- inhibits phospholipase A2
What are the uses of prednisolone/prednisone?
- anti-inflammatory
- immunosuppressant
- decrease cell injury
- inhibit collagen synthesis - decrease scar tissue formation
Describe the MOA of prednisolone/prednisone?
- inhibits phospholipase A2
- won’t release arachidonic acid
- COX-1 and COX-2 won’t be able to convert arachidonic acid to prostaglandins
Prednisolone/prednisone is very (…)
very potent
- Should patients with severe liver disease receive prednisolone or prednisone?
- Why?
- prednisolone
- liver will have a harder time breaking down prednisone (inactive) to make it active
- Which corticosteroid is most similar to the bodies natural cortisol?
- How is this given?
- What are other corticosteroid drug names?
- hydrocortisone
- topical
other corticosteroids: - hydrocortisone
- cortisone (injection)
- prednisolone/prednisone
- methylprednisolone
- triamcinolone
- dexamethasone
- betamethasone
What are the anti-inflammatory activity levels of all the corticosteroid drugs?
- hydrocortisone - 1
- cortisone - 0.8
- prednisolone/prednisone - 4
- methylprednisolone - 5
- triamcinolone - 5
- dexamethasone - 25-30
- betamethasone - 25
What are the equivalent doses of corticosteroids?
- hydrocortisone - 20 mg
- cortisone - 25 mg
- prednisolone/prednisone - 5 mg
- methylprednisolone - 4 mg
- triamcinolone - 4 mg
- dexamethasone - 0.75 mg
- betamethasone - 0.75 mg
Which corticosteroid may be the least potent? Most potent?
- hydrocortisone
- betamethasone
- What corticosteroids have the longest duration of effect?
- What are their associated plasma/biologic half-lives?
dexamethasone:
- plasma half-life: 100-300 minutes
- biologic half-life: 36 hours
betamethasone:
- plasma half-life: 100-300 minutes
- biologic half-life: 35 hours
What are some examples of corticosteroid uses?
- pulmonology/allergy - asthma, COPD, anaphylaxis
- dermatology - urticaria, contact dermatitis
- endocrinology - adrenal disorders
- GI - IBD
- hematology - hemolytic anemia, leukemia, lymphoma
- rheumatology - rheumatoid arthritis, dermatomyositis, lupus
- others - ophthalmology, organ transplant, lung maturation in newborns, cerebral edema, MS, post-MI
- How do corticosteroids assist in post-MI or cerebral edema patients?
- What do corticosteroids do in patients with lymphoma, leukemia, multiple myeloma?
- Corticosteroids can be used as replacement therapy for (…) insufficiency, which is also known as (…) disease
- stabilize cells
- work by decreasing lymphocytes
- glucocorticoid insufficiency; Addison’s disease
- What are the different routes of administration of corticosteroids?
- What is the route of administration determined by?
- You should always treat (…) when possible to avoid (…) exposure
- Adverse effects are (…) and (…) dependent in most cases
- oral, inhaled (ocular, intranasal), parenteral (IM, IV, intraarticular, intralesional)
- determined by illness
- locally; systemic exposure
- dose and duration dependent
What are some short term adverse effects of corticosteroid use?
- decreased immune response (candidiasis; new or worsening bacterial infection)
- GI bleeding and ulcers
- hyperglycemia (releasing glucose)
- mood changes (irritability/instability; worsening psychiatric problems)
- increased appetite
- insomnia
- mineralocorticoid effects (sodium retention-increased BP; hypokalemia)
- pancreatitis
- electrolyte abnormalities
Why are GI bleeds/ulcers a short term adverse effect of corticosteroids?
corticosteroids inhibit phospholipase A2, inhibiting arachidonic acid release and production of prostaglandins, so there is less protection of the stomach from mucosal lining and acid causes damage in the stomach
What are some long term effects of corticosteroid use?
- growth suppression in children
- Cushing’s syndrome (moon face, buffalo hump, redistribution of fat on the body)
- adrenal suppression - atrophy of adrenal cortex (weakness, lethargy, anorexia, nausea, myalgia)
- cataracts and glaucoma
- cardiac effects (new onset afib, heart failure, ischemia)
- androgenic effects (amenorrhea, hirsutism-excessive hair growth)
- skin (thinning, bruising, stretch marks, acne)
- obesity
- hyperlipidemia
- muscle atrophy
- osteoporosis
Why can corticosteroid use cause osteoporosis?
- inhibits osteoblasts and increases osteoclast activity
- affects collagen in bone
- decreases Ca+2 absorption in gut
Corticosteroid use is contraindicated in what conditions/situations?
- systemic fungal infection
- don’t give with live vaccines when using immunosuppressive doses - delay for 3 months after discontinuation of corticosteroid use
When should you use corticosteroids cautiously? (individuals with what conditions)
- diabetes
- PUD or active GI bleeding
- osteoporosis
- myasthenia gravis - may worsen symptoms (weakness in skeletal mm)
- cataracts/glaucoma
- pregnancy (cleft palate, hypoadrenalism-close to birth, baby will become dependent on corticosteroids)
- CNS disorders
- uncontrolled viral/bacterial infections
What should you give to patients taking corticosteroids who have PUD?
proton pump inhibitor
Why does adrenal suppression happen if taking corticosteroids long-term?
- glucocorticoids suppress pituitary release of ACTH
- zona fasciculata (cells that produce cortisol in adrenal gland) do not receive stimulation
- adrenal atrophy occurs
How long does adrenal suppression take when using corticosteroids?
- several weeks of treatment are required
- long-acting and high dose products have highest risk
- topical and inhaled products are not a concern
What can we do to decrease adrenal suppression in corticosteroid use?
- do not abruptly discontinue
- gradually taper doses over weeks to months (consider 6-15 months and monitor)
What is the preferred treatment for adrenal insufficiency (corticosteroids)? Why?
hydrocortisone is preferred treatment for adrenal insufficiency as it more closely acts like endogenous cortisol (will probably be on for life)
- Patients taking corticosteroids for (…) can stop abruptly?
- (…) often occurs even in short courses to avoid flare
- one week or less
- tapering
- Abrupt discontinuation of corticosteroids when taking (…) can lead to adrenal suppression or flare of disease that was being treated
- Treatment over (…) can be tapered quickly to physiologic dose then weaned slowly
- (…) and (…) therapies require longer tapers over months in most cases
- (…) of patients is important
- for one week or less
- over 3 weeks
- long-term and high dose therapies
- close monitoring
If a patient have a systemic fungal infection, what should they not receive/take?
corticosteroids
What is the MOA of NSAIDS?
- block the production of prostaglandins via cyto-oxygenase inhibition (COX)
- COX converts arachidonic acid to other things, so when it is inhibited, you just have arachidonic acid sitting in your system
What is the general function of NSAIDS?
- antipyretic
- anti-inflammatory
- analgesic
- inhibit platelet congregation
What is the original, prototypical NSAID?
Aspirin
What is another prototype for NSAID (other than aspirin)?
ibuprofen
Efforts to decrease side effects and increase efficacy have led to the development of several (…)
NSAIDs
What are the different types of NSAIDs?
- aspirin
- magnesium salicylate, diflunisal, salsalate, tolmetin
- fenoprofen, flurbiprofen, ketoprofen
ibuprofen - naproxen
- oxaprozin, meclofenamate, mefanamic acid, diclofenac, etodolac, indomethacin, sulindac, ketoralac
- nabumetone
- meloxicam, piroxicam
- celecoxib
What is more potent the acetaminophen?
corticosteroids
- Celecoxib is an NSAID that is selective for only (…)
- Low-dose Aspirin is an NSAID that is selective for (…)
- COX-2
- COX-1
What is the general pharmacokinetics of NSAIDs:
- absorption
- metabolism
- excretion
- absorption: well absorbed; no interference from food
- metabolism: undergoes phase I, II, or both
- excretion: mostly renal; some undergo enterohepatic recycling; some may be excreted through bile
- Repeated dosing of NSAIDs produces detectable levels in (…)
- Shorter half-life drugs stay present in (…) longer than would be expected, which could be important in ortho surgeries
- synovial fluid
- synovial fluid
What are some general NSAID indications?
- headache
- fever
- rheumatoid arthritis
- osteoarthritis
- gout
- spondylitis
- soft-tissue injuries
- menstrual pain
- tendonitis