Module 2 Flashcards
NSAIDS/APAP/CORTICOSTEROIDS/DMARDS
What chemicals are released by damaged cells in inflammation?
histamine, kinins, and prostaglandins
First step of inflammation
activation of innate and adaptive immune cells and production of cytokines
Second step of inflammation
vasodilation and increased permeability of blood vessels
Third step of inflammation
phagocyte migration to site of damage and phagocytosis (neutrophils, macrophages, mast cells)
Fourth step of inflammation
elimination of microbes and/or damaged cells and eventual tissue repair
Function of cyclooxygenase (COX)
converts arachidonic acid into prostaglandins (PGI2) and
related compounds (prostacyclin, thromboxane A2 (TXA2)
Aspirin (Salicylate)
irreversible inhibitor of COX-1 and COX-2 (acetylates a serine residue in the active site for both COX-1 and 2)
Non-aspirin NSAIDs mechanism of action
reversible (competitive) inhibitors of COX-1 and COX-2
first-generation NSAID mechanism of action
nonselective inhibition of both COX-1 and COX-2 (includes aspirin, ibuprofen, naproxen, ketorolac, diclofenac, indomethacin)
second-generation NSAID (celecoxib) mechanism of action
selective inhibition of COX-2, metabolized in liver by CYP2C9, half life = 11 hours
acetaminophen (APAP) mechanism of action
Reversibly inhibits COX-1 and COX-2 (prostaglandin synthesis) in CNS, has minimal effect on cyclooxygenase in peripheral tissue and therefore has minimal anti-inflammatory effect. Does not affect platelets.
Aspirin metabolism kinetics
follows first-order kinetics (where a constant fraction of drug is eliminated per unit of time, half life = 3.5 hrs) at low doses but changes to zero-order kinetics (where a constant amount of drug is eliminated per unit of time, half life = 12 hrs) at high anti-inflammatory doses (more than 4 g/d). Aspirin is rapidly metabolized in the liver and cleared by the kidney.
Advantages of aspirin
reduces platelet aggregation at low doses, antipyretic and analgesic at moderate doses, anti-inflammatory at high doses
Disadvantages of aspirin
May pose higher risk for GI events due to higher relative selectivity for COX-1 compared to those with lower selectivity for COX-1 (such as celecoxib). If aspirin is used in patients at high risk for GI events, PPIs should be used concomitantly to prevent NSAID-induced ulcers. Poses risk for Reye syndrome in children with viral infection.
Advantages of nonselective NSAIDs
Have antipyretic, analgesic, and anti-inflammatory activity through inhibition of both cyclooxygenase enzymes which catalyze the first step in prostaglandin synthesis.
Disadvantages of nonselective NSAIDs
Can cause negative gastrointestinal effects ranging from dyspepsia to bleeding. Because nonselective NSAIDs inhibit COX-1, they reduce beneficial levels of prostaglandins PGE2 and PGF and result in increased gastric acid secretion, diminished mucus production, and increased risk for GI bleeding and ulceration. If used in patients at high risk for GI events, PPIs should be used concomitantly to prevent ulcers.
Advantages of celecoxib (COX-2 inh.)
Mediates inflammation and pain through inhibition of COX-2, sparing COX-1, which helps maintain gastric mucosa (is associated with less GI bleeding and dyspepsia than other NSAIDs). It has no effect on platelet aggregation. Good treatment for acute pain, RA, and OA.
Disadvantages of celecoxib (COX-2 inh.)
increased risk of thrombosis due to selective inhibition of COX-2, renal ischemia, avoid in Sulfa allergy
What are the antiinflammatory effects of glucocorticoids?
Glucocorticoids lower circulating lymphocytes and inhibit the ability of leukocytes and macrophages to respond to mitogens and antigens. They also decrease the production and release of proinflammatory cytokines and block the release of arachidonic acid resulting in anti-inflammatory actions. Glucocorticoids also stabilize mast cell and basophil membranes, thereby decreasing histamine release.
Indications for steroid use
Can be used to treat severe allergic reactions, asthma, RA, other inflammatory or autoimmune disorders, and some cancers.
Adverse effects of steroid use
Osteoporosis is the most common adverse effect of long-term therapy but steroid use can also cause adrenal suppression, increased blood glucose, insomnia, mood swings, psychiatric disturbances, and fluid retention in patients with renal impairment. Sudden discontinuation of steroids can cause acute adrenal insufficiency that can be fatal.
clinical use of aspirin
Aspirin reduces fever, inflammation at very high doses, and pain at lower doses. It can also be used to reduce vasoconstriction and platelet aggregation (to reduce the risk of recurrent cardiovascular events) at low doses (commonly 81 mg) through irreversible inhibition of COX-1.
clinical use of nonaspirin nonselective NSAIDs
nonselective NSAIDs reduce inflammation, pain, and fever and are used mainly for the management of mild to moderate pain arising from MSK disorders such as OA, gout, and RA. Ibuprofen and naproxen in this class may be used to treat fever
clinical use of nonaspirin selective NSAIDs (celecoxib)
celecoxib reduces inflammation and pain and can be used to treat OA, RA, and acute pain
clinical use of acetaminophen
reduces pain and fever but is not considered an NSAID. It is used in patients with gastric complaints/risks with NSAIDs and those who do not require the antiinflammatory action of NSAIDs. Best choice for children with viral infections due to the risk of Reye syndrome with aspirin.
Factors that affect the renal elimination of aspirin
increasing the pH of urine from 6-8 can increase the rate of aspirin excretion by fourfold whereas renal and cardiovascular disease can decrease the rate of renal elimination due to decreased blood volume/flow
contraindications of aspirin
should be avoided in gout if possible or in patients taking probenecid. Avoid in children with viral illnesses due to risk of Reye syndrome. Avoid taking with warfarin, phenytoin, and valproic acid (or reduce dosage) due to potential accumulation of these drugs to toxic levels.
contraindications of NSAIDs
CABG patients for peri-operative pain due to increased risk of serious and potentially fatal cardiovascular thrombotic event, patients with cardiovascular risk factors (hypertension, history of MI, angina, edema, etc.), during pregnancy
contraindications for acetaminophen
patients with severe hepatic impairment, viral hepatitis, or a history of alcoholism are at higher risk for acetaminophen-induced hepatotoxicity
contraindications for celecoxib
patients who are at high risk for gastric ulcers and those who require aspirin for cardiovascular prevention, inhibitors of CYP2C9 such as fluconazole can increase serum levels of celecoxib
short-acting corticosteroids
cortisone, hydrocortisone (half-life = 8-12 hours)
intermediate-acting corticosteroids
prednisone, prednisolone, methylprednisolone, triamcinolone (half-life = 18-36 hours)
long-acting corticosteroids
betamethasone, dexamethasone (half-life = 36-55 hours)
gout
the build-up of uric acid crystals in kidneys and joints which causes inflammation