Aspirin
Contraindications for aspirin...
-Active ulcer disease (aspirin blocks enzyme that produces a chemical that protects the stomach lining from acid) -Hemophilia (no clots) -Hemorrhagic states (active GI bleeding, hemorrhagic stroke - no clots) - Known hypersensitivity to NSAID or salicylates -Children or adolescents with flu-like symptoms/chickenpox (Varicella) (Reye's syndrome - brain swelling and liver damage - no aspirin for viral infections)
Side effects of aspirin on skin...
-Angioedema (swelling of the deep layers of the skin) -Bruising -Hives -Rash -Urticaria (swelling of upper dermis)
Precautions to consider with aspirin...
-Chronic use may lead to GI ulcerations, bleeding, or perforation -Alcohol may increase the risk of GI bleeding -Allergic reactions are more likely if the PT has a history of asthma (aspirin hypersensitivity can cause asthma-like symptoms to occur)
Side effects of aspirin on CNS...
-Confusion -Dizziness -Drowsiness -Headache
Use aspirin cautiously with...
-GI disorders -Asthma -Impaired renal/liver function -Dehydrated children -Histories of coagulation defects -Bleeding disorders
Side effects of aspirin on respiratory system...
-Hyperpnea (Deep/rapid breathing - associated with aspirin poisoning - direct stimulation of the respiratory center, causing hyperventilation, which then causes respiratory alkalosis (basic blood pH)) -Wheezing (aspirin sensitivity; allergy symptoms can occur) -Bronchospasms (sensitivity response) -Laryngeal edema (sensitivity response)
Side effects of aspirin on metabolism...
-Hypoglycemia (increased insulin secretion/sensitivity) -Hypokalemia (low potassium - aspirin=salicylate; salicylate poisoning (overdose) = potassium shift in cells(?) and excretion of potassium in urine... this all means that there will be low potassium level in blood)) -Hyponatremia (aspirin can cause fluid retention, which would lower sodium levels)
Indications for aspirin...
-Mild/moderate pain/fever -Reducing the risk of recurrent TIAs (TIAs could lead to stroke) -Chest pain/other signs and symptoms of acute MI -EKG changes suggestive of an acute MI -Reducing inflammation
Class
-Nonsteriodal Anti-inflammatory drug (NSAID) -Antipyretic (reduce fever) -Platelet inhibitor (prevent blood clot formation) -Nonnarcotic analgesic (relieve pain/inflammation)
Side effects of aspirin on GI...
-Reversible hepatotoxicity (liver damage) -Anorexia -Diarrhea -Peptic ulcer formation (from lack of prostaglandin production which protects stomach lining from acid) -Bleeding -Heartburn -Dyspepsia (indigestion) (inhibits pepsin) = GI discomfort (common) -Nausea (common)
Aspirin delivery leads to...
-Vasodilation (platelet inhibitor/thromboxane A₂ inhibitor - thromboxane is a vasoconstrictor) -Decreased clot formation (platelet inhibitor/thromboxane A₂ inhibitor) -Reduction of inflammation (inhibition of prostaglandin synthesis) -Reduction of fever (inhibition of prostaglandin synthesis and Antipyretic properties) -Pain reduction (analgesic property)
Side effects of aspirin on blood...
-decrease in plasma iron concentration -prolonged bleeding -shortened erythrocyte (RBC) survival time (RBC may survive less than 100-120 days) -Leukopenia (life threatening) (reduction of white cells=increased risk of infection) -Thrombocytopenia (life threatening) (platelet deficiency which means slower clot formation)
Side effects of aspirin on eyes/ears...
-dim vision -reversible hearing loss -tinnitus
Approximately ____% of the population is allergic to aspirin
0.2% (2 out of 1000 people)...not too high of an incidence...but reactions can be serious and life threatening
Without aspirin, what happens to damaged vessels in regards to platelet formation?
1) "Sticky" platelets adhere to damaged vessel within 1-5 seconds. 2) Platelets release thromboxane A₂ which is responsible for platelet aggregation and vasoconstriction.
What are the 4 pharmacologic effects of Aspirin?
1. ANALGESIC EFFECT (reduces oral pain) 2. ANTIPYRETIC EFFECT (fever reducer) 3. ANTI-INFLAMMATORY EFFECT (patients with arthritis are often given large doses of aspirin to provide symptomatic relief of pain and inflammation in joints) 4. ANTIPLATELET EFFECT (results in a reduction in blood clotting (thrombi) so good for cardiovascular problems) **(FOUR A's)**
What are the drug dosages for MI?
160-325mg/day PO Non-enteric (chewing is preferred)
What are the dosages for mild pain and fever relief?
325-650mg PO
Describe the effect of aspirin on blood clotting.
At usual therapeutic doses, aspirin interferes with the blood clotting mechanism by irreversibly reducing platelet adhesiveness (stickiness or aggregation). Bleeding time is prolonged and remains prolonged until new platelets are formed. Aspirin should not be given to patients taking coumadin-type anticoagulants because internal GI tract bleeding could occur.
What are 3 early signs of Reye's syndrome that can appear in children taking aspirin with flu-like symptoms or chicken pox?
CHANGES IN BEHAVIOR NAUSEA VOMITING
What population of patients should avoid taking aspirin to prevent Reye's Syndrome?
CHILDREN WITH FLU-LIKE SYMPTOMS OR CHICKEN POX
Aspirin should not be given to patients taking ______________ because internal GI tract bleeding could occur.
COUMADIN-TYPE ANTICOAGULANTS
What enzyme is inhibited by aspirin to prevent platelet aggregation?
Cyclooxygenase-1 and 2 (COX-1 and 2) enzymes
Mechanism of Action: Aspirin acts as an Antipyretic agent by...
Fever reducing: -Prostaglandin inhibition -acting on hypothalamus (heat-regulating center) -Vasodilating/sweating
What is the most common adverse effect caused by aspirin?
GI TRACT ULCERS (and also can cause GI bleeding....if it is being taken for long periods of time)
Aspirin should not be given to patients taking coumadin-type anticoagulants because _____________ could occur.
INTERNAL GI TRACT BLEEDING
Mechanism of Action: Aspirin decreases pain/fever by...
Inhibiting prostaglandin synthesis and release (from mast cells) - prostaglandins regulate inflammation and cause a fever to be produced, among other things
Describe the mechanism of action for aspirin.
Irreversibly inhibits cyclooxygenase-1 and 2 (COX-1 and 2) enzymes, via acetylation, which results in decreased formation of prostaglandin precursors; irreversibly inhibits formation of prostaglandin derivative, thromboxane A2, via acetylation of platelet cyclooxygenase, thus inhibiting platelet aggregation; has antipyretic, analgesic, and anti-inflammatory properties
Describe the hypersensitivity reaction that occurs in people allergic to aspirin.
It is serious (can be life threatening) and results in asthmatic syndrome, shortness of breath, wheezing and bronchiolar constriction.
How is aspirin administered?
PO (orally)
______________ are chemical mediators of pain, fever and inflammation.
PROSTAGLANDINS (when prostaglandin synthesis is inhibited during the conditions of pain, fever and inflammation, there occurs a reduction in these symptoms)
Mechanism of Action: Aspirin acts as a platelet inhibitor by...
Preventing the formation of 'thromboxane A₂' (aspirin inhibits the production of thromboxane A₂)
Children with flu-like symptoms or chicken pox should avoid taking aspirin because it can cause ____________________.
REYE'S SYNDROME (changes in behavior, nausea and vomiting may be early signs of this)
The cardiovascular disease treated with aspirin is known as _________________.
THROMBOSIS
Aspirin irreversibly inhibits formation of prostaglandin derivative, _______________, via acetylation of platelet cyclooxygenase, thus inhibiting platelet aggregation.
THROMBOXANE A2
Mechanism of Action: Aspirin acts as an analgesic agent by acting on...
The peripheral nervous system (aspirin→blockade of prostaglandin production (pain-producing agents) at site of injury in the periphery vs. opioid analgesics which bind to opioid receptors in CNS)
If started within 24 hours of onset of acute MI, aspirin reduces mortality almost to the same degree of...
Thrombolytic therapy (clot-dissolving meds injected into a blood vessel to treat dangerous clots)