ASPIRIN (ACETYLSALICYLIC ACID)

(as'pe-ren)

Alka-Seltzer, A.S.A., Aspergum, Astrin

, Bayer, Bayer Children's, Cosprin, Easprin, Ecotrin, Empirin, Entrophen

, Halfprin, Measurin, Novasen

, St. Joseph Children's, Supasa

, Triaphen-10

, ZORprin
Classifications: analgesic, salicylate; antipyretic; antiplatelet;
Therapeutic: nonnarcotic analgesic, antipyretic; antiplatelet
Pregnancy Category: D

Availability

81 mg chewable tablets; 325 mg, 500 mg tablets; 81 mg, 165 mg, 325 mg, 500 mg, 650 mg, 975 mg enteric-coated tablets; 650 mg, 800 mg sustained release tablets; 120 mg, 200 mg, 300 mg, 600 mg suppositories

Action

Major action is primarily due to inhibiting the formation of prostaglandins involved in the production of inflammation, pain, and fever. Antiinflammatory action: Inhibits prostaglandin synthesis. As an antiinflammatory agent, aspirin appears to be involved in enhancing antigen removal and in reducing the spread of inflammatory substances. Analgesic action: Principally peripheral with limited action in the CNS in the hypothalamus; results in relief of mild to moderate pain. Antipyretic action: Suppress the synthesis of prostaglandin in or near the hypothalamus. Aspirin also lowers body temperature in fever by indirectly causing centrally mediated peripheral vasodilation and sweating. Antiplatelet action: Aspirin (but not other salicylates) powerfully inhibits platelet aggregation. High serum salicylate concentrations can impair hepatic synthesis of blood coagulation factors VII, IX, and X.

Therapeutic Effect

Reduces inflammation, pain, and fever. Also inhibits platelet aggregation, reducing ability of blood to clot.

Uses

To relieve pain of low to moderate intensity. Also for various inflammatory conditions, such as acute rheumatic fever, systemic lupus, rheumatoid arthritis, osteoarthritis, bursitis, and calcific tendonitis, and to reduce fever in selected febrile conditions. Used to reduce recurrence of TIA due to fibrin platelet emboli and risk of stroke in men; to prevent recurrence of MI; as prophylaxis against MI in men with unstable angina.

Unlabeled Uses

As prophylactic against thromboembolism; to prevent cataract and progression of diabetic retinopathy; and to control symptoms related to gluten sensitivity.

Contraindications

History of hypersensitivity to salicylates including methyl salicylate (oil of wintergreen); sensitivity to other NSAIDs; patients with "aspirin triad" (aspirin sensitivity, nasal polyps, asthma); chronic rhinitis; acute bronchospasm; agranulocytosis; head trauma; increased intracranial pressure; intracranial bleeding; chronic urticaria; history of GI ulceration, bleeding, or other problems; hypoprothrombinemia, vitamin K deficiency, hemophilia, or other bleeding disorders; CHF; pregnancy (category D), especially in third trimester; lactation; or in prematures, neonates, or children under 2 y, except under advice and supervision of physician; children or teenagers with chickenpox or influenza-like illnesses because of possible association with Reye's syndrome.

Cautious Use

Otic diseases; gout; children with fever accompanied by dehydration; hyperthyroidism; immunosuppressed individuals; asthma; GI disease; history of gout; cardiac disease; renal or hepatic impairment; G6PD deficiency; vitamin K deficiency; anemia; preoperatively; Hodgkin's disease.

Route & Dosage

Mild to Moderate Pain, Fever
Adult: PO/PR 350–650 mg q4h (max: 4 g/d)
Child: PO/PR 10–15 mg/kg in 4–6 h (max: 3.6 g/d)

Arthritic Conditions
Adult: PO 3.6–5.4 g/d in 4–6 divided doses
Child: PO 80–100 mg/kg/d in 4–6 divided doses; max 130 mg/kg/d

Thromboembolic Disorders
Adult: PO 81–325 mg qd

TIA Prophylaxis
Adult: PO 650 mg b.i.d.

MI Prophylaxis
Adult: PO 80–325 mg/d

Administration

Oral

Give with a full glass of water (240 mL), milk, food, or antacid to minimize gastric irritation.
Enteric-coated tablets dissolve too quickly if administered with milk and should not be crushed or chewed.
Store at 15°–30° C (59°–86° F) in airtight container and dry environment unless otherwise directed by manufacturer. Store suppositories in a cool place or refrigerate but do not freeze.

Adverse Effects (≥1%)

Body as a Whole: Hypersensitivity (urticaria, bronchospasm, anaphylactic shock (laryngeal edema). CNS: Dizziness, confusion, drowsiness. Special Senses: Tinnitus, hearing loss. GI: Nausea, vomiting, diarrhea, anorexia, heartburn, stomach pains, ulceration, occult bleeding, GI bleeding. Hematologic: Thrombocytopenia, hemolytic anemia, prolonged bleeding time. Skin: Petechiae, easy bruising, rash. Urogenital: Impaired renal function. Other: Prolonged pregnancy and labor with increased bleeding.

Diagnostic Test Interference

Bleeding time is prolonged 3–8 d (life of exposed platelets) following a single 325-mg (5 grains) dose of aspirin. Large doses of salicylates equivalent to 5 g or more of aspirin per day may cause prolonged prothrombin time by decreasing prothrombin production; interference with pregnancy tests (using mouse or rabbit); decreases in serum cholesterol, potassium, PBI, T₃ and T₄ concentrations, and an increase in T₃ resin uptake. Serum uric acid may increase when plasma salicylate levels are below 10 and decrease when above 15 mg/dL using colorimetric methods. Urine 5-HIAA: Aspirin may interfere with tests using fluorescent methods. Urine ketones: Salicylates interfere with Gerhardt test (reaction with ferric chloride produces a reddish color that persists after boiling). Urine glucose: Moderate to large doses of salicylates equivalent to an aspirin dosage ≥2.4 g/d may produce false-negative results with glucose oxidase methods (e.g., Clinistix, TesTape) and false-positive results with copper reduction methods (Benedict's solution, Clinitest). Urinary PSP excretion may be reduced by salicylates. Salicylates may cause urine VMA to be falsely elevated (by most tests), or reduced (by Pisano method). Salicylates may interfere with or cause false decreases in plasma theophylline levels using Schack and Waxler method. High plasma salicylate levels may cause abnormalities in liver function tests.

Interactions

Drug: Aminosalicylic acid increases risk of salicylate toxicity. Ammonium chloride and other acidifying agents decrease renal elimination and increase risk of salicylate toxicity. anticoagulants increase risk of bleeding. oral hypoglycemic agents increase hypoglycemic activity with aspirin doses >2 g/d. carbonic anhydrase inhibitors enhance salicylate toxicity. corticosteroids add to ulcerogenic effects. Methotrexate toxicity is increased. Low doses of salicylates may antagonize uricosuric effects of probenecid and sulfinpyrazone. Herbal: Feverfew, garlic, ginger, ginkgo may increase bleeding potential.

Pharmacokinetics

Absorption: 80–100% absorbed (depending on formulation), primarily in stomach and upper small intestine. Peak levels: 15 min to 2 h. Distribution: Widely distributed in most body tissues; crosses placenta. Metabolism: Aspirin is hydrolyzed to salicylate in GI mucosa, plasma, and erythrocytes; salicylate is metabolized in liver. Elimination: 50% of dose is eliminated in the urine in 2–4 h (low doses) or 15–30 h (high doses). Excreted into breast milk. Half-Life: Aspirin 15–20 min; salicylate 2–18 h (dose dependent).

Nursing Implications

Assessment & Drug Effects

Monitor for loss of tolerance to aspirin. The reaction is nonimmunologic; symptoms usually occur 15 min to 3 h after ingestion: profuse rhinorrhea, erythema, nausea, vomiting, intestinal cramps, diarrhea.
Lab tests: Frequent PT and IRN with concurrent anticoagulant therapy; more frequent fasting blood glucose levels with diabetes.
Monitor the diabetic child carefully for need to adjust insulin dose. Children on high doses of aspirin are particularly prone to hypoglycemia (see Appendix F).
Monitor for salicylate toxicity. In adults, a sensation of fullness in the ears, tinnitus, and decreased or muffled hearing are the most frequent symptoms associated with chronic salicylate overdosage.
Monitor children closely because salicylate toxicity is enhanced by the dehydration that frequently accompanies fever or illness. Children tend to manifest salicylate toxicity by hyperventilation, agitation, mental confusion, or other behavioral changes, drowsiness, lethargy, sweating, and constipation.
Note: Potential for toxicity is high in older adults and patients with asthma, nasal polyps, perennial vasomotor rhinitis, hay fever, or chronic urticaria.

Patient & Family Education

Do not give aspirin to children or teenagers with symptoms of varicella (chickenpox) or influenza-like illnesses because of association of aspirin usage with Reye's syndrome.
Use enteric-coated tablets, extended release tablets, buffered aspirin, or aspirin administered with an antacid to reduce GI disturbances.
Take aspirin 1–2 d before menses when prescribed for dysmenorrhea. When experiencing heavy menstrual blood loss, take another analgesic, such as acetaminophen, instead of aspirin.
Discontinue aspirin therapy about 1 wk before surgery to reduce risk of bleeding. Do not use aspirin-containing gum or gargles or chew aspirin products for at least 1 wk following oral surgery.
Note: Chronic use of high-dose aspirin during the last 3 mo of pregnancy can prolong pregnancy and labor, increase maternal bleeding before and after-delivery, and cause weight increase and hemorrhage in the neonate.
Discontinue aspirin use with onset of ringing or buzzing in the ears, impaired hearing, dizziness, GI discomfort or bleeding, and report to physician.
Do not use aspirin for self-medication of pain (adults) beyond 5 d without consulting a physician. Do not use aspirin longer than 3 d for fever (adults and children), never for fever over 38.9° C (102° F) in older adults or 39.5° C (103° F) in children and adults under 60 y or for recurrent fever without medical direction.
Consult physician before using aspirin for any fever accompanied by rash, severe headache, stiff neck, marked irritability, or confusion (all possible symptoms of meningitis).
Avoid alcohol when taking large doses of aspirin.
Observe and report signs of bleeding (e.g., petechiae, ecchymoses, bleeding gums, bloody or black stools, cloudy or bloody urine).
Maintain adequate fluid intake when taking repeated doses of aspirin.
Avoid other medications containing aspirin unless directed by physician, because of danger of overdosing (there are more than 500 OTC aspirin-containing compounds).

Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug

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