Aspirin

Dosage varies significantly based on the condition being treated. Typical ranges include:

• Pain and Fever: 325 mg to 650 mg every 4 to 6 hours as needed. Do not exceed 4,000 mg (4 grams) in a 24-hour period.
• Cardiovascular Prevention: 75 mg to 325 mg once daily, as directed by a cardiologist. The 81 mg dose is the most common "low-dose" regimen.
• Acute Myocardial Infarction (Heart Attack): 162 mg to 325 mg, usually chewed immediately upon the onset of symptoms (after calling emergency services).

Warning: Aspirin should generally not be used in children or teenagers for viral infections (such as the flu or chickenpox) due to the risk of Reye’s Syndrome, a rare but potentially fatal condition. Pediatric use is strictly limited to specific conditions like Kawasaki disease under direct specialist supervision.

Renal Impairment

Patients with severe kidney disease (GFR < 10 mL/min) should avoid Aspirin, as it can further decrease renal blood flow and lead to acute kidney injury.

Hepatic Impairment

Use with caution in patients with severe liver disease, as the liver is the primary site for metabolism and Aspirin can increase the risk of bleeding in these patients.

Elderly Patients

Older adults are at a higher risk for gastrointestinal bleeding and kidney complications. Lower doses or more frequent monitoring may be required.

• With Food: To minimize stomach upset (dyspepsia), it is often recommended to take Aspirin with a full glass of water and food or milk.
• Swallow Whole: Enteric-coated or delayed-release tablets should be swallowed whole. Do not crush or chew them unless instructed by a doctor (e.g., during a heart attack).
• Storage: Store at room temperature away from moisture and heat. If the tablets have a strong vinegar-like smell, they have begun to break down and should be discarded.

If you miss a dose, take it as soon as you remember. If it is almost time for your next dose, skip the missed dose and resume your regular schedule. Do not double the dose to catch up.

Signs of Aspirin overdose (salicylism) include ringing in the ears (tinnitus), headache, dizziness, confusion, rapid breathing (hyperventilation), and vomiting. Severe overdose can lead to seizures or coma. Seek emergency medical attention immediately if an overdose is suspected.

> Important: Follow your healthcare provider's dosing instructions. Do not adjust your dose without medical guidance.

While Aspirin is a common medication, it can cause a range of side effects, particularly with long-term use or high doses.

• Gastrointestinal Upset: Heartburn, nausea, and mild stomach pain are the most frequently reported issues.
• Increased Bleeding: Because Aspirin thins the blood, you may notice that small cuts take longer to stop bleeding, or you may bruise more easily.

• Dyspepsia: Persistent indigestion or discomfort in the upper abdomen.
• Urticaria: Skin rashes or hives.

• Tinnitus: A high-pitched ringing or buzzing in the ears, which often indicates the dose is too high.
• Hepatotoxicity: Inflammation of the liver (rare at standard doses).

> Warning: Stop taking Aspirin and call your doctor immediately if you experience any of these:

• Gastrointestinal Bleeding: Symptoms include black, tarry, or bloody stools, and vomiting blood or material that looks like coffee grounds.
• Anaphylaxis: Severe allergic reactions including swelling of the face or throat, difficulty breathing, or severe dizziness.
• Hemorrhagic Stroke: Sudden severe headache, vision changes, or weakness on one side of the body.
• Severe Bronchospasm: Difficulty breathing or wheezing, especially in patients with a history of asthma.

Chronic use of Aspirin can lead to the development of gastric ulcers (sores in the stomach lining) and chronic kidney disease. It may also lead to iron-deficiency anemia due to microscopic, undetected bleeding in the digestive tract.

While Aspirin does not carry the same cardiovascular black box warning as other NSAIDs (like Ibuprofen or Celecoxib), it does carry a significant warning regarding Reye's Syndrome.

Reye's Syndrome Warning: Aspirin should not be used in children or teenagers for viral infections, with or without fever, because of the risk of Reye's syndrome. Reye's syndrome is a rare but very serious illness that causes swelling in the liver and brain.

Report any unusual symptoms to your healthcare provider.

Aspirin is a potent medication that affects blood clotting and the stomach lining. It must be used with caution in individuals with a history of ulcers or bleeding disorders.

There is no standard FDA black box warning for adult cardiovascular risk for Aspirin; however, the warning for Reye's Syndrome in pediatric populations is the most critical safety notification associated with this drug.

• Bleeding Risk: Aspirin increases the risk of serious bleeding events, including intracranial hemorrhage (bleeding in the brain) and gastrointestinal bleeds. This risk is higher in those over 60, those taking anticoagulants, or those with a history of stomach ulcers.
• Aspirin-Exacerbated Respiratory Disease (AERD): Patients with the "aspirin triad" (asthma, nasal polyps, and aspirin sensitivity) may experience severe, life-threatening bronchospasm (tightening of the airways) if they take Aspirin.
• Renal Function: Aspirin can reduce blood flow to the kidneys, potentially leading to renal impairment, especially in patients with pre-existing kidney disease or heart failure.
• Surgery: Patients should typically stop taking Aspirin 7–10 days before elective surgery to prevent excessive bleeding, though this must be managed by the surgeon and prescribing physician.

For patients on long-term Aspirin therapy, healthcare providers may monitor:

• Hemoglobin and Hematocrit: To check for occult (hidden) blood loss.
• Renal Function: Creatinine and GFR levels.
• Liver Enzymes: Periodically, if taking high doses for inflammatory conditions.

Aspirin typically does not affect the ability to drive or operate machinery. However, if you experience dizziness or vision changes, avoid these activities and consult your doctor.

Consuming alcohol while taking Aspirin significantly increases the risk of stomach bleeding and gastric ulcers. It is generally advised to limit or avoid alcohol consumption during therapy.

For patients taking Aspirin for heart protection, stopping the medication suddenly can lead to a "rebound effect," increasing the risk of a heart attack. Never stop Aspirin therapy without consulting your cardiologist.

> Important: Discuss all your medical conditions with your healthcare provider before starting Aspirin.

• Ketorolac: Using Aspirin with Ketorolac (another NSAID) significantly increases the risk of severe gastrointestinal bleeding and should be avoided.
• Live Influenza Vaccine: There is a theoretical risk of Reye's syndrome if Aspirin is used concurrently with certain live vaccines in children.

• Anticoagulants (e.g., Warfarin, Apixaban, Rivaroxaban): Combining Aspirin with "blood thinners" greatly increases the risk of major bleeding. This combination requires strict medical supervision.
• NSAIDs (e.g., Ibuprofen, Naproxen): Ibuprofen may interfere with the antiplatelet effect of low-dose Aspirin, potentially making the Aspirin less effective for heart protection. If both are needed, Ibuprofen should be taken at least 8 hours after or 30 minutes before immediate-release Aspirin.
• Methotrexate: Aspirin can decrease the renal clearance of methotrexate, leading to toxic levels of the drug in the blood.

• SSRIs (e.g., Fluoxetine, Sertraline): These antidepressants can increase the risk of upper gastrointestinal bleeding when taken with Aspirin.
• ACE Inhibitors and Diuretics: Aspirin may reduce the blood-pressure-lowering effects of these medications and increase the risk of kidney damage.

• Alcohol: Increases the risk of GI bleeding.
• Caffeine: May increase the absorption rate of Aspirin but can also increase the risk of stomach irritation.

• Ginkgo Biloba, Garlic, Ginger, and Ginseng: These supplements have natural antiplatelet properties and may increase the risk of bleeding when combined with Aspirin.
• St. John's Wort: May increase the risk of bleeding in the digestive tract.

Aspirin may interfere with certain lab tests, including urinary glucose tests and thyroid function tests, potentially leading to false results.

> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking.

• NSAID Allergy: Aspirin must never be used in patients who have experienced asthma, hives, or allergic-type reactions after taking Aspirin or other NSAIDs.
• Active Peptic Ulcer Disease: Patients with active bleeding or perforated ulcers must avoid Aspirin as it inhibits the protective prostaglandins in the stomach lining.
• Bleeding Disorders: Conditions such as hemophilia or von Willebrand disease are absolute contraindications due to the risk of uncontrollable bleeding.
• Pediatric Viral Infection: Due to the risk of Reye's Syndrome.

• Asthma: Patients with asthma are at a higher risk for Aspirin sensitivity.
• Gout: Low-dose Aspirin can interfere with the excretion of uric acid, potentially triggering a gout flare.
• Uncontrolled Hypertension: High blood pressure increases the risk of a hemorrhagic stroke while on Aspirin therapy.

Patients allergic to Aspirin may also react to other salicylates (such as magnesium salicylate) and many nonsteroidal anti-inflammatory drugs like ibuprofen and naproxen.

> Important: Your healthcare provider will evaluate your complete medical history before prescribing Aspirin.

• First and Second Trimester: Aspirin should only be used if the potential benefit justifies the potential risk to the fetus. Low-dose Aspirin (81 mg) is sometimes used to prevent preeclampsia under strict specialist guidance.
• Third Trimester: High-dose Aspirin is generally contraindicated. It can cause premature closure of the ductus arteriosus (a vital fetal blood vessel) and lead to delayed labor or increased bleeding during delivery.

Aspirin is excreted into breast milk in low concentrations. While occasional low doses are generally considered compatible with breastfeeding, chronic high-dose therapy is discouraged due to the potential risk of Reye's syndrome in the nursing infant.

As previously noted, Aspirin is contraindicated in children and teenagers with viral illnesses. It is only used in specific pediatric conditions like Kawasaki disease or certain congenital heart defects under the direction of a pediatric specialist.

Patients over 65 are at a significantly higher risk for Aspirin-induced gastrointestinal bleeding and renal impairment. Clinical guidelines (such as those from the USPSTF) have recently become more conservative regarding the use of Aspirin for primary prevention in the elderly.

In patients with a GFR below 30 mL/min, Aspirin should be used with extreme caution or avoided, as it can further reduce renal prostaglandins, leading to acute kidney failure.

Patients with severe cirrhosis (Child-Pugh Class C) are at high risk for bleeding and should generally avoid Aspirin unless the benefits for cardiovascular health are deemed essential by a specialist.

> Important: Special populations require individualized medical assessment.

Aspirin (acetylsalicylic acid) acts as an acetylating agent. It covalently attaches an acetyl group to a serine residue in the active site of the cyclooxygenase (COX) enzyme. This irreversible inhibition distinguishes Aspirin from other NSAIDs (like Ibuprofen), which bind reversibly. By inhibiting COX-1, Aspirin prevents the formation of Thromboxane A2 in platelets, which is the basis for its antiplatelet effect.

• Onset of Action: For pain, effects begin within 30–60 minutes. For antiplatelet effects, inhibition begins within 1 hour of ingestion of non-enteric coated tablets.
• Duration: The analgesic effect lasts 4–6 hours. The antiplatelet effect lasts for the life of the platelet (7–10 days).

| Parameter | Value |

|---|---|

| Bioavailability | 80% - 100% (Rapidly absorbed) |

| Protein Binding | 80% - 90% (Primarily Albumin) |

| Half-life | 15–20 minutes (Aspirin); 2–30 hours (Salicylate metabolite) |

| Tmax | 0.25 - 2 hours (Formulation dependent) |

| Metabolism | Hepatic (Hydrolysis to Salicylic Acid) |

| Excretion | Renal (80% to 100%) |

• Molecular Formula: C9H8O4
• Molecular Weight: 180.16 g/mol
• Solubility: Slightly soluble in water; freely soluble in alcohol.
• Structure: An aromatic ring with both an acetoxy group and a carboxylic acid group.

Aspirin is a salicylate and a non-selective NSAID. It is also categorized as a platelet aggregation inhibitor.