Aspirin Tablets

Indications

• Pain relief
• Fever reduction
• Inflammatory conditions such as arthritis
• Prevention of cardiovascular diseases including myocardial infarction and stroke
• Antiplatelet therapy in patients with a history of thromboembolic events

Dosage

Adults: Dosage varies based on indication. For analgesia or antipyretic use, typical doses range from 300 mg to 1000 mg every 4 to 6

Mechanism of action

Aspirin exerts its effects primarily through the irreversible inhibition of cyclooxygenase (COX) enzymes, specifically COX-1 and COX-2. This inhibition leads to the decreased synthesis of prostaglandins and thromboxanes, which are mediators of inflammation, pain, and platelet aggregation. By blocking COX-1, aspirin reduces the formation of thromboxane A2, thereby inhibiting platelet activation and aggregation, which is crucial in preventing thrombus formation.

Pharmacodynamics

The pharmacodynamic effects of aspirin include the reduction of pain and inflammation due to decreased prostaglandin production, as well as the inhibition of platelet aggregation, which can help prevent thrombotic events such as myocardial infarction and stroke. The onset of analgesic effects occurs within 30 minutes of administration, while the anti-inflammatory effects may take a few hours to manifest.

Pharmacokinetics

Aspirin is well absorbed from the gastrointestinal tract, with peak plasma concentrations occurring within 1 to 2 hours post-administration. It is extensively metabolized in the liver to salicylic acid and other metabolites, which exhibit anti-inflammatory activity. The elimination half-life of aspirin is approximately 15 to 20 minutes, although its active metabolite, salicylic acid, has a longer half-life ranging from 2 to 3 hours. Aspirin and its metabolites are primarily excreted by the kidneys.

Contra-indications

• Active gastrointestinal bleeding
• History of peptic ulcer disease
• Severe renal impairment
• Severe hepatic impairment
• Hypersensitivity to aspirin or other NSAIDs
• Children and teenagers with viral infections (risk of Reye's syndrome)

Adverse effects

• Gastrointestinal upset
• Nausea
• Vomiting
• Gastric ulcers
• Gastrointestinal bleeding
• Tinnitus
• Allergic reactions (e.g., asthma exacerbation)
• Rash
• Hepatotoxicity
• Renal impairment

Interactions

• Increased risk of bleeding with anticoagulants (e.g., warfarin)
• Increased gastrointestinal toxicity with other NSAIDs
• Reduced effectiveness of antihypertensive medications (e.g., ACE inhibitors, diuretics)
• Potentially increased risk of salicylate toxicity with methotrexate

Precautions

• Use with caution in patients with asthma, as aspirin can induce bronchospasm
• Monitor renal function in patients with pre-existing kidney conditions
• Caution in patients with a history of gastrointestinal disorders
• Discontinue prior to surgical procedures to reduce the risk of bleeding

Pregnancy

Aspirin should be used with caution during pregnancy, particularly during the third trimester due to the risk of fetal harm and potential complications during delivery.

Breast-feeding

Aspirin is excreted in breast milk; consult a healthcare provider before use during lactation.

Storage

Store at room temperature away from moisture and light. Keep out of reach of children.

Formulations

• Tablets
• Enteric-coated tablets
• Effervescent tablets
• Powders for oral solution
• Suppositories