Paracetamol Properties

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Questions and Answers

What is the plasma protein binding of mephenamic acid?

Highly bound (correct)

50%

Partially bound

Not bound

What is the most important dose-related side effect of mephenamic acid?

Diarrhoea (correct)

Nausea

Haemolytic anaemia

Epigastric distress

What is the plasma half-life of piroxicam?

Nearly 2 days (correct)

4-6 hours

2-4 hours

12 hours

What is a rare but serious complication of mephenamic acid?

Haemolytic anaemia Signup and view all the answers

What is piroxicam primarily used for?

Rheumatoid and osteoarthritis Signup and view all the answers

How is piroxicam administered?

Single daily administration Signup and view all the answers

What is a common adverse effect of piroxicam?

Heart burn Signup and view all the answers

What is a characteristic of piroxicam's pharmacokinetics?

Rapidly and completely absorbed with 99% plasma protein binding Signup and view all the answers

What is a significant clinical use of paracetamol?

Serving as an antipyretic Signup and view all the answers

What is the primary risk associated with acute paracetamol poisoning?

Centrilobular hepatic necrosis after 12–18 hours Signup and view all the answers

Which of the following is a notable characteristic of paracetamol regarding drug interactions?

It does not have significant drug interactions Signup and view all the answers

What is the recommended dose of paracetamol for adults?

325–650 mg, 3–4 times a day Signup and view all the answers

What treatment is indicated for acute paracetamol poisoning if administered early?

N-acetylcysteine Signup and view all the answers

In which scenario should paracetamol be preferred over conventional NSAIDs?

Postextraction pain in patients with gastric intolerance to NSAIDs Signup and view all the answers

What are the early symptoms of acute paracetamol poisoning?

Nausea, vomiting, abdominal pain, and liver tenderness Signup and view all the answers

Which of the following groups can safely use paracetamol?

Infants to elderly, including pregnant/lactating women Signup and view all the answers

What is the primary mechanism of action for paracetamol (acetaminophen) in terms of pain relief?

Raising the pain threshold in the central nervous system Signup and view all the answers

Which of the following is a common adverse effect of paracetamol (acetaminophen) when used in isolated antipyretic doses?

Nausea and rashes Signup and view all the answers

How is paracetamol (acetaminophen) primarily eliminated from the body?

Conjugation with glucuronic acid and sulfate followed by urinary excretion Signup and view all the answers

Which of the following is a common clinical use of paracetamol (acetaminophen)?

Relief of headache and musculoskeletal pain Signup and view all the answers

How does paracetamol (acetaminophen) differ from selective COX-2 inhibitors (coxibs) in terms of its effect on platelet aggregation?

Both paracetamol and coxibs have minimal or no effect on platelet aggregation Signup and view all the answers

Which of the following statements is true regarding the analgesic action of paracetamol (acetaminophen) and aspirin?

Paracetamol and aspirin have similar analgesic potency Signup and view all the answers

What is the approximate half-life of paracetamol (acetaminophen) in plasma?

2-3 hours Signup and view all the answers

In the context of paracetamol (acetaminophen) poisoning, what is the primary goal of treatment?

Supportive care and administration of N-acetylcysteine Signup and view all the answers

Study Notes

Paracetamol (Acetaminophen)

Effective as an antipyretic, especially in various age groups, including infants and pregnant women.
No prolongation of bleeding time, making it safer for patients undergoing tooth extraction.
Significant for use in patients with contraindications to aspirin, such as those with gastric issues or certain diseases.
Recommended adult dosage: 325–650 mg; for children: 10–15 mg/kg, administered 3–4 times daily.
Acute overdose poses risk, particularly in children; symptoms include nausea, vomiting, abdominal pain, and potentially severe liver damage within 12–18 hours.
Antidote for overdose: N-acetylcysteine, effective only if administered within 12-16 hours post-ingestion.

Analgesics/NSAIDs in Dentistry Guidelines

For mild-to-moderate pain with minimal inflammation: recommended paracetamol or low-dose ibuprofen.
Following dental extractions: consider ketorolac, diclofenac, or nimesulide for short-term pain relief.
In patients unable to tolerate traditional NSAIDs: utilize etoricoxib or paracetamol.
For individuals with a history of asthma or allergic reactions to NSAIDs: nimesulide or COX-2 inhibitors are advisable.

Mephenamic Acid (Fenamate)

A weak anti-inflammatory drug that also serves as an analgesic and antipyretic by inhibiting COX enzymes.
Absorption is slow but complete; highly protein-bound, with a half-life of 2-4 hours.
Major side effects include diarrhea and epigastric distress; serious complications such as haemolytic anemia are rare.
Indicated for muscle, joint, and soft tissue pain, as well as dental pain, with doses of 250–500 mg taken three times daily.

Piroxicam (Enolic Acid Derivative)

A long-acting NSAID with strong anti-inflammatory and analgesic properties, acting as a reversible COX inhibitor.
Rapidly and completely absorbed; 99% plasma protein bound with a prolonged half-life of nearly 2 days.
Generally well tolerated but may cause heartburn, nausea, and anorexia, less ulcerogenic than indomethacin.
Suitable for long-term treatment of rheumatoid arthritis, osteoarthritis, and acute gout, also applicable in dental settings.

Selective COX-2 Inhibitors (Coxibs)

These inhibitors reduce production of endothelial PGI while not affecting TXA-2 synthesis, potentially increasing cardiovascular risks.
Should be prescribed at the lowest effective dose for the shortest duration, especially in high-risk patients.
Examples include Celecoxib, Etoricoxib, and Parecoxib.

Key Points on Paracetamol Pharmacokinetics

Well absorbed following oral administration, with about 25% protein binding and uniform distribution across body tissues.
Metabolized via glucuronic acid and sulfate conjugation, with rapid renal excretion and a plasma half-life of 2–3 hours.
Commonly used for headaches, toothaches, and musculoskeletal pain; generally well tolerated with occasional side effects like nausea and rash.

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Description

Discover the characteristics and uses of Paracetamol, including its antipyretic properties and safe usage in various populations.