Allopurinol

Generic Details

Generic Name

Allopurinol

Other Names

  • Zyloprim

Drug Class

  • Xanthine Oxidase Inhibitors

Chemical Formula

C5H4N4O

Molecular Weight

136.11 g/mol

Mechanism of Action

  • Allopurinol inhibits xanthine oxidase, the enzyme responsible for converting hypoxanthine to xanthine and xanthine to uric acid. By inhibiting this enzyme, allopurinol decreases the production of uric acid, reducing serum urate levels.

Indications

  • Hyperuricemia
  • Gout
  • Kidney stones

Common Dosage Forms

  • Tablet
  • Injection

Typical Dosage

  • 100-800 mg daily, depending on the condition being treated

Pediatric Dosage

  • Dosage based on body weight and medical condition, to be determined by a pediatrician

Geriatric Dosage

  • Lower starting dose may be required due to decreased kidney function in elderly patients

Side Effects

  • Rash
  • Nausea or vomiting
  • Diarrhea
  • Drowsiness
  • Headache

Contraindications

  • Hypersensitivity to allopurinol
  • Severe liver or kidney dysfunction

Pregnancy Category

  • Category C - Animal reproduction studies have shown an adverse effect on the fetus and there are no adequate and well-controlled studies in humans, but potential benefits may warrant use of the drug in pregnant women despite potential risks.

Lactation Safety

  • Caution advised. It is unknown whether allopurinol passes into breast milk. Consult healthcare provider before using.

Drug Interactions

  • Azathioprine
  • Mercaptopurine
  • Theophylline
  • Warfarin

Overdose Symptoms

  • Nausea
  • Vomiting
  • Diarrhea
  • Dizziness
  • Seizures

Antidote for Overdose

  • Symptomatic and supportive treatment

Storage Conditions

  • Store at room temperature between 20-25°C (68-77°F)

Pharmacokinetics

  • Absorption: Well absorbed from the gastrointestinal tract
  • Distribution: Widely distributed in the body, including to synovial fluid
  • Metabolism: Metabolized in the liver to oxypurinol (active metabolite)
  • Excretion: Primarily excreted in the urine

Precautions

  • Monitor renal and hepatic function during treatment
  • Stay hydrated to prevent kidney stones

Warnings

  • Hypersensitivity reactions may occur, discontinue use if rash or other signs of hypersensitivity develop

Others

  • Allopurinol may take several weeks to show its full effect on lowering uric acid levels.