Allopurinol is used to treat gout, high levels of uric acid in the body caused by certain cancer medicines and kidney stones.
Name of drugs:
Allopurinol is widely and easily available over the counter medicine across the world.
Class of drug
Allopurinol is in a class of medications called xanthine oxidase inhibitors.
- Allopurinol is used in gout and kidney stones.
- It may also be prescribed if you have some type of cancer treatment causing excessively increased uric acid levels.
- Some treatments can cause a build up of uric acid.
Mechanism of action:
Allopurinol is an xanthine oxidase inhibitor. It works by various mechanisms of action, they are as follows:
- Allopurinol is a structure of the natural purine base hypoxanthine.
- After ingestion allopurinol is metabolized to its active metabolite.
- Oxypurinol (alloxanthin) in the liver, which acts as an inhibitor of xanthine oxidase enzyme.
- This drug is about 90% absorbed from the gastrointestinal tract, peak plasma level normally occurs at 1.5hours and 4.5hours post dose for allopurinol and oxypurinol respectively.
100mg and 300mg.
Powder of injection:
Allopurinol is commonly used drugs administered as following routes:
- Oral form is given in the form of tablet’s is 300mg daily for the prevention of recurrent uric acid or calcium nephrolithiasis. Injection is given intravenous routes, allopurinol is 200-400mg/m2 daily single doses or 2 to 3 divided doses.
Allopurinol is categorised pregnancy risk C by the FDA as it inhibits purine synthesis and hence may have a direct effect on dividing cells in utero.
If allopurinol is required by the mother it is not a reason to discontinue breastfeeding but exclusively breastfeed infants should be monitored if this drug is used including observation for allergic reactions and periodic CBC and differential blood count.
Allopurinol is the urate lowering drug of choice, but its use in old age is associated with an increased incidence of both cutaneous and severe hypersensitivity reactions.
Hepatotoxicity, chronic therapy with allopurinol, is associated with transient and minor liver test abnormalities in 2%to6% of patients, which resolve spontaneously or with drug discontinuation.
Allopurinol treatment reduces risk of cardiovascular events in 71% compared with standard therapy, conclusion: allopurinol decreases C-reactive protein and slows down the progression of renal disease in patients with chronic kidney disease.
- Tingling of arms/legs.
- Easy bleeding/bruising.
- Unusual tiredness.
- Sign of kidney problems (such as change in the amount of urine, painful/bloody urination).
- Yellowing eyes/skin.
- Severe stomach / abdominal pain.
Available common brands:
Zyloprim and alloprim.
Sign of toxicity:
A life threatening toxicity syndrome consisting of
- an erythematous, desquamative skin rash,
- Eosinophilia and worsening renal function in 78 patients receiving allopurinol is described.
In the management of over doses there is no specific antidote for allopurinol/zyloprim.
Usual drug dose:
100mg/day PO initially; increased weekly to 200mg to 300mg/day.
Moderate to severe:
100mg/day PO initially, Increased weekly to 400mg to 600mg/day.
Antineoplastic induced hyperuricemia:
PO: 600mg to 800mg/ divided q8-12 hours, starting 1-2 days before chemotherapy. Intravenous: 200mg to 400mg/m2/day; Not to exceed 600mg/m2/day.