Allopurinol inhibits xanthine oxidase, the enzyme responsible for conversion of hypoxanthine to xanthine and then to uric acid. About 20% is excreted in the feces. Allopurinol is essentially cleared by glomerular filtration, whereas oxipurinol is reabsorbed in the kidney tubules.
How to Take Allopurinol
Take Allopurinol exactly as prescribed by health care provider. Allopurinol is generally available in market in the form of Powder for injection, lyophilized 500 mg, Tablets 100 mg, Tablets 300 mg. Administer immediately after meals. For patients who have difficulty swallowing, crush tablets and mix with food. Reduced dose is given in patients with this condition. Drug may exacerbate renal failure in certain patients.
Indications for Allopurinol Drug
*Tablets: Treatment of primary or secondary gout, hyperuricemia resulting from chemotherapy for malignancies, recurrent calcium oxalate renal calculi.
*Tablets and injections: Management of patients with leukemia, lymphoma, and solid tumor malignancies when concurrently receiving cancer therapy that causes elevations of serum and urinary uric acid levels. Use injection in patients who cannot tolerate oral therapy.
Interactions for Allopurinol Drug
*Aluminum salts, uricosuric agents: May lessen effectiveness of allopurinol.
*Ampicillin: May increase incidence of ampicillin-induced skin rash.
*Cyclophosphamide: May enhance bone marrow suppression.
*Theophyllines: Theophylline clearance may be decreased, leading to toxicity.
*Thiopurines (eg, azathioprine, mercaptopurine): Toxicity of these drugs may be increased.
Drugs that are physically incompatible in solution with allopurinol sodium for injection are the following: amikacin; amphotericin B; carmustine; cefotaxime; chlorpromazine; cimetidine; clindamycin; cytarabine; dacarbazine; daunorubicin; diphenhydramine; doxorubicin; doxycycline; droperidol; floxuridine; gentamicin; haloperidol; hydroxyzine; idarubicin; imipenem plus cilastatin; mechlorethamine; meperidine; metoclopramide; methylprednisolone sodium succinate; minocycline; nalbuphine; netilmicin; ondansetron; prochlorperazine edisylate; promethazine; sodium bicarbonate; streptozocin; tobramycin; vinorelbine tartrate.
What are the Side Effects of Allopurinol –
Like other medicines, Allopurinol can cause side effects. Some of the more common side effects of Allopurinol include
* Drowsiness; generalized seizure (injectable); headache; neuritis; paresthesias; peripheral neuropathy.
* Allergic vasculitis; alopecia; ecchymosis; skin rash. Allergic reactions may be severe and sometimes fatal.
* Abdominal pain; diarrhea; dyspepsia; gastritis; granulomatous changes; nausea; vomiting.
* Epistaxis; myopathy; taste disturbance.
* Renal failure; uremia.
* Bone marrow depression; eosinophilia; leukocytosis; leukopenia; thrombocytopenia.
* Cholestatic jaundice; elevated liver enzymes; hepatic necrosis; hepatitis; reversible hepatomegaly.
* Acute gouty attacks; arthralgia; fever; myopathy; necrotizing angiitis.
Warnings and precautions before taking Allopurinol :
* Advise patient before using Allopurinol that drug may cause drowsiness, and to use caution while driving or performing other tasks requiring mental alertness.
* Instruct patient before using Allopurinol to stop taking medication and notify health care provider if rash or flu-like symptoms develop.
* If urine output is decreased, dosage may need to be decreased. Consult health care provider before using Allopurinol.
* Advise women before using Allopurinol to inform health care provider if pregnant, planning to become pregnant, or breastfeeding while taking Allopurinol. Insulin is recommended to maintain blood glucose levels during pregnancy. Prolonged severe neonatal hypoglycemia can occur if sulfonylureas are administered at time of delivery.
* For treatment of gout, obtain baseline uric acid level. Monitor q 1 to 2 wk for dosage adjustment, then monitor every few months.
What if Overdose of Allopurinol ?
If you think you or anyone else taken overdose of Allopurinol , immediately telephone your doctor or contact your local or regional Poisons Information Centre Seek medical attention immediately. You may need urgent medical attention. Chills, headache, arthralgia, sinusitis are may be the overdose symptoms of Allopurinol.
What if Missed Dose of Allopurinol ?
If you miss a dose of Allopurinol medicine and you remember within an hour or so, take the dose immediately. If you do not remember until later, skip the dose you missed and go back to your regular schedule. Do not double doses.
Storage Conditions for Allopurinol :
Store Allopurinol reconstituted solution at 20° to 25°C; do not refrigerate or dilute product. Store Allopurinol unreconstituted powder at room temperature. Store Allopurinol tablets in tightly closed container in cool location.