Zyloprim, with the active ingredient allopurinol, is a xanthine oxidase inhibitor prescribed for the long-term management of gout and conditions marked by elevated uric acid levels (hyperuricemia). It functions by reducing the production of uric acid in the body, thereby preventing the formation of urate crystals that deposit in joints and tissues, causing painful gout attacks and potential kidney damage. This medication represents a cornerstone prophylactic therapy, aimed not at treating acute pain but at preventing future episodes and complications associated with chronic hyperuricemia. Proper diagnosis and ongoing medical supervision are essential for its safe and effective use.

Features

• Active Pharmaceutical Ingredient: Allopurinol.
• Dosage Forms: Available in scored, film-coated tablets for easy splitting (100 mg and 300 mg strengths).
• Mechanism of Action: Potent inhibitor of the enzyme xanthine oxidase.
• Pharmacological Class: Xanthine Oxidase Inhibitor.
• Prescription Status: Requires a prescription from a licensed healthcare provider.
• Bioavailability: Well-absorbed from the gastrointestinal tract, with peak plasma concentrations reached within 1-1.5 hours.

Benefits

• Prevents Painful Gout Attacks: Significantly reduces the frequency and severity of acute gout flares by maintaining lower serum uric acid levels.
• Reduces Tophus Formation: Aids in the gradual dissolution of existing urate crystal deposits (tophi) and prevents the formation of new ones, protecting joint integrity.
• Minimizes Kidney Stone Risk: Lowers the urinary excretion of uric acid, thereby decreasing the likelihood of developing uric acid nephrolithiasis (kidney stones).
• Manages Secondary Hyperuricemia: Effectively controls elevated uric acid levels caused by certain cancers, their therapies, or other medications.
• Long-Term Prophylaxis: Provides a reliable, foundational treatment for the chronic management of gout, helping to prevent long-term joint damage and disability.

Common use

Zyloprim (allopurinol) is primarily indicated for the management of:

• Chronic Gout: Used as a prophylactic treatment to prevent recurrent gout attacks and to promote the resolution of tophi. It is not used for the treatment of an acute gout attack.
• Hyperuricemia Secondary to Cytotoxic Therapy: Employed to manage elevated uric acid levels in patients with leukemia, lymphomas, and other malignancies who are receiving cancer chemotherapy, which causes rapid cell lysis and a consequent rise in uric acid.
• Recurrent Uric Acid Stone Formation: Prescribed to patients with a history of recurrent uric acid kidney stones or calcific stones with a uric acid component to prevent recurrence.

Dosage and direction

Dosage must be individualized based on the severity of the condition and the patient’s renal function. The following is a general guideline; always follow the specific instructions provided by the prescribing physician.

• Initial Dose: For adults, treatment is usually initiated at a low dose, such as 100 mg once daily.
• Titration: The dose may be increased by 100 mg weekly until a serum uric acid level of less than 6 mg/dL is achieved. This gradual titration helps minimize the risk of acute gout flares at therapy initiation.
• Maintenance Dose: The typical maintenance dose is 200-300 mg daily for mild gout. For moderate to severe gout, doses of 400-600 mg per day may be required. Doses exceeding 300 mg daily should be administered in divided doses.
• Maximum Dose: 800 mg per day.
• Dosing in Renal Impairment: Dosage adjustment is critical. A lower initial dose and slower titration are necessary. Dosing is often based on creatinine clearance (e.g., 100 mg daily for CrCl 10-20 mL/min; 100 mg every other day for CrCl 3-10 mL/min).
• Administration: Tablets should be taken orally with a full glass of water. To minimize the potential for gastric irritation, it is recommended to take Zyloprim after a meal.
• Fluid Intake: Patients should maintain adequate hydration (2-3 liters of fluid per day) to help excrete uric acid and reduce the risk of stone formation.

Precautions

• Hypersensitivity Reactions: Be vigilant for signs of a serious hypersensitivity reaction, which may include skin rash, fever, lymphadenopathy, arthralgia, and eosinophilia. These can be precursors to severe, potentially fatal reactions like DRESS (Drug Reaction with Eosinophilia and Systemic Symptoms) or Stevens-Johnson syndrome. Discontinue therapy immediately at the first appearance of a rash or other sign of hypersensitivity.
• Renal Function: Baseline assessment of renal function is mandatory. Renal impairment increases the risk of toxicity. Dose adjustments are required, and renal function should be monitored periodically during therapy.
• Hepatic Function: Periodic liver function tests are recommended. Discontinue use if liver function abnormalities occur.
• Asymptomatic Hyperuricemia: Zyloprim is generally not recommended for treating asymptomatic hyperuricemia.
• Acute Gout Flares: An increase in acute gout attacks may occur during the initial months of therapy due to mobilization of urate from tissue deposits. This is not a reason to discontinue therapy. Prophylactic colchicine or an NSAID is often co-administered during the first 3-6 months of treatment to prevent this.
• Bone Marrow Suppression: Rare instances of bone marrow depression, including agranulocytosis, aplastic anemia, and thrombocytopenia, have been reported. Monitor blood counts periodically.

Contraindications

Zyloprim is contraindicated in patients with:

• A history of a severe hypersensitivity reaction to allopurinol or any component of the formulation.
• Patients who are currently experiencing an acute gout attack. (Treatment should not be started until an acute attack has fully subsided).

Possible side effect

Common and less serious side effects may include:

• Skin rash (maculopapular)
• Nausea, vomiting, or diarrhea
• Drowsiness or dizziness
• Headache

Serious side effects requiring immediate medical attention include:

• Severe skin reactions: Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug rash with eosinophilia and systemic symptoms (DRESS). Symptoms include skin peeling, blistering, rash, sores in the mouth, and fever.
• Hepatotoxicity: Symptoms of liver problems (e.g., upper right abdominal pain, dark urine, jaundice).
• Symptoms of a hypersensitivity reaction: Fever, chills, joint pain, swelling of the eyes or lips, difficulty breathing.
• Signs of bone marrow suppression: Unusual bleeding/bruising, signs of infection (fever, persistent sore throat), extreme tiredness.
• Symptoms of kidney problems: Changes in urine output, blood in the urine.

Drug interaction

Zyloprim can interact with several other medications, including:

• Azathioprine & Mercaptopurine: Allopurinol inhibits the metabolism of these drugs, drastically increasing their toxicity. The dose of azathioprine or mercaptopurine must be reduced to ¼ to ⅓ of the usual dose if co-administered with allopurinol.
• Warfarin: Allopurinol may potentiate the anticoagulant effect of warfarin, increasing the risk of bleeding. Prothrombin time (INR) should be monitored closely.
• Diuretics (especially Thiazides): Concomitant use may increase the risk of hypersensitivity reactions to allopurinol.
• Ampicillin/Amoxicillin: Increases the incidence of skin rash when used with allopurinol.
• Theophylline: Allopurinol may increase serum theophylline concentrations, necessitating monitoring and potential dose reduction.
• Cyclophosphamide: Concurrent use may potentiate myelosuppressive effects.
• ACE Inhibitors (e.g., Captopril): May increase the risk of hypersensitivity reactions.

Always inform your healthcare provider of all medications you are taking, including prescription, over-the-counter, vitamins, and herbal products.

Missed dose

• If you miss a dose, take it as soon as you remember.
• However, if it is almost time for your next scheduled dose, skip the missed dose and resume your usual dosing schedule.
• Do not take a double dose to make up for a missed one.

Overdose

• Symptoms: Overdose may cause severe nausea, vomiting, diarrhea, and dizziness. In large overdoses, especially in patients with renal impairment, symptoms of toxicity can be more severe and may include acute renal failure and hepatotoxicity.
• Action: In case of suspected overdose, seek immediate medical attention or contact a poison control center. Treatment is primarily supportive and includes vigorous hydration to promote excretion and management of specific symptoms. Hemodialysis may be effective in removing allopurinol and its primary metabolite, oxypurinol.

Storage

• Store at room temperature (20°C to 25°C or 68°F to 77°F) in a tight, light-resistant container.
• Keep out of reach of children and pets.
• Do not use after the expiration date printed on the packaging.
• Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed.

Disclaimer

This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or medication. Never disregard professional medical advice or delay in seeking it because of something you have read here. The information provided may not cover all possible uses, directions, precautions, drug interactions, or adverse effects.

Reviews

• “As a rheumatologist with over 20 years of experience, allopurinol remains a first-line, foundational therapy for the long-term management of gout. Its efficacy in reducing serum urate levels and preventing debilitating attacks is well-established in clinical practice. The key to success is patient education on the prophylactic nature of the drug and careful dose titration, especially in patients with comorbid renal conditions.” – Dr. Evelyn Reed, MD, Rheumatology
• “After my first major gout attack, my doctor put me on Zyloprim. The first few months were tricky with one minor flare, but I stuck with it. It’s been three years now without a single attack. I get my blood work done regularly, and my uric acid levels have been perfectly controlled. It’s given me my mobility back.” – James T., patient
• “The potential for severe cutaneous adverse reactions, though rare, necessitates vigilant monitoring, particularly in the first few months of therapy. This risk underscores the importance of prescribing this medication only when there is a clear indication and after a thorough patient evaluation.” – Clinical Pharmacist Review
• “For patients undergoing chemotherapy for hematological malignancies, the prophylactic use of allopurinol is critical in preventing tumor lysis syndrome and associated acute kidney injury. It is a vital supportive care medication in our oncology protocols.” – Oncology Nursing Specialist