Allopurinol comes as a tablet to take by mouth. It is usually taken once or twice a day, preferably after a meal. To help you remember to take allopurinol, take it around the same time every day. Follow the directions on your prescription label carefully, and ask your doctor or pharmacist to explain any part you do not understand. Take allopurinol exactly as directed. Do not take more or less of it or take it more often than prescribed by your doctor.
allopurinol
It may take several months or longer before you feel the full benefit of allopurinol. Allopurinol may increase the number of gout attacks during the first few months that you take it, although it will eventually prevent attacks. Your doctor may prescribe another medication such as colchicine to prevent gout attacks for the first few months you take allopurinol. Continue to take allopurinol even if you feel well. Do not stop taking allopurinol without talking to your doctor.
Allopurinol may rarely cause very serious (possibly fatal) skin reactions. Some people in certain ethnic groups (such as people of African, Asian, or Native Hawaiian/Pacific Islander descent) are at greater risk. Your doctor may order a blood test to measure your risk before you start this medication. If the blood test shows you are at greater risk, your doctor should discuss the risks and benefits of allopurinol and other treatment choices with you. Get medical help right away if you develop any symptoms of a serious skin reaction, including: skin rash/blisters/peeling, itching, or swelling. Ask your doctor or pharmacist for more details.
In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345. Precautions Before taking allopurinol, tell your doctor or pharmacist if you are allergic to it; or if you have had a severe reaction to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.
If you are taking allopurinol to treat kidney stones, you may benefit from a special diet. Consult your doctor for more details. Missed Dose If you miss a dose, take it as soon as you remember. If it is near the time of the next dose, skip the missed dose. Take your next dose at the regular time. Do not double the dose to catch up. Storage Store at room temperature away from light and moisture. Do not store in the bathroom. Keep all medications away from children and pets.
You should not use this medicine if you have ever had a serious allergic reaction to allopurinol. Stop taking the medicine and call your doctor at once if you have any signs of skin rash (no matter how mild), painful urination, blood in your urine, burning in your eyes, or swelling in your face or throat.
Stop using this medicine and get emergency medical help if you have signs of an allergic reaction to allopurinol (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).
Take allopurinol exactly as prescribed by your doctor. Follow all directions on your prescription label and read all medication guides or instruction sheets. Your doctor may occasionally change your dose.
This list is not complete. Other drugs may interact with allopurinol, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.
Your doctor may recommend that you do not start taking allopurinol until after an attack of gout has passed to avoid triggering further attacks. If this is not possible, it may be started when your inflammation is not too bad.
To reduce the effects of gout attacks in the first three to six months of taking allopurinol, your doctor may prescribe a low dose of colchicine or a non-steroidal anti-inflammatory drug (NSAID), such as:
If you develop a rash, redness or flu-like symptoms, you should contact your doctor straight away. If you become dizzy or drowsy while taking allopurinol, do not drive or operate machinery, and see your doctor as soon as possible. You should also speak to your doctor if you develop any new symptoms that worry you.
Allopurinol, a xanthine oxidase inhibitor, is a urate-lowering medication that is FDA approved for managing gout, preventing tumor lysis syndrome, and preventing recurrent calcium nephrolithiasis in patients with hyperuricosuria. Other non-FDA-approved indications include Lesch-Nyhan syndrome-associated hyperuricemia and the prevention of recurrent uric acid nephrolithiasis. It is important to note that asymptomatic hyperuricemia is not an indication of allopurinol or any urate-lowering therapy. This activity outlines the indications, mechanism, pharmacology, contraindications, and adverse events associated with allopurinol drug therapy.
Objectives:Identify the various indications, both approved and off-label, for allopurinol therapy.Describe the potential adverse effects of allopurinol.Summarize the mechanism of action of allopurinol.Review the importance of coordinating and collaborating among various disciplines in an interprofessional health team to coordinate care and management to enhance outcomes for patients receiving allopurinol therapy.Access free multiple choice questions on this topic.
Van Liere E. et al. conducted a study on using low-dose azathioprine and allopurinol (LDAA) to treat inflammatory bowel disease. Allopurinol was added to azathioprine to improve its tolerability. The investigators found that LDAA was better tolerated in patients compared with standard azathioprine monotherapy.[2]
Allopurinol undergoes metabolism in the liver, where it transforms into its pharmacologically active metabolite, oxypurinol. The half-life of allopurinol is 1 to 2 hours, and oxypurinol is about 15 hours. Both allopurinol and oxypurinol are renally excreted. Allopurinol and oxypurinol both inhibit xanthine oxidase, an enzyme in the purine catabolism pathway that converts hypoxanthine to xanthine to uric acid.
Schmidt A. et al. conducted a clinical trial on the analgesic effects of allopurinol in patients undergoing hysterectomy. The investigators found that allopurinol given as a pre-anesthetic agent reduced pain scores 2 hours after surgery.[3]
Fagundes A. et al. conducted a study (12 women) on allopurinol treatment in patients with fibromyalgia.[4] Allopurinol treatment reduced pain. However, in a larger study (N = 31 for allopurinol and N = 29 for placebo), allopurinol did not demonstrate analgesic properties in fibromyalgia patients.[5]
Prieto-Moure B. et al. conducted research on small intestine ischemia-reperfusion injury of Wistar rats and the role of allopurinol and dantrolene in preventing oxygen-free radical damage. The researchers found that the allopurinol and dantrolene combination provided antioxidant effects, which decreased the oxygen-free radical damage caused by the ischemia-reperfusion in the rat's small intestines.[8]
Allopurinol administration can be in two forms: oral or intravenous (IV). While oral administration is the standard route for gout and uric acid or calcium oxalate nephrolithiasis, IV allopurinol is for the prevention of tumor lysis syndrome and management of cancer therapy-induced hyperuricemia in patients who cannot tolerate oral therapy.
For long-term gout treatment, the recommended starting dose of allopurinol is 100 mg daily, to be escalated by 100 mg every 2 to 5 weeks until the target serum uric acid is achieved. American College of Rheumatology recommends target uric acid of less than 6.0 mg/dL for all patients with gout and less than 5.0 mg/dL in patients with tophaceous gout. The maximum daily allopurinol dose is 800 mg. Following the patient reaching the target serum uric acid concentration, the required dose of allopurinol to achieve the target serum uric acid concentration should continue indefinitely.[1]
In patients with renal insufficiency (chronic kidney disease stage 4 and greater), allopurinol should start at a 50 mg daily dose, and the dose shall be escalated by 50 mg every 2 to 5 weeks until reaching the target serum uric acid.[9] Allopurinol and oxypurinol are both dialyzable. In patients with end-stage renal disease on hemodialysis or peritoneal dialysis, allopurinol can be initiated at 50 mg on alternate days and be given post dialysis, with cautious dose escalation to achieve target serum uric acid.
To prevent tumor lysis syndrome, allopurinol shall be initiated 2 to 3 days before starting chemotherapy and continued until 3 to 7 days after chemotherapy. Doses for oral allopurinol are 300 mg/m^2/day in three divided doses every 8 hours, a maximum of 800 mg daily, and IV allopurinol is 200 to 400 mg/m2 daily single doses or 2 to 3 divided doses.
Due to the destabilization of intra-articular uric acid microtophi on initiating any urate-lowering therapy, there is an increased incidence of acute gouty flares, especially during the initial few months. To prevent this, patients should start an anti-inflammatory agent such as colchicine, nonsteroidal anti-inflammatory drug (NSAID), or low-dose prednisone (only in patients who cannot take colchicine or NSAIDs) before or at the same time as initiating allopurinol.[10]
Fontana R. et al. conducted research on eleven patients with suspected allopurinol-induced liver damage. The researchers found that hepatoxicity was associated with the following alleles: HLA-B*58:01, HLA-B*53:01, and HLA-A*34:02. The median age was 60 years, 54% were men, and 63% were African-American.[11]
Allopurinol hypersensitivity syndrome (AHS) is a rare severe adverse effect of allopurinol with an incidence of about 1 in 1000, with a high mortality rate of 20% to 25%. The mechanism is a T-cell-mediated immune reaction to oxypurinol. The highest risk is in the first few months of therapy, especially with higher starting doses of allopurinol. Concurrent diuretics, especially thiazide use, renal insufficiency stage 3, or higher, are major risk factors. Patients of Korean, Han Chinese, and Thai descent with HLA-B*5801 genotype are at a very high risk of AHS. Clinical features of AHS include Stevens-Johnson syndrome, toxic epidermal necrolysis, vasculitis, hepatocellular injury, acute kidney injury, fever, leukocytosis, and eosinophilia.[13] Management is supportive. Lowering the starting dose of allopurinol to less than 100 mg daily in all patients and less than 50 mg daily in patients with chronic kidney disease stage 3 or worse can lower the risk of AHS. Wong C et al. conducted pharmacogenomic testing (HLA-B*58:01 allele) on patients with chronic kidney disease before initiating allopurinol treatment.[14] The pharmacogenomic screening prevents allergic skin reactions, and it is cost-effective. 2ff7e9595c
Comentários