Tuesday, February 1, 2022

Allopurinol: Uses, Indications, Dosages, Precautions, Contraindications, Side Effects & Interactions

Allopurinol: Uses, Indications, Dosages, Precautions, Contraindications, Side Effects & Interactions


Classification and Category
Pharmacotherapeutic: Xanthine oxidase inhibitor
Antigout drug, antihyperuricemic
Pregnancy category: C
Apo-Allopurinol (CAN), Lopurin, Purinol (CAN), Zyloprim

General Information

Allopurinol is used to prevent gout, which is caused by deposits of uric acid crystals in the joints. Allopurinol blocks an enzyme called xanthine oxidase which is involved in the formation of uric acid. It is also used to lower high uric acid levels (hyperuricaemia) caused by other drugs. Allopurinol should never be started until several weeks after an acute attack subsides because it could cause a new episode

Treatment with the drug should be continued indefinitely to prevent new attacks. An acute attack may occur at the start of treatment, and colchicine or an anti-inflammatory drug may also be given until uric acid levels are reduced. If an acute attack occurs while taking allopurinol, treatment should be continued along with an anti-inflammatory drug


It inhibits the enzyme xanthine oxidase, reducing the synthesis of uric acid

Therapeutic Effect

Reduces uric acid concentrations in serum and urine

Availability (Rx)

Tablets (Zyloprim): 100 mg, 300 mg
Powder for Injection (Aloprim): 500 mg


• PO: Management of primary or secondary gout (e.g., acute attack, nephropathy)
Treatment of secondary hyperuricemia that may occur during cancer treatment.
Management of recurrent uric acid and calcium oxalate calculi
• Injection: Management of elevated uric acid in cancer treatment for leukemia, lymphoma, or solid tumor malignancies
Unlabeled uses: Preservation of cadaveric kidneys for transplantation


Pregnancy (C), breastfeeding, children, renal/hepatic disease
Make sure to tell your doctor if:
• You have long-term hepatic or kidney problems
• You have had a previous sensitivity reaction to allopurinol
• You have a current attack of gout
• You are taking other medicines

Indications and Dosages

 To increased uric acid levels in malignancies 

• Adult: 
600-800 mg/day in divided doses, for 2-3 days; start up to 1-2 days prior to chemotherapy
Child 6-10 yr: 300 mg/day, adjust dose after 48 hr
Child ,6 yr: 150 mg/day, adjust dose after 48 hr
• Adult: INF 200-400 mg/m2/day, max 600 mg/day 24-48 hr prior to chemotherapy, may be divided at 6-, 8-, 12-hr intervals
 Child: INF 200 mg/m2/day, initially as a single dose or divided q6-12hr

‣ To treat Gout (mild)

• Adults, Elderly. 100 mg/day, increase qwk based on uric acid levels, max 800 mg/day, maintenance dose 100-200 mg bid-tid

 To treat Gout (moderate-severe)

• Adults:400-600 mg/day in a single dose or divided bid-tid, max 800 mg/day, doses .300 mg should be given in divided doses

To treat gout and hyperuricemia

• Adults: 200 to 600 mg daily in divided doses, depending on disease severity. Usual: 200 to 300 mg daily. Maximum: 800 mg daily 

‣ To treat secondary hyperuricemia caused by neoplastic disease

• Children ages 6 to 10. 300 mg daily, adjusted after 48 hr, depending on response to treatment
 Children under age 6. 150 mg daily, adjusted after 48 hr, depending on response to treatment

‣ To treat recurrent calcium oxalate calculi

• Adults: 200 to 300 mg daily as a single dose or in divided doses; Elderly. Initially, 100 mg/day, adjusted based on 24-hr urine urate level

‣ To treat increased serum and urine uric acid levels in patients with leukemia, lymphoma, and solid tumors whose cancer chemotherapy has increased those levels and who can’t tolerate oral therapy

• Adult: 200 to 400 mg/m2 daily as a single infusion or in equally divided infusions every 6, 8, or 12 hr. Maximum: 600 mg daily
 Children: 200 mg/m2 daily as a single infusion or in equally divided infusions every 6, 8, or 12 hr

Dosage in renal impairment

PO/IV (Dosage is modified based on creatinine clearance)
 Adults: CCr 81-100 ml/min 300 mg/day; CCr 61-80 ml/min 250 mg/day; CCr 41-60 ml/min 200 mg/day; CCr 21-40 ml/min 150 mg/day; CCr 10-20 ml/min 100-200 mg/day; CCr 3-9 ml/min 100 mg/day or 100 mg every other day; CCr,3 ml/min 100 mg q24hr or longer or 100 mg every third day 


Well absorbed from the GI tract. Widely distributed. Metabolized in the liver to active metabolite. Excreted primarily in urine. Removed by hemodialysis. Half-life: 1-3 h; metabolite, 12-30 h


PO route

• Give with meals to prevent GI symptoms; crush and mix with food or fluids for patients with swallowing difficulties
• Increase fluid intake to 2 L/day
• Give 1-2 days before antineoplastic therapy if using for hyperuricemia associated with malignancy

Intermittent IV infusion route

• Reconstitute 30-ml vial with 25 ml of sterile water for inj; dilute to desired conc (#6 mg/ml) with 0.9% NaCl for inj or D5 for inj, begin inf within 10 hr

IV Incompatibilities

Amikacin (Amikin), amphotericin B, carmustine (BiCNU), cefotaxime (Claforan), chlorpromazine (Thorazine), cimetidine (Tagamet), clindamycin (Cleocin), cytarabine (Ara-C), dacarbazine (DTIC), daunorubicin, diphenhydramine (Benadryl), doxorubicin (Adriamycin), doxycycline (Vibramycin), droperidol (Inapsine), floxuridine, fludarabine (Fludara), gentamicin (Garamycin), haloperidol (Haldol), hydroxyzine (Vistaril), idarubicin (Idamycin), imipenem-cilastatin (Primaxin), mechlorethamine, meperidine (Demerol), methylprednisolone (Solu-Medrol), metoclopramide (Reglan), minocycline, nalbuphine, netilmicin, ondansetron (Zofran), prochlorperazine (Compazine), promethazine (Phenergan), sodium bicarbonate, streptozocin (Zanosar), tobramycin (Nebcin), vinorelbine (Navelbine)

IV compatibilities

Acyclovir, aminophylline, amphotericin B lipid complex, anidulafungin, argatroban, atenolol, aztreonam, bivalirudin, bleomycin, bumetanide, buprenorphine, butorphanol, calcium gluconate, CARBOplatin, caspofungin, ceFAZolin, cefoperazone, cefoTEtan, cefTAZidime, ceftizoxime, cefTRIAXone, cefuroxime, CISplatin, cyclophosphamide, DACTINomycin, DAUNOrubicin liposome, dexamethasone, dexmedetomidine, DOCEtaxel, DOXOrubicin liposomal, enalaprilat, etoposide, famotidine, fenoldopam, filgrastim, fluconazole, fludarabine, fluorouracil, furosemide, gallium, ganciclovir, gatifloxacin, gemcitabine, gemtuzumab, granisetron, heparin, hydrocortisone phosphate, hydrocortisone succinate, HYDROmorphone, ifosfamide, linezolid, LORazepam, mannitol, mesna, methotrexate, metroNIDAZOLE, milrinone, mitoXANtrone, morphine, nesiritide, octreotide, oxytocin, PACLitaxel, pamidronate, pantoprazole, PEMEtrexed, piperacillin, piperacillin-tazobactam, plicamycin, potassium chloride, ranitidine, sodium, sulfamethoxazole-trimethoprim, teniposide, thiotepa, ticarcillin, ticarcillin clavulanate, tigecycline, tirofiban, vancomycin, vasopressin, vinBLAStine, vinCRIStine, voriconazole, zidovudine, zoledronic acid


Hypersensitivity to allopurinol


Individual drugs

Ammonium chloride, potassium/sodium phosphate, vit C: increased kidney stone formation
Ampicillin, amoxicillin: increased risk of rash, avoid concurrent use
AzaTHIOprine: increased bone marrow depression
Mercaptopurine: increased bone marrow depression
Rasburicase: increased xanthine nephropathy, calculi
Theophylline: increased action of theophylline

Drug classifications

• ACE inhibitors: May increase risk of hypersensitivity reactions
• Anticoagulants (oral): increased action of oral anticoagulants
• Antidiabetics (oral): increased action of antidiabetics
• Antineoplastics: increased bone marrow suppression
 Azathioprine, mercaptopurine: May increase therapeutic effect and toxicity of azathioprine and mercaptopurine
 Cyclophosphamide: May increase cyclophosphamide myelosuppressive effect, increasing risk of bleeding and infection
 Warfarin: May increase anticoagulant effect of coumarins
 Thiazide diuretics: May decrease renal elimination of allopurinol. Monitor need for dose adjustment.

Drug/laboratory tests

• May increase serum BUN, alkaline phosphatase, ALT, AST, creatinine


• None known

Side effects

CNS: Chills, drowsiness, fever, headache,
neuritis, paresthesia, peripheral neuropathy,
CV: Vasculitis
EENT: Epistaxis, loss of taste
GI: Abdominal pain, diarrhea, dysphagia, elevated liver function test results, gastritis, granulomatous hepatitis, hepatic necrosis, hepatomegaly, nausea, vomiting
GU: Exacerbated renal calculi, renal failure
HEME: Agranulocytosis, aplastic anemia, bone marrow depression, eosinophilia,
leukocytosis, leukopenia, thrombocytopenia
MS: Arthralgia, exacerbation of gout, myopathy
SKIN: Alopecia; ecchymosis; jaundice; maculopapular, scaly, or exfoliative rash (sometimes fatal); pruritus; urticaria

Nursing considerations

Baseline assessment

• Obtain baseline BMP, LFT. 
 Instruct pt to drink minimum of 2,500–3,000 mL of fluid daily while taking medication


• Discontinue medication immediately if rash or other evidence of allergic
reaction occurs
• Monitor I&O (output should be at least 2,000 mL/day)
• Assess serum chemistries, uric acid, hepatic function. Assess urine for cloudiness, unusual color, odor
• Gout: Assess for therapeutic response: relief of pain, stiffness, swelling; increased joint mobility; reduced joint tenderness; improved grip strength

Equipment must be available for anaphylaxis

• Assess for pain including location, characteristics, onset/duration, frequency, quality, intensity or severity of pain, precipitating factors; gout: joint pain, swelling, may use with NSAIDs for acute gouty attacks
• Monitor uric acid levels q2wk; normal uric acid levels are 6 mg/dl or less; effect may take several wk; check I&O ratio, increase fluids to 2 L/day to prevent stone formation, toxicity
• Monitor CBC, AST, BUN, creatinine before starting treatment, monthly; check blood glucose in diabetic patients


Positive therapeutic result

• Decreased pain in joints
• Decreased stone formation in kidney
• Decreased uric acid level to 6 mg/dl

Patient/family teaching

• Tell patient To take as prescribed; if dose is missed, take as soon as remembered; do not double dose; tabs may be crushed
• Instruct patient to take with or immediately after meals or milk. Drink enough fluid daily to maintain a urine output of 2 L/day, if possible
• Tell patient to Maintain adequate hydration; drink 2,500–3,000 mL of fluid daily while taking medication
• Instruct patient to report unusual bleeding or bruising, fever, chills, gout attack, numbness, and tingling.
• Inform patient that acute gout attacks may occur more often early in allopurinol
treatment and that results may not be noticeable for 2 weeks or longer
• Instruct patient not to drive or perform hazardous tasks if drug causes drowsiness
• Tell patient to report skin rash, stomatitis, malaise, aching; product should be
• Advise patient to avoid hazardous activities if drowsiness or dizziness occurs; response may take several days to determine
• Tell patient to avoid alcohol, caffeine; these substances increase uric acid levels and decrease allopurinol levels
• Teach patient to report side effects and adverse reactions to prescriber, including rash, itching, nausea, vomiting
• Instruct patient to administer dosages > 300 mg/day in divided doses. It may take 1 wk or longer for the full therapeutic effect of the drug to be evident.
• Inform patient that for IV use, reconstitute 500-mg vial with 25 mL sterile water for injection, which produces a clear, almost colorless solution (concentration of
20 mg/mL). Further dilute with 0.9% NaCl or D5W as desired, with a final maximum concentration of 6 mg/mL. Infuse over 30-60 min

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