However, specific recommendations for allopurinol dosage adjustment in patients with hepatic impairment are not available. The correct dose and frequency of dosage for maintaining the serum uric acid concentration within the normal range are best determined by using the serum uric acid level as an index. Serious toxicity may occur, especially in patients with impaired renal function see Adverse Events. The maintenance of a neutral or, preferably, slightly alkaline urine is desirable.
Extemporaneous Compounding-Oral Extemporaneous oral suspension formulation: This route of administration is not FDA-approved. Crush mg allopurinol and levigate with glycerin or distilled water. Add 40 ml methylcellulose Cologel ; then add enough 2: Store in the refrigerator and shake well prior to use.
The suspension is stable for 8 weeks. Injectable Administration Administer intravenously. Do not inject intramuscularly. Visually inspect parenteral products for particulate matter and discoloration prior to administration whenever solution and container permit.
Reconstitute the 30 ml vial with 25 ml Sterile Water for Injection. The reconstituted solution is clear, almost colorless, and has no more than a slight opalescence. The third patient had lymphosarcoma and produced an extremely large amount of uric acid because of rapid cell lysis during chemotherapy. Peak plasma levels generally occur at 1. Because of its rapid oxidation to oxipurinol and a renal clearance rate approximately that of glomerular filtration rate, ZYLOPRIM allopurinol has a plasma half-life of about 1 to 2 hours.
Oxipurinol, however, has a longer plasma half-life approximately 15 hours and therefore effective xanthine oxidase inhibition is maintained over a hour period with single daily doses of ZYLOPRIM allopurinol. Whereas ZYLOPRIM allopurinol is cleared essentially by glomerular filtration, oxipurinol is reabsorbed in the kidney tubules in a manner similar to the reabsorption of uric acid.
The clearance of oxipurinol is increased by uricosuric drugs, and as a consequence, the addition of a uricosuric agent reduces to some degree the inhibition of xanthine oxidase by oxipurinol and increases to some degree the urinary excretion of uric acid.
In practice, the net effect of such combined therapy may be useful in some patients in achieving minimum serum uric acid levels provided the total urinary uric acid load does not exceed the competence of the patient's renal function. Hyperuricemia may be primary, as in gout, or secondary to diseases such as acute and chronic leukemia , polycythemia vera , multiple myeloma , and psoriasis.
It may occur with the use of diuretic agents, during renal dialysis, in the presence of renal damage, during starvation or reducing diets, and in the treatment of neoplastic disease where rapid resolution of tissue masses may occur. Gout is a metabolic disorder which is characterized by hyperuricemia and resultant deposition of monosodium urate in the tissues, particularly the joints and kidneys.
The etiology of this hyperuricemia is the overproduction of uric acid in relation to the patient's ability to excrete it. If progressive deposition of urates is to be arrested or reversed, it is necessary to reduce the serum uric acid level below the saturation point to suppress urate precipitation. The degree of this decrease can be manipulated almost at will since it is dose-dependent.
A week or more of treatment with ZYLOPRIM allopurinol may be required before its full effects are manifested; likewise, uric acid may return to pretreatment levels slowly usually after a period of 7 to 10 days following cessation of therapy.
This reflects primarily the accumulation and slow clearance of oxipurinol. Is it possible that allopurinol could help the excretion of the calcium pyrophosphate from her joints as it does uric acid in gout?
Also, she is reluctant to resume higher doses of prednisone during severe flare-ups because she and her physician believe it will cause her low-grade diabetes to worsen. What do you recommend? Pseudogout is a form of arthritis that is brought on by deposits of calcium crystals in the joints. This causes pain, swelling and inflammation of the joint, and sometimes may be accompanied by fever.
It is not always clear why people develop pseudogout. Risk factors may include: Some of the treatments that may be used for pseudogout include: It is not known whether allopurinol will harm an unborn baby. Tell your doctor if you are pregnant or plan to become pregnant while using this medication. Allopurinol can pass into breast milk and may harm a nursing baby. Do not use this medication without telling your doctor if you are breast-feeding a baby. Pregnancy and breastfeeding warnings in more detail How should I take allopurinol?
Take allopurinol exactly as prescribed by your doctor. Do not take in larger or smaller amounts or for longer than recommended. This is in contrast to the nullifying effect of salicylates on uricosuric drugs.
Allopurinol also inhibits the enzymatic oxidation of mercaptopurine, the sulfur-containing analogue of hypoxanthine, to 6-thiouric acid. This oxidation, which is catalyzed by xanthine oxidase, inactivates mercaptopurine.
Allopurinol tablets USP reduces serum and urinary uric acid concentrations. Allopurinol tablet USP is indicated in: Treatment with allopurinol tablets USP should be discontinued when the potential for overproduction of uric acid is no longer present. Therapy in such patients should be carefully assessed initially and reassessed periodically to determine in each case that treatment is beneficial and that the benefits outweigh the risks. A few cases of reversible clinical hepatotoxicity have been noted in patients taking allopurinol, and in some patients, asymptomatic rises in serum alkaline phosphatase or serum transaminase have been observed.
If anorexia, weight loss, or pruritus develop in patients on allopurinol, evaluation of liver function should be part of their diagnostic workup. In patients with pre-existing liver disease, periodic liver function tests are recommended during the early stages of therapy.
Due to the occasional occurrence of drowsiness, patients should be alerted to the need for due precaution when engaging in activities where alertness is mandatory. The occurrence of hypersensitivity reactions to allopurinol may be increased in patients with decreased renal function receiving thiazides and allopurinol concurrently. For this reason, in this clinical setting, such combinations should be administered with caution and patients should be observed closely.
An increase in acute attacks of gout has been reported during the early stages of administration of allopurinol , even when normal or subnormal serum uric acid levels have been attained. Accordingly, maintenance doses of colchicine generally should be given prophylactically when allopurinol is begun.
The use of colchicine or anti-inflammatory agents may be required to suppress gouty attacks in some cases. The attacks usually become shorter and less severe after several months of therapy.
The mobilization of urates from tissue deposits which cause fluctuations in the serum uric acid levels may be a possible explanation for these episodes. Even with adequate therapy with allopurinol, it may require several months to deplete the uric acid pool sufficiently to achieve control of the acute attacks. A fluid intake sufficient to yield a daily urinary output of at least 2 liters and the maintenance of a neutral or, preferably, slightly alkaline urine are desirable to 1 avoid the theoretical possibility of formation of xanthine calculi under the influence of therapy with allopurinol and 2 help prevent renal precipitation of urates in patients receiving concomitant uricosuric agents.
Some patients with pre-existing renal disease or poor urate clearance have shown a rise in BUN during administration of allopurinol. Although the mechanism responsible for this has not been established, patients with impaired renal function should be carefully observed during the early stages of administration of allopurinol and the dosage decreased or the drug withdrawn if increased abnormalities in renal function appear and persist. Renal failure in association with administration of allopurinol has been observed among patients with hyperuricemia secondary to neoplastic diseases.
Concurrent conditions such as multiple myeloma and congestive myocardial disease were present among those patients whose renal dysfunction increased after allopurinol was begun.
Renal failure is also frequently associated with gouty nephropathy and rarely with hypersensitivity reactions associated with allopurinol. Albuminuria has been observed among patients who developed clinical gout following chronic glomerulonephritis and chronic pyelonephritis. Patients with decreased renal function require lower doses of allopurinol than those with normal renal function. Lower than recommended doses should be used to initiate therapy in any patients with decreased renal function and they should be observed closely during the early stages of administration of allopurinol.
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