Allopurinol Theophylline

There is an increased incidence of skin rash when allopurinol and ampidllin are administered concurrently. Concurrent administration of allopurinol and theophylline... 

C5H7NO2 105-56-6) see Allopurinol Amlexanox Bemegride Ethosuximide Etozolin Folic acid Gabapentin Paroxetine Phensuximide Sulfadimethoxine Theophylline Tinoridinc Trimethoprim Valdetamide Valproic acid ethyl 2-(2 -cyanobiphenyl-4-ylmethylamino)-3-nitroben-zoate... 

CH3NO 75-12-7) see Allopurinol Chlorothiazide Cimetidine Fludarabinc phosphate Fluspirilene Heptaminol Primidone Protriptyline Pyridoxine Razoxane Sulfadoxine Theophylline... 

There are several important drug-drug interactions with allopurinol. The effects of both theophylline and warfarin may be potentiated by allopurinol. Azathioprine and 6-mercaptopurine are purines whose metabolism is inhibited... 

Agents that may increase theophylline levels include allopurinol, beta blockers (nonselective), calcium channel blockers, cimetidine, oral contraceptives, corticosteroids, disulfiram, ephedrine, influenza virus vaccine, interferon, macrolides, mexiletine, quinolones, thiabendazole, thyroid hormones, carbamazepine, isoniazid, and loop diuretics. 

Drugs that may be affected by allopurinol include ampicillin anticoagulants cyclophosphamide theophyllines thiopurines. 

In addition to theophylline, purine or pyrimidine derivatives of pharmaceutical interest which have been analyzed include ftorafur, a fluorouracii derivative (429), arabinosides of adenine and hypoxanthine (408), ace-phylline (430), and allopurinol and oxipurinol (431). 

ALLOPURINOL BRONCHODILATORS -THEOPHYLLINE t theophylline levels Allopurinol inhibits xanthine oxidase Watch for early features of toxicity of theophylline (headache, nausea)... 

Allopurinol and some antibiotics increase plasma concentrations of theophylline and increase the risk of adverse effects of theophylline. 

When used concomitantly, theophylline increases the excretion of lithium. Also, cimetidine, allopurinol (high dose), propranolol, erythromycin, and troleandomycin may cause an increase in serum concentrations of theophylline by decreasing the hepatic clearance. Barbiturates and phenytoin enhance hepatic clearance and hepatic metabolism of theophylline, decreasing plasma levels. Beta-adrenergic blockers exert an antagonistic pharmacologic effect. 

Noninterfering albuterol, allopurinol, alprenolol, aspirin, atenolol, captopril, carbimazole, clonidine, coloxyl, danthron, diazepam, digoxin, doxepin, glibenclamide, hydralazine, in-domethacin, labetalol, metformin, methyldopa, metoprolol, mianserin, minoxidil, nifedipine, nitrazepam, oxazepam, oxprenolol, pindolol, prazosin, propranolol, senokot, theophylline, trifluoperazine... 

Simultaneous acetaminophen, aldosterone, allopurinol, amitriplyline, caffeine, calcitriol, cephalothin, chlordiazepoxide, chlorothiazide, corticosterone, cortisone, dexamethasone, diazepam, ephedrine, ethinyl estradiol, furosemide, hydrocortisone, ibuprofen, imipra-mine, indomethacin, mechlorethamine, methylprednisone, metolazone, nandrolone, naproxen, phenacetin, phenobarbital, phen3doin, probenecid, progesterone, propranolol, sulfasalazine, testosterone, theophylline, vincristine... 

It remains to be established whether the increased incidence of rash in patients receiving concurrent allopurinol and ampicillin should be ascribed to allopurinol or to hyperuricemia. Hypersensitivity reactions have been reported in patients with compromised renal function, especially those who are receiving a combination of allopurinol and a thiazide diuretic. The concomitant administration of allopurinol and theophylline leads to increased accumulation of an active metabolite of theophylline, l-methybcanthine the concentration of theophylline in plasma also may be increased (see Chapter 27). 

Manfredi, R. L. and Vesell, E. S., Inhibition of theophylline metabolism by long-term allopurinol administration, Clin. Pharmacol. Ther., 29(2) 224—229, 1981. 

No clinically important pharmacokinetic interactions appear to occur when famciclovir is given with allopurinol, digoxin or theophylline. 

Evidence from clinical studies and a single case report indicate that the effects of theophylline may be increased by allopurinoL... 

The peak plasma levels of theophylline 450 mg daily rose by 38% in a patient who took allopurinol for 3 days. In a study in 12 healthy subjects, allopurinol 300 mg twice daily for 14 days increased the half-life of a single 5-mg/kg oral dose of theophylline by 25%, and increased its AUC by 27%. Similar increases were seen when a second dose of theophylline was given 28 days after starting the allopurinol. ... 

However, in two other studies allopurinol 300 mg daily for 7 days did not have any effect on the pharmacokinetics of theophylline, following a single 5-m kg intravenous dose of aminophylline. Similarly, steady-state theophylline levels were not affected by allopurinol 100 mg three times daily in 4 subjects. However, there was an alteration in the proportion of different urinary theophylline metabolites methyluric acid decreased and methylxanthine increased. ... 

Uncertain. Allopurinol, a xanthine oxidase inhibitor, can block the conversion of methylxanthine to methylurie aeid, but this had no effeet on theophylline levels in two studies. One suggestion is that allopurinol inhibits the oxidative metabolism of theophylline by the liver. ... 

Evidence appears to be limited to a single case report and the studies in healthy subjects. The interaction only appears to be of moderate importance. Nevertheless, it would seem prudent to check for any signs of theophylline adverse effects (headache, nausea, tremor) during concurrent use, particularly in situations where the metabolism of the theophylline may already be reduced (other drugs or diseases), or where high doses of allopurinol are used. For mention that allopurinol may invalidate the results of phenotyping tests using caffeine, see Caffeine + Allopurinol ,... 

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