Methylprednisolone Theophylline

Erythromycin Drugs that may be affected by erythromycin include alfentanil, anticoagulants, benzodiazepines, buspirone, carbamazepine, cisapride, cyclosporine, digoxin, disopyramide, ergot alkaloids, felodipine, fluoroquinolones, HMG-CoA reductase inhibitors, lincosamides, methylprednisolone, penicillins, and theophyllines. Drugs that may affect erythromycin include antacids, pimozide, rifamycins, and theophyllines. 

Erythromycin metabolites can inhibit cytochrome P450 enzymes and thus increase the serum concentrations of numerous drugs, including theophylline, oral anticoagulants, cyclosporine, and methylprednisolone. Erythromycin increases serum concentrations of oral digoxin by increasing its bioavailability. 

Erythromycin inhibits a cytochrome P450 isoenzyme and impairs the metabolism of theophylline, warfarin, carbamazepine and methylprednisolone. The mean reduction in drug clearance is 20-25%. 

The kinetic behavior of theophylline given concomitantly with methylprednisolone and auranofin to six women suggested a possible interaction of theophylline with auranofin, although a role of the corticosteroid could not be ruled out. The observed concentrations of theophylline were lower than expected, suggesting the need to measure serum theophylline concentrations in patients who also take steroids and gold salts (54). 

Noninterfering aminophylline, beclomethasone, cloprednol, dexamethasone, fenoterol, ipratropium bromide, methylprednisolone, orciprenahne, prednisolone, reproterol, limi-terol, salmeterol, sodium cromoglycate, theophylline... 

Simultaneous acebutolol, acetazolamide, acetophenetidin, adrenosterone, aldosterone, amitriptyline, androsten-3,17-dione, aspirin, carbamazepine, cephalothin, chlorothiazide, dehydrocorticosterone, deoxycorticosterone, deo cortisol, desipramine, dexamethasone, diazepam, equilenin, estradiol, estriol, estrone, fluorometholone, furosemide, hydrochlorothiazide, hydroxycorticosterone, hydroxyprogesterone, hydroxyprogesterone, imip-ramine, indomethacin, methylhydroxyprogesterone, methylprednisolone, nandrolone, nordiazepam, nortriptyline, pheniramine, phenobarbital, phenytoin, prednisolone, prednisone, primidone, probenecid, progesterone, quinine, spironolactone, testosterone, theophylline, triamcinolone, tripelennamine... 

Noninterfering diazepam, digoxin, methylprednisolone, midazolam, nifedipine, penicillamine, ranitidine, theophylline... 

Since erythromycin complexes and inactivates drug oxidizing systems such as cytochrome P-450, it has the potential to alter the metabolism of other drugs. The metabolism and excretion of theophylline, warfarin, carbamaz-epine, and methylprednisolone are inhibited by erythromycin [283-286]. As a potent antibiotic, it can also affect metabolism by gut micro-organisms of drugs such as digoxin. At least some of the newer derivatives may cause fewer drug interactions and thus may be better tolerated if co-administered with medications for other illnesses [287-289]. 

An infusion of isoprenaline increased the clearance of theophylline (given as intravenous aminophylline) by a mean of 19% in 6 children with status asthmaticus and respiratory failure. Two of them had increases in clearance of greater than 30%. Another study in 12 patients with status asthmaticus found that an isoprenaline infusion (mean maximum rate 0.77 micrograms/kg per minute) caused a mean fall in serum theophylline levels of almost 6 micrograms/mL. The levels rose again when isoprenaline was stopped. A critically ill patient receiving intravenous aminophylline, phenytoin and nebulised terbutaline had a marked 4.5-fold increase in theophylline clearance when an isoprenaline infusion and intravenous methylprednisolone were added to the regimen. ... 

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