Norfloxacin Theophylline

Cimetidine Phenytoin Ciprofloxacin Ranitidine Digoxin Tetracycline Norfloxacin Theophylline... 

Ciprofloxacin/norfloxacin Theophylline Decreased metabolism of theophylline Monitor theophylline... 

Theophylline [P] Ciprofloxacin, enoxacin, and, to a lesser extent, norfloxacin inhibit theophylline metabolism gatifloxacin, levofloxacin, lomefloxacin, ofloxacin, and sparfloxacin appear to have little effect. 

Composite MIP membranes can also be obtained by incorporation of MIP particles into the membrane polymer matrix by mixing the particles in an appropriate solvent with the membrane-forming polymer that is then solidified by the phase inversion process. Membranes thus prepared were used for separation, with targets such as tetracycline [257], theophylline [255], methylphosphonic acid [258], bisphenol [259], indole derivatives [260], propanolol [261], luteolin [262] and norfloxacin... 

The interaction between the quinolone antibacterials and CYP1A2 has been studied in some depth for enoxacin and pefloxacin. Both compounds have been shown to inhibit CYPlA2-mediated metabolism of caffeine in vitro (49). This in vitro inhibition translated into a twofold decrease in caffeine clearance by pefloxacin and a sixfold decrease in clearance by enoxacin (50). Because pefloxacin undergoes N-demethylation to norfloxacin (51) and norfloxacin is much more potent as an inhibitor than pefloxacin (50), the observed in vivo interaction seen for pefloxacin may, in part, be due to norfloxacin. Many other quinolone antibacterial agents have been investigated for their interaction with theophylline, and ciprofloxacin has also been shown to have notable inhibitory effects (52). 

Fluoroquinolones are potent inhibitors of hepatic cytochrome P450 isozymes (150). They inhibit theophylline metabolism, and accumulation of theophylline has led to seizures (151). Theophylline clearance is reduced by about 10% by norfloxacin, 30% by ciprofloxacin, and 70% by enoxacin (152-162). In a comparison of grepa-floxacin (400 and 600 mg/day) and ciprofloxacin, increased theophylline concentrations associated with clinical symptoms were found with both doses of grepa-floxacin but not in patients taking ciprofloxacin (17). The dosage of theophylline should be reduced when a quino-lone is given. 

Bowles SK, Popovski Z, Rybak MJ, Beckman HB, Edwards DJ. Effect of norfloxacin on theophylline pharmacokinetics at steady state. Antimicrob Agents Chemother 1988 32(4) 510-12. 

Ho G, Tierney MG, Dales RE. Evaluation of the effect of norfloxacin on the pharmacokinetics of theophylline. Clin Pharmacol Ther 1988 44(l) 35-8. 

Davis RL, Kelly HW, Quenzer RW, Standefer J, Steinberg B, Gallegos J. Effect of norfloxacin on theophylline metabolism. Antimicrob Agents Chemother 1989 33(2) 212-14. 

Norfloxacin and ciprofloxacin decrease the systemic clearance of theophylline to an extent that could be of clinical significance (Prince et al.r 1989). The effect of the interaction can be avoided by adjusting the dosage rate of theophylline in accordance with the decreased clearance so that steady-state plasma theophylline concentrations remain within the therapeutic range (6-16 pig/mL). 

More recently Brochot et al. [89] reported an extension of the isobolographic approach to interaction studies for convulsant interaction among pelloxacin, norfloxacin, and theophylline in rats. Their contribution is unique in that they started out by explaining pharmacodynamic interactions for two drugs, but then extended the approach to derive an isobol for three drug interaction. In addition they included Bayesian analysis and developed a population model with Markov chain Monte Carlo methods. 

Brochot C, Marchand S, Couet W, Gelman A, Bois FY. Extension of the isobolographic approach to interactions studies between more than two drugs Illustration with the convulsant interaction between pefloxacin, norfloxacin, and theophylline in rats. J Pharm Sci 2004 93 553-62. 

Noninterfering adenosine, albuterol, alphenal, aspirin, caffeine, carbamazepine, cefazo-lin, cephalexin, cephalothin, cimetidine, ciprofloxacin, claforan, desipramine, enoxacin, fleroxacin, furosemide, hydralazine, hydrochlorothiazide, minoxidil, norfloxacin, pheny-toin, propafenone, sulindac, teicoplanin, theophylline, vancomycin Interfering some indocyanine green impurities... 

Drugs of this class, especially those that undergo metabolism (e.g., norfloxacin, enoxacin and ciprofloxacin) can decrease the clearance of theophylline and significantly elevate plasma levels. 

Enoxacin decreases theophylline Cl by 40-60%, peflocacin and ciprofloxacin by 30%.No effect was described for ofloxacin and norfloxacin. 

Theophylline serum levels can be markedly increased in most patients by enoxacin. Pipemidic acid and clinafloxacin probably interact similarly. Theophylline levels can also be markedly increased in some patients by ciprofloxacin, and possibly pe-floxacin. Norfloxacin, ofloxacin, pazufloxacin, or prulifloxacin normally cause a much smaller rise in theophylline levels. However, serious toxicity has been seen in few patients given norfloxacin. Fleroxacin, flumequine, gatifloxacin, gemifloxacin, levofloxacin, lomefloxacin, moxifloxacin, nalidixic acid, rufloxacin, spar-floxacin and trovafloxacin appear not to interact. 

No clinically significant changes in theophylline levels occurred in a patient given norfloxacin who subsequently had marked changes when given ciprofloxacin. This report and the studies in Table 33.4 , (p.ll93) contrast with the records of the FDA in the US, which describe 3 patients (up to 1989)" and 9 patients (up to 1991) who experienced marked increases in theophylline levels ranging from 64 to 171% (mean 103%). Three patients developed seizures, and one died. ... 

Noninterfering amikacin, aztreonam, carbamazepine, cephalosporins, ciprofloxacin, clavulanic acid, difloxacin, digitoxin, digoxin, fleroxacin, fosfomycin, furosemide, gentamicin, imipenem, lidocaine, netilmicin, norfloxacin, ofloxacin, pefloxacin, penicillins, phenobarbital, phenytoin, primidone, procainamide, quinidine, rifampin, salicylic acid, teicoplanin, theophylline, tobramycin, valproic acid, vancomycin... 

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