Cimetidine Amoxicillin

Figure 6.3 Plot of the fraction of dose absorbed (in %) of various drugs as a function of the permeability estimates in the Caco-2 system. Key 1 D-glucose 2 verapamil 3 piroxicam 4 phenylalanine 5 cyclosporin 6 enalapril 7 cephalexim 8 losartan 9 lisinopril 10 amoxicillin 11 methyldopa 12 naproxen 13 an-tipyrine 14 desipramine 15 propanolol 16 amiloride 17 metoprolol 18 terbu-taline 19 mannitol 20 cimetidine 21 ranitidine 22 enalaprilate 23 atenolol 24 hydrochlorothiazide.

Transporter absorptive effects predominant Examples. Acyclovir, Amiloride -, Amoxicillin Atenolol Atropine, Bidisomide Bisphosphonates Captoprit, Cefazolin Cetirizine Cimetidine Ciprofloxacin, Cloxacillin Dicloxacillin Erythromycin - -, Famotidine Fexofenadine Folinic acid Furosemide, Ganciclovir Hydrochlorothiazide, Lisinopril Metformin Methotrexate, Nadolol Penicillins Pravastatin Ranitidine Tetracycline Trimethoprim Valsartan Zalcitabine... 

Noninterfering amiloride, acebutolol, acenocoumarol, acetaminophen, aspirin, allopuri-nol, ambroxol, amoxicillin, atenolol, bendroflumethiazide, benzbromarone, bezafibrate, biperiden, bisacodyl, bromazepam, butizide, captopril, cimetidine, ciprofloxacin, clobu-tinol, clonidine, cotinine, diazepam, diclofenac, digitoxin, digoxin, dihydrocodeine, dihy-droergotamine, diltiazem, doxepin, doxycycline, enalapril, erythromycin, fenoterol, furosemide, glibenclamide, heparin, h3qjoxanthine, ibuprofen, indomethacin, isosorbide... 

Cimetidine does not adversely affect the bioavailability of ampicillin or co-amoxiclav, but the bioavailability of oral benzylpenicillin may be increased in some subjects. Ranitidine does not affect the pharmacokinetics of amoxicillin, but may possibly reduce the bioavailability of bacampicillin. 

Cimetidine 200 mg, given three times daily the day before and with a single 200-mg dose of co-amoxiclav (amoxicillin with clavulanic acid), had no significant effect on the bioavailability of amoxicillin or clavulanic acid. Another study found that ranitidine (300 mg given the day before and 150 mg given with the antibacterial) had no effect on the pharmacokinetics of a single 1-g dose of amoxicillin. ... 

A child who was stable taking phenytoin and sultiame developed phenytoin toxicity within 48 hours of starting co-trimoxazole. Toxicity resolved when the antibacterial was changed to amoxicillin. A clinical study found that co-trimoxazole and trimethoprim can increase the phenytoin half-life by 39% and 51%, respectively, and decrease the mean metabolic clearance by 27% and 30%, respectively. Sulfamethoxazole alone had only a small effect on the half-life and did not affect the clearance of phenytoin. A case report describes fatal acute hepatic failure in a 60-year-old woman 10 days after starting co-trimoxazole and 14 days after starting phenytoin. This patient was also given cimetidine, which may raise phenytoin levels (see Phenytoin + H2-receptor antagonists , p.559). 

Probenecid inhibits the renal secretion of the active metabolite of oseltamivir and marked raises its plasma levels, but this is not clinically relevant because of the wide safety margin of oseltamivir. There was no pharmacokinetic interaction between amoxicillin and oseltamivir, and cimetidine did not alter oseltamivir pharmacokinetics. 

Probenecid appears to completely inhibit the renal tubular secretion of the active metabolite of oseltamivir via the anionic renal transporter process. Oseltamivir does not alter amoxicillin pharmacokinetics, suggesting minimal potential to inhibit the renal anionic transport process. Cimetidine, which inhibits the renal tubular secretion of drugs via the cationic secretion transport process, had no effect on oseltamivir. 

Probenecid markedly increased the AUC of the active metabolite of oseltamivir, but because of the large safety margin of oseltamivir, this increase is not considered to be clinically relevant. " Oseltamivir did not alter amoxicillin pharmacokinetics, and is therefore unlikely to interact with other renally secreted organic acids. Other drugs that are involved in the active anionic tubular secretion mechanism are also unlikely to interact. Cimetidine does not interact with oseltamivir, and other drugs that are inhibitors of the renal cationic secretion transport process are unlikely to interact. ... 

Atherton JC, Cockayne A, Balsitis M, et al. Detection of the intragastric sites at which Helicobacter pylori evades treatment with amoxicillin and cimetidine. Gut 1995 36 670-674. 

Simultaneous acetaminophen, amoxicillin, aspirin, caffeine, cimetidine, codeine, diazepam, omeprazole, ranitidine, theophylline Interfering imipramine... 

---