Didanosine Ciprofloxacin

Proquin XR Proquin XR and other oral formulations of ciprofloxacin are not interchangeable. Proquin XR should be administered orally once daily for 3 days with a main meal of the day, preferably the evening meal. Proquin XR should be administered at least 4 hours before or 2 hours after antacids containing magnesium or aluminum, sucralfate, Videx (didanosine) chewable/buffered tablets or pediatric powder, metal cations such as iron, and multivitamin preparations containing zinc. Pragy/n XR tablets should be taken whole and never split, crushed, or chewed. 

Ciprofloxacin (Cipro, Cipro XR, Proquin XR) [Antibiotic/ Fluoroquinolone] Uses Rx lower resp tract, sinuses, skin skin structure, bone/joints, urinary tract Infxns including prostatitis Action Quinolone antibiotic DNA gyrase Dose Adults. 250-750 mg PO ql2h XR 500-1000 mg PO q24h or 200-400 mg IV ql2h in renal impair Caution [C, /-] Children <18 y Contra Component sensitivity Disp Tabs, susp, inj SE Restlessness, N/V/D, rash, ruptured tendons, T LFTs Interactions T Effects Wf probenecid T effects OF diazepam, theophylline, caffeine, metoprolol, propranolol, phenytoin, warfarin effects W/ antacids, didanosine, Fe salts. Mg, sucralfate, Na bicarbonate,... 

All quinolones interact with multivalent cations, forming chelation complexes resulting in reduced absorption. Major offenders are antacids vitamins containing calcium and iron can also be problematic. All fluoroquinolones interact with warfarin, didanosine (ddi), and phenytoin, resulting in decreased absorption or metabolism. Ciprofloxacin and other second-generation drugs interact with theophylline by decreasing its clearance, which leads to theophylline toxicity. 

Damle BD, Mummaneni V, Kaul S, Knupp C. Lack of effect of simultaneously administered didanosine encapsulated enteric bead formulation (Videx EC) on oral absorption of indinavir, ketoconazole, or ciprofloxacin. Antimicrob Agents Chemother 2002 46(2) 385-91. 

QUINOLONES DIDANOSINE 1 efficacy of ciprofloxacin and possibly levofloxacin, moxifloxacin, norfloxacin and ofloxacin with buffered didanosine Cations in the buffer of didanosine preparation chelate and adsorb ciprofloxacin. Absorption of the other quinolones may be i by the buffered didanosine formulation, which raises gastric pH Give the antibiotic 2 hours before or 6 hours after didanosine. Alternatively, consider using the enteric-coated formulation of didanosine, which does not have to be given separately... 

Didanosine one enteric-coated capsule/day (400 mg/day) did not affect the absorption of ciprofloxacin in 16 patients (71). 

Noninterfering acetaminophen, amphotericin B, brotizolam, ceftazidime, ciprofloxacin, codeine, diclofenac, didanosine, domperidone, fluoxetine, foscarnet, gangiclovir, methadone, metoclopramide, mianserin, nystatin, pyrimethamine, ranitidine, sulfamethoxazole, temazepam, trimethoprim, zidovudine... 

An extremely marked reduction in the serum levels of ciprofloxacin occurs if it is given at the same time as didanosine tablets, because of an interaction with the antacid buffers in the didanosine formulation. Taking the ciprofloxacin 2 hours before or 6 hours after didanosine tablets minimises this interaction. Other quinolones are expected to interact similarly. Didanosine enteric-coated capsules do not interact with ciprofloxacin. 

When 12 healthy subjeets were given ciprofloxacin 750 mg with two didanosine plaeebo tablets (i.e. all of the antacid additives but no didanosine), the ciprofloxacin AUC and maximum serum levels were reduced by 98% and 93%, respectively. The antacids in this formulation were dihy-droxyaluminium sodium carbonate and magnesium hydroxide. 

Other studies have looked at whether separating the administration times affects this interaction. When 16 HIV-positive patients were given ciprofloxacin 1.5 g daily 2 hours before didanosine tablets, the ciprofloxacin AUC was reduced by only 26%. Another study in just one subject found that when ciprofloxacin 500 mg was given 2 hours after taking two didanosine placebo tablets the ciprofloxacin serum levels were reduced below minimal inhibitory concentrations, but giving the ciprofloxacin 2 hours before the didanosine placebo tablets resulted in normal blood levels. The enteric-coated capsule formulation of didanosine (which does not contain antacids) does not interact with ciprofloxacin. ... 

Didanosine is extremely acid labile at pH values below 3, so one ofthe formulations contains buffering agents (dihydroxyaluminium sodium carbonate and magnesium hydroxide) to keep the pH as high as possible to minimise the acid-induced hydrolysis. Ciprofloxacin forms insoluble non-absorbable chelates with these metallic ions in the buffer so that its bioavailability is markedly reduced. See also Quinolones + Antacids or Calcium compounds , p.328. 

Direct information is limited to these reports but the interaction between buffered didanosine and ciprofloxacin appears to be clinically important. Such drastic reductions in serum ciprofloxacin levels mean that minimal inhibitory concentrations are unlikely to be achieved. Ciprofloxacin should be given at least 2 hours before or 6 hours after didanosine tablets (see Quinolones + Antacids or Calcium compounds , p.328). Other qui-nolone antibacterials that interact with antacids are also expected to interact with didanosine tablets, but so far reports are lacking. Didanosine enteric-coated capsules do not interact. 

Sahai J, Gallicano K, Oliveras L, Khaliq S, Hawley-Foss N, Garber G. Cations in the didanosine tablet reduce ciprofloxacin bioavaihbilily. C Pharmacol Ther( 99y) 53,292-7. 

Class 3 (Low Permeability, High Solrrbility) Atropine, Aciclovir, Valsartan, Gan-cyclovir, Didanosine, Dicloxacillin, Zaldtabine, Lomefloxacin, Methyldopa, Meth-otrexatum. Nadolol, Pravastatin, Ranitidine, TetracycUne, Famotidine, Cefazolin, Ciprofloxacin, Erythromycin, Atenolol, Hydrochlorothiazide, Metformin. ... 

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