Urinary drug excretion in man during oral dosage of different nitrofurantoin formulations

Abstract

Nitrofurantoin, a urinary tract antibacterial agent, was administered orally to human subiects in a therapeutic dose regimen for 7 days in microcrystalline form in a tablet or in macrocrystalline form in a capsule. The urine consistently contained substantial amounts of nitrofurantoin in each case, although the drug was not detectable in any of the blood samples collected during the study. Even though significantly greater urinary drug recoveries were obtained after the tablet than after the macrocrystalline drug, both formulations yielded adequate amounts of the drug in urine for potential antibacterial effectiveness. The differences in urinary drug recovery and in urinary drug-excretion patterns between the two formulations suggests a slower rate of absorption of the macrocrystals in a capsule than of the microcrystalline form in a tablet.

Excretion of nitrofurantoin in dog hepatic bile

“…-In contrast, apparent saturation of the urinary system for nitrofurantoin excretion (0 to 6 h) occurred after a dose of 6-0 mg/kg, with marked inhibition noted after either 12-0 or 24-0 mg/kg. A large amount of nitrofurantoin is excreted in urine after either oral or parenteral drug dosage (Conklin & Hailey, 1969;Conklin, Sobers & Wagner, 1969). In our study, urine drug recoveries ranging from 24 1 % ± S.D.…”

“…Since enzymatic degradation of nitrofurantoin by mammalian tissues has also been reported (Paul et al, 1960;Buzard et al, 1961), a large portion of the drug dose administered is accounted for. These results, when coupled with the relatively low concentrations of drug in the blood usually obtained with nitrofurantoin and its short half-life in blood, explain at least partially why significant biological drug residues have not been encountered with nitrofurantoin under clinical conditions (Conklin & Hailey, 1969;. Brauer (1959) divided substances which are excreted in bile into three groups on the basis of their bile to blood drug concentration ratios.…”

Liver microsomal biotransformation of nitro‐aryl drugs: mechanism for potential oxidative stress induction

“…There is an abundance of date on the oxidative metabolism of N-1,4-DHPs in the literature (Auer et al, 1982;Rush et al, 1986;Scherling et al, 1988;Grundy and Foster, 1996) but no antecedents exist for the oxidative metabolism of nitrofurantoin and nifurtimox. Published data indicate only that one-third of the nitrofurantoin dose administered is eliminated without being metabolized (Conklin and Hailey, 1969;Albert et al, 1974). To investigate the possible oxidative metabolism of these drugs, we assayed the spectral changes of Cyt-P450 oxidase in their presence.…”

Effect of food on nitrofurantoin absorption

“…It is a weak acid (pKa 7.2) and is poorly soluble at the normal pH of the gastrointestinal (GI) tract. Its dissolution rate, absorption rate, and bioavailabilit y 4,9,12,14 are dependent on its particle size.Adverse reactions associated with nitrofurantoin therapy are nausea and vomiting,…”