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In connexion with the compound produce, nitrofurantoin sulphadiazine (ratio 1:3), it was questioned whether the relative disc (ratio 1:1, produced by BBL-USA on the findings of Tiesler, 1969), should be incorporated in the routine testing of urinary bacteria in addition to the testing of pure nitrofurantoin. Since pure sulphonamide is not in our routine test programme the sulphonamide-trimethoprim combination was also included in the study at a later time on the basis of initial results. Statistical analysis showed the overall superiority of the combination of nitrofurantoin with sulphadiazine and, moreover, a significant difference in sensitivity of E. coli in comparison with problematic gram-negative bacteria where the sensitivity values and likewise, the discordance quota were markedly higher for the compound preparation. The sulphonamide-trimethoprim combination proved even less effective and demonstrated a higher level of discordance than with pure nitrofurantoin. Annually about 45% of all examined urinary samples yield gram-negative bacteria posing therapeutic problems. Hence, the nitrofurantoin-sulphadiazine compound product (BBL-disc) was incorporated in our routine test programme.
Nitrofurantoin and nitrofurantoin with liquorice were given to healthy volunteers and patients suffering from urinary tract infections. The excretion rates of the drug, colony counts and side effects were studied in patients and excretion rates in the volunteers. The excretion rates of the drug were significantly higher in patients receiving the drug with liquorice and also side effects were minimal. There was no significant difference in the excretion rates of the drug with addition of liquorice in healthy volunteers.
The combination of subinhibitory concentrations of trimethoprim (Tp) and nitrofurantoin (NT) seemed additively inhibitory against sensitive Escherichia coli K12, chromosomally mediated NT, R-plasmid mediated Tp and NT-resistant E. coli strains, respectively. The minimal inhibitory concentrations of 6 micrograms/NT/ml and 2 micrograms Tp/ml against the sensitive strain were respectively reduced 5-fold by a minimum inhibitory combination of Tp + NT. The 30-fold chromosomally mediated and 15-fold R-plasmid NT resistance were 3- and 5-fold respectively reduced by a minimum inhibitory combination of Tp + NT. The minimum inhibitory combination of Tp + NT also reduced more than 20-fold the at least 1,000-fold resistance level of the R-plasmid mediated Tp resistance. This in vitro activity of NT and Tp could be of clinical relevance in the therapy of urinary tract infections due to multiple antibiotic-resistant strains.
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Nitrofurantoin was studied and evaluated because of its widespread use as a drug for treating urinary tract infections in humans, its structural relationship to known carcinogenic 5-nitrofuran compounds, and the lack of adequate studies to assess its carcinogenicity. Toxicology and carcinogenesis studies of nitrofurantoin were conducted by administering nitrofurantoin (greater than 99% pure) in feed to groups of F344/N rats and B6C3F1 mice of each sex for 14 days, 13 weeks, or 2 years. Fourteen-Day and Thirteen-Week Studies: None of the rats (at dietary concentrations up to 20,000 ppm) died before the end of the 14-day studies. Rats that received 5,000, 10,000, or 20,000 ppm lost weight. Four of five male and 4/5 female mice that received 10,000 ppm and 1/5 females that received 5,000 ppm nitrofurantoin died before the end of the studies. Mice that received 5,000 ppm and male mice that received 10,000 ppm lost weight. In the 13-week studies, final mean body weights of rats that received 2,500, 5,000, or 10,000 ppm were 10%, 34%, or 47% lower than that of the controls for males and 15%, 31%, or 41% lower for females. Feed consumption by dosed and control rats was generally similar. Degeneration of the germinal epithelium of the seminiferous tubules of the testis was observed in male rats that received 2,500 to 10,000 ppm nitrofurantoin. Necrosis of the ovarian follicles was observed in 8/10 female rats that received 10,000 ppm, in 3/10 females that received 5,000 ppm, and in 1/10 that received 2,500 ppm. For mice, final mean body weights of the 5,000-ppm groups were 13% lower than that of the controls for males and 15% lower for females. Two of 10 male mice that received 5,000 ppm and 1/10 males that received 300 ppm died before the end of the 13-week studies. Estimated feed consumption was similar for dosed and control groups. Degeneration of the germinal epithelium of the testis was observed in males that received 1,300 to 5,000 ppm; necrosis of the ovarian follicles was observed in females that received 5,000 ppm but not in the lower dose groups. Necrosis of the renal tubular epithelium was observed in 2/9 males that received 5,000 ppm. Based on these results, 2-year studies of nitrofurantoin were conducted by feeding diets containing 0, 1,300, or 2,500 ppm nitrofurantoin to groups of 50 male F344/N rats and to groups of 50 male and female B6C3F1 mice for 103 weeks. Groups of 50 female F344/N rats were fed diets containing 0, 600, or 1,300 ppm nitrofurantoin on the same schedule. Body Weight and Survival in the Two-Year Studies: Mean body weight and average daily feed consumption of dosed male and female rats were similar to those of the controls throughout the studies. The average amount of nitrofurantoin consumed per day was estimated to be 60 and 110 mg/kg for low and high dose male rats and 30 and 60 mg/kg for low and high dose female rats. No significant differences in the number of rats surviving to the end of the studies were observed between any groups of rats of either sex (male: control, 24/50; low dose, 27/50; high dose, 26/50; female: 25/50; 26/50; 31/50). Mean body weights of high dose male and female mice were up to 12% lower than those of the controls throughout most of the studies. The average daily feed consumption by dosed mice ranged from 93% to 100% that by controls. The average amount of nitrofurantoin consumed per day was estimated to be 280-300 mg/kg and 570-580 mg/kg for low and high dose mice. The survival of the control group of female mice was lower than that of the dosed groups (control, 19/50; low dose, 37/50; high dose, 37/50). The decrease in survival was most likely related to the increase in microbial infection in the reproductive tract observed in the controls. Groups of male mice had similar survival (28/50; 29/50; 34/50). Nonneoplastic and Neoplastic Effects in the Two-Year Studies: Organs showing toxicity from nitrofurantoin exposure identified in the short-term studies were the testis in male rats and mice, the ovary in female rats and mice, and the kidney in male mice. Lesions oband mice, the ovary in female rats and mice, and the kidney in male mice. Lesions observed in the 2-year studies were in the testis in male rats and mice, ovary in female mice, and kidney in male rats. Chronic nephropathy was observed in nearly all rats, but the severity of the lesions was judged to be greater in dosed male rats. Hyperplasia of the transitional cell epithelium (control, 0/50; low dose, 5/50; high dose, 2/50) and hydronephrosis of the renal pelvis (0/50; 5/50; 2/50) were also observed in dosed male rats. In the standard single sections of the left and right kidney from each rat, tubular cell adenomas were observed in one low dose and two high dose males; a tubular cell carcinoma was observed in another high dose male. Because the number of renal tubular cell neoplasms identified by standard procedures in the dosed male rats was low, additional step-sections of the kidney were evaluated. The incidences of tubular cell adenomas derived from the step-sections and original sections (combined) were significantly increased in dosed male rats (adenomas: 3/50; 11/50; 19/50); tubular cell carcinomas occurred in two high dose males only. Lesions considered to be associated with the nephropathy and nitrofurantoin exposure were observed in male rats and included hyperplasia of the parathyroid glands (3/49; 18/47; 23/49), fibrous osteodystrophy of the bone (0/50; 5/50; 5/50), and mineralization of the glandular stomach (1/49; 8/50; 14/50). Atypical cells of the epididymis (0/50; 0/50; 12/50) and degeneration of the testis (0/50; 0/50; 36/50) were observed in high dose male rats. Fibrinoid necrosis of arterioles (1/50; 8/50; 15/50) and perivascular infiltration of mononuclear cells (3/50; 9/50; 19/50) were also observed in the testis of male rats. Interstitial cell adenomas of the testis occurred with a negative trend (47/50; 45/50; 21/50), and no adenomas or carcinomas of the preputial gland were seen in high dose male rats (12/48; 11/50; 0/47). The incidence of clitoral gland neoplasms was increased in low dose female rats (5/44; 10/38; 4/42). Osteosarcomas were observed in the bone of one low dose and two high dose male rats. The historical incidence of osteosarcomas in untreated male F344/N rats is 8/1,937 (0.4%). The incidences of subcutaneous tissue neoplasms in dosed male rats were greater than that in the controls (1/50; 7/50; 5/50). No neoplastic lesions in dosed female rats or male mice were considered to be compound related at the doses of nitrofurantoin administered. For female mice, ovarian atrophy was observed in 48/50 low dose and 49/50 high dose mice but not in controls. Tubular cell adenomas of the ovary (0/50; 0/50; 5/50), benign mixed tumors (tubular and stromal) (0/50; 0/50; 4/50), and granulosa cell tumors (0/50; 3/50; 2/50)) were observed in dosed female mice. One granulosa cell tumor in the high dose group was malignant. Ovarian abscesses (18/50) and suppurative inflammation of the uterus (11/50) were observed in control female mice but not in dosed female mice and are believed to be related to indigenous microbial infections and most likely were the cause of early deaths in this group. Adenocarcinomas of the uterus were seen in one low dose and in one high dose mouse. Testicular aspermatogenesis (1/49; 1/49; 16/50), degeneration of the germinal epithelium (0/49; 3/49; 23/50), and atypical cells (0/50; 0/49; 26/50) and depletion (1/50; 1/49; 15/50) of the epididymis were observed at increased incidences in high dose male mice. Spindle cell hyperplasia of the adrenal cortex was observed in dosed female mice (3/50; 41/50; 45/50). A spindle cell adenoma (adrenal capsule adenoma) was seen in one low dose female mouse, and a spindle cell carcinoma (adrenal capsule carcinoma) was seen in one low dose male mouse. Mineralization of the renal medulla (male: 0/50; 0/50; 17/50; female: 0/50; 0/50; 7/50) and dilatation of the renal tubules (male: 0/50; 0/50; 14/50) were observed in high dose mice. Hepatocellular neoplasms (adenomas or carcinomas, combined) were observed at an increased incidence in high dose female mice (2/50; 2/50; 8/50). An Ito cell tumor of the liver was observed in one low dose and one high dose female mouse. Malignant lymphomas occurred in female mice (12/50; 19/50; 24/50). Genetic Toxicology: Nitrofurantoin was mutagenic in Salmonella typhimurium strains TA98 and TA100, with and without metabolic activation, but was not mutagenic for strains TA1535 or TA1537. Nitrofurantoin induced forward mutations at the TK+/- locus of L5178Y mouse lymphoma cells in the absence of metabolic activation (it was not tested with activation). Nitrofurantoin induced increased numbers of sister chromatid exchanges and chromosomal aberrations in cultured Chinese hamster ovary cells with and without metabolic activation. Results of the sex-linked recessive lethal assay in Drosophila were negative after administration of nitrofurantoin by feeding or by injection. Conclusions: Under the conditions of these 2-year feed studies, there was some evidence of carcinogenic activity of nitrofurantoin for male F344/N rats as shown by increased incidences of uncommon kidney tubular cell neoplasms. Uncommon osteosarcomas of the bone and neoplasms of the subcutaneous tissue were observed in dosed male rats. Incidences of interstitial cell adenomas of the testis and neoplasms of the preputial gland were decreased in the 2,500-ppm group of male rats. There was no evidence of carcinogenic activity of nitrofurantoin for female F344/N rats fed diets containing 600 ppm or 1,300 ppm for 2 years. Female rats may have been able to tolerate higher doses. There was no evidence of carcinogenic activity of nitrofurantoin for male B6C3F1 mice fed diets containing 1,300 ppm or 2,500 ppm for 2 years. There was clear evidence of carcinogenic activity of nitrofurantoin for female B6C3F1 mice as shown by increased incidences of tubular adenomas, benign mixed tumors, and granulosa cell tumors of the ovary. Nonneoplastic lesions considered related to nitrofurantoin exposure were chronic nephropathy and associated lesions (hyperplasia of the parathyroid gland, fibrous osteodystrophy of the bone, and mineralization of the glandular stomach) in male rats and testicular degeneration in male rats and mice. Ovarian atrophy and hyperplasia of the adrenal cortex spindle cells were observed in dosed female mice. Synonyms: 1-(((5-nitro-2-furanyl)methylene)amino-2,4-imidazolidinedione); 1-(5-nitro-2-furfurylideneamino)-hydantoin; N-(5-nitro-2-furfurlidene)-1-aminohydantoin; 1-((5-nitrofurfurylidene)amino)hydantoin Trade Names: Benkfuran; Benkfurin; Chemiofuran; Cyantin; Dantafur; Furadantin; Furadantine; Furadantoin; Furadonin; Furadonine; Furantoin; Furatoin; Furobactina; Ituran; Macrodantin; Nifurantin; NSC 2107; N-Toin; Orafuran; Parafuran; Urizept; USAF EA-2; Welfurin; Zoofurin
The effect of different milk volumes on the extent and consistency of nitrofurantoin (1-[(5-nitrofurfurylidene)amino]hydantoin) absorption from freeze-dried nitrofurantoin-milk formulations was studied in four male volunteers in three separate crossover designs. Each volunteer received six single-dose treatments (one 100-mg nitrofurantoin capsule with 100, 200, and 400 mL of milk and 100 mg of nitrofurantoin as a freeze-dried nitrofurantoin milk formulation regenerated with 100, 200, and 400 mL of water). Analysis of the urine data revealed superiority of the nitrofurantoin-milk formulations regenerated with 200 and 400 mL of milk over the corresponding capsule formulations in the rates and extents of nitrofurantoin excretion. The binding of nitrofurantoin to casein and bovine serum albumin and its solubility in the presence of the proteins were measured in vitro. The presence of both proteins caused increases in the solubility of nitrofurantoin. Normal protein binding is responsible for the increase of nitrofurantoin solubility in the presence of bovine serum albumin, whereas the increase of nitrofurantoin solubility in the presence of casein is attributed to the formation of aggregates in casein solution at 37 degrees C. The in vivo data were discussed in light of the in vitro data. The freeze-dried nitrofurantoin-milk formulation regenerated with 200 mL of water has a potential for use as a nitrofurantoin delivery system.
Nitrofurantoin is an effective urinary tract antibacterial to which no clinically significant resistance development has occurred. We have previously shown that nitrofurantoin susceptibility in bacteria correlates with the presence of bacterial nitroreductases which convert nitrofurantoin to highly reactive electrophilic intermediates. These intermediates were shown to attack bacterial ribosomal proteins non-specifically, causing complete inhibition of protein synthesis. In the present study, we confirm previous reports that low concentrations of nitrofurantoin specifically inhibit inducible enzyme synthesis in bacteria, and show that this inhibition occurs at levels equivalent to the MICs of nitrofurantoin for several bacterial species. Our previous studies had shown that nitrofurantoin at different concentrations interacts with bacterial ribosomal proteins in qualitatively the same fashion; we now report that quantitative differences are seen in the labelling observed at different nitrofurantoin concentrations and discuss these differences as they may relate to the inhibition of inducible enzyme synthesis. In addition, we have now demonstrated the existence of a novel mechanism of action for nitrofurantoin which does not require the production of reactive nitrofurantoin metabolites by bacterial reductases. The lack of clinically significant bacterial resistance development to nitrofurantoin is likely due to the combination of nitrofurantoin's multiple sites of attack and multiple mechanisms of action.
Five spontaneous nitrofurantoin-resistant mutants (one each of Clostridium leptum, Clostridium paraputrificum, two other Clostridium spp. strains from the human intestinal microflora, and Clostridium perfringens ATCC 3626) were selected by growth on a nitrofurantoin-containing medium. All of the Clostridium wild-type and mutant strains produced nitroreductase, as was shown by the conversion of 4-nitrobenzoic acid to 4-aminobenzoic acid. High-performance liquid chromatography (HPLC) analysis of the mutants during incubation with 50 microg of nitrofurantoin per ml showed the gradual disappearance of the nitrofurantoin peak. The nitrofurantoin peak also disappeared when cell-free supernatants instead of cultures of each of the resistant and wild-type bacteria were used, but it persisted if the cell-free supernatants had been inactivated by heat. At least two of the mutants converted nitrofurantoin to metabolites without antibacterial activity, as was shown by a bioassay with a nitrofurantoin-susceptible Bacillus sp. strain. Nitrofurantoin at a high concentration (50 microg/ml) continued to exert some toxicity, even on the resistant strains, as was evident from the longer lag phases. This study indicates that Clostridium strains can develop resistance to nitrofurantoin while retaining the ability to produce nitroreductase; the mutants metabolized nitrofurantoin to compounds without antibacterial activity.
The main objectives of this study were to determine whether the nitroreductase enzyme encoded by the rdxA gene of Helicobacter pylori was responsible for reductive activation of nitrofurantoin and whether a triple-therapy regimen with nitrofurantoin was able to eradicate metronidazole-sensitive and -resistant H. pylori infections from mice. The susceptibilities to nitrofurantoin of parent and isogenic rdxA mutant strains (three pairs), as well as a series of matched metronidazole-sensitive and -resistant strains isolated from mice (30) and patients (20), were assessed by agar dilution determination of the MIC. Groups of mice colonized with the metronidazole-sensitive H. pylori SS1 strain or a metronidazole-resistant rdxA SS1 mutant were treated with either metronidazole or nitrofurantoin as part of a triple-therapy regimen. One month after the completion of treatment the mice were sacrificed and their stomachs were cultured for H. pylori. The nitrofurantoin MICs for all strains tested were between 0.5 and 4.0 microg/ml. There was no significant difference between the susceptibility to nitrofurantoin of the parental strains and those of respective rdxA mutants or between those of matched metronidazole-sensitive and -resistant H. pylori isolates. The regimen with metronidazole eradicated infection from all eight SS1-infected mice and from one of eight mice inoculated with the rdxA mutant (P < or =0.001). The regimen with nitrofurantoin failed to eradicate infection from any of the six SS1-infected mice (P < or =0.001) and cleared infection from one of seven mice inoculated with the rdxA mutant. These results demonstrate that, despite the good in vitro activity of nitrofurantoin against H. pylori and the lack of cross-resistance between metronidazole and nitrofurantoin, eradication regimens involving nitrofurantoin are unable to eradicate either metronidazole-sensitive or -resistant H. pylori infections from mice.
Nitrofurantoin is a urinary tract antibacterial agent whose clinical effectiveness depends on the high urinary drug levels encountered during therapeutic drug dosage. Under these conditions, only low blood drug concentrations are usually found. On the basis of urinary nitrofurantoin excretion determined after oral and intravenous drug administration, orally administered nitrofurantoin in a suitable dosage form is well absorbed. In vitro testing does not accurately reflect nitrofurantoin bioavailability, which is affected by formulation differences, drug particle size, and dosage form. Nitrofurantoin is readily absorbed and quickly distributed into most body fluids. It is rapidly excreted in large amounts in bile and urine. With the exception of the active drug secretion in the kidney tubule and biliary drug transport, nitrofurantoin transfer across body membranes occurs by diffusion. Nitrofurantoin has a short elimination half-life in whole blood or plasma. In conjunction with its rapid excretion by the primary routes, there is little evidence for any prolonged binding of nitrofurantoin to either plasma proteins or tissues. The first-order kinetics involved in nitrofurantoin absorption and elimination is most appropriately described by a one-compartment open model. Biliary and urinary excretion of unchanged nitrofurantoin and enzymatic degradation are the primary means of elimination.
Six lactating white healthy women (26-36 years old, weighing 45-58 kg) were treated with 50 mg nitrofurantoin tablets, a urinary antiseptic. They received either 50 mg (group I; n = 3) or 100 mg (group II; n = 3) 3 times a day (09.00, 16.00, 19.00 h) for 24 h, 2-5 days after the delivery of a full-term neonate. The study was performed on the 4th dose at 09.00 h just before breakfast. Milk samples were collected before, 3 and 6 h after the nitrofurantoin administration with an Egnell SMB breast pump. The complete milk samples were collected from each breast, and pooled. 5 ml venous blood samples were drawn before, 1, 2, 3 and 6 h after nitrofurantoin administration. Plasma and milk nitrofurantoin concentrations were measured by HPLC. Apparent elimination half-life and apparent plasma clearance were the same in both groups, 0.8 +/- 0.09 h and 27.6 +/- 5.57 l/h, respectively. Nitrofurantoin was not detectable in the milk just before the 4th administration. The amount excreted in the milk within 6 h after nitrofurantoin administration was 22-57 micrograms (I) and 61-284 micrograms (II) which represents 0.05-0.11% (I) and 0.06-0.28 (II) of the nitrofurantoin dose. The nitrofurantoin concentration ratio of the breast milk to the plasma collected at 3 h was 2.2 +/- 1.2 (I) and 2.3 +/- 1.6 (II). These results show that nitrofurantoin excretion in human milk is low: below 0.12 (I) and 0.29% (II). It suggested that breast-fed newborn infants from mothers treated with nitrofurantoin would be exposed to small amounts of drug.(ABSTRACT TRUNCATED AT 250 WORDS)
The possibility that nitrofurantoin is a complete carcinogen or is an initiator or promoter of urinary bladder carcinogenesis was evaluated in male weanling F344 rats. No increase in tumor incidence was observed in rats fed nitrofurantoin at a level of 0.187% of the diet for 2 years compared to a control group. Also, no evidence of bladder initiating activity by nitrofurantoin was observed using sodium saccharin (5% of the diet) as a promoter, and no promoting activity was observed when nitrofurantoin was fed after initiation by N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide (0.2% of the diet for 4 weeks). In a second experiment, nitrofurantoin (at a dose of 0.187% of the diet) was administered for 6 weeks to rats with a rapidly proliferating bladder epithelium following freeze ulceration, and then the rats were treated with 5% sodium saccharin in the diet for 98 weeks. In additional rats, labelling index following [3H]thymidine injection, determined after 12 weeks of feeding nitrofurantoin, was not increased above control levels in the urinary bladder, stomach, duodenum, or liver. Metabolism of nitrofurantoin by prostaglandin H synthase (PHS) was examined using solubilized ram seminal vesicle microsomes. The rate of nitrofurantoin metabolism by PHS was much less than that observed with benzidine, and the proportion of total metabolite bound to protein was also much less than that with benzidine. These results are consistent with previous reports describing the lack of effect of nitrofurantoin on urinary bladder carcinogenesis.
OBJECTIVE: To determine the effect of nitrofurantoin prophylaxis on rates of bacteriuria and symptomatic urinary tract infection in children with chronic neurogenic bladder receiving clean intermittent catheterization. DESIGN: Double-blind, placebo-controlled, crossover trial of 15 children receiving nitrofurantoin or placebo for 11 months (5 months receiving one drug, then 1 month of washout followed by 5 months of the alternate drug). Weekly home visits were made. During each visit a sample of bladder urine was obtained by intermittent catheterization, signs and symptoms of urinary tract infection were recorded, and all medications were recorded as well as a capsule count of the study drug. RESULTS: During nitrofurantoin the frequency of bacteriuria remained high. Cultures of 74% (203 of 274) of the 274 samples on placebo were positive for a pathogen (> or = 10(4) colony-forming units per milliliter) compared with 65% (165 of 252) of the 252 samples on nitrofurantoin. The bacterial species responsible for bacteriuria, however, were altered; Escherichia coli, the most common pathogen isolated during placebo, was replaced by resistant Klebsiella spp. and Pseudomonas spp. during nitrofurantoin. The carriage of these resistant organisms tripled during nitrofurantoin. Symptomatic infection dropped in half on nitrofurantoin, but this decline was due solely to infections caused by E. coli. Despite an increased frequency of resistant organisms on nitrofurantoin prophylaxis, an increase in urinary tract infections caused by these resistant organisms did not occur. CONCLUSION: Routine use of nitrofurantoin prophylaxis in an attempt to eradicate bacteriuria in patients with chronic neurogenic bladder is not effective.
1. After the intravenous administration of nitrofurantoin sodium to dogs at nitrofurantoin doses of 1.5-24.0 mg/kg, a substantial amount of nitrofurantoin is excreted in bile. The bile to blood drug ratios were about 200. A marked hydrocholeretic effect which correlated directly with the amount of nitrofurantoin administered was also observed.2. The excretion of nitrofurantoin in bile and the hydrocholeretic effect were linear with the dose of drug over the range 1.5-12.0 mg/kg. Maximum increases in hepatic bile flows were usually from 5-10 ml/0.5 h, while average control bile flow was 1.6 ml +/- S.D. 0.6/0.5 hours. The lowest dose at which the hydrocholeretic effect was still detectable was 0.09 mg/kg.3. Apparent saturation of the biliary excretion system for nitrofurantoin and the hydrocholeretic mechanism occurred after a dose of 24.0 mg/kg. Saturation of the urinary system for nitrofurantoin excretion was noted after a dose of 6.0 mg/kg.4. Biliary nitrofurantoin recoveries ranged from 16.5% +/- S.D. 4.2 to 22.6% +/- S.D. 4.7 for the 6 h period after doses of 1.5, 3.0, and 6.0 mg/kg. Urinary nitrofurantoin recoveries for the same interval ranged from 24.1% +/- S.D. 6.6 to 36.2% +/- S.D. 8.3.5. In comparison to values obtained in normal dogs, only about one-tenth of the drug excretion in bile and about one-fifth of the hydrocholeretic effect were obtained after intravenous drug administration to dogs with hepatic impairment induced by CCl(4).