nitrofurantoin 5 MG/ML Oral Suspension

INDICATIONS AND USAGE: Nitrofurantoin Capsules, USP (monohydrate/ macrocrystals) are indicated only for the treatment of acute uncomplicated urinary tract infections (acute cystitis) caused by susceptible strains of Escherichia coli or Staphylococcus saprophyticus . Nitrofurantoin is not indicated for the treatment of pyelonephritis or perinephric abscesses. To reduce the development of drug-resistant bacteria and maintain the effectiveness of Nitrofurantoin Capsules, USP (monohydrate/ macrocrystals) and other antibacterial drugs,Nitrofurantoin Capsules, USP (monohydrate/ macrocrystals) should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy. Nitrofurantoins lack the broader tissue distribution of other therapeutic agents approved for urinary tract infections. Consequently, many patients who are treated with Nitrofurantoin Capsules, USP (monohydrate/ macrocrystals) are predisposed to persistence or reappearance of bacteriuria. (see Error! Hyperlink reference not valid. ). Urine specimens for culture and susceptibility testing should be obtained before and after completion of therapy. If persistence or reappearance of bacteriuria occurs after treatment with Nitrofurantoin Capsules, USP (monohydrate/ macrocrystals), other therapeutic agents with broader tissue distribution should be selected. In considering the use of Nitrofurantoin Capsules, USP (monohydrate/ macrocrystals), lower eradication rates should be balanced against the increased potential for systemic toxicity and for the development of antimicrobial resistance when agents with broader tissue distribution are utilized.

DOSAGE AND ADMINISTRATION Adult Patients: 50 mg to 100 mg four times a day - the lower dosage level is recommended for uncomplicated urinary tract infections. (2.2) Pediatric Patients: 5 mg/kg to 7 mg/kg of body weight per 24 hours, given in four divided doses (contraindicated under one month of age). (2.3) 2.1 Recommended Dosage and Administration in Adult Patients The recommended dosage is 50 mg to 100 mg of nitrofurantoin oral suspension four times a day. For long-term suppressive therapy in adults, a reduction of dosage to 50 mg to 100 mg at bedtime may be adequate . The benefits of long-term suppressive therapy should be balanced against the increased potential for systemic toxicity and for the development of antibacterial resistance [see Warnings and Precautions ( 5.2, 5.4, 5.6 ) ]. Administer nitrofurantoin oral suspension with food to improve drug absorption [see Clinical Pharmacology ( 12.3 )] and, in some patients, tolerance. 2.2 Recommended Dosage and Administration in Pediatric Patients (1 month of age and older) The recommended dosage of nitrofurantoin oral suspension is 5 mg/kg to 7 mg/kg of body weight per 24 hours, given in four divided doses in pediatric patients aged 1 month and older. Administer nitrofurantoin oral suspension with food to improve drug absorption [ s ee Clinical Pharmacology ( 12.3 )] and, in some patients, tolerance. Table 1 lists individual dosage volumes for two different strengths of nitrofurantoin oral suspension (25 mg/5 mL and 50 mg/5 mL) based on body weight for pediatric patients. Table 1: Nitrofurantoin Oral Suspension Pediatric Dosing Table for Pediatric Patients 1 month of Age and Older Weight in Kilograms (kg) Pediatric Doses (mL), Frequency: Four times Daily 25 mg/5 mL oral suspension 50 mg/5 mL oral suspension 4 kg or lower 1 0.5 Greater than 4 kg to 5 kg 1.4 0.7 Greater than 5 kg to 7 kg 1.8 0.9 Greater than 7 kg to 10 kg 2.5 1.25 Greater than 10 kg to 14 kg 3.5 1.75 Greater than 14 kg to 20 kg 5 2.5 Greater than 20 kg to 25 kg 7 3.5 Greater than 25 kg to 30 kg 8.5 4.25 Greater than 30 kg to 40 kg 10 5 40 kg or greater See Adult Dose See Adult Dose To measure the correct pediatric doses, it is important to administer nitrofurantoin oral suspension with an appropriate size oral dosing syringe with graduations that align with the volume prescribed in Table 1 above. Continue therapy for one week or for at least 3 days after sterility of the urine is obtained. Continued infection indicates the need for reevaluation. For long-term suppressive therapy in pediatric patients, doses as low as 1 mg/kg per 24 hours, given in a single dose or in two divided doses, may be adequate [see Warnings and Precautions ( 5.2, 5.4, 5.6 ) ]. 2.1 Recommended Dosage and Administration in Adult Patients The recommended dosage is 50 mg to 100 mg of nitrofurantoin oral suspension four times a day. For long-term suppressive therapy in adults, a reduction of dosage to 50 mg to 100 mg at bedtime may be adequate . The benefits of long-term suppressive therapy should be balanced against the increased potential for systemic toxicity and for the development of antibacterial resistance [see Warnings and Precautions ( 5.2, 5.4, 5.6 ) ]. Administer nitrofurantoin oral suspension with food to improve drug absorption [see Clinical Pharmacology ( 12.3 )] and, in some patients, tolerance. 2.2 Recommended Dosage and Administration in Pediatric Patients (1 month of age and older) The recommended dosage of nitrofurantoin oral suspension is 5 mg/kg to 7 mg/kg of body weight per 24 hours, given in four divided doses in pediatric patients aged 1 month and older. Administer nitrofurantoin oral suspension with food to improve drug absorption [ s ee Clinical Pharmacology ( 12.3 )] and, in some patients, tolerance. Table 1 lists individual dosage volumes for two different strengths of nitrofurantoin oral suspension (25 mg/5 mL and 50 mg/5 mL) based on body weight for pediatric patients. Table 1: Nitrofurantoin Oral Suspension Pediatric Dosing Table for Pediatric Patients 1 month of Age and Older Weight in Kilograms (kg) Pediatric Doses (mL), Frequency: Four times Daily 25 mg/5 mL oral suspension 50 mg/5 mL oral suspension 4 kg or lower 1 0.5 Greater than 4 kg to 5 kg 1.4 0.7 Greater than 5 kg to 7 kg 1.8 0.9 Greater than 7 kg to 10 kg 2.5 1.25 Greater than 10 kg to 14 kg 3.5 1.75 Greater than 14 kg to 20 kg 5 2.5 Greater than 20 kg to 25 kg 7 3.5 Greater than 25 kg to 30 kg 8.5 4.25 Greater than 30 kg to 40 kg 10 5 40 kg or greater See Adult Dose See Adult Dose To measure the correct pediatric doses, it is important to administer nitrofurantoin oral suspension with an appropriate size oral dosing syringe with graduations that align with the volume prescribed in Table 1 above. Continue therapy for one week or for at least 3 days after sterility of the urine is obtained. Continued infection indicates the need for reevaluation. For long-term suppressive therapy in pediatric patients, doses as low as 1 mg/kg per 24 hours, given in a single dose or in two divided doses, may be adequate [see Warnings and Precautions ( 5.2, 5.4, 5.6 ) ].

WARNINGS AND PRECAUTIONS Hypersensitivity Reactions: Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients receiving nitrofurantoin oral suspension. If signs and symptoms of a hypersensitivity reaction occurs, immediately discontinue nitrofurantoin oral suspension. ( 5.1 ) Pulmonary Reactions: Discontinue if sign and symptoms of pulmonary reactions occur and take appropriate measures. ( 5.2 ) Hepatotoxicity: Discontinue if signs/symptoms of hepatitis occur. Monitor liver function tests. (5.3) Neuropathy: Peripheral neuropathy has occurred. ( 5.4 ) Hemolytic Anemia: Discontinue if sign and symptoms of hemolysis occur. ( 5.5 ) Clostridioides difficile -associated diarrhea: Evaluate patients if diarrhea occurs. ( 5.6 ) 5.1 Hypersensitivity Reactions Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients receiving nitrofurantoin oral suspension [see Adverse Reactions ( 6 )]. If signs and symptoms of a hypersensitivity reaction occurs, immediately discontinue nitrofurantoin oral suspension and initiate appropriate medications and/or supportive care. Nitrofurantoin oral suspension is contraindicated in patients with known hypersensitivity to nitrofurantoin. 5.2 Pulmonary Reactions Acute, subacute, or chronic pulmonary reactions have been reported in patients treated with nitrofurantoin oral suspension. If these reactions occur, discontinue nitrofurantoin oral suspension and take appropriate measures. Reports have cited pulmonary reactions as a contributing cause of death. Chronic pulmonary reactions (diffuse interstitial pneumonitis or pulmonary fibrosis, or both) can develop insidiously. These reactions occur generally in patients receiving therapy for six months or longer. Close monitoring of the pulmonary condition of patients receiving long-term therapy is warranted and requires that the benefits of therapy be weighed against potential risks [see Adverse Reactions ( 6 )]. 5.3 Hepatotoxicity Hepatic reactions, including hepatitis, cholestatic jaundice, chronic active hepatitis, and hepatic necrosis, has occurred. Fatalities have been reported. The onset of chronic active hepatitis may be insidious. Monitor patients periodically for changes in biochemical tests that would indicate liver injury. If hepatitis occurs, discontinue nitrofurantoin oral suspension immediately, and take appropriate measures. 5.4 Neuropathy Peripheral neuropathy, which may become severe or irreversible, has occurred. Fatalities have been reported. Conditions such as renal impairment (creatinine clearance under 60 mL per minute or clinically significant elevated serum creatinine), anemia, diabetes mellitus, electrolyte imbalance, vitamin B deficiency, and debilitating disease may enhance the occurrence of peripheral neuropathy. Monitor patients receiving long-term therapy periodically for changes in renal function. Optic neuritis has been reported with nitrofurantoin formulations [see Adverse Reactions ( 6 )] . 5.5 Hemolytic Anemia Cases of hemolytic anemia of the primaquine-sensitivity type have been induced by nitrofurantoin. Hemolysis appears to be linked to a glucose-6-phosphate dehydrogenase deficiency in the red blood cells of the affected patients. This deficiency is found in 10 percent of Blacks and a small percentage of ethnic groups of Mediterranean and Near-Eastern origin. If hemolysis occurs, discontinue nitrofurantoin oral suspension immediately; hemolysis ceases when the drug is withdrawn. 5.6 Clostridioides difficile -associated Diarrhea Clostridioides difficile -associated Diarrhea (CDAD) has been reported with use of nearly all antibacterial agents, including nitrofurantoin, and may range in severity from mild diarrhea to fatal colitis. Treatment with antibacterial agents alters the normal flora of the colon leading to overgrowth of C. difficile . C. difficile produces toxins A and B which contribute to the development of CDAD. Hypertoxin producing strains of C. difficile cause increased morbidity and mortality, as these infections can be refractory to antibacterial therapy and may require colectomy. CDAD must be considered in all patients who present with diarrhea following antibacterial use. Careful medical history is necessary since CDAD has been reported to occur over two months after the administration of antibacterial agents. If CDAD is suspected or confirmed, ongoing antibacterial use not directed against C. difficile may need to be discontinued. Appropriate fluid and electrolyte management, protein supplementation, antibacterial treatment of C. difficile , and institute surgical evaluation as clinically indicated. 5.7 Persistence or Reappearance of Bacteriuria Nitrofurantoin lacks the broader tissue distribution of other therapeutic agents approved for urinary tract infections. Consequently, many patients who are treated with nitrofurantoin oral suspension are predisposed to persistence or reappearance of bacteriuria. If persistence or reappearance of bacteriuria occurs with symptoms of urinary tract infection, after treatment with nitrofurantoin oral suspension, other therapeutic agents with broader tissue distribution should be selected. In considering the use of nitrofurantoin oral suspension, lower eradication rates should be balanced against the increased potential for systemic toxicity and for the development of antibacterial resistance when agents with broader tissue distribution are utilized. 5.1 Hypersensitivity Reactions Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients receiving nitrofurantoin oral suspension [see Adverse Reactions ( 6 )]. If signs and symptoms of a hypersensitivity reaction occurs, immediately discontinue nitrofurantoin oral suspension and initiate appropriate medications and/or supportive care. Nitrofurantoin oral suspension is contraindicated in patients with known hypersensitivity to nitrofurantoin. 5.2 Pulmonary Reactions Acute, subacute, or chronic pulmonary reactions have been reported in patients treated with nitrofurantoin oral suspension. If these reactions occur, discontinue nitrofurantoin oral suspension and take appropriate measures. Reports have cited pulmonary reactions as a contributing cause of death. Chronic pulmonary reactions (diffuse interstitial pneumonitis or pulmonary fibrosis, or both) can develop insidiously. These reactions occur generally in patients receiving therapy for six months or longer. Close monitoring of the pulmonary condition of patients receiving long-term therapy is warranted and requires that the benefits of therapy be weighed against potential risks [see Adverse Reactions ( 6 )]. 5.3 Hepatotoxicity Hepatic reactions, including hepatitis, cholestatic jaundice, chronic active hepatitis, and hepatic necrosis, has occurred. Fatalities have been reported. The onset of chronic active hepatitis may be insidious. Monitor patients periodically for changes in biochemical tests that would indicate liver injury. If hepatitis occurs, discontinue nitrofurantoin oral suspension immediately, and take appropriate measures. 5.4 Neuropathy Peripheral neuropathy, which may become severe or irreversible, has occurred. Fatalities have been reported. Conditions such as renal impairment (creatinine clearance under 60 mL per minute or clinically significant elevated serum creatinine), anemia, diabetes mellitus, electrolyte imbalance, vitamin B deficiency, and debilitating disease may enhance the occurrence of peripheral neuropathy. Monitor patients receiving long-term therapy periodically for changes in renal function. Optic neuritis has been reported with nitrofurantoin formulations [see Adverse Reactions ( 6 )] . 5.5 Hemolytic Anemia Cases of hemolytic anemia of the primaquine-sensitivity type have been induced by nitrofurantoin. Hemolysis appears to be linked to a glucose-6-phosphate dehydrogenase deficiency in the red blood cells of the affected patients.

CONTRAINDICATIONS Nitrofurantoin oral suspension is contraindicated in: • patients with known hypersensitivity to nitrofurantoin [see Warnings and Precautions ( 5.1 )]. • patients with a previous history of cholestatic jaundice/hepatic dysfunction associated with nitrofurantoin [see Warnings and Precautions ( 5.3 )]. • patients who have anuria, oliguria, or significant impairment of renal function (creatinine clearance under 60 mL per minute or clinically significant elevated serum creatinine) due to an increased risk of toxicity resulting from impaired excretion of the drug [see Warnings and Precautions ( 5.4 )]. • pregnant patients at term (38 weeks to 42 weeks gestation), during labor and delivery, or when the onset of labor is imminent and in pediatric patients younger than 1 month of age because of the possibility of hemolytic anemia due to immature erythrocyte enzyme systems (glutathione instability) [see Warnings and Precautions ( 5.5 ) and Use in Specific Populations ( 8.1 and 8.4 )]. • Known hypersensitivity to nitrofurantoin. ( 4 ) • History of cholestatic jaundice/hepatic dysfunction associated with nitrofurantoin. ( 4 ) • Patients who have anuria, oliguria, or significant impairment of renal function (creatinine clearance under 60 mL per minute or clinically significant elevated serum creatinine). ( 4 ) • Pregnant patients at term (38 weeks to 42 weeks gestation), during labor and delivery, or when the onset of labor is imminent. ( 4 ) • Pediatric Patients under one month of age. ( 4 )

CLINICAL PHARMACOLOGY Each nitrofurantoin capsule (monohydrate/macrocrystals) contains two forms of nitrofurantoin. Twenty-five percent is macrocrystalline nitrofurantoin, which has slower dissolution and absorption than nitrofurantoin monohydrate. The remaining 75% is nitrofurantoin monohydrate contained in a powder blend which, upon exposure to gastric and intestinal fluids, forms a gel matrix that releases nitrofurantoin over time. Based on urinary pharmacokinetic data, the extent and rate of urinary excretion of nitrofurantoin from the 100 mg nitrofurantoin capsules (monohydrate/macrocrystals) are similar to those of the 50 mg or 100 mg nitrofurantoin (macrocrystals) capsules. Approximately 20% to 25% of a single dose of nitrofurantoin is recovered from the urine unchanged over 24 hours. Plasma nitrofurantoin concentrations after a single oral dose of the 100 mg nitrofurantoin capsules (monohydrate/macrocrystals) are low, with peak levels usually less than 1 mcg/mL. Nitrofurantoin is highly soluble in urine, to which it may impart a brown color. When nitrofurantoin (monohydrate/macrocrystals) is administered with food, the bioavailability of nitrofurantoin is increased by approximately 40%. Microbiology Nitrofurantoin is a nitrofuran antimicrobial agent with activity against certain Gram-positive and Gram-negative bacteria. Mechanism of Action: The mechanism of the antimicrobial action of nitrofurantoin is unusual among antibacterials. Nitrofurantoin is reduced by bacterial flavoproteins to reactive intermediates which inactivate or alter bacterial ribosomal proteins and other macromolecules. As a result of such inactivations, the vital biochemical processes of protein synthesis, aerobic energy metabolism, DNA synthesis, RNA synthesis, and cell wall synthesis are inhibited. Nitrofurantoin is bactericidal in urine at therapeutic doses. The broad-based nature of this mode of action may explain the lack of acquired bacterial resistance to nitrofurantoin, as the necessary multiple and simultaneous mutations of the target macromolecules would likely be lethal to the bacteria. Interactions with Other Antibiotics: Antagonism has been demonstrated in vitro between nitrofurantoin and quinolone antimicrobials. The clinical significance of this finding is unknown. Development of Resistance: Development of resistance to nitrofurantoin has not been a significant problem since its introduction in 1953. Cross-resistance with antibiotics and sulfonamides has not been observed, and transferable resistance is, at most, a very rare phenomenon. Nitrofurantoin has been shown to be active against most strains of the following bacteria both in vitro and in clinical infections: (see INDICATIONS AND USAGE ). Aerobic and Facultative Gram-Positive Microorganisms Staphylococcus saprophyticus Aerobic and Facultative Gram-Negative Microorganisms Escherichia coli At least 90 percent of the following microorganisms exhibit an in vitro minimum inhibitory concentration (MIC) less than or equal to the susceptible breakpoint for nitrofurantoin. However, the efficacy of nitrofurantoin in treating clinical infections due to these microorganisms has not been established in adequate and well-controlled trials. Aerobic and Facultative Gram-Positive Microorganisms Coagulase-negative staphylococci (including Staphylococcus epidermidis ) Enterococcus faecalis Staphylococcus aureus Streptococcus agalactiae Group D streptococci Viridans group streptococci Aerobic and Facultative Gram-Negative Microorganisms Citrobacter amalonaticus Citrobacter diversus Citrobacter freundii Klebsiella oxytoca Klebsiella ozaenae Nitrofurantoin is not active against most strains of Proteus species or Serratia species. It has no activity against Pseudomonas species. Susceptibility Test Methods: When available, the clinical microbiology laboratory should provide cumulative results of the in vitro susceptibility test results for antimicrobial drugs used in resident hospitals to the physician as periodic reports that describe the susceptibility profile of nosocomial and community-acquired pathogens. These reports should aid the physician in selecting the most effective antimicrobial. Dilution Techniques : Quantitative methods are used to determine antimicrobial minimum inhibitory concentrations (MICs). These MICs provide estimates of the susceptibility of bacteria to antimicrobial compounds. The MICs should be determined using a standardized procedure. Standardized procedures are based on a dilution method (broth or agar) (1) or equivalent with standardized inoculum concentrations and standardized concentrations of nitrofurantoin powder. The MIC values should be interpreted according to the criteria provided in Table 1. Diffusion Technique: Quantitative methods that require measurement of zone diameters also provide reproducible estimates of the susceptibility of bacteria to antimicrobial compounds. One such standardized procedure (2) requires the use of standardized inoculum concentrations. This procedure uses paper disks impregnated with 300 µg of nitrofurantoin to test the susceptibility of microorganisms to nitrofurantoin. The disk diffusion interpretive criteria are provided in Table 1. Table 1. Susceptibility Interpretive Criteria for Nitrofurantoin Pathogen Susceptibility Interpretive Criteria Minimum Inhibitory Concentrations (µg/mL) Disk Diffusion (Zone diameter in mm) S I R S I R Enterobacteriaceae ≤ 32 64 ≥ 128 ≥ 17 15 – 16 ≤ 14 Staphylococcus spp. ≤ 32 64 ≥ 128 ≥ 17 15 – 16 ≤ 14 A report of Susceptible indicates that the pathogen is likely to be inhibited if the antimicrobial compound in the urine reaches the concentrations usually achievable. A report of Intermediate indicates that the result should be considered equivocal, and, if the microorganism is not fully susceptible to alternative, clinically feasible drugs, the test should be repeated. This category implies possible clinical applicability in body sites where the drug is physiologically concentrated or in situations where a high dosage of drug can be used. This category also provides a buffer zone, which prevents small, uncontrolled technical factors from causing major discrepancies in interpretation. A report of Resistant indicates that the pathogen is not likely to be inhibited if the antimicrobial compound in the urine reaches the concentrations usually achievable; other therapy should be selected. Quality Control: Standardized susceptibility test procedures require the use of quality control microorganisms to control the technical aspects of the test procedures (3). Standard nitrofurantoin powder should provide the following range of values noted in Table 2. Table 2. Acceptable Quality Control Ranges for Nitrofurantoin QC Strain Acceptable Quality Control Ranges Minimum Inhibitory Concentration (µg/mL) Disk Diffusion (zone diameter in mm) Escherichia coli ATCC 25922 4 – 16 20 – 25 Enterococcus faecalis ATCC 29212 4 – 16 NA Not applicable Staphylococcus aureus ATCC 29213 8 – 32 NA Staphylococcus aureus ATCC 25923 NA a 18 – 22