Nitrofurantoin

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 Nitrofurantoin capsules, (macrocrystals) should be given with food to improve drug absorption and, in some patients, tolerance. Adults: 50 mg to 100 mg four times a day - the lower dosage level is recommended for uncomplicated urinary tract infections. 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). Therapy should be continued 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 adults, a reduction of dosage to 50 mg to 100 mg at bedtime may be adequate. 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 SECTION REGARDING RISKS ASSOCIATED WITH LONG-TERM THERAPY.

CONTRAINDICATIONS: Anuria, oliguria, or significant impairment of renal function (creatinine clearance under 60 mL per minute or clinically significant elevated serum creatinine) are contraindications. Treatment of this type of patient carries an increased risk of toxicity because of impaired excretion of the drug. Because of the possibility of hemolytic anemia due to immature erythrocyte enzyme systems (glutathione instability), the drug is contraindicated in pregnant patients at term (38 to 42 weeks gestation), during labor and delivery, or when the onset of labor is imminent. For the same reason, the drug is contraindicated in neonates under one month of age. Nitrofurantoin Capsules, USP (monohydrate/ macrocrystals) is contraindicated in patients with a previous history of cholestatic jaundice/hepatic dysfunction associated with nitrofurantoin. Nitrofurantoin Capsules, USP (monohydrate/ macrocrystals) is also contraindicated in those patients with known hypersensitivity to nitrofurantoin.

ADVERSE REACTIONS: In clinical trials of Nitrofurantoin Capsules, USP (monohydrate/macrocrystals), the most frequent clinical adverse events that were reported as possibly or probably drug-related were nausea (8%), headache (6%), and flatulence (1.5%). Additional clinical adverse events reported as possibly or probably drug-related occurred in less than 1% of patients studied and are listed below within each body system in order of decreasing frequency: Gastrointestinal: Diarrhea, dyspepsia, abdominal pain, constipation, emesis Neurologic : Dizziness, drowsiness, amblyopia Respiratory: Acute pulmonary hypersensitivity reaction (see Error! Hyperlink reference not valid. ) Allergic: Pruritus, urticaria Dermatologic: Alopecia Miscellaneous: Fever, chills, malaise The following additional clinical adverse events have been reported with the use of nitrofurantoin: Gastrointestinal: Sialadenitis, pancreatitis. There have been sporadic reports of pseudomembranous colitis with the use of nitrofurantoin. The onset of pseudomembranous colitis symptoms may occur during or after antimicrobial treatment (see Error! Hyperlink reference not valid. ). Neurologic: 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 diseases may increase the possibility of peripheral neuropathy (see Error! Hyperlink reference not valid. ). Asthenia, vertigo, and nystagmus also have been reported with the use of nitrofurantoin. Benign intracranial hypertension (pseudotumor cerebri), confusion, depression, optic neuritis, and psychotic reactions have been reported rarely. Bulging fontanels, as a sign of benign intracranial hypertension in infants, have been reported rarely. Respiratory: CHRONIC, SUBACUTE, OR ACUTE PULMONARY HYPERSENSITIVITY REACTIONS MAY OCCUR WITH THE USE OF NITROFURANTOIN. CHRONIC PULMONARY REACTIONS GENERALLY OCCUR IN PATIENTS WHO HAVE RECEIVED CONTINUOUS TREATMENT FOR SIX MONTHS OR LONGER. MALAISE, DYSPNEA ON EXERTION, COUGH, AND ALTERED PULMONARY FUNCTION ARE COMMON MANIFESTATIONS WHICH CAN OCCUR INSIDIOUSLY. RADIOLOGIC AND HISTOLOGIC FINDINGS OF DIFFUSE INTERSTITIAL PNEUMONITIS OR FIBROSIS, OR BOTH, ARE ALSO COMMON MANIFESTATIONS OF THE CHRONIC PULMONARY REACTION. FEVER IS RARELY PROMINENT. THE SEVERITY OF CHRONIC PULMONARY REACTIONS AND THEIR DEGREE OF RESOLUTION APPEAR TO BE RELATED TO THE DURATION OF THERAPY AFTER THE FIRST CLINICAL SIGNS APPEAR. PULMONARY FUNCTION MAY BE IMPAIRED PERMANENTLY, EVEN AFTER CESSATION OF THERAPY. THE RISK IS GREATER WHEN CHRONIC PULMONARY REACTIONS ARE NOT RECOGNIZED EARLY. In subacute pulmonary reactions, fever and eosinophilia occur less often than in the acute form. Upon cessation of therapy, recovery may require several months. If the symptoms are not recognized as being drug-related and nitrofurantoin therapy is not stopped, the symptoms may become more severe. Acute pulmonary reactions are commonly manifested by fever, chills, cough, chest pain, dyspnea, pulmonary infiltration with consolidation or pleural effusion on x-ray, and eosinophilia. Acute reactions usually occur within the first week of treatment and are reversible with cessation of therapy. Resolution often is dramatic (see Error! Hyperlink reference not valid. ). Changes in EKG (e.g., non-specific ST/T wave changes, bundle branch block) have been reported in association with pulmonary reactions. Cyanosis has been reported rarely. Hepatic: Hepatic reactions, including hepatitis, cholestatic jaundice, chronic active hepatitis, and hepatic necrosis, occur rarely (see Error! Hyperlink reference not valid. ). Allergic: Lupus-like syndrome associated with pulmonary reaction to nitrofurantoin has been reported. Also, angioedema; maculopapular, erythematous, or eczematous e …

Drug Interactions Antacids containing magnesium trisilicate, when administered concomitantly with nitrofurantoin, reduce both the rate and extent of absorption. The mechanism for this interaction probably is adsorption of nitrofurantoin onto the surface of magnesium trisilicate. Uricosuric drugs, such as probenecid and sulfinpyrazone, can inhibit renal tubular secretion of nitrofurantoin. The resulting increase in nitrofurantoin serum levels may increase toxicity, and the decreased urinary levels could lessen its efficacy as a urinary tract antibacterial. Drug/Laboratory Test Interactions As a result of the presence of nitrofurantoin, a false-positive reaction for glucose in the urine may occur. This has been observed with Benedict's and Fehling's solutions but not with the glucose enzymatic test.

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.

DESCRIPTION Nitrofurantoin, USP is an antibacterial agent specific for urinary tract infections. Nitrofurantoin capsules, USP (monohydrate/macrocrystals) are a hard gelatin capsule shell containing the equivalent of 100 mg of nitrofurantoin, USP in the form of 25 mg of nitrofurantoin macrocrystals and 75 mg of nitrofurantoin monohydrate. The chemical name of nitrofurantoin macrocrystals is 1-[[[5-nitro-2-furanyl]methylene]amino]-2,4-imidazolidinedione. The chemical structure is the following: The chemical name of nitrofurantoin monohydrate is 1-[[[5-nitro-2-furanyl]methylene]amino]-2,4- imidazolidinedione monohydrate. The chemical structure is the following: Inactive Ingredients: Each capsule contains carbomer 934P, carboxymethylcellulose, corn starch, D&C Yellow No. 10, FD&C Red No. 40, gelatin, iron oxide black, iron oxide yellow, lactose, magnesium stearate, maltodextrin, povidone, sodium lauryl sulfate, sugar, talc and titanium dioxide. The black monogramming ink contains butyl alcohol, dehydrated alcohol, iron oxide black, isopropyl alcohol, potassium hydroxide, propylene glycol, purified water, shellac and strong ammonia solution. The white monogramming ink contains butyl alcohol, dehydrated alcohol, isopropyl alcohol, povidone, propylene glycol, shellac, sodium hydroxide and titanium dioxide. Meets USP Dissolution Test 7. Macrocrystals Structural Formula mono

OVERDOSAGE Occasional incidents of acute overdosage of nitrofurantoin capsules (macrocrystals) have not resulted in any specific symptoms other than vomiting. Induction of emesis is recommended. There is no specific antidote, but a high fluid intake should be maintained to promote urinary excretion of the drug. It is dialyzable.

HOW SUPPLIED Nitrofurantoin Capsules, USP (Macrocrystals), 25 mg are white opaque cap / white opaque body, size 4, hard gelatin capsules imprinted with “A219” on cap in black ink, filled with light yellow to yellow, free flowing powder. NDC 62332-389-31 Bottle of 100 capsules NDC 62332-389-91 Bottle of 1000 capsules Nitrofurantoin Capsules, USP (Macrocrystals), 50 mg are yellow opaque cap / white opaque body, size 3, hard gelatin capsules imprinted with “A220” on cap in black ink, filled with light yellow to yellow, free flowing powder. NDC 62332-390-31 Bottle of 100 capsules NDC 62332-390-91 Bottle of 1000 capsules Nitrofurantoin Capsules, USP (Macrocrystals), 100 mg are yellow opaque cap / yellow opaque body, size 2, hard gelatin capsules imprinted with “A221” on cap in black ink, filled with light yellow to yellow, free flowing powder. NDC 62332-391-31 Bottle of 100 capsules NDC 62332-391-91 Bottle of 1000 capsules Store at 25°C (77°F); excursions permitted to 15° to 30°C (59° to 86°F) [see USP Controlled Room Temperature]. Dispense in a tight, light-resistant container as defined in the USP using a child-resistant closure. For more information call Alembic Pharmaceuticals Limited at 1-866-210-9797. Manufactured by: Alembic Pharmaceuticals Limited (Formulation Division), Panelav 389350, Gujarat, India Manufactured for: Alembic Pharmaceuticals, Inc. Bedminster, NJ 07921, USA Revised: 05/2023