Macrodantin 100mg Capsules
It is used to treat or prevent a urinary tract infection (UTI).
Drug Class
Urinary anti-infective
Pharmacologic Class
Nitrofuran derivative
Pregnancy Category
Category B (old system); Contraindicated at term (38-42 weeks gestation)
FDA Approved
Mar 1953
DEA Schedule
Not Controlled
Overview
What is this medicine?
Nitrofurantoin is an antibiotic used to treat and prevent urinary tract infections (UTIs). It works by stopping the growth of bacteria in the urine. It is important to take this medication exactly as prescribed and to finish the entire course, even if you feel better.
How to Use This Medicine
Taking Your Medication Correctly
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. Take your medication with food to help your body absorb it properly. Continue taking your medication as directed by your doctor or healthcare provider, even if you start to feel better.
It's also important to drink plenty of non-caffeinated liquids, unless your doctor advises you to limit your fluid intake. However, do not take antacids containing magnesium trisilicate while taking this medication, as it may interfere with its effectiveness.
Storing and Disposing of Your Medication
To keep your medication safe and effective, store it at room temperature in a dry place, away from the bathroom. Keep all medications out of the reach of children and pets to avoid accidental ingestion. When you're finished with your medication or it's expired, dispose of it properly. Do not flush it down the toilet or pour it down the drain unless instructed to do so by your doctor or pharmacist. Instead, check with your pharmacist for guidance on the best way to dispose of your medication, or look into drug take-back programs in your area.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To get the most benefit from your medication, follow your doctor's instructions carefully. Read all the information provided with your prescription and follow the instructions closely. Take your medication with food to help your body absorb it properly. Continue taking your medication as directed by your doctor or healthcare provider, even if you start to feel better.
It's also important to drink plenty of non-caffeinated liquids, unless your doctor advises you to limit your fluid intake. However, do not take antacids containing magnesium trisilicate while taking this medication, as it may interfere with its effectiveness.
Storing and Disposing of Your Medication
To keep your medication safe and effective, store it at room temperature in a dry place, away from the bathroom. Keep all medications out of the reach of children and pets to avoid accidental ingestion. When you're finished with your medication or it's expired, dispose of it properly. Do not flush it down the toilet or pour it down the drain unless instructed to do so by your doctor or pharmacist. Instead, check with your pharmacist for guidance on the best way to dispose of your medication, or look into drug take-back programs in your area.
What to Do If You Miss a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take with food or milk to improve absorption and reduce stomach upset.
- Drink plenty of fluids unless otherwise directed by your doctor.
- Complete the full course of medication, even if symptoms improve, to prevent recurrence and antibiotic resistance.
- Urine may turn a brown or orange color; this is a harmless side effect.
Available Forms & Alternatives
Available Strengths:
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
Acute uncomplicated UTI: 50-100 mg orally four times a day for 7 days. Prophylaxis: 50-100 mg orally once daily at bedtime.
Dose Range:
50 - 100 mg
Condition-Specific Dosing:
Acute uncomplicated UTI:
50-100 mg QID for 7 days
UTI prophylaxis:
50-100 mg once daily at bedtime
Pediatric Dosing
Neonatal:
Not established (contraindicated in infants <1 month of age due to risk of hemolytic anemia)
Infant:
Not established (contraindicated in infants <1 month of age)
Child:
Acute uncomplicated UTI (âĨ1 month): 5-7 mg/kg/day orally in 4 divided doses for 7 days. Prophylaxis: 1-2 mg/kg/day orally once daily at bedtime.
Adolescent:
Acute uncomplicated UTI: 50-100 mg orally four times a day for 7 days. Prophylaxis: 50-100 mg orally once daily at bedtime.
Dose Adjustments
Renal Impairment:
Mild:
No specific adjustment, but caution advised.
Moderate:
Contraindicated if CrCl < 60 mL/min (or < 30 mL/min by some newer guidelines) due to lack of efficacy and increased risk of toxicity (e.g., peripheral neuropathy).
Severe:
Contraindicated.
Dialysis:
Contraindicated; not effectively removed by dialysis.
Hepatic Impairment:
Mild:
No specific adjustment.
Moderate:
Use with caution; monitor liver function.
Severe:
Use with caution; monitor liver function.
Pharmacology
Mechanism of Action
Nitrofurantoin is reduced by bacterial flavoproteins to reactive intermediates that inactivate or damage bacterial ribosomal proteins, DNA, RNA, and other macromolecules. This leads to inhibition of bacterial growth and cell death. It is bacteriostatic at low concentrations and bactericidal at higher concentrations.
Pharmacokinetics
Absorption:
Bioavailability:
Variable (Macrocrystals are absorbed more slowly and completely than microcrystals)
Tmax:
Approximately 4 hours (Macrodantin)
FoodEffect:
Food enhances absorption and duration of therapeutic concentrations in urine, and reduces gastrointestinal upset.
Distribution:
Vd:
Not available (widely distributed to body tissues, but not therapeutically effective in systemic infections)
ProteinBinding:
Approximately 60%
CnssPenetration:
Limited
Elimination:
HalfLife:
0.3 to 1 hour
Clearance:
Rapid renal clearance
ExcretionRoute:
Renal (primarily glomerular filtration and tubular secretion)
Unchanged:
25-50% (excreted unchanged in urine)
Pharmacodynamics
OnsetOfAction:
Rapid (therapeutic concentrations in urine within 30 minutes)
PeakEffect:
Not available (related to urinary concentration)
DurationOfAction:
Approximately 6-8 hours (related to urinary concentration)
Safety & Warnings
Side Effects
Urgent Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Rarely, allergic reactions can be fatal.
Signs of pancreatitis (pancreas problem), such as:
+ Severe stomach pain
+ Severe back pain
+ Severe upset stomach or vomiting
Signs of lupus, such as:
+ Rash on the cheeks or other body parts
+ Easy sunburn
+ Muscle or joint pain
+ Chest pain or shortness of breath
+ Swelling in the arms or legs
Inability to control eye movements
Diarrhea, especially if it is severe, bloody, or watery (may be a sign of C. diff-associated diarrhea, a potentially life-threatening condition)
Stomach pain, cramps, or very loose stools (if you experience these symptoms, contact your doctor before treating diarrhea)
Signs of liver problems, such as:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Liver problems can be fatal, so it is essential to seek medical attention immediately if you notice any of these symptoms.
Nerve problems, such as:
+ Burning sensation
+ Numbness
+ Tingling
Nerve problems can be severe, permanent, or even fatal, especially in people with kidney problems, anemia, diabetes, electrolyte problems, or low vitamin B levels.
Other Possible Side Effects
Most people do not experience severe side effects, but some may occur. If you notice any of the following symptoms, contact your doctor or seek medical attention if they bother you or do not go away:
Headache
Upset stomach or vomiting
Decreased appetite
Stomach pain or diarrhea
Dizziness, drowsiness, tiredness, or weakness
Hair loss (usually reversible when the medication is stopped)
Urine color change to brown (harmless and temporary)
Reporting Side Effects
If you have any questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor or seek medical attention immediately:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Rarely, allergic reactions can be fatal.
Signs of pancreatitis (pancreas problem), such as:
+ Severe stomach pain
+ Severe back pain
+ Severe upset stomach or vomiting
Signs of lupus, such as:
+ Rash on the cheeks or other body parts
+ Easy sunburn
+ Muscle or joint pain
+ Chest pain or shortness of breath
+ Swelling in the arms or legs
Inability to control eye movements
Diarrhea, especially if it is severe, bloody, or watery (may be a sign of C. diff-associated diarrhea, a potentially life-threatening condition)
Stomach pain, cramps, or very loose stools (if you experience these symptoms, contact your doctor before treating diarrhea)
Signs of liver problems, such as:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Liver problems can be fatal, so it is essential to seek medical attention immediately if you notice any of these symptoms.
Nerve problems, such as:
+ Burning sensation
+ Numbness
+ Tingling
Nerve problems can be severe, permanent, or even fatal, especially in people with kidney problems, anemia, diabetes, electrolyte problems, or low vitamin B levels.
Other Possible Side Effects
Most people do not experience severe side effects, but some may occur. If you notice any of the following symptoms, contact your doctor or seek medical attention if they bother you or do not go away:
Headache
Upset stomach or vomiting
Decreased appetite
Stomach pain or diarrhea
Dizziness, drowsiness, tiredness, or weakness
Hair loss (usually reversible when the medication is stopped)
Urine color change to brown (harmless and temporary)
Reporting Side Effects
If you have any questions or concerns about side effects, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Numbness, tingling, or weakness in hands or feet (signs of peripheral neuropathy)
- Persistent cough, shortness of breath, or chest pain (signs of lung problems)
- Yellowing of skin or eyes, dark urine, severe stomach pain, or unusual tiredness (signs of liver problems)
- Fever, chills, or body aches (signs of acute lung reaction or other severe reaction)
- Severe diarrhea (may indicate C. difficile infection)
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following conditions before starting this medication:
Any allergies you have, including allergies to this drug, its components, or other substances, such as foods or medications. Be sure to describe the symptoms you experienced.
Kidney disease, as this may affect how your body processes the medication.
Difficulty urinating, as this could be a sign of an underlying condition that may interact with the medication.
Previous liver problems caused by this medication, as this may increase your risk of further liver damage.
Pregnancy, particularly if you are 38 weeks or more pregnant, as this medication may affect the fetus.
Special Considerations for Children:
If the patient is a child under 1 month of age, do not administer this medication, as it is not recommended for this age group.
Additional Important Information:
This list is not exhaustive, and it is crucial to discuss all your medications, including prescription and over-the-counter drugs, natural products, and vitamins, with your doctor and pharmacist. This will help ensure that it is safe to take this medication with your other medications and health conditions. Never start, stop, or change the dose of any medication without consulting your doctor first.
It is essential to inform your doctor about the following conditions before starting this medication:
Any allergies you have, including allergies to this drug, its components, or other substances, such as foods or medications. Be sure to describe the symptoms you experienced.
Kidney disease, as this may affect how your body processes the medication.
Difficulty urinating, as this could be a sign of an underlying condition that may interact with the medication.
Previous liver problems caused by this medication, as this may increase your risk of further liver damage.
Pregnancy, particularly if you are 38 weeks or more pregnant, as this medication may affect the fetus.
Special Considerations for Children:
If the patient is a child under 1 month of age, do not administer this medication, as it is not recommended for this age group.
Additional Important Information:
This list is not exhaustive, and it is crucial to discuss all your medications, including prescription and over-the-counter drugs, natural products, and vitamins, with your doctor and pharmacist. This will help ensure that it is safe to take this medication with your other medications and health conditions. Never start, stop, or change the dose of any medication without consulting your doctor first.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication.
If you have a deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD), you should exercise caution, as this condition may increase your risk of developing anemia. Individuals of African, South Asian, Middle Eastern, and Mediterranean descent are more likely to have low G6PD levels.
If you have diabetes and regularly test your urine for glucose, consult your doctor to determine the most suitable testing methods for you.
Do not exceed the prescribed duration of treatment with this medication, as this may lead to the development of a secondary infection.
Although rare, this medication has been associated with severe and potentially life-threatening lung problems, particularly in patients who have been taking it for six months or longer. These lung problems can occur without warning signs. If you are taking this medication long-term, your doctor will monitor your lung function. Immediately contact your doctor if you experience symptoms such as fever, chills, chest pain, an abnormal cough, difficulty breathing, or other respiratory problems.
If you are 65 years of age or older, use this medication with caution, as you may be more susceptible to side effects.
If you are pregnant, planning to become pregnant, or breastfeeding, discuss the potential benefits and risks of this medication with your doctor to ensure the best possible outcome for you and your baby.
If you have a deficiency of the enzyme glucose-6-phosphate dehydrogenase (G6PD), you should exercise caution, as this condition may increase your risk of developing anemia. Individuals of African, South Asian, Middle Eastern, and Mediterranean descent are more likely to have low G6PD levels.
If you have diabetes and regularly test your urine for glucose, consult your doctor to determine the most suitable testing methods for you.
Do not exceed the prescribed duration of treatment with this medication, as this may lead to the development of a secondary infection.
Although rare, this medication has been associated with severe and potentially life-threatening lung problems, particularly in patients who have been taking it for six months or longer. These lung problems can occur without warning signs. If you are taking this medication long-term, your doctor will monitor your lung function. Immediately contact your doctor if you experience symptoms such as fever, chills, chest pain, an abnormal cough, difficulty breathing, or other respiratory problems.
If you are 65 years of age or older, use this medication with caution, as you may be more susceptible to side effects.
If you are pregnant, planning to become pregnant, or breastfeeding, discuss the potential benefits and risks of this medication with your doctor to ensure the best possible outcome for you and your baby.
Overdose Information
Overdose Symptoms:
- Nausea
- Vomiting
- Diarrhea
What to Do:
Seek immediate medical attention or call a poison control center (1-800-222-1222). Treatment is supportive; no specific antidote.
Drug Interactions
Major Interactions
- Magnesium trisilicate-containing antacids (decreased absorption of nitrofurantoin)
- Probenecid (decreased renal excretion of nitrofurantoin, leading to increased serum levels and toxicity, and decreased urinary efficacy)
- Sulfinpyrazone (decreased renal excretion of nitrofurantoin, leading to increased serum levels and toxicity, and decreased urinary efficacy)
Moderate Interactions
- Live bacterial vaccines (e.g., Typhoid vaccine - may reduce efficacy of vaccine)
- Quinolone antibiotics (possible antagonism, though clinical significance is debated)
Confidence Interactions
Monitoring
Baseline Monitoring
Renal function (CrCl)
Rationale: To assess appropriate dosing and risk of toxicity, as nitrofurantoin is contraindicated in significant renal impairment.
Timing: Prior to initiation of therapy.
Liver function tests (LFTs)
Rationale: To establish baseline, especially if prolonged therapy is anticipated or patient has history of liver disease, due to risk of hepatotoxicity.
Timing: Prior to initiation of therapy for long-term use or if clinically indicated.
G6PD status
Rationale: To identify patients at risk for hemolytic anemia, particularly in populations with higher prevalence of G6PD deficiency.
Timing: Prior to initiation, especially if patient's ethnicity suggests risk.
Routine Monitoring
Renal function (CrCl)
Frequency: Periodically, especially with prolonged therapy or in elderly patients.
Target: CrCl > 60 mL/min
Action Threshold: Discontinue if CrCl falls below 60 mL/min or if signs of toxicity appear.
Liver function tests (LFTs)
Frequency: If symptoms of hepatotoxicity develop (e.g., nausea, vomiting, dark urine, jaundice) or with prolonged therapy.
Target: Within normal limits
Action Threshold: Discontinue if LFTs are significantly elevated or if clinical signs of liver injury occur.
Pulmonary function tests (PFTs)
Frequency: If respiratory symptoms (e.g., cough, dyspnea) develop during long-term therapy.
Target: Within normal limits
Action Threshold: Discontinue if PFTs show evidence of pulmonary injury.
Symptom Monitoring
- Peripheral neuropathy (numbness, tingling, weakness in extremities)
- Pulmonary reactions (acute: fever, chills, cough, chest pain, dyspnea; chronic: insidious onset of dyspnea, cough, interstitial pneumonitis/fibrosis)
- Hepatotoxicity (fatigue, nausea, vomiting, dark urine, jaundice, abdominal pain)
- Hemolytic anemia (fatigue, pallor, dark urine, jaundice)
- Gastrointestinal upset (nausea, vomiting, diarrhea, abdominal pain)
Special Patient Groups
Pregnancy
Generally considered safe for use in the first and second trimesters for the treatment of UTIs. However, it is contraindicated at term (38-42 weeks gestation) due to the theoretical risk of hemolytic anemia in the neonate, especially in infants with immature enzyme systems or G6PD deficiency.
Trimester-Specific Risks:
First Trimester:
Low risk; generally considered safe for treatment of UTIs.
Second Trimester:
Low risk; generally considered safe for treatment of UTIs.
Third Trimester:
Contraindicated at term (38-42 weeks gestation) due to risk of hemolytic anemia in neonate.
Lactation
Excreted in breast milk in very small amounts. Generally considered compatible with breastfeeding, but caution is advised in infants with G6PD deficiency or those less than one month of age due to the theoretical risk of hemolytic anemia.
Infant Risk:
Low risk for most infants; caution in G6PD deficient infants or neonates (<1 month).
Pediatric Use
Contraindicated in infants younger than one month of age due to the possibility of hemolytic anemia secondary to immature erythrocyte enzyme systems. Use with caution in older pediatric patients, adhering to weight-based dosing.
Geriatric Use
Use with caution due to increased risk of adverse effects, particularly pulmonary toxicity, hepatotoxicity, and peripheral neuropathy. Contraindicated if creatinine clearance is less than 60 mL/min due to decreased efficacy and increased toxicity risk. Monitor renal function closely.
Clinical Information
Clinical Pearls
- Always take nitrofurantoin with food or milk to enhance absorption and minimize gastrointestinal upset.
- Inform patients that their urine may turn a harmless brown or orange color.
- Nitrofurantoin is effective only for urinary tract infections and does not achieve therapeutic concentrations in systemic tissues.
- Emphasize the importance of completing the full course of therapy to prevent resistance and recurrence.
- Counsel patients on the signs and symptoms of serious adverse effects, such as pulmonary reactions, hepatotoxicity, and peripheral neuropathy, and advise them to seek immediate medical attention if these occur.
Alternative Therapies
- Trimethoprim/sulfamethoxazole (Bactrim)
- Fosfomycin (Monurol)
- Cephalexin (Keflex)
- Ciprofloxacin (Cipro)
- Levofloxacin (Levaquin)
Cost & Coverage
Average Cost:
Varies widely, typically $15-$50 per 30 capsules (100mg)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or 2 (Generic)
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more information. If you have any questions or concerns about this medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide details about the overdose, including the medication taken, the amount, and the time it occurred.