Zithromax 250mg Tabs (z-Pak)
It is used to treat or prevent bacterial infections.
Drug Class
Antibiotic
Pharmacologic Class
Macrolide antibiotic
Pregnancy Category
Category B
FDA Approved
Nov 1991
DEA Schedule
Not Controlled
Overview
What is this medicine?
Azithromycin is an antibiotic used to treat various bacterial infections, such as respiratory infections (like bronchitis or pneumonia), skin infections, and certain sexually transmitted infections. It works by stopping the growth of bacteria. The 'Z-Pak' is a common way it's prescribed, involving a higher dose on the first day followed by smaller doses for a few more days.
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. You can take this medication with or without food. However, do not take antacids containing magnesium or aluminum at the same time as your medication. If you have any questions, consult your doctor or pharmacist.
It's essential to continue taking your medication as directed by your doctor or healthcare provider, even if you start feeling well. This will help ensure that you receive the full benefits of the treatment.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature in a dry place, away from the bathroom. Keep all medications in a secure location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist. Instead, check with your pharmacist for guidance on the best disposal method or explore local drug take-back programs.
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. You can take this medication with or without food. However, do not take antacids containing magnesium or aluminum at the same time as your medication. If you have any questions, consult your doctor or pharmacist.
It's essential to continue taking your medication as directed by your doctor or healthcare provider, even if you start feeling well. This will help ensure that you receive the full benefits of the treatment.
Storing and Disposing of Your Medication
To maintain the effectiveness and safety of your medication, store it at room temperature in a dry place, away from the bathroom. Keep all medications in a secure location, out of the reach of children and pets. When disposing of unused or expired medication, do not flush it down the toilet or pour it down the drain unless instructed to do so by your pharmacist. Instead, check with your pharmacist for guidance on the best disposal method or explore local drug take-back programs.
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 the medication exactly as prescribed, even if you feel better. Do not skip doses or stop early.
- Can be taken with or without food. If stomach upset occurs, try taking it with food.
- Avoid antacids containing aluminum or magnesium within 2 hours of taking azithromycin.
- Do not share this medication with others.
- Stay hydrated, especially if experiencing diarrhea.
Available Forms & Alternatives
Available Strengths:
- Zithromax 200mg Sus 15ml(purple Bx)
- Zithromax 100mg Susp 15ml(green Bx)
- Zithromax 200mg Sus 22.5ml(white Bx
- Zithromax 1gm Powder Packet
- Zithromax 200mg Sus 30ml(yellow Bx)
- Zithromax 600mg Tabs
- Zithromax 250mg Tabs (z-Pak)
- Zithromax 500mg Tab Tri-Pak
- Zithromax 500mg Tablets
- Zithromax 500mg Sdv Inj, 1 Vial
- Zithromax 250mg Tablets
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
For respiratory tract infections, skin and skin structure infections, and sexually transmitted diseases: 500 mg as a single dose on Day 1, followed by 250 mg once daily on Days 2 through 5. Total dose: 1.5 g.
Dose Range:
250 - 500 mg
Condition-Specific Dosing:
Community-acquired pneumonia (CAP):
500 mg as a single dose on Day 1, followed by 250 mg once daily on Days 2 through 5.
Pharyngitis/Tonsillitis (Streptococcus pyogenes):
500 mg as a single dose on Day 1, followed by 250 mg once daily on Days 2 through 5.
Acute bacterial exacerbations of chronic bronchitis (ABECB):
500 mg as a single dose on Day 1, followed by 250 mg once daily on Days 2 through 5. OR 500 mg once daily for 3 days.
Uncomplicated skin and skin structure infections:
500 mg as a single dose on Day 1, followed by 250 mg once daily on Days 2 through 5.
Urethritis and cervicitis (Chlamydia trachomatis):
1 g as a single oral dose.
Genital ulcer disease (Haemophilus ducreyi):
1 g as a single oral dose.
Pediatric Dosing
Neonatal:
Not established for routine use; use with caution and specific indications only.
Infant:
For acute otitis media: 10 mg/kg (max 500 mg) on Day 1, then 5 mg/kg (max 250 mg) on Days 2-5. OR 30 mg/kg as a single dose. OR 10 mg/kg once daily for 3 days. For pharyngitis/tonsillitis: 12 mg/kg once daily for 5 days (max 500 mg/day).
Child:
Same as infant dosing, weight-based.
Adolescent:
Same as adult dosing, weight-based or adult fixed dose if weight appropriate.
Dose Adjustments
Renal Impairment:
Mild:
No dosage adjustment necessary (CrCl > 10 mL/min).
Moderate:
No dosage adjustment necessary (CrCl > 10 mL/min).
Severe:
No dosage adjustment necessary (CrCl < 10 mL/min), but caution is advised due to limited data.
Dialysis:
Not significantly removed by hemodialysis or peritoneal dialysis. No specific dose adjustment needed, but caution due to limited data in severe impairment.
Hepatic Impairment:
Mild:
No dosage adjustment necessary.
Moderate:
No dosage adjustment necessary.
Severe:
Use with caution; azithromycin is primarily eliminated by the liver. Specific dosage recommendations are not available.
Pharmacology
Mechanism of Action
Azithromycin inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, thereby blocking the translocation of peptides. This action is typically bacteriostatic, but can be bactericidal at high concentrations against susceptible organisms.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 37%
Tmax:
2-3 hours
FoodEffect:
Food decreases Cmax by 50% but does not significantly affect AUC. Can be taken with or without food, but taking with food may reduce GI upset.
Distribution:
Vd:
Extremely large (31.1 L/kg), indicating extensive tissue distribution and intracellular accumulation.
ProteinBinding:
Concentration-dependent, 7% at 1 mcg/mL to 51% at 0.02 mcg/mL.
CnssPenetration:
Limited, generally not considered adequate for CNS infections.
Elimination:
HalfLife:
Terminal elimination half-life is 2-4 days (due to extensive tissue distribution and slow release).
Clearance:
Not readily quantifiable due to extensive tissue distribution.
ExcretionRoute:
Primarily biliary excretion of unchanged drug and metabolites. A small amount is excreted renally (approximately 6% of an IV dose).
Unchanged:
Approximately 6% (renal) to 50% (biliary) of an administered dose.
Pharmacodynamics
OnsetOfAction:
Rapid, within hours of first dose.
PeakEffect:
Peak plasma concentrations reached in 2-3 hours, but tissue concentrations are much higher and sustained.
DurationOfAction:
Prolonged due to long tissue half-life, allowing for once-daily dosing and shorter treatment courses (e.g., 5-day Z-Pak).
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 immediate medical attention:
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
Chest pain or pressure
Fast heartbeat or abnormal heartbeat
Dizziness or fainting
Changes in hearing
Fever
Changes in eyesight
Diarrhea, especially if it is severe, bloody, or watery (see below for more information on diarrhea)
Stomach pain, cramps, or very loose stools
Important Information About Diarrhea
Diarrhea is a common side effect of antibiotics. However, in rare cases, a severe form of diarrhea called Clostridioides difficile-associated diarrhea (CDAD) may occur. CDAD can happen during or several months after taking antibiotics and may lead to a life-threatening bowel problem. If you experience stomach pain, cramps, or very loose, watery, or bloody stools, contact your doctor immediately. Before treating diarrhea, consult with your doctor.
Liver Problems and Severe Skin Reactions
Liver problems, including rare cases of fatal outcomes, have been associated with this medication. If you notice any signs of liver problems, such as:
Dark urine
Tiredness
Decreased appetite
Upset stomach or stomach pain
Light-colored stools
Vomiting
Yellow skin or eyes
contact your doctor right away.
Severe skin reactions, including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and other serious reactions, may also occur. These reactions can be life-threatening and may affect other organs. If you experience any of the following symptoms, seek medical help immediately:
Red, swollen, blistered, or peeling skin
Red or irritated eyes
Sores in your mouth, throat, nose, eyes, genitals, or any areas of skin
Fever
Chills
Body aches
Shortness of breath
Swollen glands
Other Side Effects
Like all medications, this drug may cause side effects. Many people experience no side effects or only minor ones. However, if you notice any of the following side effects or any other symptoms that bother you or do not go away, contact your doctor or seek medical help:
Headache
Diarrhea
Stomach pain
Upset stomach
* Vomiting
This is not an exhaustive list of possible side effects. If you have 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 immediate medical attention:
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
Chest pain or pressure
Fast heartbeat or abnormal heartbeat
Dizziness or fainting
Changes in hearing
Fever
Changes in eyesight
Diarrhea, especially if it is severe, bloody, or watery (see below for more information on diarrhea)
Stomach pain, cramps, or very loose stools
Important Information About Diarrhea
Diarrhea is a common side effect of antibiotics. However, in rare cases, a severe form of diarrhea called Clostridioides difficile-associated diarrhea (CDAD) may occur. CDAD can happen during or several months after taking antibiotics and may lead to a life-threatening bowel problem. If you experience stomach pain, cramps, or very loose, watery, or bloody stools, contact your doctor immediately. Before treating diarrhea, consult with your doctor.
Liver Problems and Severe Skin Reactions
Liver problems, including rare cases of fatal outcomes, have been associated with this medication. If you notice any signs of liver problems, such as:
Dark urine
Tiredness
Decreased appetite
Upset stomach or stomach pain
Light-colored stools
Vomiting
Yellow skin or eyes
contact your doctor right away.
Severe skin reactions, including Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), and other serious reactions, may also occur. These reactions can be life-threatening and may affect other organs. If you experience any of the following symptoms, seek medical help immediately:
Red, swollen, blistered, or peeling skin
Red or irritated eyes
Sores in your mouth, throat, nose, eyes, genitals, or any areas of skin
Fever
Chills
Body aches
Shortness of breath
Swollen glands
Other Side Effects
Like all medications, this drug may cause side effects. Many people experience no side effects or only minor ones. However, if you notice any of the following side effects or any other symptoms that bother you or do not go away, contact your doctor or seek medical help:
Headache
Diarrhea
Stomach pain
Upset stomach
* Vomiting
This is not an exhaustive list of possible side effects. If you have 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:
- Severe or watery diarrhea, especially if it contains blood or mucus (may occur up to several months after stopping the medication)
- Signs of an allergic reaction: rash, hives, itching, swelling of the face/lips/tongue/throat, difficulty breathing
- Chest pain, fast or irregular heartbeat, dizziness, fainting (signs of heart rhythm problems)
- Yellowing of the skin or eyes (jaundice), dark urine, severe stomach pain (signs of liver problems)
- Unusual bleeding or bruising
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 to ensure safe treatment:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction and its symptoms.
If you have previously experienced liver problems or jaundice (yellowing of the skin or eyes) while taking this medication.
Certain heart conditions, such as:
+ Abnormal heart rhythms, including a prolonged QT interval on an electrocardiogram (ECG)
+ Slow heartbeat
+ Low potassium or magnesium levels
+ Heart failure (a weakened heart)
+ A history of torsades de pointes, a specific type of abnormal heartbeat
If you are taking any medications that can cause abnormal heart rhythms, including those that prolong the QT interval. There are many medications that can have this effect, so it is crucial to consult your doctor or pharmacist if you are unsure.
This list is not exhaustive, and it is vital to discuss all your medications, including prescription and over-the-counter drugs, natural products, and vitamins, with your doctor and pharmacist. They will help you determine if it is safe to take this medication with your existing treatments and health conditions. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.
It is essential to inform your doctor about the following conditions to ensure safe treatment:
Any allergies you have, including allergies to this medication, its components, or other substances. Be sure to describe the allergic reaction and its symptoms.
If you have previously experienced liver problems or jaundice (yellowing of the skin or eyes) while taking this medication.
Certain heart conditions, such as:
+ Abnormal heart rhythms, including a prolonged QT interval on an electrocardiogram (ECG)
+ Slow heartbeat
+ Low potassium or magnesium levels
+ Heart failure (a weakened heart)
+ A history of torsades de pointes, a specific type of abnormal heartbeat
If you are taking any medications that can cause abnormal heart rhythms, including those that prolong the QT interval. There are many medications that can have this effect, so it is crucial to consult your doctor or pharmacist if you are unsure.
This list is not exhaustive, and it is vital to discuss all your medications, including prescription and over-the-counter drugs, natural products, and vitamins, with your doctor and pharmacist. They will help you determine if it is safe to take this medication with your existing treatments and health conditions. Never start, stop, or adjust the dosage of any medication without first consulting your doctor.
Precautions & Cautions
Important Warnings and Cautions for Patients Taking This Medication
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Adhere to the prescribed duration of treatment, as prolonged use may increase the risk of a second infection.
Severe Heart Rhythm Changes
This medication can cause severe heart rhythm changes, including prolonged QT interval, which may be life-threatening or fatal. If you have any questions or concerns, consult your doctor.
Myasthenia Gravis
If you have myasthenia gravis, discuss your treatment with your doctor. Monitor your symptoms closely, and contact your doctor if they worsen. Additionally, be aware that myasthenia gravis symptoms can occur in people without a prior diagnosis. Seek immediate medical attention if you experience new or worsening muscle weakness, difficulty chewing or swallowing, breathing problems, droopy eyelids, or changes in vision, such as blurred vision or double vision.
Special Considerations
If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects.
Pregnancy and Breastfeeding
If you are pregnant, plan to become pregnant, or are breastfeeding, consult your doctor to discuss the potential benefits and risks to you and your baby.
Newborns
In newborns taking this medication, a severe stomach problem can occur. If your child vomits or becomes irritable during feeding, contact your doctor immediately.
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Adhere to the prescribed duration of treatment, as prolonged use may increase the risk of a second infection.
Severe Heart Rhythm Changes
This medication can cause severe heart rhythm changes, including prolonged QT interval, which may be life-threatening or fatal. If you have any questions or concerns, consult your doctor.
Myasthenia Gravis
If you have myasthenia gravis, discuss your treatment with your doctor. Monitor your symptoms closely, and contact your doctor if they worsen. Additionally, be aware that myasthenia gravis symptoms can occur in people without a prior diagnosis. Seek immediate medical attention if you experience new or worsening muscle weakness, difficulty chewing or swallowing, breathing problems, droopy eyelids, or changes in vision, such as blurred vision or double vision.
Special Considerations
If you are 65 years or older, use this medication with caution, as you may be more susceptible to side effects.
Pregnancy and Breastfeeding
If you are pregnant, plan to become pregnant, or are breastfeeding, consult your doctor to discuss the potential benefits and risks to you and your baby.
Newborns
In newborns taking this medication, a severe stomach problem can occur. If your child vomits or becomes irritable during feeding, contact your doctor immediately.
Overdose Information
Overdose Symptoms:
- Severe nausea
- Vomiting
- Diarrhea
- Reversible hearing loss
What to Do:
In case of suspected overdose, contact a poison control center immediately (call 1-800-222-1222 in the US) or seek emergency medical attention. Treatment is symptomatic and supportive.
Drug Interactions
Major Interactions
- QTc prolonging drugs (e.g., Class IA and III antiarrhythmics, cisapride, pimozide, terfenadine, astemizole, some antipsychotics, some fluoroquinolones)
- Nelfinavir (increases azithromycin levels)
Moderate Interactions
- Antacids (aluminum- or magnesium-containing) - decrease peak serum levels of azithromycin, but not AUC. Administer azithromycin at least 2 hours before or after antacids.
- Warfarin (monitor INR, increased anticoagulant effect reported)
- Digoxin (increased digoxin levels reported)
- Cyclosporine (monitor cyclosporine levels, increased levels reported)
- Ergot derivatives (theoretical risk of ergotism, avoid concomitant use)
- Statins (theoretical risk of rhabdomyolysis with some macrolides, though less with azithromycin)
Monitoring
Baseline Monitoring
Culture and Susceptibility Testing
Rationale: To identify the causative pathogen and confirm its susceptibility to azithromycin, especially for serious infections or when empiric therapy fails.
Timing: Prior to initiating therapy, if clinically indicated.
Electrolytes (Potassium, Magnesium)
Rationale: To identify pre-existing electrolyte imbalances that could predispose to QT prolongation.
Timing: Prior to initiation in patients at risk for arrhythmias.
ECG
Rationale: To assess baseline QT interval in patients with known cardiac conditions, risk factors for QT prolongation, or those on other QTc-prolonging medications.
Timing: Prior to initiation in high-risk patients.
Routine Monitoring
INR (International Normalized Ratio)
Frequency: Regularly, especially upon initiation or discontinuation of azithromycin
Target: Therapeutic range for warfarin
Action Threshold: Significant deviation from target INR; adjust warfarin dose as needed.
Signs/Symptoms of C. difficile-associated diarrhea (CDAD)
Frequency: Throughout therapy and for up to several months post-therapy
Target: Absence of symptoms
Action Threshold: Onset of severe, persistent diarrhea; discontinue azithromycin and initiate appropriate therapy.
Signs/Symptoms of Hepatotoxicity
Frequency: Periodically, if prolonged therapy or pre-existing hepatic impairment
Target: Absence of symptoms
Action Threshold: Onset of jaundice, dark urine, abdominal pain; discontinue azithromycin and evaluate liver function.
Symptom Monitoring
- Diarrhea (especially severe or bloody)
- Abdominal pain or cramping
- Nausea, vomiting
- Rash, itching, hives (signs of allergic reaction)
- Swelling of face, lips, tongue, or throat (angioedema)
- Difficulty breathing or swallowing
- Chest pain, palpitations, irregular heartbeat, dizziness, fainting (signs of QT prolongation/arrhythmia)
- Yellowing of skin or eyes (jaundice)
- Dark urine
- Unusual tiredness or weakness
Special Patient Groups
Pregnancy
Azithromycin is generally considered safe for use during pregnancy when clearly needed. It is classified as Pregnancy Category B (older system), meaning animal reproduction studies have not demonstrated a fetal risk, but there are no adequate and well-controlled studies in pregnant women. Clinical data suggest low risk.
Trimester-Specific Risks:
First Trimester:
Low risk, often used for chlamydial infections.
Second Trimester:
Low risk.
Third Trimester:
Low risk.
Lactation
Azithromycin is excreted in breast milk in low concentrations. It is generally considered compatible with breastfeeding, but caution is advised. Monitor the infant for potential adverse effects such as diarrhea, vomiting, or rash.
Infant Risk:
Low risk (L3 - Moderately safe).
Pediatric Use
Widely used in pediatric populations for various infections, including otitis media, pharyngitis, and community-acquired pneumonia. Dosing is weight-based. Safety and efficacy established for children 6 months and older for specific indications. Not recommended for infants younger than 6 months for certain indications.
Geriatric Use
No specific dosage adjustment is required based solely on age. However, elderly patients may be at increased risk for QT prolongation and associated arrhythmias, especially if they have pre-existing cardiac conditions or are on other QTc-prolonging medications. Monitor carefully for adverse cardiac events.
Clinical Information
Clinical Pearls
- Azithromycin has a very long tissue half-life, allowing for shorter treatment courses (e.g., 5-day Z-Pak) and once-daily dosing.
- It achieves high concentrations in tissues and phagocytes, which contributes to its efficacy against intracellular pathogens.
- Unlike erythromycin and clarithromycin, azithromycin has minimal interaction with the CYP450 system, leading to fewer drug-drug interactions.
- Despite its generally good safety profile, be mindful of the risk of QT prolongation, especially in patients with pre-existing cardiac conditions or those on other QTc-prolonging drugs.
- Always consider the risk of Clostridioides difficile-associated diarrhea (CDAD) with any antibiotic, including azithromycin, which can occur even weeks after therapy completion.
- The Z-Pak regimen (500mg Day 1, then 250mg Days 2-5) is designed to rapidly achieve therapeutic tissue levels and maintain them due to the drug's pharmacokinetic properties.
Alternative Therapies
- Other macrolides (e.g., Clarithromycin, Erythromycin)
- Doxycycline (for atypical pneumonia, chlamydia)
- Amoxicillin/Clavulanate (for respiratory tract infections)
- Levofloxacin or Moxifloxacin (for respiratory tract infections, but with higher risk of side effects)
- Cephalexin (for skin infections)
- Penicillin V (for streptococcal pharyngitis)
Cost & Coverage
Average Cost:
$15 - $50 per 6 tablets (Z-Pak)
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 discuss them with your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek emergency medical attention. When seeking help, be prepared to provide details about the medication, including the amount taken and the time it happened, to facilitate prompt and effective treatment.