Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
BIAXIN XL vs BIAXIN
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Clarithromycin is a macrolide antibiotic that inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, blocking peptide chain elongation.
Binds to the 50S ribosomal subunit, inhibiting bacterial protein synthesis by blocking peptide chain elongation.
Acute bacterial exacerbation of chronic obstructive pulmonary disease,Acute maxillary sinusitis,Community-acquired pneumonia,Pharyngitis/tonsillitis caused by Streptococcus pyogenes,Uncomplicated skin and skin structure infections,Mycobacterium avium complex infection (prevention and treatment),Helicobacter pylori infection (in combination with other drugs)
Acute bacterial exacerbation of chronic bronchitis,Acute maxillary sinusitis,Community-acquired pneumonia,Pharyngitis/tonsillitis,Uncomplicated skin and skin structure infections,Helicobacter pylori eradication (as part of triple or dual therapy),Mycobacterium avium complex prophylaxis and treatment (off-label for some indications)
500 mg orally once daily for 7 to 14 days
250-500 mg orally every 12 hours for 7-14 days; extended-release: 1000 mg orally every 24 hours for 7-14 days
Terminal elimination half-life is 5-7 hours in healthy adults; prolonged to 20-40 hours in patients with severe hepatic impairment (Child-Pugh Class C).
Terminal elimination half-life: 3-7 hours (single dose, 250-500 mg); with multiple dosing, half-life may extend to 7-10 hours due to saturable metabolism. Clinical context: Shorter half-life requires twice-daily dosing; extended half-life (via 14-hydroxy metabolite, t1/2 ~11 h) contributes to antibacterial activity.
Primarily metabolized by the cytochrome P450 system, mainly CYP3A4, to active metabolites such as 14-hydroxyclarithromycin.
Primarily metabolized by CYP3A4 isoenzyme; clarithromycin undergoes first-pass metabolism to form 14-hydroxyclarithromycin (active metabolite).
Approximately 20-30% of the dose is excreted unchanged in urine, with the remainder as metabolites (primarily via biliary/fecal elimination). Renal clearance accounts for about 12% of total clearance.
Approximately 20-30% of administered dose is excreted unchanged in urine; remainder is hepatically metabolized and excreted in bile and feces (~50% fecal elimination).
Approximately 70% bound to plasma proteins, primarily to albumin and alpha-1-acid glycoprotein.
65-75% bound, primarily to albumin and alpha-1-acid glycoprotein.
Volume of distribution is 3-4 L/kg, indicating extensive tissue penetration (e.g., lungs, sinuses, tonsils).
Vd: 2.6-3.5 L/kg. Clinical meaning: Large Vd indicates extensive tissue penetration, including lungs, tonsils, and sinuses, exceeding serum concentrations.
Oral bioavailability is approximately 50% due to first-pass metabolism; food does not significantly affect the extended-release formulation.
Oral bioavailability: 50-55% (250 mg tablet); may be increased to 60-70% when administered with food. Intravenous: 100%.
Cr Cl <30 m L/min: 500 mg orally once daily or 250 mg twice daily. Cr Cl <30 m L/min not recommended for BIAXIN XL due to decreased clearance.
Cr Cl <30 m L/min: reduce dose by 50%; Cr Cl <10 m L/min: not recommended; no adjustment for Cr Cl >30 m L/min
Child-Pugh Class C: reduce dose by 50% or consider alternative therapy. Child-Pugh Class A or B: no adjustment necessary.
Child-Pugh Class C: reduce dose by 50% or consider alternative; mild to moderate hepatic impairment: no adjustment
Not approved for use in children less than 12 years of age. For children ≥12 years: same as adult dosing.
15 mg/kg/day orally divided every 12 hours; maximum 500 mg/day for 10 days; for extended-release, not recommended for children <12 years
Increased risk of QT prolongation. Monitor renal function and consider dose adjustment based on creatinine clearance. No specific dose adjustment is recommended solely for age.
No specific dose adjustment; monitor renal function and adjust per renal guidelines; increased risk of QT prolongation
No FDA boxed warning.
None
Increased risk of cardiac arrhythmias (QT prolongation, torsades de pointes) in patients with pre-existing cardiac conditions or electrolyte abnormalities,Hepatotoxicity, including hepatic failure and jaundice,Exacerbation of myasthenia gravis symptoms,Increased risk of colchicine toxicity when used with P-glycoprotein inhibitors,Potential for drug interactions due to CYP3A4 inhibition
Increased risk of cardiac arrhythmias, including QT prolongation and torsades de pointes; avoid in patients with known QT prolongation or concurrent use with QT-prolonging drugs.,Potential for hepatotoxicity (elevated liver enzymes, hepatitis); monitor liver function.,Exacerbation of myasthenia gravis symptoms.,Clostridioides difficile-associated diarrhea (CDAD).,Drug interactions via CYP3A4 inhibition (e.g., statins, warfarin, colchicine, and other macrolides).,Pregnancy Category C; avoid use unless no alternative (clarithromycin associated with increased risk of miscarriage and fetal abnormalities in animal studies).
Hypersensitivity to clarithromycin, erythromycin, or any macrolide antibiotic,Concomitant use with ergotamine or dihydroergotamine,Concomitant use with HMG-Co A reductase inhibitors that are extensively metabolized by CYP3A4 (e.g., lovastatin, simvastatin),Concomitant use with pimozide,History of cholestatic jaundice or hepatic dysfunction associated with prior clarithromycin use,QTc prolongation or cardiac arrhythmia history (relative contraindication)
Hypersensitivity to clarithromycin, erythromycin, or any macrolide antibiotic.,Concurrent use with pimozide, ergotamine, dihydroergotamine, lovastatin, simvastatin, or colchicine in renal/hepatic impairment.,History of cholestatic jaundice/hepatic dysfunction associated with prior clarithromycin use.,QT prolongation or history of ventricular arrhythmias (including torsades de pointes).,Concurrent use with antiarrhythmics (e.g., quinidine, procainamide, amiodarone) or other QT-prolonging drugs.,Severe hepatic failure or acute porphyria.
Take with food to enhance absorption and reduce GI intolerance. Avoid grapefruit and grapefruit juice as they may alter drug metabolism. No other significant food interactions.
Grapefruit and grapefruit juice should be avoided as they inhibit CYP3A4 and may increase clarithromycin levels, raising risk of QT prolongation. High-fat meals may delay absorption but do not significantly alter total exposure. Alcohol is not specifically contraindicated but may increase gastrointestinal irritation; avoid concurrent use of statins (especially simvastatin, lovastatin) due to increased myopathy risk.
Pregnancy Category C. First trimester: Limited human data; animal studies show no teratogenicity at clinically relevant doses, but maternal toxicity at high doses produced fetal malformations. Second and third trimesters: No known fetal risks from limited human studies; however, due to rare reports of pyloric stenosis in infants exposed to macrolides late in pregnancy, consider risk-benefit. Overall, use only if clearly needed.
FDA Pregnancy Category C. Animal studies have shown fetal harm (cleft palate, skeletal abnormalities) at doses 2-5 times the human clinical dose. No adequate human studies. First trimester: Avoid unless benefit justifies risk. Second and third trimesters: Limited data; use only if clearly needed. Monitor for potential maternal hepatotoxicity.
Clarithromycin is excreted into breast milk. M/P ratio is approximately 1.0 (based on total drug). Consider the potential for infant gastrointestinal effects (diarrhea, candidiasis) and theoretical risk of antibiotic-associated colitis. Compatible with breastfeeding with monitoring for adverse effects in the infant.
Clarithromycin is excreted into human breast milk; the milk-to-plasma ratio is approximately 0.25-0.5. Infants exposed via breast milk may experience gastrointestinal disturbances or altered gut flora. Use with caution, especially in infants younger than 6 weeks of age due to risk of hypertrophic pyloric stenosis. Consider temporary discontinuation during therapy if high doses are used.
No specific dose adjustments are recommended for pregnancy; however, pharmacokinetic changes (increased volume of distribution, altered clearance) may occur, but clinical significance is not established. Use standard adult dosing with caution.
No specific pharmacokinetic studies have demonstrated a need for dose adjustment during pregnancy. However, pregnancy can increase volume of distribution and renal clearance; empirical dose monitoring is not required. Standard dosing regimens are applied unless hepatic or renal impairment is present.
BIAXIN XL (clarithromycin extended-release) is a macrolide antibiotic with a long half-life allowing once-daily dosing. It is a strong CYP3A4 inhibitor, increasing levels of many drugs including statins, warfarin, and oral contraceptives. Prolongs QT interval; avoid in patients with known QTc prolongation or concurrent use of other QT-prolonging agents. Common adverse effects include metallic taste and gastrointestinal upset. Monitor liver function in hepatic impairment.
Biaxin (clarithromycin) is a macrolide antibiotic with activity against atypical pathogens (e.g., Legionella, Mycoplasma, Chlamydia). It is a potent CYP3A4 inhibitor, increasing levels of statins, warfarin, and colchicine. Use caution in myasthenia gravis; may exacerbate weakness. QT prolongation risk: avoid use with other QT-prolonging drugs, correct electrolyte abnormalities. For H. pylori eradication, combine with amoxicillin and a PPI as first-line. Renal dose adjustment required for Cr Cl <30 m L/min.
Take with food to reduce stomach upset.,Do not crush or chew the tablet; swallow whole.,Complete the full course even if you feel better.,Avoid alcohol during treatment.,Inform your doctor about all medications, including OTC and herbal supplements, due to drug interactions.,Report symptoms of arrhythmia (dizziness, palpitations, fainting) or severe diarrhea.,May cause metallic taste; this is temporary.,Use alternate contraception if on oral contraceptives due to interaction.
Take with or without food, but taking with food may reduce stomach upset.,Complete the full course even if you feel better to prevent resistance.,Avoid grapefruit or grapefruit juice while on this medication.,Report any signs of liver problems: yellowing of skin/eyes, dark urine, severe nausea/vomiting.,May cause metallic or bitter taste in the mouth; this is usually temporary.,Tell your doctor if you have myasthenia gravis, as clarithromycin can worsen symptoms.,Avoid driving or operating heavy machinery if you experience dizziness or vision changes.,Use effective contraception if applicable; clarithromycin may reduce oral contraceptive efficacy.
No interactions on record
No interactions on record
Explore head-to-head clinical comparisons of other medications in the same therapeutic classes.
Common clinical questions about BIAXIN XL vs BIAXIN, answered by our medical review team.
BIAXIN XL is a Macrolide Antibiotic that works by Clarithromycin is a macrolide antibiotic that inhibits bacterial protein synthesis by binding to the 50S ribosomal subunit, blocking peptide chain elongation.. BIAXIN is a Macrolide Antibiotic that works by Binds to the 50S ribosomal subunit, inhibiting bacterial protein synthesis by blocking peptide chain elongation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between BIAXIN XL and BIAXIN depend on the specific clinical indication. These are both Macrolide Antibiotic agents and are not directly interchangeable by dose. A physician or clinical pharmacist should guide any therapeutic switching decisions.
The standard adult dose of BIAXIN XL is: 500 mg orally once daily for 7 to 14 days. The standard adult dose of BIAXIN is: 250-500 mg orally every 12 hours for 7-14 days; extended-release: 1000 mg orally every 24 hours for 7-14 days. Dosing should always be individualized based on indication, renal and hepatic function, age, and other patient factors.
No direct drug-drug interaction has been formally documented between BIAXIN XL and BIAXIN in current clinical databases. However, individual patient risk factors including other medications, organ function, and comorbidities should always be evaluated by a qualified healthcare provider.
The maternal-fetal safety profiles differ. BIAXIN XL is classified as Category C. Pregnancy Category C. First trimester: Limited human data; animal studies show no teratogenicity at clinically relevant doses, but maternal toxicity at high doses produced fetal ma. BIAXIN is classified as Category C. FDA Pregnancy Category C. Animal studies have shown fetal harm (cleft palate, skeletal abnormalities) at doses 2-5 times the human clinical dose. No adequate human studies. First t. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.