Head-to-head clinical analysis & difference comparison: details on mechanism of action, dosing, half-life, interactions, and maternal-fetal safety.
AKNE-MYCIN vs ALTABAX
Clinician-reviewed, head-to-head comparison of mechanism, dosing, pharmacokinetics, and safety profiles.
Last clinically reviewed: July 2026 · OpiCalc Medical Review Team
Erythromycin, a macrolide antibiotic, binds to the 50S subunit of bacterial ribosomes and inhibits protein synthesis by blocking translocation of peptidyl-t RNA. Topically, it reduces Propionibacterium acnes colonization and exhibits anti-inflammatory properties.
Retapamulin is a pleuromutilin antibiotic that selectively inhibits bacterial protein synthesis by interacting with the 50S ribosomal subunit, specifically at the L3 ribosomal protein and the peptidyl transferase center, thereby preventing peptide bond formation.
Topical treatment of acne vulgaris
FDA-approved for topical treatment of impetigo due to Staphylococcus aureus and Streptococcus pyogenes in patients aged 9 months and older
Topical application of 2% solution twice daily to affected areas.
1% ointment applied topically to affected area twice daily for 5 days. Total treatment area should not exceed 100 cm². Maximum single dose is 0.5 g per 100 cm².
2-3 hours (normal renal function); up to 24-36 hours in severe renal impairment
Terminal half-life is approximately 11-14 hours in adults after topical application, supporting twice-daily dosing.
Not systemically absorbed to a clinically significant degree after topical application. If absorbed, erythromycin is primarily metabolized by hepatic cytochrome P450 enzymes, mainly CYP3A4.
Retapamulin undergoes hepatic metabolism primarily via cytochrome P450 (CYP) isoenzymes, including CYP3A4, and is excreted in feces and urine.
Primarily renal (60-80% unchanged); minor biliary/fecal (15-30%)
Retapamulin is primarily eliminated via the fecal route (96.5% of dose), with minimal renal excretion (<0.5% of dose).
Bound primarily to albumin (10-20%)
Retapamulin is approximately 94% bound to human plasma proteins, primarily albumin.
0.2-0.3 L/kg, indicating limited extravascular distribution (primarily extracellular fluid)
Volume of distribution after IV administration is approximately 3.1 L/kg, indicating extensive tissue distribution.
Topical: 2-5% (minimal systemic absorption); oral: 75-85%
Systemic bioavailability after topical application is low and highly variable, with mean values <2% in adults.
No dosage adjustment required for topical use; systemic absorption negligible.
No dose adjustment required for renal impairment as systemic absorption is negligible.
No dosage adjustment required for topical use; systemic absorption negligible.
No dose adjustment required for hepatic impairment as systemic absorption is negligible.
Safety and efficacy not established in children under 12 years; for age ≥12 years, same as adult dosing.
Children 9 months and older: Apply 1% ointment to affected area twice daily for 5 days. Maximum treatment area 100 cm². For children under 9 months: safety and efficacy not established.
No specific adjustments; use with caution due to potential increased skin sensitivity.
No specific dose adjustment required. Use same as adult dosing due to minimal systemic absorption.
None
No black box warnings.
For external use only; avoid contact with eyes, mouth, and mucous membranes. May cause skin irritation, burning, stinging, or dryness. Reported cases of pseudomembranous colitis with topical use (rare). Use with caution in patients with hepatic impairment if significant systemic absorption occurs. Cross-resistance with other macrolides may develop. Use during pregnancy only if clearly needed (category B).
Not for use on mucous membranes (e.g., eyes, mouth, vagina).,May cause application site reactions (e.g., pruritus, erythema, pain).,Clostridium difficile-associated diarrhea (CDAD) has been reported with nearly all antibacterial agents, including retapamulin.,Prolonged use may result in overgrowth of nonsusceptible organisms.
Hypersensitivity to erythromycin or any component of the formulation. Concurrent use with pimozide or ergot alkaloids (potential for QT prolongation and ergotism, though systemic absorption low).
Hypersensitivity to retapamulin or any component of the formulation.
No specific food interactions. Take with or without food. Avoid excessive intake of spicy or greasy foods, which may exacerbate acne.
None known. Topical application with negligible systemic absorption; no dietary restrictions.
Akne-Mycin (erythromycin topical) is Pregnancy Category B. No evidence of teratogenicity in animal studies; adequate human studies are lacking. Systemic absorption is minimal with topical use, but risk cannot be completely excluded. First trimester: low risk, but use only if clearly needed. Second and third trimesters: generally considered safe with minimal systemic exposure.
No adequate and well-controlled studies in pregnant women. Animal studies: oral doses up to 50 mg/kg/day in rats (0.8 times MRHD based on AUC) and 40 mg/kg/day in rabbits (1.6 times MRHD) showed no fetal harm. However, systemic absorption after topical application is minimal, so fetal exposure is negligible. Risk cannot be ruled out; classify as pregnancy category B.
Erythromycin is excreted in human milk in small amounts. Topical Akne-Mycin results in negligible systemic absorption, making significant infant exposure unlikely. M/P ratio not reported for topical use; oral erythromycin M/P ratio is approximately 0.5. Caution is advised, but use is generally compatible with breastfeeding.
Not known if retapamulin is excreted in human milk. Systemic absorption is negligible after topical use, so risk to infant is likely low. M/P ratio not determined. Caution if applied to breast area to avoid infant ingestion.
No dose adjustment necessary. Pharmacokinetic changes in pregnancy (increased volume of distribution, altered metabolism) are not clinically relevant for topical Akne-Mycin due to minimal systemic absorption. Apply as directed regardless of pregnancy trimester.
No dose adjustment needed. Pharmacokinetics unchanged as systemic absorption is minimal (<1%) and not affected by pregnancy. Standard dosing: apply thin layer to affected area twice daily for 5 days.
Akne-Mycin (erythromycin topical) is effective for mild to moderate acne vulgaris. It can be combined with benzoyl peroxide to reduce antibiotic resistance. Avoid use with other topical erythromycin products to prevent overuse. Monitor for local skin reactions like erythema, scaling, or itching.
Retapamulin (Altabax) is a topical pleuromutilin antibiotic indicated for impetigo due to S. aureus or S. pyogenes. Apply to lesions twice daily for 5 days. Avoid contact with eyes, mouth, or mucous membranes. No systemic absorption significant; safe for use in children ≥9 months. Do not use on open wounds or burns. Monitor for local irritation; discontinue if hypersensitivity occurs.
Apply a thin layer to affected areas once or twice daily as directed.,Wash skin gently with mild soap and pat dry before application.,Avoid contact with eyes, mouth, and mucous membranes.,Do not use more often than prescribed; overuse can increase irritation.,Inform your doctor if you develop severe redness, peeling, or discomfort.,Use sunscreen daily as this medication may increase sun sensitivity.
Apply a thin layer to the affected area twice daily for 5 days, even if symptoms improve.,Wash hands before and after application unless treating hand lesions.,Do not cover the area with bandages unless instructed by your doctor.,Avoid getting the ointment in your eyes, nose, mouth, or on vaginal area.,Stop use and inform your doctor if you develop severe irritation, redness, or swelling.,Store at room temperature away from heat and moisture.
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 AKNE-MYCIN vs ALTABAX, answered by our medical review team.
AKNE-MYCIN is a Topical Antibiotic that works by Erythromycin, a macrolide antibiotic, binds to the 50S subunit of bacterial ribosomes and inhibits protein synthesis by blocking translocation of peptidyl-t RNA. Topically, it reduces Propionibacterium acnes colonization and exhibits anti-inflammatory properties.. ALTABAX is a Topical Antibiotic that works by Retapamulin is a pleuromutilin antibiotic that selectively inhibits bacterial protein synthesis by interacting with the 50S ribosomal subunit, specifically at the L3 ribosomal protein and the peptidyl transferase center, thereby preventing peptide bond formation.. They differ in pharmacokinetic profiles, FDA-approved indications, and side effect profiles.
Potency comparisons between AKNE-MYCIN and ALTABAX depend on the specific clinical indication. These are both Topical 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 AKNE-MYCIN is: Topical application of 2% solution twice daily to affected areas.. The standard adult dose of ALTABAX is: 1% ointment applied topically to affected area twice daily for 5 days. Total treatment area should not exceed 100 cm². Maximum single dose is 0.5 g per 100 cm².. 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 AKNE-MYCIN and ALTABAX 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. AKNE-MYCIN is classified as Category C. Akne-Mycin (erythromycin topical) is Pregnancy Category B. No evidence of teratogenicity in animal studies; adequate human studies are lacking. Systemic absorption is minimal with . ALTABAX is classified as Category C. No adequate and well-controlled studies in pregnant women. Animal studies: oral doses up to 50 mg/kg/day in rats (0.8 times MRHD based on AUC) and 40 mg/kg/day in rabbits (1.6 time. Always consult a maternal-fetal medicine specialist before taking either drug during pregnancy or lactation.