BENZACLIN
Clinical safety rating: caution
Comprehensive clinical and safety monograph for BENZACLIN (BENZACLIN).
BENZACLIN (clindamycin 1% and benzoyl peroxide 5%) is a combination antibacterial agent. Clindamycin is a lincosamide antibiotic that binds to the 50S ribosomal subunit of bacteria, inhibiting protein synthesis and reducing Propionibacterium acnes growth. Benzoyl peroxide has bactericidal and keratolytic properties; it releases free radical oxygen species that oxidize bacterial proteins, decreasing P. acnes, and also causes drying and peeling of the skin.
| Metabolism | Clindamycin is metabolized primarily by hepatic CYP3A4 to active and inactive metabolites; benzoyl peroxide is degraded to benzoic acid on the skin and excreted in urine. |
| Excretion | Benzaclin (clindamycin 1% - benzoyl peroxide 5%) is a topical formulation; systemic absorption is minimal. After topical application, less than 1% of clindamycin is absorbed. Absorbed clindamycin is primarily excreted in urine (10% as active drug, 90% as metabolites) and feces (<5%). Benzoyl peroxide is metabolized to benzoic acid, which is conjugated and excreted in urine. Overall, renal excretion accounts for the majority of clearance of absorbed components. |
| Half-life | After topical application, plasma concentrations of clindamycin are negligible; the systemic half-life of clindamycin from absorbed fraction is approximately 2.5-3 hours in adults. However, due to minimal systemic absorption, the terminal half-life is not clinically relevant for topical therapy. |
| Protein binding | If absorbed, clindamycin is 92-94% bound to plasma proteins (primarily albumin). Benzoyl peroxide is extensively metabolized and not significantly protein bound. Due to minimal systemic absorption, protein binding is not clinically relevant for topical use. |
| Volume of Distribution | For absorbed clindamycin, volume of distribution is approximately 0.6-1.2 L/kg. However, after topical application, systemic absorption is negligible (<1%), so Vd is not clinically applicable. |
| Bioavailability | Topical bioavailability of clindamycin from Benzaclin is less than 1% (0.1-0.5%) based on urinary recovery studies. Benzoyl peroxide is metabolized in the skin; systemic absorption of parent drug is negligible. |
| Onset of Action | Clinical improvement in acne lesions may be observed within 2-4 weeks of twice-daily topical application. Maximum effect typically seen after 8-12 weeks. |
| Duration of Action | The duration of action after a single topical application is not well-defined; the product is applied twice daily. Continuous therapy is required to maintain suppression of Propionibacterium acnes and reduction of inflammatory lesions. Discontinuation leads to gradual return of acne within weeks. |
Topical gel applied once or twice daily to affected areas. Each gram contains 1% clindamycin and 5% benzoyl peroxide.
| Dosage form | GEL |
| Renal impairment | No adjustment required for topical use. |
| Liver impairment | No adjustment required for topical use. |
| Pediatric use | Approved for patients ≥12 years; apply a thin layer to affected area once daily (Benzaclin) or twice daily (Benzaclin Pump). |
| Geriatric use | No specific considerations; use with caution due to potential skin sensitivity. |
| 1st trimester | Consult provider |
| 2nd trimester | Consult provider |
| 3rd trimester | Consult provider |
Clinical note
Comprehensive clinical and safety monograph for BENZACLIN (BENZACLIN).
| Breastfeeding | Benzoyl peroxide: not detected in breast milk after topical use. Clindamycin: systemically absorbed (4-5%) after topical application; M/P ratio not reported for topical form. Oral clindamycin is excreted in milk with M/P ratio 0.5-3.0. Use caution due to potential for GI effects in nursing infant. American Academy of Pediatrics considers topical clindamycin compatible with breastfeeding. |
| Teratogenic Risk | BENZACLIN contains clindamycin and benzoyl peroxide. Clindamycin is in pregnancy category C. There are no adequate and well-controlled studies in pregnant women. Benzoyl peroxide is category C based on lack of studies. First trimester: insufficient data; risk cannot be ruled out. Second and third trimesters: limited data suggest low systemic absorption of topical clindamycin; theoretical risk of C. difficile colitis in mother. Overall, topical use is unlikely to pose significant fetal risk, but avoid if not clearly needed. |
■ FDA Black Box Warning
Clindamycin, a component of BENZACLIN, can cause severe and sometimes fatal colitis, including pseudomembranous colitis. If significant diarrhea occurs, the drug should be discontinued. This warning is not specific to topical clindamycin but applies due to potential systemic absorption.
| Serious Effects |
["History of hypersensitivity to clindamycin, benzoyl peroxide, lincomycin, or any component of the formulation.","History of regional enteritis, ulcerative colitis, or antibiotic-associated colitis (clindamycin component)."]
| Precautions | ["Colitis: Clindamycin may cause pseudomembranous colitis; discontinue if diarrhea occurs.","Skin reactions: May cause severe allergic reactions including anaphylaxis; erythema, scaling, itching, burning, or stinging may occur.","Photosensitivity: Benzoyl peroxide may increase sensitivity to UV light; avoid sun exposure.","Avoid contact with eyes, mouth, lips, and mucous membranes."] |
| Food/Dietary | No clinically significant food interactions. Take on an empty stomach or with food; no restrictions. |
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| Fetal Monitoring | No specific fetal monitoring required for topical use. Monitor maternal skin for irritation or allergic reaction. If clindamycin-induced pseudomembranous colitis occurs, monitor electrolytes and hydration. |
| Fertility Effects | No known effects on fertility from topical clindamycin or benzoyl peroxide. Animal studies with oral clindamycin showed no impairment of fertility. |
| Clinical Pearls | BENZACLIN is a combination of clindamycin 1% and benzoyl peroxide 5% for topical acne treatment. Clindamycin is a lincosamide antibiotic that inhibits bacterial protein synthesis, while benzoyl peroxide has bactericidal and keratolytic effects. The combination reduces antibiotic resistance risk. Warn patients that benzoyl peroxide can bleach hair, towels, and clothing. Use pea-sized amounts for the entire face to avoid excessive dryness. Tailor frequency based on skin tolerance: start with once daily, then increase to twice daily if tolerated. |
| Patient Advice | Apply a thin layer to affected areas once or twice daily as directed. · Avoid contact with eyes, mouth, and mucous membranes. · Benzoyl peroxide may bleach hair, colored fabrics, towels, and bedding. · Use sunscreen daily as this product may increase sun sensitivity. · Inform your doctor if you have a history of colitis or regional enteritis. · Do not use with other topical acne products unless instructed by your doctor. · If severe irritation occurs, reduce frequency or discontinue and consult your doctor. |