Benzamycin® Pak contains erythromycin [(3R*, 4S*, 5S*, 6R*, 7R*, 9R*, 11R*, 12R*, 13S*, 14R*)-4-[(2,6- dideoxy-3-C-methyl-3-O-methyl-a- L-ribo-hexopyranosyl)-oxy]-14- ethyl-7,12,13-trihydroxy- 3,5,7,9,11,13-hexa-methyl-6-[ [3,4,6-trideoxy-3-(dimethylamino)-b-D- xylo-hexopyranosyl] oxy]oxacyclotetradecane-2,10- dione]. Erythromycin is a macrolide antibiotic produced from a strain of Saccharopolyspora erythraea (formerly Streptomyces erythreus). It is a base and readily forms salts with acids. Chemically, erythromycin is (C₃₇H₆₇NO₁₃).  It has the following structural formula:

Erythromycin has the molecular weight of 733.94. It is a white crystalline powder and has a solubility of approximately 1 mg/mL in water and is soluble in alcohol at 25°C. Benzamycin® Pak also contains benzoyl peroxide for topical use. Benzoyl peroxide is an oxidizing agent demonstrating antibacterial activity. Chemically, benzoyl peroxide is (C₁₄H₁₀O₄).  It has the following structural formula:

Benzoyl peroxide has the molecular weight of 242.23. It is a white granular powder and is sparingly soluble in water and alcohol and soluble in acetone, chloroform and ether. Each gram of product, as dispensed, contains 30 mg of erythromycin and 50 mg of benzoyl peroxide in a base of SD Alcohol 40B, purified water, hydroxypropyl cellulose, carbomer 934, sodium hydroxide, dioctyl sodium sulfosuccinate 75%. Each Benzamycin® Pak contains 0.8 grams of product.

Last updated on RxList: 6/10/2008

BENZAMYCIN Topical Gel is indicated for the topical treatment of acne vulgaris.

BENZAMYCIN Topical Gel should be applied twice daily, morning and evening, or as directed by a physician, to affected areas after the skin is thoroughly washed, rinsed with warm water and gently patted dry.

Compounding Directions

Size (Net Weight)	NDC 0066-	Benzoyl Peroxide Gel	Active Erythromycin Powder (In Plastic Vial)	Ethyl Alcohol (70%) To Be Added
23.3 grams (as dispensed)	0510-23	20 grams	0.8 grams	3 mL
46.6 grams (as dispensed)	0510-46	40 grams	1.6 grams	6 mL

Prior to dispensing, tap vial until powder flows freely. Add indicated amount of ethyl alcohol (70%) to vial (to the mark) and immediately shake to completely dissolve erythromycin. Add this solution to gel and stir until homogeneous in appearance (1 to 1½ minutes). BENZAMYCIN Topical Gel should then be stored under refrigeration. Do not freeze. Place a 3-month expiration date on the label.

NOTE: Prior to reconstitution, store at room temperature between 15° and 30°C (59° - 86°F).

After reconstitution, store under refrigeration between 2° and 8°C (36° - 46°F). Do not freeze. Keep tightly closed. Keep out of the reach of children.

Prescribing Information as of January 2003. Manufactured for Dermik Laboratories, A Division of Aventis Pharmaceuticals Inc. Berwyn, PA 19312, USA. by Aventis Pharmaceuticals Puerto Rico Inc. Manati, Puerto Rico 00674. FDA Rev date: 1/27/2003

Last updated on RxList: 6/6/2008

In controlled clinical trials, the incidence of adverse reactions associated with the use of BENZAMYCIN Topical Gel was approximately 3%. These were dryness and urticarial reaction.

The following additional local adverse reactions have been reported occasionally: irritation of the skin including peeling, itching, burning sensation, erythema, inflammation of the face, eyes and nose, and irritation of the eyes. Skin discoloration, oiliness and tenderness of the skin have also been reported.

No information provided.

Last updated on RxList: 6/6/2008

Pseudomembranous colitis has been reported with nearly all antibacterial agents, including erythromycin, and may range in severity from mild to life-threatening. Therefore, it is important to consider this diagnosis in patients who present with diarrhea subsequent to the administration of antibacterial agents.

Treatment with antibacterial agents alters the normal flora of the colon and may permit overgrowth of clostridia. Studies indicate that a toxin produced by Clostridium difficile is one primary cause of "antibiotic-associated colitis."

After the diagnosis of pseudomembranous colitis has been established, therapeutic measures should be initiated. Mild cases of pseudomembranous colitis usually respond to drug discontinuation alone. In moderate to severe cases, consideration should be given to management with fluids and electrolytes, protein supplementation and treatment with an antibacterial drug clinically effective against C. difficile colitis.

General: For topical use only; not for ophthalmic use. Concomitant topical acne therapy should be used with caution because a possible cumulative irritancy effect may occur, especially with the use of peeling, desquamating or abrasive agents. If severe irritation develops, discontinue use and institute appropriate therapy. The use of antibiotic agents may be associated with the overgrowth of nonsusceptible organisms including fungi. If this occurs, discontinue use and take appropriate measures.

Avoid contact with eyes and all mucous membranes.

Carcinogenesis, Mutagenesis And Impairment Of Fertility

Data from a study using mice known to be highly susceptible to cancer suggests that benzoyl peroxide acts as a tumor promoter. The clinical significance of this is unknown.

No animal studies have been performed to evaluate the carcinogenic and mutagenic potential or effects on fertility of topical erythromycin. However, long-term (2-year) oral studies in rats with erythromycin ethylsuccinate and erythromycin base did not provide evidence of tumorigenicity. There was no apparent effect on male or female fertility in rats fed erythromycin (base) at levels up to 0.25% of diet.

Pregnancy: Teratogenic Effects: Pregnancy CATEGORY C: Animal reproduction studies have not been conducted with BENZAMYCIN Topical Gel or benzoyl peroxide.

There was no evidence of teratogenicity or any other adverse effect on reproduction in female rats fed erythromycin base (up to 0.25% diet) prior to and during mating, during gestation and through weaning of two successive litters. There are no well-controlled trials in pregnant women with BENZAMYCIN Topical Gel. It also is not known whether BENZAMYCIN Topical Gel can cause fetal harm when administered to a pregnant woman or can affect reproductive capacity. BENZAMYCIN Topical Gel should be given to a pregnant woman only if clearly needed.

Nursing Women: It is not known whether BENZAMYCIN Topical Gel is excreted in human milk after topical application. However, erythromycin is excreted in human milk following oral and parenteral erythromycin administration. Therefore, caution should be exercised when erythromycin is administered to a nursing woman.

Pediatric Use: Safety and effectiveness of this product in pediatric patients below the age of 12 have not been established.

Last updated on RxList: 6/6/2008

No information provided.

BENZAMYCIN Topical Gel is contraindicated in those individuals who have shown hypersensitivity to any of its components.

Last updated on RxList: 6/6/2008

The exact mechanism by which erythromycin reduces lesions of acne vulgaris is not fully known; however, the effect appears to be due in part to the antibacterial activity of the drug.

Benzoyl peroxide has a keratolytic and desquamative effect which may also contribute to its efficacy. Benzoyl peroxide has been shown to be absorbed by the skin where it is converted to benzoic acid.

Microbiology

Erythromycin acts by inhibition of protein synthesis in susceptible organisms by reversibly binding to 50 S ribosomal subunits, thereby inhibiting translocation of aminoacyl transfer-RNA and inhibiting polypeptide synthesis. Antagonism has been demonstrated in vitro between erythromycin, lincomycin, chloramphenicol and clindamycin.

Benzoyl peroxide is an antibacterial agent which has been shown to be effective against Propionibacterium acnes, an anaerobe found in sebaceous follicles and comedones. The antibacterial action of benzoyl peroxide is believed to be due to the release of active oxygen.

Last updated on RxList: 6/6/2008

Patients using BENZAMYCIN Topical Gel should receive the following information and instructions:

1. This medication is to be used as directed by the physician. It is for external use only. Avoid contact with the eyes, nose, mouth, and all mucous membranes.
2. This medication should not be used for any disorder other than that for which it was prescribed.
3. Patients should not use any other topical acne preparation unless otherwise directed by physician.
4. Patients should report to their physician any signs of local adverse reactions.
5. BENZAMYCIN® Topical Gel may bleach hair or colored fabric.
6. Keep product refrigerated and discard after 3 months.

Last updated on RxList: 6/6/2008

IMPORTANT NOTE: This is a summary and does not contain all possible information about this product. For complete information about this product or your specific health needs, ask your health care professional. Always seek the advice of your health care professional if you have any questions about this product or your medical condition. This information is not intended as individual medical advice and does not substitute for the knowledge and judgment of your health care professional. This information does not contain any assurances that this product is safe, effective, or appropriate for you.

ERYTHROMYCIN/BENZOYL PEROXIDE - TOPICAL

(eh-rith-row-MY-sin/BEN-zoh-ill per-OX-ide)

COMMON BRAND NAME(S): Benzamycin

USES: This medication is used on the skin to treat moderate-to-severe acne. This medication is a combination of erythromycin (a macrolide antibiotic) and benzoyl peroxide (an antibiotic and skin-peeling agent). It works by stopping the growth of bacteria that cause the acne. It also helps new skin to form as old skin flakes off.

HOW TO USE: Review instructions on the product carton. This medication is for use only on the skin. Avoid contact with eyes, inside of the nose, mouth, and all mucous membranes. Do not mix or apply medication near an open flame.

Wash affected areas of the skin thoroughly, rinse with warm water, then gently pat dry. Apply a thin layer of this medication twice daily (in the morning and in the evening), or as directed by your doctor.

If using the individual foil pouches, the medication is stored in 2 separated compartments inside the pouch. Cut or tear the top off the pouch. Squeeze the entire contents of the pouch into the palm of your hand. There will be 2 gels, 1 clear and 1 white. Before using, mix the 2 gels together completely. Apply product immediately after mixing. Wash hands after using medication.

Your dosage and treatment plan is based on your medical condition and response to treatment.

Use this medication regularly to get the most benefit from it. To help you remember, use it at the same times each day.

Tell your doctor if your condition does not improve or if it worsens after 12 weeks.

SIDE EFFECTS: Skin irritation, dryness, peeling, itching, burning feeling, redness, puffiness, and other skin effects may occur. If any of these effects persist or worsen, tell your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Use of this medication for prolonged or repeated periods may result in a fungal infection. Contact your doctor if you notice new symptoms on affected skin areas.

A very serious allergic reaction to this drug is rare. However, seek immediate medical attention if you notice any symptoms of a serious allergic reaction, including: rash, itching, swelling, severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

Contact your doctor for medical advice about side effects. The following numbers do not provide medical advice, but in the US you may report side effects to the Food and Drug Administration (FDA) at 1-800-FDA-1088. In Canada, you may call Health Canada at 1-866-234-2345.

PRECAUTIONS: Before using erythromycin with benzoyl peroxide, tell your doctor or pharmacist if you are allergic to either of these medications; or to other macrolide antibiotics (e.g., clarithromycin); or if you have any other allergies.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: other skin conditions.

This drug may bleach hair or colored fabric (e.g., clothing, bedding, and towels). Use caution when applying near the hairline, while dressing, and while choosing towel and bed sheet colors (if leaving on the skin overnight).

This medication may make you more sensitive to the sun. Avoid prolonged sun exposure, tanning booths, and sunlamps. Use a sunscreen and wear a hat or other protective clothing when outdoors.

During pregnancy, this medication should be used only when clearly needed. Discuss the risks and benefits with your doctor.

It is not known whether this drug passes into breast milk when used on the skin. However, when taken by mouth or given as an injection, erythromycin passes into breast milk. Consult your doctor before breast-feeding.

DRUG INTERACTIONS: Your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor or pharmacist first.

Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of: medicated soaps or cosmetic products containing alcohol (e.g., aftershave lotion), other acne skin treatments (e.g., tretinoin).

This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.

OVERDOSE: This medicine may be harmful if swallowed. If swallowing or overdose is suspected, contact your poison control center or emergency room immediately. US residents can call the US National Poison Hotline at 1-800-222-1222. Canada residents can call a provincial poison control center.

NOTES: Do not share this medication with others.

MISSED DOSE: If you miss a dose, apply it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up.

STORAGE: Before mixing, store foil pouches at room temperature between 68-77 degrees F (20-25 degrees C) away from heat and open flame.

Refrigerate pre-mixed product between 36-46 degrees F (2-8 degrees C). Do not freeze. Keep the container tightly closed. Discard after 3 months.

Keep all medicines away from children and pets.

Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.

Information last revised July 2008 Copyright(c) 2008 First DataBank, Inc.