Benzamycin (Erythromycin)


Dermik Laboratories Canada

Erythromycin – Benzoyl Peroxide

Acne Therapy

Action And Clinical Pharmacology: Erythromycin is a bacteriostatic macrolide antibiotic, but may be bactericidal in high concentrations. Although the mechanism by which erythromycin acts in reducing inflammatory lesions of acne vulgaris is not fully elucidated, it is presumably due to its antibiotic action. It inhibits the growth of P. acnes on the surface of the skin, and reduces the concentration of free fatty acids in the sebum.

Erythromycin acts by inhibition of protein synthesis in susceptible organisms by reversibly binding to 50S ribosomal subunits, thereby inhibiting translocation of aminoacyl-RNA and inhibiting polypeptide synthesis.

Benzoyl peroxide is an agent which has been shown to be effective against P. 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. Benzoyl peroxide has keratolytic, desquamative and antiseborrheic effects 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. Approximately 5% of the metabolite is excreted unchanged in the urine.

Indications And Clinical Uses: For the topical treatment of moderate acne vulgaris characterized by comedones, inflammatory papules/pustules, with or without an occasional cyst or nodule (Grade II to III*). Benzamycin is not indicated for the treatment of cystic acne (Grade IV*).

[*Pillsbury DM., Heaton C. Manual of Dermatology 1980.]

Contra-Indications: In those patients with a history of hypersensitivity to erythromycin, benzoyl peroxide or any of the ingredients in the preparation (see Supplied).

Manufacturers’ Warnings In Clinical States: For external use only.

Not for ophthalmic use. Avoid contact with eyes, nose, lips, mouth and other mucous membranes. If contact occurs, rinse thoroughly with water.

Benzamycin contains drying and peeling agents that are potential irritants. Therefore, reduction in frequency of application may be necessary to avoid excessive irritation. If severe irritation develops, discontinue use and institute appropriate therapy. Concomitant topical acne therapy should be used with caution because a possible cumulative irritancy effect may occur, especially with peeling, desquamating or abrasive agents.

Precautions: General: The use of antibiotic agents may be associated with the overgrowth of nonsusceptible organisms including fungi. If this occurs, administration of Benzamycin should be discontinued, and appropriate measures taken.

Pregnancy : The safety of Benzamycin in pregnancy has not been established, nor have any animal reproduction studies been conducted with Benzamycin. It is also not known whether Benzamycin can cause fetal harm when administered to a pregnant woman or can affect reproductive capacity. Benzamycin should be given to a pregnant woman only if clearly needed.

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

Children: The safety and effectiveness of Benzamycin in children below the age of 12 years have not been established.

Drug Interactions: Antagonism has been demonstrated in vitro between erythromycin, lincomycin, chloramphenicol and clindamycin. Therefore erythromycin, lincomycin, chloramphenicol and clindamycin should not be used concomitantly with Benzamycin, although no studies have been conducted testing for antagonism of Benzamycin with these antibiotics.

Adverse Reactions: Local irritation reactions such as irritation of the skin including: peeling, itching, burning sensation, erythema, inflammation of the face, eyes and nose, irritation of the eyes, skin discoloration, oiliness, tenderness of the skin, pruritus and edema may occur while using Benzamycin.

In clinical trials conducted with Benzamycin, 5 of 155 patients experienced adverse reactions. Four of the adverse reactions were dryness, and 1 was an urticarial reaction which responded to symptomatic treatment.

Symptoms And Treatment Of Overdose: Symptoms and Treatment: Acute overdosage with the topical use of Benzamycin is unlikely. In the event of accidental ingestion, appropriate intervention should be initiated.

Dosage And Administration: Benzamycin should be applied as a thin layer to affected areas twice daily, morning and evening, or as directed by physician. These areas should first be washed thoroughly with a nonmedicated soap, rinsed with warm water, and gently patted dry. Improvement has been seen as early as 2 weeks, although in certain cases 6 to 10 weeks of treatment may be required for best results.

Compounding Directions: Benzamycin is supplied to the pharmacist in a package containing 20 g of benzoyl peroxide gel and 0.8 g of active erythromycin powder in a plastic vial. Prior to dispensing, tap the vial of erythromycin until all powder flows freely. Add 3 mL of ethyl alcohol (70%) to the vial (to the mark) and immediately shake to completely dissolve the erythromycin. Add this solution to the gel and stir until homogeneous in appearance (1 to 1 1/2 minute).

Availability And Storage: Each g of topical gel contains: erythromycin 3% (30 mg/g) and benzoyl peroxide 5% (50 mg/g). Nonmedicinal ingredients: alcohol, carboxypolymethylene, dioctyl sodium sulfosuccinate, lemon fragance oil, methyl salicylate, purified water and sodium hydroxide.

Prior to dispensing, the package containing 20 g of benzoyl peroxide and 0.8 g of active erythromycin powder in a plastic vial should be stored at room temperature (15 to 25°C). Following compounding (see Compounding Directions), Benzamycin should be stored under refrigeration (2 to 8°C). Do not freeze. A 3-month expiration date is to be placed on the label.

BENZAMYCIN® Dermik Laboratories Canada Erythromycin – Benzoyl Peroxide Acne Therapy

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