Benzaclin
(benzoyl peroxide / clindamycin)Benzaclin Prescribing Information
Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5% is indicated for the topical treatment of acne vulgaris.
Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5% should be applied twice daily, morning and evening, or as directed by a physician, to affected areas after the skin is gently washed, rinsed with warm water and patted dry.
Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5% is contraindicated in those individuals who have shown hypersensitivity to any of its components or to lincomycin. It is also contraindicated in those having a history of regional enteritis, ulcerative colitis, or antibiotic-associated colitis.
During clinical trials, the most frequently reported adverse event in the Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5% treatment group was dry skin (12%). The Table below lists local adverse events reported by at least 1% of patients in the Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5% and vehicle groups.
Clindamycin Phosphate | Vehicle | |
Application Site Reaction | 13 (3%) | 1 (< 1%) |
Dry Skin | 50 (12%) | 10 (6%) |
Pruritis | 8 (2%) | 1 (< 1%) |
Peeling | 9 (2%) | - |
Erythema | 6 (1%) | 1 (< 1%) |
Sunburn | 5 (1%) | - |
The actual incidence of dry skin might have been greater were it not for the use of a moisturizer in these studies.
Anaphylaxis, as well as allergic reactions leading to hospitalization, have been reported during post-marketing use of clindamycin/benzoyl peroxide products. Because these reactions are reported voluntarily from a population of uncertain size, it is not always possible to reliably estimate their frequency or establish a causal relationship to drug exposure.
Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5% contains clindamycin phosphate, (7(S)-chloro-7-deoxylincomycin-2-phosphate). Clindamycin phosphate is a water soluble ester of the semi-synthetic antibiotic produced by a 7(S)-chloro-substitution of the 7(R)-hydroxyl group of the parent antibiotic lincomycin.
Chemically, clindamycin phosphate is (C18H34ClN2O8PS). The structural formula for clindamycin is represented below:
Clindamycin phosphate has a molecular weight of 504.97 and its chemical name is Methyl 7-chloro-6,7,8-trideoxy-6-(1-methyl-trans- 4-propyl-L-2-pyrrolidinecarboxamido) - 1-thio-L- threo-alpha-D- galacto-octopyranoside 2-(dihydrogen phosphate).
Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5% also contains benzoyl peroxide, for topical use.
Chemically, benzoyl peroxide is (C14H10O4). It has the following structural formula:
Benzoyl peroxide has a molecular weight of 242.23.
Each gram of Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5% contains, as dispensed, 10 mg (1%) clindamycin as phosphate and 50 mg (5%) benzoyl peroxide in a base of carbomer, propylene glycol, potassium hydroxide, and purified water.
An in vitro percutaneous penetration study comparing Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5% and topical 1% clindamycin gel alone, demonstrated there was no statistical difference in penetration between the two drugs. Mean systemic bioavailability of topical clindamycin in Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5% is suggested to be less than 1%.
Benzoyl peroxide has been shown to be absorbed by the skin where it is converted to benzoic acid. Less than 2% of the dose enters systemic circulation as benzoic acid. It is suggested that the lipophilic nature of benzoyl peroxide acts to concentrate the compound into the lipid-rich sebaceous follicle.
Pharmacokinetics
The pharmacokinetics (plasma and urine) of clindamycin from Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5% was studied in male and female patients (n=13) with acne vulgaris. Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5% (~2g) was applied topically to the face and back twice daily for four and a half (4.5) days. Quantifiable (>LOQ=1ng/mL) clindamycin plasma concentrations were obtained in six of thirteen subjects (46.2%) on Day 1 and twelve of thirteen subjects (92.3%) on Day 5. Peak plasma concentrations (Cmax) of clindamycin ranged from 1.47 ng/mL to 2.77 ng/mL on Day 1 and 1.43 ng/mL to 7.18 ng/mL on Day 5. The AUC (0-12h) ranged from 2.74 ng.h/mL to 12.86 ng.h/mL on Day 1 and 11.4 ng.h/mL to 69.7 ng.h/mL on Day 5.
The amount of clindamycin excreted in the urine during the 12 hour dosing interval increased from a mean (SD) of 5745 (3130) ng on Day 1 to 12069 (7660) ng on Day 5. The mean % (SD) of the administered dose that was excreted in the urine ranged from 0.03% (0.02) to 0.08% (0.04).
A comparison of the single (Day 1) and multiple (Day 5) dose plasma urinary concentrations of clindamycin indicates that there is accumulation of clindamycin following multiple dosing of Clindamycin Phosphate and Benzoyl Peroxide Gel, 1%/5%. The degree of accumulation calculated from the plasma and urinary excretion data was ~2-fold.
Microbiology
The clindamycin and benzoyl peroxide components individually have been shown to have in vitro activity against Propionibacterium acnes an organism which has been associated with acne vulgaris; however, the clinical significance of this activity against P. acnes was not examined in clinical trials with this product.