Pharmacotherapeutic group: Clindamycin, combinations
ATC Code: D10AF51
Clindamycin is a lincosamide antibiotic with bacteriostatic action against Gram- positive aerobes and a wide range of anaerobic bacteria. Lincosamides such as clindamycin bind to the 23S subunit of the bacterial ribosome and inhibit the early stages of protein synthesis. The action of clindamycin is predominantly bacteriostatic although high concentrations may be slowly bactericidal against sensitive strains.
Although clindamycin phosphate is inactive in-vitro, rapid in-vivo hydrolysis converts this compound to the antibacterial active clindamycin. Clindamycin activity has been demonstrated clinically in comedones from acne patients at sufficient levels to be active against most strains of Propionibacterium acnes. Clindamycin in-vitro inhibits all Propionibacterium acnes cultures tested (MIC 0.4mcg/ml). Free fatty acids on the skin surface have been decreased from approximately 14% to 2% following application of clindamycin.
Benzoyl peroxide is mildly keratolytic acting against comedones at all stages of their development. It is an oxidising agent with bactericidal activity against Propionibacterium acnes, the organism implicated in acne vulgaris. Furthermore, it is sebostatic, counteracting the excessive sebum production associated with acne.
Clindamycin + Benzoyl Peroxide Gel has a combination of mild keratolytic and antibacterial properties providing activity particularly against inflamed lesions of mild to moderate acne vulgaris.
The prevalence of acquired resistance may vary geographically and with time for selected species. Local information of resistance is desirable, particularly when treating severe infections.
The inclusion of benzoyl peroxide in clindamycin 10 mg/g + benzoyl peroxide 50 mg/g gel reduces the potential for the emergence of organisms resistant to clindamycin. This has not been studied in Clindamycin + Benzoyl Peroxide 10 mg/g + 30 mg/g Gel.
The presentation of both active ingredients in one product is more convenient and ensures patient compliance.
Clinical efficacy and safety
The safety and efficacy of a Clindamycin + Benzoyl Peroxide 10 mg/g + 30 mg/g Gel applied once daily were evaluated in a 12-week multicentre, randomised, double- blind phase III study in 1315 subjects with acne vulgaris, aged 12 to 45 years.
Clindamycin + Benzoyl Peroxide 10 mg/g + 30 mg/g Gel was compared with clindamycin 1 % in vehicle gel, benzoyl peroxide 3 % in vehicle gel, and vehicle gel alone. The primary efficacy measures for acne severity were evaluated using lesion counts and the 6-point Investigator's Static Global Assessment (ISGA) scale. The ISGA scoring scale used in the clinical trial was as follows:
| Grade/ Score | Description |
| 0 | Clear skin with no inflammatory or non-inflammatory lesions. |
| 1 | Almost clear: rare non-inflammatory lesions present, with no more than rare papules. |
| 2 | Mild severity: greater than Grade 1, some non-inflammatory lesions with no more than a few inflammatory lesions (papules/pustules only, no nodular lesions). |
| 3 | Moderate severity: greater than Grade 2, many non-inflammatory lesions and may have some inflammatory lesions, but no more than 1 small nodular lesion. |
| 4 | Severe: greater than Grade 3, up to many non-inflammatory and inflammatory lesions, but no more than a few nodular lesions. |
| 5 | Very severe: many non-inflammatory and inflammatory lesions and more than a few nodular lesions. May have cystic lesions. |
The mean age of subjects was 20.4 years old and 60 % were females and 79 % were Caucasian. At baseline, the mean number of acne lesions per subject was 72 total lesions, with 45.3 non-inflammatory lesions and 26.6 inflammatory lesions. The majority of subjects (62 %) enrolled with a baseline ISGA score of 3 (range 2 to 4). The efficacy results at week 12 are presented in the following table.
Efficacy Results at Week 12
| | Clindamycin + Benzoyl Peroxide 10 mg/g + 30 mg/g Gel (N=327) | Clindamycin 1% gel (N=328) | Benzoyl Peroxide 3% gel (N=328) | Vehicle gel (N=332) |
| Inflammatory Lesions |
| Mean absolute reduction* | 18.2 | 15.6 | 16.8 | 13.1 |
| Mean percentage reduction | 68.9 % | 58.1 % | 61.8 % | 48.8 % |
| Non-inflammatory Lesions |
| Mean absolute reduction* | 24.8 | 19.8 | 22.2 | 14.8 |
| Mean percentage reduction | 53.9 % | 43.3 % | 50.8 % | 34.0 % |
| Total Lesions |
| Mean absolute reduction* | 43.0 | 35.5 | 39.0 | 27.8 |
| Mean percentage reduction | 59.8 % | 49.2 % | 55.5 % | 40.4 % |
| Investigator's Global Assessment |
| Percentage of subjects with minimum 2-grade improvement in ISGA from baseline to week 12* | 39 % | 25 % | 30 % | 18 % |
| Percentage of subjects with ISGA of clear or almost clear skin at week 12 | 45 % | 28 % | 35 % | 24 % |
| *Primary endpoints. Statistically significant differences from Clindamycin + Benzoyl Peroxide10mg/g + 30mg/g Gel highlighted in bold. |
The Clindamycin + Benzoyl Peroxide 10 mg/g + 30 mg/g Gel was superior to clindamycin gel, benzoyl peroxide 3% gel, and vehicle gel in the proportion of subjects who had at least a 2-grade improvement in ISGA. Clindamycin + Benzoyl Peroxide 10 mg/g + 30 mg/g Gel was superior to clindamycin gel and vehicle gel in the absolute reduction of inflammatory, non-inflammatory, and total lesions, and was superior to benzoyl peroxide 3 % gel in the absolute reduction of inflammatory and total lesions.
Secondary endpoints showed that the percentage reduction in all lesion counts from baseline to week 12 for Clindamycin + Benzoyl Peroxide 10 mg/g + 30 mg/g Gel was superior to clindamycin 1 % gel and vehicle gel and the percentage reduction in inflammatory lesions was superior to benzoyl peroxide 3 % gel. The percentage of subjects with ISGA score of 0 (clear) or 1 (almost clear) at week 12 was significantly greater for Clindamycin + Benzoyl Peroxide 10 mg/g + 30 mg/g Gel relative to its active constituents and the vehicle gel.
In a separate analysis of the data it was observed that a greater proportion of subjects in the Clindamycin + Benzoyl Peroxide 10 mg/g + 30 mg/g Gel group had a 2-grade improvement in ISGA from baseline to week 12 together with an ISGA score of 0 (clear) or 1 (almost clear) at week 12 compared with clindamycin gel (P<0.001), benzoyl peroxide gel (P=0.003), and vehicle gel (P<0.001).
Other Endpoints
In an assessment of other endpoints, improvement versus vehicle or clindamycin gel on inflammatory and non-inflammatory lesions was apparent from week 2 of treatment (P<0.05). Lesion count continued to decrease throughout the 12 week course of the study.