Adapalene is a topical retinoid primarily used in the treatment of acne and is also used (off-label) to treat keratosis pilaris as well as other skin conditions Indications Adapalene is indicated for the topical treatment of acne vulgaris. Adapalene has been shown to enhance the efficacy of topical clindamycin. Application of adapalene gel to the skin 2-5 minutes before application of clindamycin enhances the overall efficacy of the treatment as compared to clindamycin alone Adapalene was approved in 1996 by the U.S. Food and Drug Administration for use in the treatment of acne. Pharmacology Pharmacodynamics

Adapalene in small concentrations is a moderator of cellular differentiation, keratinization, and inflammatory processes. The exact mode of action of adapalene is unknown. Pharmacokinetics

Adapalene is applied topically to the skin, and its absorption into the blood through this medium is very low. Only trace amounts of adapalene have been found in the plasma of chronically treated patients. Clindamycin phosphate topical gel, 1% is a topical antibiotic approved for the treatment of acne vulgaris. This drug belongs to the class of antibiotics known as lincosamides. By inhibiting bacteria protein synthesis at the ribosomal level (the site of protein synthesis), clindamycin is believed to kill bacteria associated with acne. The term "acne vulgaris" refers to the more common form of acne, consisting of non-inflammatory and mildly inflammatory lesions. The more severe form of acne is characterized by the presence of nodules. Nearly 17 million people in the United States have acne, making it the most common skin disease. Although acne is not a serious health threat, severe acne can lead to disfiguring, permanent scarring, which can be upsetting for people who suffer from the disorder. Clinical Results

Trial results indicated that clindamycin phosphate gel was more effective than a vehicle gel in the treatment of mild to moderate acne vulgaris. The 12-week, multicenter, randomized, vehicle-controlled trial compared clindamycin phosphate topical gel, 1% once daily to a vehicle gel administered once daily. The mean percent reduction in lesion counts at the end of treatment was 51% for clindamycin phosphate gel versus 40% for the vehicle gel for inflammatory lesions. For non-inflammatory lesions, the mean percent reduction was 25% for clindamycin phosphate gel and 12% for the vehicle gel. The total mean percent reduction in lesion counts at the end of treatment was 38% for clindamycin phosphate gel and 27% for the vehicle gel. In a contact sensitization trial, four of the 200 subjects appeared to develop suggestive evidence of allergic contact sensitization to clindamycin phosphate gel. There was no signal for contact sensitization in the clinical trials under normal use conditions.

Side Effects

Adverse reactions associated with the use of clindamycin phosphate gel include itching and peeling skin. Cases of diarrhea, bloody diarrhea, and colitis have been reported as adverse reactions in subjects treated with oral and parenteral (intravenous) formulations of clindamycin, and have been reported rarely with topical clindamycin. Abdominal pain and gastrointestinal disturbances, as well as gram-negative folliculitis (bacterial infection and inflammation of hair follicles), have also been reported in association with the use of topical formulations of clindamycin. Mechanism of Action

Although clindamycin phosphate is inactive in vitro, rapid in vitro hydrolysis converts this compound to clindamycin which has antibacterial activity. Clindamycin inhibits bacteria protein synthesis at the ribosomal level by binding to the 50S ribosomal subunit and affecting the process of peptide chain initiation