Clindamycin Phosphate

Clindamycin Phosphate Topical Solution, USP 1%

For External Use

Clindamycin Phosphate Topical Solution contains clindamycin phosphate, USP, at a concentration equivalent to 10 mg clindamycin per milliliter.

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. The solution contains isopropyl alcohol 50% v/v, propylene glycol, sodium hydroxide, and water. The structural formula is represented below:

The structural formula represented below is Clindamycin phosphate is a water-soluble ester of the semi-synthetic antibiotic produced by a 7(S) - chloro-substitution of the 7(R)-...

The chemical name for clindamycin phosphate is Methyl-7-chloro-6,7,8-trideoxy-6-(1-methyl- trans-4- propyl-L-2-pyrrolidinecarboxamido)-1-thio-L- threo-α-D- galacto-octopyranoside 2-(dihydrogen phosphate).

Mechanism of Action

The mechanism of action of clindamycin in treating acne vulgaris is unknown.

Following multiple topical applications of clindamycin phosphate at a concentration equivalent to 10 mg clindamycin per mL in an isopropyl alcohol and water solution, very low levels of clindamycin are present in the serum (0–3 ng/mL) and less than 0.2% of the dose is recovered in urine as  clindamycin.

Although clindamycin phosphate is inactive in vitro, rapid in vivo hydrolysis converts this compound to the antibacterially active clindamycin.

Clindamycin inhibits bacterial protein synthesis by binding to the 23S RNA of the 50S subunit of the ribosome. Clindamycin is bacteriostatic.

Antimicrobial Activity

Clindamycin is active in vitro against most isolates of Propionibacterium acnes; however, the clinical significance is unknown.

Resistance

Resistance to clindamycin is most often caused by modification of specific bases of the 23S ribosomal RNA. Cross-resistance between clindamycin and lincomycin is complete. Because the binding sites for these antibacterial drugs overlap, cross-resistance is sometimes observed among lincosamides, macrolides and streptogramin B. Macrolide inducible resistance to clindamycin occurs in some isolates of macrolide-resistant bacteria.

Clindamycin Phosphate Topical Solution USP, 1% is indicated in the treatment of acne vulgaris. In view of the potential for diarrhea, bloody diarrhea and pseudomembranous colitis, the physician should consider whether other agents are more appropriate. (See CONTRAINDICATIONS,  WARNINGS and ADVERSE REACTIONS).

Clindamycin Phosphate Topical Solution USP, 1% is contraindicated in individuals with a history of hypersensitivity to preparations containing clindamycin or lincomycin, a history of regional enteritis or ulcerative colitis, or a history of antibiotic-associated colitis.

Orally and parenterally administered clindamycin has been associated with severe colitis which may result in patient death. Use of the topical formulation of clindamycin results in absorption of the antibiotic from the skin surface. Diarrhea, bloody diarrhea, and colitis (including pseudomembranous colitis) have been reported with the use of topical and systemic clindamycin.

Studies indicate a toxin(s) produced by clostridia is one primary cause of antibiotic-associated colitis. The colitis is usually characterized by severe persistent diarrhea and severe abdominal cramps and may be associated with the passage of blood and mucus. Endoscopic examination may reveal pseudomembranous colitis. Stool culture for Clostridium difficile and s tool assay for C. difficile toxin may be helpful diagnostically.

When significant diarrhea occurs, the drug should be discontinued. Large bowel endoscopy should be considered to establish a definitive diagnosis in cases of severe diarrhea.

Antiperistaltic agents such as opiates and diphenoxylate with atropine may prolong and/or worsen the condition. Vancomycin has been found to be effective in the treatment of antibiotic- associated pseudomembranous colitis produced by Clostridium difficile. The usual adult dosage is 500 milligrams to 2 grams of vancomycin orally per day in three to four divided doses administered for 7 to 10 days. Choles tyramine or coles tipol res ins bind vancomycin in vitro. If both a resin and vancomycin are to be administered concurrently, it may be advisable to separate the time of administration of each drug.

Diarrhea, colitis, and pseudomembranous colitis have been observed to begin up to several weeks following cessation of oral and parenteral therapy with clindamycin.

In 18 clinical studies of various formulations of Clindamycin Phosphate Topical Solution using placebo vehicle and/or active comparator drugs as controls, patients experienced a number of treatment emergent adverse dermatologic events [see table below].

Number of Patients Reporting Event

Orally and parenterally administered clindamycin has been associated with severe colitis which may end fatally.

Cases of diarrhea, bloody diarrhea and colitis (including pseudomembranous colitis) have been reported as adverse reactions in patients treated with oral and parenteral formulations of clindamycin and rarely with topical clindamycin (see WARNINGS).

Abdominal pain, gastrointestinal disturbances, gram-negative folliculitis, eye pain and contact dermatitis have also been reported in association with the use of topical formulations of clindamycin.

Topically applied Clindamycin Phosphate Topical Solution can be absorbed in sufficient amounts to produce systemic effects (see  WARNINGS).

Apply a thin film of Clindamycin Phosphate Topical Solution USP, 1% twice daily to affected area. Keep all liquid dosage forms in containers tightly closed.

Product: 50090-5779

NDC: 50090-5779-0 60 mL in a BOTTLE, WITH APPLICATOR / 1 in a CARTON