Clindamycin

Question 1

MOA

Answer 1

Clindamycin inhibits protein synthesis by exclusively binding (reversibly) to the 50S ribosomal subunit.

Question 2

MOR

Answer 2

1. Alteration of the ribosomal binding site – ribosomal methylation by erm-encoded enzymes; cross-resistance with macrolides and streptogramins occur in the presence of this enzyme (MLSb resistance)

Clindamycin is NOT a substrate for macrolide efflux pumps, and strains that are resistant to macrolides by this mechanism remain susceptible to clindamycin.

Question 3

Spectrum of activity

Answer 3

Gram-Positive Aerobes – clindamycin is active against many Gram-positive aerobes

Group streptococci
Viridans streptococci
Streptococcus pneumoniae (PSSP)
Staphylococcus aureus (MSSA and CA-MRSA)

B. Anaerobes – clindamycin is active against many Gram-positive and Gram-negative anaerobes, but is most useful for anaerobes above the diaphragm

Question 4

Pharmacology

Answer 4

primarily bacteriostatic, but can display time-dependent bactericidal

Question 5

Absorption

Answer 5

rapidly and almost completely absorbed after oral administration; bioavailability approaches 90%; food has minimal effect on the absorption of clindamycin

Question 6

Distribution

Answer 6

Clindamycin penetrates into most body tissues and fluids including sputum, bile, pleural fluid and bone.

3. Clindamycin does NOT penetrate the CSF, even in the presence of inflamed meninges.

Question 7

Elimination

Answer 7

Clindamycin is primarily metabolized by the liver (85%) to metabolites with varying antimicrobial activity, which are eliminated in the urine.

Question 8

Adverse effects

Answer 8

1. GI - C. Diff n/v/d
2. Hepatotoxicity