What is the bioavailability of clindamycin (antibiotic)?

From the Guidelines

Clindamycin has excellent bioavailability, with oral formulations achieving approximately 90% of the serum concentrations obtained with intravenous administration. When taken orally, clindamycin is rapidly absorbed from the gastrointestinal tract, with peak serum concentrations typically occurring within 45-60 minutes after ingestion 1. Food does not significantly impair absorption, though it may slightly delay the time to peak concentration. The standard oral dosing for adults is typically 150-450 mg every 6 hours, with total daily doses ranging from 600-1800 mg depending on the severity of infection.

Key Points

• Clindamycin distributes well into most tissues and body fluids, including bone, which makes it particularly useful for bone and joint infections.
• It penetrates well into abscesses and achieves good concentrations in the lungs, peritoneal fluid, and pleural fluid.
• The drug undergoes hepatic metabolism and is primarily excreted in bile and urine.
• Patients with severe hepatic impairment may require dosage adjustments due to prolonged half-life.
• Clindamycin's high bioavailability makes it an excellent option for step-down therapy after initial intravenous treatment for many infections, particularly those caused by anaerobes, streptococci, and susceptible staphylococci 1.

Dosage

• The recommended dosage for adults is 300-450 mg every 6 hours, with a maximum daily dose of 1800 mg.
• For children, the recommended dosage is 10-13 mg/kg/dose every 6-8 hours, not to exceed 40 mg/kg/day.

Important Considerations

• Clindamycin is effective against a wide range of bacteria, including MRSA, but its use should be guided by susceptibility testing and clinical judgment.
• The risk of Clostridium difficile-associated diarrhea should be considered when prescribing clindamycin, particularly in patients with a history of antibiotic use or underlying medical conditions.

From the FDA Drug Label

Absorption of an oral dose is virtually complete (90%), and the concomitant administration of food does not appreciably modify the serum concentrations; The bioavailability of clindamycin is approximately 90% after oral administration, as indicated by the fact that absorption of an oral dose is virtually complete.

• The presence of food does not significantly affect the bioavailability of clindamycin. 2

From the Research

Bioavailability of Clindamycin

• The bioavailability of clindamycin has been studied in several research papers, including a pharmacokinetics and bioequivalence study published in 2008 3.
• This study compared the bioavailability of clindamycin from three different formulations in healthy Chinese male volunteers and found that the two test formulations were bioequivalent to the reference formulation for clindamycin.
• The study reported maximum plasma concentrations (C(max)) of 3.06 +/- 1.10 microg/mL, 3.10 +/- 1.59 microg/mL, and 3.06 +/- 1.15 microg/mL for the test 1, test 2, and reference preparations, respectively.
• The areas under the plasma concentration-time curve (AUC(0-infinity)) were 10.73 +/- 4.29 microg x h/mL, 10.54 +/- 4.10 microg x h/mL, and 11.29 +/- 4.98 microg x h/mL for the test 1, test 2, and reference preparations, respectively.

Comparison with Other Antibiotics

• Clindamycin has been compared with other antibiotics, such as linezolid, in the treatment of severe invasive group A streptococcus skin and soft tissue infections 4, 5.
• These studies found that linezolid may be a viable option for the treatment of serious group A streptococcus infections, with no significant difference in reduction of Sequential Organ Failure Assessment (SOFA) score between patients receiving clindamycin and those receiving linezolid.
• Another study compared the activities of clindamycin, daptomycin, doxycycline, linezolid, trimethoprim-sulfamethoxazole, and vancomycin against community-associated methicillin-resistant Staphylococcus aureus with inducible clindamycin resistance 6.
• This study found that clindamycin's activity against inducible macrolide lincosamide-streptogramin type B (iMLS(B)) strains was partially impacted by inoculum size, and that daptomycin followed by vancomycin demonstrated the most significant kill against all strains.