Although clindamycin palmitate HCl is inactive in vitro, rapid in vivo hydrolysis converts this compound to the antibacterially active clindamycin.
Clindamycin has been shown to have in vitro activity against isolates of the following organisms:
Aerobic gram positive cocci, including:
- Staphylococcus aureus (penicillinase and non-penicillinase producing strains). When tested by in vitro methods some staphylococcal strains originally resistant to erythromycin rapidly develop resistance to clindamycin.
- Staphylococcus epidermidis (penicillinase and non-penicillinase producing strains). When tested by in vitro methods some staphylococcal strains originally resistant to erythromycin rapidly develop resistance to clindamycin.
- Streptococci (except Streptococcus faecalis)
Anaerobic gram negative bacilli, including:
- Bacteroides species (including Bacteroides fragilis group and Bacteroides melaninogenicus group)
- Fusobacterium species
Anaerobic gram positive nonsporeforming bacilli, including:
- Actinomyces species
Anaerobic and microaerophilic gram positive cocci, including:
- Peptococcus species
- Peptostreptococcus species
- Microaerophilic streptococci
Clostridia: Clostridia are more resistant than most anaerobes to clindamycin.
Most Clostridium perfringens are susceptible, but other species, e.g., Clostridium sporogenes and Clostridium tertium are frequently resistant to clindamycin. Susceptibility testing should be done.
Cross resistance has been demonstrated between clindamycin and lincomycin.
Antagonism has been demonstrated between clindamycin and erythromycin.
Blood level studies comparing clindamycin palmitate HCl with clindamycin hydrochloride show that both drugs reach their peak active serum levels at the same time, indicating a rapid hydrolysis of the palmitate to the clindamycin.
Clindamycin is widely distributed in body fluids and tissues (including bones). Approximately 10% of the biological activity is excreted in the urine. The average serum half-life after doses of CLEOCIN PEDIATRIC is approximately two hours in pediatric patients.
Serum half-life of clindamycin is increased slightly in patients with markedly reduced renal function. Hemodialysis and peritoneal dialysis are not effective in removing clindamycin from the serum.
Serum level studies with clindamycin palmitate HCl in normal pediatric patients weighing 50–100 lbs given 2, 3 or 4 mg/kg every 6 hours (8, 12 or 16 mg/kg/day) demonstrated mean peak clindamycin serum levels of 1.24, 2.25 and 2.44 mcg/mL respectively, one hour after the first dose. By the fifth dose, the 6-hour serum concentration had reached equilibrium. Peak serum concentrations after this time would be about 2.46, 2.98 and 3.79 mcg/mL with doses of 8, 12 and 16 mg/kg/day, respectively.
Serum levels have been uniform and predictable from person to person and dose to dose. Multiple-dose studies in neonates and infants up to 6 months of age show that the drug does not accumulate in the serum and is excreted rapidly. Serum levels exceed the MICs for most indicated organisms for at least six hours following administration of the usually recommended doses of CLEOCIN PEDIATRIC in adults and pediatric patients.
No significant levels of clindamycin are attained in the cerebrospinal fluid, even in the presence of inflamed meninges.
Pharmacokinetic studies in elderly volunteers (61–79 years) and younger adults (18–39 years) indicate that age alone does not alter clindamycin pharmacokinetics (clearance, elimination half-life, volume of distribution, and area under the serum concentration-time curve) after IV administration of clindamycin phosphate.
After oral administration of clindamycin hydrochloride, elimination half-life is increased to approximately 4.0 hours (range 3.4 – 5.1 h) in the elderly compared to 3.2 hours (range 2.1 – 4.2 h) in younger adults; administration of clindamycin palmitate HCl resulted in a similar elimination half-life value of about 4.5 hours in elderly subjects. However, the extent of absorption is not different between age groups and no dosage alteration is necessary for the elderly with normal hepatic function and normal (age-adjusted) renal function1.
One year oral toxicity studies in Spartan Sprague-Dawley rats and beagle dogs at dose levels up to 300 mg/kg/day (approximately 1.6 and 5.4 times the highest recommended adult human oral dose based on mg/m2, respectively) have shown clindamycin to be well tolerated. No appreciable difference in pathological findings has been observed between groups of animals treated with clindamycin and comparable control groups. Rats receiving clindamycin hydrochloride at 600 mg/kg/day (approximately 3.2 times the highest recommended adult human oral dose based on mg/m2) for 6 months tolerated the drug well; however, dogs dosed at this level (approximately 10.8 times the highest recommended adult human oral dose based on mg/m2) vomited, would not eat, and lost weight.