Antibacterial antibiotics and anti-infections.
Serum level studies with a 150-mg oral dose of Dalacin in 24 normal adult volunteers showed that Dalacin was rapidly absorbed after oral administration. An average peak serum level of 2.5 mcg/mL was reached in 45 min; serum levels averaged 1.51 mcg/mL at 3 hrs and 0.7 mcg/mL at 6 hrs. Absorption of an oral dose is virtually complete (90%), and the concomitant administration of food does not appreciably modify the serum concentrations; serum levels have been uniform and predictable from person to person and dose to dose. Serum level studies following multiple doses of clindamycin HCl hydrate for up to 14 days show no evidence of accumulation or altered metabolism of drug.
Serum half-life of Dalacin is increased slightly in patients with markedly reduced renal function. Hemodialysis and peritoneal dialysis are not effective in removing Dalacin from the serum.
Concentrations of Dalacin in the serum increased linearly with increased dose. Serum levels exceed the MIC for most indicated organisms for at least 6 hrs following administration of the usual recommended doses. Dalacin is widely distributed in body fluids and tissues (including bones). The average biological half-life is 2.4 hrs. Approximately 10% of the bioactivity is excreted in the urine and 3.6% in the feces; the remainder is excreted as bio-inactive metabolites. Doses of up to 2 g of Dalacin/day for 14 days have been well tolerated by healthy volunteers, except that the incidence of gastrointestinal side effects is greater with the higher doses.
No significant levels of clindamycin are attained in the cerebrospinal fluid, even in the presence of inflamed meninges.
: Biologically inactive clindamycin phosphate is rapidly converted to active clindamycin. By the end of short-term IV infusion, peak serum levels of active clindamycin are reached. Biologically inactive clindamycin phosphate disappears rapidly from the serum, the average disappearance half-life is 6 min; however, the serum disappearance half-life of active clindamycin is about 3 hrs in adults and 2½ hrs in children. After IM injection of clindamycin phosphate, peak levels of active clindamycin are reached within 3 hrs in adults and 1 hr in children. Serum level curves may be constructed from IV peak serum levels as given in Table 1 by application of disappearance half-lives listed previously. Serum levels of clindamycin can be maintained above the in vitro
minimum inhibitory concentrations for most indicated organisms by administration of clindamycin phosphate every 8-12 hrs in adults and every 6-8 hrs in children or by continuous IV infusion. An equilibrium state is reached by the 3rd dose. No significant levels of clindamycin are attained in the cerebrospinal fluid, even in the presence of inflamed meninges. The disappearance half-life of clindamycin is increased slightly in patients with markedly reduced renal or hepatic function; dosage schedules need not be modified in the presence of mild or moderate renal or hepatic disease. Serum assays for active clindamycin require an inhibitor to prevent in vitro
hydrolysis of clindamycin phosphate. (See Table 1.)
Click on icon to see table/diagram/image
Although clindamycin phosphate is inactive in vitro
, rapid in vivo
hydrolysis converts this compound to the antibacterially active clindamycin. The Dalacin/Dalacin C spectrum of in vitro
activity includes the following gram-positive aerobic organisms: Staphylococcus aureus
and Staphylococcus epidermidis
(both penicillinase- and nonpenicillinase-producing strains), Streptococci (except S. faecalis
), Pneumococci and anaerobic organisms: Anaerobic gram-negative bacilli eg, Bacteroides
spp; anaerobic gram-positive nonspore-forming bacilli eg, Propionibacterium
spp; and anaerobic and microaerophilic gram-positive cocci eg, Peptococcus
sp and microaerophilic Streptococci; and Clostridium
sp. (Clostridium perfringens
for Dalacin C Phosphate.)
Dalacin/Dalacin C demonstrates cross-resistance with lincomycin. When tested by in vitro
methods, some staphylococcal strains originally resistant to erythromycin rapidly developed resistance to Dalacin/Dalacin C.
Dalacin/Dalacin C susceptibility discs may be used for determination of the in vitro
susceptibility of aerobic bacteria to Dalacin/Dalacin C.
Dalacin/Dalacin C susceptibility powder may be used for determination of the in vitro
susceptibility of anaerobic and aerobic bacteria to Dalacin/Dalacin C*.
*Dalacin/Dalacin C susceptibility discs 2 mcg. Dalacin/Dalacin C susceptibility powder 20 mg.
Susceptibility Testing: In vitro
(Dalacin C Phosphate), a standardized disc testing procedure* is recommended for determining susceptibility of aerobic bacteria to clindamycin. A description is contained in the Dalacin/Dalacin C susceptibility disc insert. Using this method, the laboratory can designate isolates as resistant, intermediate or susceptible. Tube or agar dilution methods may be used for both anaerobic and aerobic bacteria following the directions in the Dalacin/Dalacin C susceptibility powder insert.
At present, only dilution methods can be recommended for testing antibiotic susceptibility of obligate/fastidious anaerobes.
Additional data and simplification of techniques will be necessary before the routine employment of disc susceptibility testing of anaerobes can be recommended as a reliable means of assaying in vitro
susceptibility of these organisms.
*Bauer, A.W., Kirby, W.M.M., Sherris, J.C., Turck.M.: Antibiotic susceptibility testing by a standardized single disc method. Am.J.Clin.Path., 45: 493-496.