Pharmacology: Dicloxacillin is a semisynthetic penicillinase-resistant penicillin. The drug is active against most gram-positive cocci including beta-hemolytic streptococci, pneumococci and staphylococci especially penicillinase-producing strains of Staphylococcus aureus and S. epidermidis that are resistant to other penicillins.
Dicloxacillin is resistant to inactivation by gastric secretions and is rapidly but incompletely absorbed from the GI tract. Food generally decreases the rate and extent of absorption. Dicloxacillin is distributed into bone, bile, pleural fluid, and synovial fluid. The drug can cross the placenta and is distributed into milk. Approx. 95-99% of the drug is bound to plasma proteins. The serum half-life in adults is 0.6-0.8 hour and in children 2-16 years of age is 1.9 hours. The half-life is slightly prolonged in patients with impaired renal function.
Dicloxacillin is partially metabolized to active and inactive metabolites. 31-65% of the dose is excreted in urine as unchanged drug and active metabolites within 6-8 hours, approx, 10-20% of this is the active metabolites.