Veterinary Drug Handbook (VDH) is the reference veterinarians turn to when they want an independent source of information on the drugs that are used in veterinary medicine today.


Chemistry - An isoxazolyl-penicillin, dicloxacillin sodium is a semisynthetic penicillinase-resistantpenicillin. It is available commercially as the monohydrate sodium salt which occurs as a white tooff-white, crystalline powder that is freely soluble in water and has a pKa of 2.7-2.8. One mg ofdicloxacillin sodium contains not less than 850 micrograms of dicloxacillin.
Dicloxacillin sodium may also be known as sodium dicloxacillin, dichlorphenylmethyl isoxazolylpenicillin sodium or methyldichlorophenyl isoxazolyl penicillin sodium.

Storage, Stability, Compatibility

Dicloxacillin sodium capsules and powder for oral suspension should be stored at temperatures less than 40°C and preferably at room temperature (15-30°C).
After reconstituting, any remaining oral suspension should be refrigerated and discard after 14days. If kept at room temperature, the oral suspension is stable for 7 days.
Pharmacology/Uses, Indications - Refer to the Cloxacillin monograph for information regardingthis drug.
Pharmacokinetics (specific) - Dicloxacillin is only available in oral dosage forms. Dicloxacillinsodium is resistant to acid inactivation in the gut, but is only partially absorbed. The bioavailabilityafter oral administration in humans has been reported to range from 35-76% and, if given with food, both the rate and extent of absorption is decreased.
The drug is distributed to the liver, kidneys, bone, bile, pleural fluid, synovial fluid and ascitic fluid.
However, one manufacturer states that levels of the drug that are achieved in ascitic fluid are notclinically therapeutic. As with the other penicillins, only minimal amounts are distributed into the
CSF. In humans, approximately 95-99% of the drug is bound to plasma proteins.
Dicloxacillin is partially metabolized to both active and inactive metabolites. These metabolites andthe parent compound are rapidly excreted in the urine via both glomerular filtration and tubularsecretion mechanisms. A small amount of the drug is also excreted in the feces via biliaryelimination. The serum half-life in humans with normal renal function ranges from about 24-48minutes. In dogs, 20-40 minutes has been reported as the elimination half-life.