DICLOXACILLIN SODIUM

Dicloxacillin sodium, USP is a semisynthetic antibiotic substance which resists destruction by the enzyme penicillinase (beta - lactamase). It is monosodium (2 S ,5 R ,6 R )-6-[3-(2,6-dichlorophenyl)-5-methyl-4-isoxazolecarboxamido]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo [3.2.0]heptane-2-carboxylate monohydrate. Dicloxacillin is administered orally via capsule form or powder for reconstitution. Structurally, dicloxacillin sodium, USP may be represented as follows: C 19 H 16 Cl 2 N 3 NaO 5 S·H 2 O MW 510.32 Structural formula for dicloxacillin sodium Inactive Ingredients

To reduce the development of drug-resistant bacteria and maintain the effectiveness of dicloxacillin sodium capsules and other antibacterial drugs, dicloxacillin sodium capsules should be used only to treat or prevent infections that are proven or strongly suspected to be caused by susceptible bacteria. When culture and susceptibility information are available, they should be considered in selecting or modifying antibacterial therapy. In the absence of such data, local epidemiology and susceptibility patterns may contribute to the empiric selection of therapy. Dicloxacillin is indicated in the treatment of infections caused by penicillinase-producing staphylococci which have demonstrated susceptibility to the drug. Cultures and susceptibility tests should be performed initially to determine the causative organisms and their sensitivity to the drug (see CLINICAL PHARMACOLOGY – Susceptibility Plate Testing ) . Dicloxacillin may be used to initiate therapy in suspected cases of resistant staphylococcal infections prior to the availability of laboratory test results. The penicillinase-resistant penicillins should not be used in infections caused by organisms susceptible to penicillin G. If the susceptibility tests indicate that the infection is due to an organism other than a resistant staphylococcus, therapy should not be continued with a penicillinase-resistant penicillin.

Bacteriologic studies to determine the causative organisms and their sensitivity to the penicillinase-resistant penicillins should always be performed. Duration of therapy varies with the type and severity of infection as well as the overall condition of the patient, therefore it should be determined by the clinical and bacteriological response of the patient. In severe staphylococcal infections, therapy with penicillinase-resistant penicillins should be continued for at least 14 days. Therapy should be continued for at least 48 hours after the patient has become afebrile, asymptomatic and cultures are negative. The treatment of endocarditis and osteomyelitis may require a longer term of therapy. Concurrent administration of the penicillinase-resistant penicillins and probenecid increases and prolongs serum penicillin levels. Probenecid decreases the apparent volume of distribution and slows the rate of excretion by competitively inhibiting renal tubular secretion of penicillin. Penicillin-probenecid therapy is generally limited to those infections where very high serum levels of penicillin are necessary. Oral preparations of the penicillinase-resistant penicillins should not be used as initial therapy in serious, life-threatening infections (see PRECAUTIONS - General ). Oral therapy with the penicillinase-resistant penicillins may be used to follow up the previous use of a parenteral agent as soon as the clinical condition warrants. For intramuscular gluteal injections, care should be taken to avoid sciatic nerve injury. With intravenous administration, particularly in elderly patients, care should be taken because of the possibility of thrombophlebitis. NB: INFECTIONS CAUSED BY GROUP A BETA-HEMOLYTIC STREPTOCOCCI SHOULD BE TREATED FOR AT LEAST 10 DAYS TO HELP PREVENT THE OCCURRENCE OF ACUTE RHEUMATIC FEVER OR ACUTE GLOMERULONEPHRITIS.

A history of a hypersensitivity (anaphylactic) reaction to any penicillin is a contraindication.

Body as a Whole The reported incidence of allergic reactions to penicillin ranges from 0.7% to 10% (see WARNINGS ). Sensitization is usually the result of treatment, but some individuals have had immediate reactions to penicillin when first treated. In such cases, it is thought that the patients may have had prior exposure to the drug via trace amounts present in milk and vaccines. Two types of allergic reactions to penicillin are noted clinically, immediate and delayed. Immediate reactions usually occur within 20 minutes of administration and range in severity from urticaria and pruritus to angioneurotic edema, laryngospasm, bronchospasm, hypotension, vascular collapse and death. Such immediate anaphylactic reactions are very rare (see WARNINGS ) and usually occur after parenteral therapy, but have occurred in patients receiving oral therapy. Another type of immediate reaction, an accelerated reaction, may occur between 20 minutes and 48 hours after administration and may include urticaria, pruritus and fever. Although laryngeal edema, laryngospasm and hypotension occasionally occur, fatality is uncommon. Delayed allergic reactions to penicillin therapy usually occur after 48 hours and sometimes as late as two to four weeks after initiation of therapy. Manifestations of this type of reaction include serum sickness-like symptoms (i.e., fever, malaise, urticaria, myalgia, arthralgia, abdominal pain) and various skin rashes. Nausea, vomiting, diarrhea, stomatitis, black or hairy tongue and other symptoms of gastrointestinal irritation may occur, especially during oral penicillin therapy. Nervous System Reactions Neurotoxic reactions similar to those observed with penicillin G may occur with large intravenous doses of the penicillinase-resistant penicillins, especially with patients with renal insufficiency. Urogenital Reactions Renal tubular damage and interstitial nephritis have been associated with the administration of methicillin sodium and, infrequently, with the administration of nafcillin and oxacillin. Manifestations of this reaction may include rash, fever, eosinophilia, hematuria, proteinuria and renal insufficiency. Methicillin-induced nephropathy does not appear to be dose-related and is generally reversible upon prompt discontinuation of therapy. Metabolic Reactions Agranulocytosis, neutropenia and bone marrow depression have been associated with the use of methicillin sodium and nafcillin. Hepatotoxicity, characterized by fever, nausea and vomiting associated with abnormal liver function tests, mainly elevated SGOT levels, has been associated with the use of oxacillin. RECOMMENDED DOSAGES FOR DICLOXACILLIN IN MILD TO MODERATE AND SEVERE INFECTIONS DRUG ADULTS CHILDREN Mild to Moderate Severe Mild to Moderate Severe Dicloxacillin 125 mg every 250 mg every 12.5 mg/kg/day 1 25 mg/kg/day 1 6 hours 6 hours in equally in equally divided doses divided doses every 6 hours every 6 hours 1. Patients weighing less than 40 kg (88 lbs)

Tetracycline, a bacteriostatic antibiotic, may antagonize the bactericidal effect of penicillin and concurrent use of these drugs should be avoided.