Class: Penicillinase-resistant Penicillins
Chemical Name: [2S-(2α,5α,6β)]-6-[[[3-(2,6-Dichlorophenyl)-5-methyl-4-isoxazolyl]carbonyl]amino]-3,3-dimethyl-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid monosodium salt monohydrate
CAS Number: 13412-64-1
Medically reviewed by Drugs.com. Last updated on April 21, 2020.
Uses for Dicloxacillin
Should not be used for initial treatment of severe, life-threatening infections, including endocarditis, but may be used as follow-up after a parenteral penicillinase-resistant penicillin (nafcillin, oxacillin).1 2 5 6 8 9
If used empirically, consider whether staphylococci resistant to penicillinase-resistant penicillins (oxacillin-resistant [methicillin-resistant] staphylococci) are prevalent in the hospital or community.a (See Staphylococci Resistant to Penicillinase-resistant Penicillins under Cautions.)
Dicloxacillin Dosage and Administration
Duration of treatment depends on type and severity of infection and should be determined by the clinical and bacteriologic response of the patient.1 2 5 6 8 Usually continued for ≥48 hours after cultures are negative and patient becomes afebrile and asymptomatic.1 2 For severe staphylococcal infections, continue therapy for ≥14 days;1 2 5 6 more prolonged therapy is necessary for treatment of osteomyelitis, endocarditis, or other metastatic infections.1 2 5 6 13 54
Mild to Moderate InfectionsOral
Children ≥1 month of age: AAP recommends 25–50 mg/kg daily in 4 divided doses.9
More Severe InfectionsOral
Inappropriate for severe infections per AAP.9
Acute or Chronic OsteomyelitisOral
50–100 mg/kg daily given in divided doses every 6 hours as follow-up to initial parenteral therapy.12 13 14 16 54 If an oral regimen is used, compliance must be assured and some clinicians suggest that serum bactericidal titers (SBTs) be used to monitor adequacy of therapy and adjust dosage.13 14 15 16 17 53 54
When used as follow-up in treatment of acute osteomyelitis, oral regimen usually given for 3–6 weeks or until total duration of parenteral and oral therapy is ≥6 weeks;12 13 14 16 54 when used as follow-up in treatment of chronic osteomyelitis, oral regimen usually given for ≥1–2 months and has been given for as long as 1–2 years.13 18 54
Mild to Moderate InfectionsOral
More Severe InfectionsOral
Cautions for Dicloxacillin
Serious and occasionally fatal hypersensitivity reactions, including anaphylaxis, reported with penicillins.1 2 Anaphylaxis occurs most frequently with parenteral penicillins but has occurred with oral penicillins.1 2
Prior to initiation of therapy, make careful inquiry regarding previous hypersensitivity reactions to penicillins, cephalosporins, or other drugs.1 2 Partial cross-allergenicity occurs among penicillins and other β-lactam antibiotics including cephalosporins and cephamycins.1 2 22 23 24 25
If a severe hypersensitivity reaction occurs, discontinue immediately and institute appropriate therapy as indicated (e.g., epinephrine, corticosteroids, maintenance of an adequate airway and oxygen).1 2
Periodically assess organ system functions, including renal, hepatic, and hematopoietic, during prolonged therapy.1
Because adverse hematologic effects have occurred with penicillinase-resistant penicillins, total and differential WBC counts should be performed prior to and 1–3 times weekly during therapy.1 2 5 6 26 27
Selection and Use of Anti-infectives
To reduce development of drug-resistant bacteria and maintain effectiveness of dicloxacillin and other antibacterials, use only for treatment or prevention of infections proven or strongly suspected to be caused by susceptible bacteria.
When selecting or modifying anti-infective therapy, use results of culture and in vitro susceptibility testing.1 2 In the absence of such data, consider local epidemiology and susceptibility patterns when selecting anti-infectives for empiric therapy.1 2
Staphylococci Resistant to Penicillinase-resistant Penicillins
Consider that staphylococci resistant to penicillinase-resistant penicillins (referred to as oxacillin-resistant [methicillin-resistant] staphylococci) are being reported with increasing frequency.a
If dicloxacillin used empirically for treatment of any infection suspected of being caused by staphylococci, the drug should be discontinued and appropriate anti-infective therapy substituted if the infection is found to be caused by any organism other than penicillinase-producing staphylococci susceptible to penicillinase-resistant penicillins.1 2 If staphylococci resistant to penicillinase-resistant penicillins (oxacillin-resistant staphylococci) are prevalent in the hospital or community, empiric therapy of suspected staphylococcal infections should include another appropriate anti-infective (e.g., vancomycin).a
Each 250-mg capsule contains approximately 0.6 mEq of sodium.52
If used in neonates, monitor closely for clinical and laboratory evidence of toxic or adverse effects, determine serum concentrations frequently, and make appropriate reductions in dosage and frequency of administration when indicated.1 2 6
Common Adverse Effects
GI effects (nausea, vomiting, epigastric distress, loose stools, diarrhea, flatulence); hypersensitivity reactions.a
Interactions for Dicloxacillin
In vitro evidence of synergistic antibacterial effects against penicillinase-producing and nonpenicillinase-producing S. aureusa
Anticoagulants, oral (warfarin)
Possible decreased hypothrombinemic effecta
Monitor PTs and adjust anticoagulant dosage if indicateda
Only minimal concentrations attained in CSF.2
Plasma Protein Binding
Approximately 10% of absorbed drug is hydrolyzed to penicilloic acids which are microbiologically inactive;46 also hydroxylated to a small extent to a microbiologically active metabolite which appears to be slightly less active than dicloxacillin.47
Children 2–16 years of age: average half-life is 1.9 hours.39
Actions and Spectrum
Spectrum of activity includes many gram-positive aerobic cocci, some gram-positive bacilli, and a few gram-negative aerobic cocci; generally inactive against gram-negative bacilli and anaerobic bacteria.a Inactive against mycobacteria, Mycoplasma, Rickettsia, fungi, and viruses.a
Gram-positive aerobes: active in vitro against penicillinase-producing and nonpenicillinase-producing Staphylococcus aureus and S. epidermidis, S. pyogenes (group A β-hemolytic streptococci), S. agalactiae (group B streptococci), groups C and G streptococci, S. pneumoniae, and some viridans streptococci.a Enterococci (including E. faecalis) usually are resistant.a
Like other penicillinase-resistant penicillins, dicloxacillin is resistant to inactivation by staphylococcal penicillinases and is active against many penicillinase-producing strains of S. aureus and S. epidermidis resistant to natural penicillins, aminopenicillins, or extended-spectrum penicillins.1 2 4 6 7 30 31 32
Staphylococci resistant to penicillinase-resistant penicillins (referred to as oxacillin-resistant [methicillin-resistant] staphylococci) are being reported with increasing frequency.a Complete cross-resistance occurs among the penicillinase-resistant penicillins (dicloxacillin, nafcillin, oxacillin).a
Advice to Patients
Advise patients that antibacterials (including dicloxacillin) should only be used to treat bacterial infections and not used to treat viral infections (e.g., the common cold).
Advise patients that skipping doses or not completing the full course of therapy may decrease effectiveness and increase the likelihood that bacteria will develop resistance and will not be treatable with dicloxacillin or other antibacterials in the future.
Importance of discontinuing dicloxacillin and notifying clinician if they develop shortness of breath, wheezing, rash, mouth irritation, black tongue, sore throat, nausea, vomiting, diarrhea, fever, swollen joints, or any unusual bleeding or bruising during dicloxacillin treatment.1 2
Importance of women informing clinician if they are or plan to become pregnant or to breast-feed.1
Importance of informing patients of other important precautionary information. (See Cautions.)
Excipients in commercially available drug preparations may have clinically important effects in some individuals; consult specific product labeling for details.
Please refer to the ASHP Drug Shortages Resource Center for information on shortages of one or more of these preparations.
* available from one or more manufacturer, distributor, and/or repackager by generic (nonproprietary) name
250 mg (of dicloxacillin)*
500 mg (of dicloxacillin)*
AHFS DI Essentials™. © Copyright 2021, Selected Revisions May 1, 2004. American Society of Health-System Pharmacists, Inc., 4500 East-West Highway, Suite 900, Bethesda, Maryland 20814.
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