dicloxacillin

Brand: Dynapen

Prototype: oxacillin

Drug Class: penicillinase-resistant penicillin

Drug Family: antibiotic

Subclass: oral antistaphylococcal penicillin

Organ Systems: infectious-disease

Mechanism of Action

Binds penicillin-binding proteins, inhibiting bacterial cell wall synthesis. Beta-lactamase stable due to bulky side chain.

penicillin-binding proteins (PBPs)

Absorption	oral; must be taken on empty stomach (food reduces absorption by 50%)
Distribution	highly protein-bound (~97%); poor CSF penetration
Metabolism	hepatic (partial)
Excretion	renal and biliary
Half-life	0.5–1 hour
Onset	30–60 minutes
Peak	1 hour
Duration	4–6 hours
Protein Binding	97%
Vd	low

Drug / Agent	Mechanism	Severity
warfarin	reduced vitamin K production by gut flora; enhanced anticoagulation	moderate
methotrexate	reduced renal excretion of methotrexate; toxicity risk	major

Administer on an empty stomach, 1 hour before or 2 hours after meals to maximize absorption.
Monitor for signs of hepatotoxicity: jaundice, right upper quadrant pain, dark urine, elevated LFTs.
Complete the full course to prevent resistance; instruct patient not to share medication.
Assess for penicillin or cephalosporin allergy before administration.

Dicloxacillin is the preferred oral agent for MSSA skin and soft tissue infections when parenteral therapy is not required.
Its beta-lactamase stability makes it effective against penicillinase-producing Staphylococcus aureus, unlike penicillin G or V.

Pregnancy generally-safe

Lactation use-with-caution

Renal Adjustment Not required

Hepatic Adjustment Required

TDM Not required

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