DYNAPEN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for DYNAPEN (DYNAPEN).

How it works

Dynapen (dicloxacillin) is a penicillinase-resistant penicillin that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death.

What the body does with it

Metabolism	Hepatic metabolism to active and inactive metabolites; primarily excreted via renal tubular secretion and glomerular filtration.
Excretion	Renal: 60-80% as unchanged drug via glomerular filtration and tubular secretion; biliary/fecal: <10%.
Half-life	0.5-1 hour in normal renal function; prolonged to 7-10 hours in anuria.
Protein binding	80% primarily to serum albumin.
Volume of Distribution	0.12-0.18 L/kg, indicating distribution primarily into extracellular fluid.
Bioavailability	Intramuscular: 70-80%; oral: not available.
Onset of Action	Intravenous: immediate (within minutes); intramuscular: 30-60 minutes.
Duration of Action	Intravenous: 2-4 hours; intramuscular: 4-6 hours.

Classification & Brands

Dosing & administration

250-500 mg orally every 6 hours for skin and soft tissue infections; up to 500 mg every 6 hours for respiratory tract infections.

Dosage form	FOR SUSPENSION
Renal impairment	CrCl 10-50 mL/min: administer every 8-12 hours; CrCl < 10 mL/min: administer every 12-18 hours. Hemodialysis: dose after dialysis.
Liver impairment	No dose adjustment required for mild to moderate hepatic impairment. Not studied in severe impairment; use with caution.
Pediatric use	Children >12 years: 250-500 mg orally every 6 hours; children <12 years: 12.5-25 mg/kg/day in divided doses every 6 hours.
Geriatric use	No specific adjustment for age alone. Monitor renal function; dose based on creatinine clearance.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for DYNAPEN (DYNAPEN).

Breastfeeding	Excreted into breast milk in small amounts. M/P ratio unknown. Considered compatible with breastfeeding; monitor infant for diarrhea or rash.
Teratogenic Risk	FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, but no adequate human studies. Generally considered low risk; however, use only if clearly needed. No known teratogenic effects in first, second, or third trimester.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Known hypersensitivity to penicillins or any component of the formulation.","Avoid use in patients with a history of immediate-type allergic reaction to cephalosporins."]

Clinical Precautions

Precautions

["Serious hypersensitivity reactions (anaphylaxis) can occur, especially in patients with a history of penicillin allergy.","Patients with a history of cephalosporin allergy may cross-react.","Clostridium difficile-associated diarrhea (CDAD) can occur.","Use with caution in patients with renal impairment; dose adjustment may be necessary.","Superinfection with resistant organisms may occur."]

Clinical Tips & Counseling

Drug interactions

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DYNAPEN

Clinical safety rating: caution

Comprehensive clinical and safety monograph for DYNAPEN (DYNAPEN).

How it works

Dynapen (dicloxacillin) is a penicillinase-resistant penicillin that inhibits bacterial cell wall synthesis by binding to penicillin-binding proteins (PBPs), leading to cell lysis and death.

What the body does with it

Metabolism	Hepatic metabolism to active and inactive metabolites; primarily excreted via renal tubular secretion and glomerular filtration.
Excretion	Renal: 60-80% as unchanged drug via glomerular filtration and tubular secretion; biliary/fecal: <10%.
Half-life	0.5-1 hour in normal renal function; prolonged to 7-10 hours in anuria.
Protein binding	80% primarily to serum albumin.
Volume of Distribution	0.12-0.18 L/kg, indicating distribution primarily into extracellular fluid.
Bioavailability	Intramuscular: 70-80%; oral: not available.
Onset of Action	Intravenous: immediate (within minutes); intramuscular: 30-60 minutes.
Duration of Action	Intravenous: 2-4 hours; intramuscular: 4-6 hours.

Classification & Brands

Dosing & administration

250-500 mg orally every 6 hours for skin and soft tissue infections; up to 500 mg every 6 hours for respiratory tract infections.

Dosage form	FOR SUSPENSION
Renal impairment	CrCl 10-50 mL/min: administer every 8-12 hours; CrCl < 10 mL/min: administer every 12-18 hours. Hemodialysis: dose after dialysis.
Liver impairment	No dose adjustment required for mild to moderate hepatic impairment. Not studied in severe impairment; use with caution.
Pediatric use	Children >12 years: 250-500 mg orally every 6 hours; children <12 years: 12.5-25 mg/kg/day in divided doses every 6 hours.
Geriatric use	No specific adjustment for age alone. Monitor renal function; dose based on creatinine clearance.

Use during pregnancy

1st trimester	Consult provider
2nd trimester	Consult provider
3rd trimester	Consult provider

Clinical note

Comprehensive clinical and safety monograph for DYNAPEN (DYNAPEN).

Breastfeeding	Excreted into breast milk in small amounts. M/P ratio unknown. Considered compatible with breastfeeding; monitor infant for diarrhea or rash.
Teratogenic Risk	FDA Pregnancy Category B. Animal studies have not demonstrated fetal risk, but no adequate human studies. Generally considered low risk; however, use only if clearly needed. No known teratogenic effects in first, second, or third trimester.
Fetal Monitoring

Warnings & precautions

■ FDA Black Box Warning

None.

Side Effect Profile

Serious Effects

Absolute Contraindications

["Known hypersensitivity to penicillins or any component of the formulation.","Avoid use in patients with a history of immediate-type allergic reaction to cephalosporins."]