Medication Guide App

Penicillin Dosage

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Usual Adult Dose for Actinomycosis

Cervicofacial: Aqueous penicillin G 1 to 6 million units IV per day
Thoracic and abdominal: Aqueous penicillin G 10 to 20 million units IV per day

Duration: 4 to 6 weeks, followed by oral therapy for 6 to 12 months depending on the nature and severity of the infection

Usual Adult Dose for Inhalation Bacillus anthracis

If penicillin-susceptible: Aqueous penicillin G 4 million units IV every 4 hours plus 1 or 2 additional antibiotics with activity against the causative organism

The additional drugs may include ciprofloxacin, doxycycline, rifampin, vancomycin, chloramphenicol, imipenem, clindamycin, and macrolides.

Usual Adult Dose for Cutaneous Bacillus anthracis

If penicillin-susceptible: Aqueous penicillin G 4 million units IV every 4 to 6 hours

Usual Adult Dose for Aspiration Pneumonia

Aqueous penicillin G 2 to 3 million units IV every 4 to 6 hours plus metronidazole 500 mg IV every 8 hours for 7 to 14 days, depending on the nature and severity of the infection

Usual Adult Dose for Clostridial Infection

Wound botulism: Aqueous penicillin G 3 to 4 million units IV every 4 hours for 7 to 14 days, as an adjunct to debridement; once the patient improves, penicillin V potassium 250 to 500 mg orally every 6 hours

Usual Adult Dose for Deep Neck Infection

Penicillin G 2 to 4 million units IV or IM every 4 to 6 hours for 2 to 3 weeks, depending on the nature and severity of the infection

The addition of metronidazole to high-dose penicillin therapy is recommended by many experts to treat parapharyngeal infections because of the increasing frequency of penicillin-resistant anaerobes. Removal of abscessed material is also necessary for successful treatment.

Usual Adult Dose for Diphtheria

As an adjunct to antitoxin to prevent carrier state: Aqueous penicillin G 2 to 3 million units IV per day in divided doses every 4 to 6 hours for 10 to 12 days

Usual Adult Dose for Endocarditis

Patients with normal renal function:
Native valve infections due to highly penicillin-susceptible Streptococcus viridans and S bovis (MIC less than or equal to 0.12 mcg/mL): Aqueous penicillin G 12 to 18 million units/day IV continuously or in 4 or 6 divided doses for 4 weeks; may add gentamicin 3 mg/kg IV every 24 hours for 2 weeks

Native valve infections due to relatively resistant strains of S viridans and S bovis (MIC greater than 0.12 mcg/mL and less than 0.5 mcg/mL): Aqueous penicillin G 24 million units/day IV continuously or in 4 to 6 divided doses for 4 weeks plus gentamicin 3 mg/kg IV every 24 hours for 2 weeks

Prosthetic valve infections due to penicillin-susceptible S viridans and S bovis (less than or equal to 0.12 mcg/mL): Aqueous penicillin G 24 million units/day IV continuously or in 4 to 6 divided doses for 6 weeks with or without gentamicin 3 mg/kg IV every 24 hours for 2 weeks

Prosthetic valve infections due to relatively or fully resistant S viridans and S bovis (MIC greater than 0.12 mcg/mL): Aqueous penicillin G 24 million units/day IV continuously or in 4 to 6 divided doses for 6 weeks plus gentamicin 3 mg/kg IV every 24 hours for 6 weeks

Native valve or prosthetic valve infections due to susceptible enterococci: Aqueous penicillin G sodium 18 to 30 million units/day IV continuously or in 6 divided doses, plus gentamicin 3 mg/kg IM or IV every 24 hours or streptomycin 7.5 mg/kg IV or IM (if gentamicin resistant) every 12 hours for 4 to 6 weeks

Erysipelothrix rhusiopathiae: Aqueous penicillin G 12 to 20 million units/day IV continuously or in divided doses every 4 to 6 hours for 4 to 6 weeks

Listeria monocytogenes: Aqueous penicillin G 15 to 20 million units/day IV in divided doses every 4 to 6 hours for 4 weeks

Refer to current published guidelines for detailed recommendations.

Usual Adult Dose for Fusospirochetosis

Aqueous penicillin G 5 to 10 million units IV per day in 4 to 6 divided doses

Usual Adult Dose for Joint Infection

Aqueous penicillin G 2 to 3 million units IV every 4 hours for 2 weeks, depending on the nature and severity of the infection

Usual Adult Dose for Leptospirosis

Aqueous penicillin G 1.5 million units IV every 6 hours for 7 days

Usual Adult Dose for Lyme Disease - Arthritis

Recurrent arthritis after oral treatment: Aqueous penicillin G 3 to 4 million units IV every 4 hours (18 to 24 million units/day)
Duration: 14 to 28 days

Ceftriaxone is considered the parenteral drug of choice.

Usual Adult Dose for Lyme Disease - Carditis

Third-degree heart block: Aqueous penicillin G 3 to 4 million units IV every 4 hours (18 to 24 million units/day), with cardiac monitoring and a temporary pacemaker for complete heart block
Duration: 14 to 21 days

Ceftriaxone is considered the parenteral drug of choice.

Usual Adult Dose for Lyme Disease - Erythema Chronicum Migrans

250 to 500 mg orally every 6 hours for 14 to 21 days

Amoxicillin and doxycycline are considered the oral drugs of choice.

Usual Adult Dose for Lyme Disease - Neurologic

Meningitis, radiculopathy, or late-Lyme CNS or peripheral nerve disease: Aqueous penicillin G 3 to 4 million units IV every 4 hours (18 to 24 million units/day)
Duration: 14 to 28 days

Ceftriaxone is considered the parenteral drug of choice.

Usual Adult Dose for Meningitis

Listerial meningitis: Aqueous penicillin G 15 to 20 million units/day IV administered in equally divided doses every 4 to 6 hours for 2 weeks
Pasteurella meningitis: Aqueous penicillin G 1 million units IV every 4 to 6 hours for 2 weeks

Usual Adult Dose for Meningitis - Meningococcal

Aqueous penicillin G 6 million units IV every 4 hours or 24 million units/day continuous IV infusion for 14 days or until afebrile for 7 days

If meningococcal meningitis is suspected, immediate treatment with penicillin is required, and should be started before lumbar puncture confirmation of the diagnosis. The mortality of this disease is 50% within the first 24 hours.

Usual Adult Dose for Meningitis - Pneumococcal

Penicillin-sensitive (MIC less than 0.1 mcg/mL): Aqueous penicillin G 4 million units IV every 4 hours for 14 days

Usual Adult Dose for Otitis Media

Streptococcal: Penicillin V potassium 250 to 500 mg orally every 6 hours for 2 weeks

Usual Adult Dose for Pneumonia

Penicillin-susceptible pneumococci: Aqueous penicillin G 1 to 2 million units IV every 4 hours for 7 to 14 days, depending on the nature and severity of the infection

Mild to moderate infection: Penicillin V potassium 250 to 500 mg orally every 6 hours

Usual Adult Dose for Prevention of Perinatal Group B Streptococcal Disease

Aqueous penicillin G 5 million units IV as a loading dose, followed by 2.5 million units every 4 hours until delivery

Usual Adult Dose for Rat-bite Fever

Mild infection: Penicillin V potassium 500 mg orally every 6 hours
Moderate to severe infection: Aqueous penicillin G 3 to 5 million units IV every 6 hours (12 to 20 million units/day)

Duration: 10 to 14 days

Usual Adult Dose for Rheumatic Fever Prophylaxis

Penicillin G benzathine: 1.2 million units IM every 3 to 4 weeks
Penicillin V potassium: 250 mg orally twice daily

For high-risk patients, penicillin G benzathine given every 3 weeks may be more effective and is recommended. Oral penicillin can be used for prevention in lower risk patients whose compliance can be ensured.

Usual Adult Dose for Skin or Soft Tissue Infection

Streptococcal cellulitis: Aqueous penicillin G 1 to 2 million units IV every 6 hours for 7 to 10 days
Prevention of recurrent erysipelas (Milroy disease): Penicillin G benzathine 1.2 million units IM every 4 weeks

Usual Adult Dose for Syphilis - Early

Primary, secondary: Penicillin G benzathine 2.4 million units IM once

All patients should undergo clinical and serological testing every 6 months for 2 to 3 years.

Usual Adult Dose for Syphilis - Latent

Early latent: Penicillin G benzathine 2.4 million units IM once
Late latent or unknown duration: Penicillin G benzathine 2.4 million units IM once a week for 3 weeks (total dose 7.2 million units)

All patients should undergo clinical and serological testing every 6 months for 2 to 3 years.

Usual Adult Dose for Neurosyphilis

Aqueous penicillin G 3 to 4 million units IV every 4 hours or 18 to 24 million units per day as a continuous infusion for 10 to 14 days; may follow with penicillin G benzathine 2.4 million units IM once a week for up to 3 weeks

All patients should undergo clinical and serological testing every 6 months for 2 to 3 years.

Usual Adult Dose for Tertiary Syphilis

Penicillin G benzathine 2.4 million units IM once a week for 3 weeks

All patients should undergo clinical and serological testing every 6 months for 2 to 3 years.

Usual Adult Dose for Tonsillitis/Pharyngitis

Streptococcal pharyngitis: Penicillin V potassium 500 mg orally every 6 hours for 10 days

Usual Adult Dose for Upper Respiratory Tract Infection

Mild streptococcal infection: Penicillin V potassium 250 to 500 mg orally every 6 to 8 hours for 10 days
Pneumococcal empyema: Penicillin G 5 to 24 million units/day IV in divided doses every 4 to 6 hours

Usual Pediatric Dose for Bacterial Infection

Aqueous penicillin G:
Neonates:
0 to 4 weeks, birthweight less than 1200 g: 25,000 to 50,000 units/kg IV or IM every 12 hours
Less than 1 week, birthweight 1200 to 2000 g: 25,000 to 50,000 units/kg IV or IM every 12 hours
Less than 1 week, birthweight greater than 2000 g: 25,000 to 50,000 units/kg IV or IM every 8 hours
1 to 4 weeks, birthweight 1200 to 2000 g: 25,000 to 50,000 units/kg IV or IM every 8 hours
1 to 4 weeks, birthweight greater than 2000 g: 25,000 to 50,000 units/kg IV or IM every 6 hours

Greater than 1 month:
Mild to moderate infections: 6250 to 12,500 units/kg IV or IM every 6 hours
Severe infections: 250,000 to 400,000 units/kg per day IV or IM in 4 to 6 divided doses

Maximum dose: 24 million units

Penicillin G benzathine:
Mild to moderate infections:
1 month or older, less than 27 kg: 300,000 to 600,000 units IM once
1 month or older, 27 kg or more: 900,000 to 1,200,000 units IM once

Penicillin V potassium:
Mild to moderate infections:
Greater than 1 month to less than 12 years: 25 to 50 mg/kg per day orally in divided doses every 6 to 8 hours
Maximum dose: 3 g/day

12 years or older: 125 to 500 mg orally every 6 to 8 hours

Usual Pediatric Dose for Endocarditis

Patients with normal renal function (dosage should not exceed adult dose):
Native valve infections due to highly penicillin-susceptible Streptococcus viridans and S bovis (MIC less than or equal to 0.12 mcg/mL): Aqueous penicillin G 200,000 units/kg/day IV in 4 or 6 divided doses for 4 weeks; may add gentamicin 1 mg/kg IM or IV every 8 hours or 3 mg/kg IV every 24 hours for 2 weeks

Native valve infections due to relatively resistant strains of S viridans and S bovis (MIC greater than 0.12 mcg/mL and less than 0.5 mcg/mL): Aqueous penicillin G 300,000 units/day IV in 4 to 6 divided doses for 4 weeks plus gentamicin 1 mg/kg IM or IV every 8 hours or 3 mg/kg IV every 24 hours for 2 weeks

Prosthetic valve infections due to penicillin-susceptible S viridans and S bovis (less than or equal to 0.12 mcg/mL): Aqueous penicillin G 300,000 units/day IV in 4 to 6 divided doses for 6 weeks with or without gentamicin 1 mg/kg IM or IV every 8 hours or 3 mg/kg IV every 24 hours for 2 weeks

Prosthetic valve infections due to relatively or fully resistant S viridans and S bovis (MIC greater than 0.12 mcg/mL): Aqueous penicillin G 300,000 units/day IV in 4 to 6 divided doses for 6 weeks plus gentamicin 1 mg/kg IM or IV every 8 hours for 6 weeks

Native valve or prosthetic valve infections due to susceptible enterococci: Aqueous penicillin G 300,000 units/day IV in 4 to 6 divided doses, plus gentamicin 1 mg/kg IM or IV every 8 hours or streptomycin 10 to 15 mg/kg IV or IM (if gentamicin resistant) every 12 hours for 4 to 6 weeks

Erysipelothrix rhusiopathiae: Aqueous penicillin G 12 to 20 million units/day IV continuously or in divided doses every 4 to 6 hours for 4 to 6 weeks

Listeria monocytogenes: Aqueous penicillin G 15 to 20 million units/day IV in divided doses every 4 to 6 hours for 4 weeks

Refer to current published guidelines for detailed recommendations.

Usual Pediatric Dose for Lyme Disease - Arthritis

Recurrent arthritis after oral treatment: Aqueous penicillin G 50,000 to 100,000 units/kg IV every 4 hours
Maximum dose: 24 million units/day

Duration: 14 to 28 days

Usual Pediatric Dose for Lyme Disease - Carditis

Third-degree heart block: Aqueous penicillin G 50,000 to 100,000 units/kg IV every 4 hours, with cardiac monitoring and a temporary pacemaker for complete heart block
Maximum dose: 24 million units/day

Duration: 14 to 21 days

Usual Pediatric Dose for Lyme Disease - Neurologic

Meningitis, radiculopathy, or late-Lyme CNS or peripheral nerve disease: Aqueous penicillin G 50,000 to 100,000 units/kg IV every 4 hours
Maximum dose: 24 million units/day

Duration: 14 to 28 days

Usual Pediatric Dose for Rheumatic Fever Prophylaxis

Penicillin G benzathine 25,000 to 50,000 units/kg IM once every 3 to 4 weeks
Maximum dose: 1.2 million units/dose

Usual Pediatric Dose for Congenital Syphilis

Aqueous penicillin G:
Less than 1 month (symptomatic infants and asymptomatic infants with abnormal CSF): 50,000 units/kg IV every 12 hours during the first 7 days of life and every 8 hours thereafter for 10 days

Greater than 1 month: 50,000 units/kg IV every 4 to 6 hours for 10 days

Penicillin G benzathine:
Asymptomatic neonates weighing greater than 1200 g: 50,000 units/kg IM one time

Infants and children: 50,000 units/kg IM once a week for 3 weeks
Maximum dose: 2.4 million units/dose

Usual Pediatric Dose for Syphilis - Early

Greater than 1 month: Penicillin G benzathine 50,000 units/kg IM once
Maximum dose: 2.4 million units/dose

Usual Pediatric Dose for Syphilis - Latent

Penicillin G benzathine:
Early latent: 50,000 units/kg IM once
Late latent or unknown duration: 50,000 units/kg IM once a week for 3 weeks

Maximum dose: 2.4 million units/dose

Renal Dose Adjustments

Adults:
Aqueous penicillin G:
CrCl 10 to 30 mL/min: Administer usual dose every 6 to 8 hours.
CrCl less than 10 mL/min: Administer usual dose every 8 to 12 hours.

Penicillin V potassium: Administer usual dose every 8 hours in patients with renal failure.

Infants:
Because of incompletely developed renal function in infants, the rate of elimination will be slow. Use caution when administering penicillin to neonates and evaluate organ system function frequently.

Liver Dose Adjustments

No adjustment required in patients with only hepatic impairment; however, dose reductions are recommended in patients with hepatic and renal impairment.

Precautions

Penicillin G benzathine is for deep intramuscular injection only. Inadvertent intravenous administration of penicillin benzathine has resulted in cardiorespiratory arrest and fatalities. Injection of any penicillin into or near an artery or a nerve is contraindicated due to the risk of severe neurovascular damage (i.e., transverse myelitis with permanent paralysis, gangrene requiring amputation, and necrosis and sloughing at and around the injection site). Intravascular administration has also resulted in immediate pallor, mottling, or cyanosis of the extremity followed by bleb formation, and severe edema requiring anterior and/or exterior compartment fasciotomy in lower extremities, especially in infants and small children.

IV penicillin G is preferable to IM administration in neonates since sterile abscesses occur more frequently with this age group than older patients.

The drug should be discontinued immediately and appropriate measures taken at the first appearance of a skin rash or other signs of hypersensitivity.

Clostridium difficile associated diarrhea (CDAD) has been reported with almost all antibiotics and may potentially be life-threatening. Therefore, it is important to consider this diagnosis in patients who present with diarrhea following penicillin therapy. Mild cases generally improve with discontinuation of the drug, while severe cases may require supportive therapy and treatment with an antimicrobial agent effective against C difficile. Hypertoxin producing strains of C difficile cause increased morbidity and mortality; these infections can be resistant to antimicrobial treatment and may necessitate colectomy.

High doses of intravenous penicillin G (greater than 10 million units) should be administered slowly because electrolyte imbalances may occur due to its potassium and/or sodium content.

The 20-million unit dosage of penicillin G should only be administered by intravenous infusion.

Periodic monitoring of renal, hepatic, and hematologic function is recommended during high-dose or prolonged therapy because the risk of neutropenia and serum sickness-like reactions may be increased.

Oral penicillin should not be used for the treatment of patients with severe infections, nausea, vomiting, gastric dilatation, cardiospasm, or intestinal hypermotility.

If penicillin is used to treat gonococcal infections and syphilis is suspected, clinical and serologic testing should be performed before treatment and monthly for at least 4 months. If penicillin is used to treat syphilis, all patients should undergo clinical and serological testing every 6 months for 2 to 3 years.

In patients with streptococcal infections, clinicians should take measure to ascertain that therapy is sufficient to eradicate the organism and to prevent streptococcal sequelae.

To reduce the risk of development of drug-resistant organisms, antibiotics should only be used to treat or prevent proven or suspected infections caused by bacteria. Culture and susceptibility information should be considered when selecting treatment or, if no data are available, local epidemiology and susceptibility patterns may be considered when selecting empiric therapy. Ambulatory patients should be advised to avoid missing doses and to complete the entire course of therapy.

Dialysis

Doses should be given after dialysis sessions on dialysis days, or a supplemental dose should be given.

CAPD: 50,000 units as a loading dose, followed by 25,000 units IP per/L

Due to its potassium content, the maximum dose of penicillin G potassium recommended for patients with end-stage renal disease is 6 million units/day.

Other Comments

Parenteral formulations of penicillin contain various amounts of sodium and/or potassium. Caution is advised when using these agents in patients with highly electrolyte-sensitive conditions.

Oral penicillin should be taken on an empty stomach 1 hour before or 2 hours after meals.

Penicillin V potassium: 250 mg = 400,000 units; 500 mg = 800,000 units

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