Dosing & Uses
Dosing Form & Strengths
injectable suspension
- 600,000 units/1mL syringe
- 1.2 million units/2mL syringe
Pneumonia
Indicated for moderately severe uncomplicated pneumococcal pneumonia
600,000-1,000,000 units IM qDay
Streptococcal Infections (Group A)
Indicated for moderately severe-to-severe tonsillitis, erysipelas, scarlet fever, upper respiratory tract, skin and soft tissue infections
600,000-1,000,000 units IM qDay for at least 10 days
Staphylococcal Infections
600,000-1,000,000 units IM qDay
Bacterial Endocarditis
Indicated only for treatment of extremely sensitive infections; not indicated for prophylaxis
600,000 -1,000,000 units IM qDay
Syphilis
Primary, secondary, and latent: 600,000 units IM qDay for 8 days
Late (tertiary and latent syphilis with positive spinal fluid): 600,000 units IM qDay for 10-15 days (total 6-9 million units)
Neurosyphilis: 2.4 million units IM qDay x10-14 days; administer with probenecid 500 mg PO QID (penicillin G aqueous preferred)
Anthrax
Cutaneous: 600,000-1,000,000 units IM qDay
Inhaled (post-exposure): 1.2 million units IM q12hr for up to 2 weeks, THEN switch to PO treatment (total treatment 60 days)
Diphtheria
Adjunct with antitoxin: 300,000-600,000 units IM qDay
Carrier state: 300,000 units IM qDay
Vincent’s Infection (fusospirochetosis)
600,000-1,000,000 units IM qDay
Erysipeloid
600,000-1,000,000 units IM qDay
Rat-Bite Fever
Indicated for Streptobacillus moniliformis and Spirillum minus (rat-bite fever)
600,000-1,000,000 units IM qDay
Whipple’s disease
1.2 million units IM qDay for 10-14 days; coadminister with streptomycin, THEN
Trimethoprim/sulfamethoxazole or doxycycline PO for 1 yr
Renal Impairment
CrCl 10-50 mL/min: Decrease dose by 25%
CrCl <10 mL/min: Decrease dose by 50-70%
Hemodialysis: Removed by hemodialysis; administer after dialysis
Other Indications & Uses
Indicated for susceptible microorganisms that respond to low and persistent penicillin G serum levels (if high, sustained serum levels required, use aqueous penicillin G IV/IM)
Streptococci Groups A, C, G, H, L, and M are sensitive (Group D, ie, enterococcus is resistant); aqueous penicillin G recommended for streptococcal bacteremia
Moderate/severe respiratory tracts infection caused by pneumococci (use aqueous penicillin G for acute stage of severe pneumonia, empyema, bacteremia, pericarditis, meningitis, peritonitis, or arthritis)
Moderate/severe skin infections caused by susceptible staphylococci
Susceptible fusiform bacilli and spirochetes (fusospirochetosis)
Syphilis (all stages) caused by susceptible Treponema pallidum
Yaws, Bejel, Pinta
C diphtheriae carrier stage
Anthrax
Rat-bite fever caused by Streptobacillus moniliformis and Spirillum minus
Erysipeloid caused by Erysipelothrix rhusiopathiae
Subacute bacterial endocarditis, only in extremely sensitive infections caused by susceptible Group A streptococci
Dosing Form & Strengths
injectable suspension
- 600,000 units/1mL syringe
- 1.2 million units/2mL syringe
General Dosing for Infections
Infants/children: 25,000-50,000 units/kg/day IM
Avoid use in neonates; higher risk of abscess and procaine toxicity
Pneumonia
Indicated for pneumonia caused by streptococcal Group A and staphylococcal infections
<60 pounds: 300,000 units IM qDay
60 pounds or greater: As adults; 600,000 units IM qDay
Syphilis
Congenital Syphilis: <70 pounds: 50,000 units/kg IM qDay for 10 days
Primary, secondary, and latent (aged 12 years or older): As adults; 600,000 units IM qDay for 8 days
Anthrax
Inhaled (post-exposure): 25,000 units/kg IM q12hr for up to 2 weeks; not to exceed 1.2 million units q12hr, THEN switch to PO treatment (total treatment 60 days)
Renal Impairment
Not defined in children; see adult recommendations
Other Indications & Uses
Indicated for susceptible microorganisms that respond to low and persistent penicillin G serum levels (if high, sustained serum levels required, use aqueous penicillin G IV/IM)
Streptococci Groups A, C, G, H, L, and M are sensitive (Group D, ie, enterococcus is resistant); aqueous penicillin G recommended for streptococcal bacteremia
Moderate/severe respiratory tracts infection caused by pneumococci (use aqueous penicillin G for acute stage of severe pneumonia, empyema, bacteremia, pericarditis, meningitis, peritonitis, or arthritis)
Moderate/severe skin infections caused by susceptible staphylococci
Susceptible fusiform bacilli and spirochetes (fusospirochetosis)
Syphilis (all stages) caused by susceptible Treponema pallidum
Yaws, Bejel, Pinta C diphtheriae carrier stage
Anthrax
Rat-bite fever caused by Streptobacillus moniliformis and Spirillum minus
Adverse Effects
Frequency Not Defined
Skin rashes including maculopapular eruptions and exfoliative dermatitis
Urticaria
Serum-sicknesslike reactions (eg, chills, fever, edema, arthralgia, prostration)
Jarisch-Herxheimer reaction reported when treating syphilis
Pseudomembranous colitis
Warnings
Contraindications
Hypersensitivity to drug or excipients
Cautions
For deep IM administration only; do not administer IV, SC, or IT
No longer indicated for gonorrhea; should not be used for beta-lactamase producing organisms which include most strains of Neisseria gonorrhea
Avoid use in neonates; increased risk for sterile abscess development and procaine toxicity
Severe cutaneous adverse reactions (SCAR), such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP) reported in patients taking penicillin G (the active moiety in penicillin G procaine); when SCAR suspected, discontinue therapy immediately and consider alternative treatment
Prescribing penicillin G procaine in absence of a proven or strongly suspected bacterial infection or a prophylactic indication is unlikely to provide benefit to patient and increases risk of development of drug-resistant bacteria
Penicillin should be used with caution in individuals with histories of significant allergies and/or asthma
Care should be taken to avoid intravenous or intra-arterial administration, or injection into or near major peripheral nerves or blood vessels, since such injections may produce neurovascular damage
A small percentage of patients are sensitive to procaine; if there is a history of sensitivity, make the usual test: inject intradermally 0.1 mL of a 1 to 2 percent procaine solution; development of erythema, wheal, flare, or eruption indicates procaine sensitivity; sensitivity should be treated by usual methods, including barbiturates, and the procaine penicillin preparations not used; antihistaminics appear beneficial in treatment of procaine reactions
The use of antibiotics may result in overgrowth of nonsusceptible organisms; constant observation of patient is essential; if new infections due to bacteria or fungi appear during therapy, the drug should be discontinued and appropriate measures taken
Whenever allergic reactions occur, penicillin should be withdrawn unless, in the opinion of the physician, the condition being treated is life-threatening and amenable only to penicillin therapy
Anaphylaxis
- Serious and fatal hypersensitivity (anaphylactic reactions) have been reported in patients receiving penicillin therapy; reactions are likely occur in individuals with history of sensitivity to multiple allergens
- Some individuals with hypersensitivity to penicillin have experienced severe reactions when treated with cephalosporins; carefully inquire about previous hypersensitivity reactions before initiating therapy with any penicillin, cephalosporins, or other allergens
- If allergic reaction occurs, discontinue therapy and institute appropriate therapy; serious anaphylactic reactions require immediate emergency treatment with epinephrine, oxygen, intravenous steroids, and airway management, including intubation as indicated
Methemoglobinemia
- Cases of methemoglobinemia reported in association with local anesthetic use; although all patients are at risk for methemoglobinemia, patients with glucose-6-phosphate dehydrogenase deficiency, congenital or idiopathic methemoglobinemia, cardiac or pulmonary compromise, infants under 6 months of age, and concurrent exposure to oxidizing agents or their metabolites are more susceptible to developing clinical manifestations of the condition; if local anesthetics must be used, monitor for symptoms and signs of methemoglobinemia closely
- Signs of methemoglobinemia may occur immediately or may be delayed some hours after exposure and are characterized by cyanotic skin discoloration and/or abnormal coloration of the blood; methemoglobin levels may continue to rise; therefore, immediate treatment is required to avert more serious central nervous system (CNS) and cardiovascular adverse effects, including seizures, coma, arrhythmias, and death
- Discontinue this drug and any other oxidizing agents; depending on severity of signs and symptoms, patients may respond to supportive care, eg, oxygen therapy, hydration; a more severe clinical presentation may require treatment with methylene blue, exchange transfusion, or hyperbaric oxygen
Pseudomembranous colitis
- Pseudomembranous colitis reported with nearly all antibacterial agents, including penicillin G, and may range in severity from mild to life-threatening; it is important to consider this diagnosis in patients who present with diarrhea subsequent to administration of antibacterial agents
- Treatment with antibacterial agents alters the normal flora of the colon and may permit overgrowth of clostridioides; studies indicate that a toxin produced by Clostridioides difficile is one primary cause of "antibiotic-associated colitis"
- After diagnosis of pseudomembranous colitis established, therapeutic measures should be initiated; mild cases of pseudomembranous colitis usually respond to drug discontinuation alone
- In moderate to severe cases, consideration should be given to management of fluids and electrolytes, protein supplementation and treatment with an antibacterial drug clinically effective against C. difficile colitis
Procaine reactions
- Immediate toxic reactions to procaine may occur; these reactions may be manifested by mental disturbances, including anxiety, confusion, agitation, depression, weakness, seizures, hallucinations, combativeness, and expressed "fear of impending death"
- Reactions have been reported primarily in some patients who have received large doses of penicillin G procaine (4.8 million units); reactions are transient, lasting from 15 to 30 minutes
Pregnancy & Lactation
Pregnancy
Reproduction studies performed on the mouse, rat, and rabbit have revealed no evidence of impaired fertility or harm to fetus due to penicillin G
Human experience with the penicillins during pregnancy has not shown any positive evidence of adverse effects on the fetus
There are no adequate and well-controlled studies in pregnant women showing conclusively that harmful effects of these drugs on the fetus can be excluded
Because animal reproduction studies are not always predictive of human response, this drug should be used during pregnancy only if clearly needed
Lactation
Penicillins are excreted in human milk; exercise caution when penicillins are administered to a nursing woman
Pregnancy Categories
A: Generally acceptable. Controlled studies in pregnant women show no evidence of fetal risk.
B: May be acceptable. Either animal studies show no risk but human studies not available or animal studies showed minor risks and human studies done and showed no risk. C: Use with caution if benefits outweigh risks. Animal studies show risk and human studies not available or neither animal nor human studies done. D: Use in LIFE-THREATENING emergencies when no safer drug available. Positive evidence of human fetal risk. X: Do not use in pregnancy. Risks involved outweigh potential benefits. Safer alternatives exist. NA: Information not available.Pharmacology
Half-Life: 20-30 minutes
Absorption: IM, slow absorption for up to 24 hr
Vd: 0.3-0.47 L/kg
Peak Plasma Time: 2-4 hr
Peak Plasma Concentration: 1.5 units/mL
Protein Bound: 60%
Metabolism: ~30% in liver
Excretion: urine (60-90% within 24-36 hr)
Mechanism of Action
Interferes with cell wall mucopeptide synthesis during active multiplication, resulting in bactericidal activity against susceptible microorganisms
Administration
IM Administration
Do not inject near artery or nerve (may result in permanent neurologic damage)
Neonates, infants, small children: Midlateral aspect of thigh preferable
Older children and adults: Deep IM injection in upper outer quadrant of buttock
Because of high concentration of suspended matter, needle may be blocked if injection is not made at slow, steady rate
Storage
Store refrigerated at 2-8 degrees C (36-46 degrees F)
Do not freeze
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